Lecture 9-Health and Disease

Question 1

What is a disease?

Answer 1

any disorder of any bodily or mental function

Question 2

Two categories of diseases

Answer 2

Communicable and non communicable

Question 3

Communicable diseases

Answer 3

include all diseases caused by other living organisms. These organisms may be transmitted from one person to another either directly or indirectly, causing them to spread. In our first session we will look briefly at a few examples of communicable diseases, including AIDS, in some detail.

Question 4

Non-communicable diseases

Answer 4

cannot be “caught” from the external environment. They have their origins within us. We cover diabetes, hypertension, heart disease, and cancer, at present the four most important “killers” in the Caribbean. They are of interest not only because of their heavy social cost but because they are largely preventable or controllable. Substance abuse is also included here because of its connection to AIDS, other STDs and other conditions of ill health.

Question 5

Communicable diseases A brief look at incidence in the region

Answer 5

The incidence of many communicable diseases in the region has been reduced. With few exceptions, those that have the potential to be fatal are on the wane. This can be credited to the health services of the region and a reasonable basic standard of living compared to many other developing countries. A few countries are free of malaria. Nevertheless, we remain vigilant as travel to sources of infection can cause its return. Cholera, yellow fever, and typhoid are mostly confined to specific areas.

Successful vaccination campaigns have eliminated many vaccine preventable diseases. Smallpox and poliomyelitis have been eradicated, and we are the first region in the world to have got rid of indigenous measles (CAREC, 2001). High rates of childhood vaccination, higher than in the United States, have been responsible for this. Vaccinations against diptheria, whooping cough, tetanus and polio are required for acceptance into public schools in some territories.

Dengue fever remains a problem. Outbreaks of this mosquito borne viral disease have increased in frequency and intensity over the past ten years. The mosquito that spreads the disease, the Aedes aegypti, is present throughout the region. In 1998, there was an outbreak in Jamaica, and in the following year, Trinidad and Tobago had its first major outbreak of dengue haemorrhagic fever which is potentially fatal.

Tuberculosis is also of concern. After years of decline, the incidence level began to increase in the early 1990s. Figures of 37.5, 25.4, and 22.7 per 100,000 in the population are estimated for Guyana, Bahamas, and Trinidad and Tobago, respectively. In Haiti and the Dominican Republic, the figures are much higher. Some of this increase is no doubt associated with the increasing incidence of HIV/AIDS. But in addition to this is a weakening of the infrastructure to deal with the disease. There has been a reduction of funding and trained staff because it was felt that tuberculosis was no longer a cause for concern in the English speaking region.

Question 6

Sexually transmitted diseases (STD)

Answer 6

Many of the traditional sexually transmitted diseases (STDs) have declined in recent years. These include the bacterial diseases syphilis and gonorrhoea and the viral disease Herpes
genitalis (Herpes simplex virus 2 or HSV2) which causes genital sores. However, about 10 to 15% of sexually active women have been shown to have the bacterial infection Chlamydia(CAREC, 2001). The rate of infection with these diseases is important, since their presence in individuals may make infection with the AIDS virus easier.

Question 7

Acquired Immune Deficiency Syndrome (AIDS)

Answer 7

IDS is caused by infection with the human immunodeficiency virus, HIV-1. The time between infection and the appearance of symptoms varies, and may sometimes be years.

Question 8

HIV transmission in the Caribbean

Answer 8

The predominant mode of transmission in the region is by heterosexual intercourse (60%). As a result of this, the number of women with the disease is rising and with that the possibility for infection of children before or at birth, or through breast-feeding. Infection through blood products is less than 3%, but this is not good enough. We must improve the safety of our supplies still further throughout the region. Sharing needles by substance abusers is not a common source of infection but high crack-cocaine use seems to be associated with high risk of HIV, as shown in the Bahamas, Trinidad and Tobago and Jamaica (CAREC, 1999). This association may result from impaired decision making, as in the case of alcohol and marijuana users. For example, it is highly likely that persons under the influence of a drug will have unprotected or indiscriminate sex, sometimes to support their habit.

Question 9

Populations at high risk provide a pool of infection for further transmission of the virus. In addition to substance abusers, other high risk groups include:

Answer 9

• young people (they may be unprotected by condom use, especially as sexual activity tends to begin early)
• male homosexuals
• newborns of HIV-positive mothers
• pregnant women (Cuba has no sign in this group)
• commercial sex workers
• persons with a history of STDs. (As at 2000, some 39% of AIDS cases in Jamaica had a history of other STDs

Question 10

Treating AIDS

Answer 10

In the English-speaking Caribbean, AIDS is the largest cause of death in the 15–44 year group (63% in 1996). The high rate is due to many factors, including lack of access to drugs to treat HIV, and to medicines to deal with the secondary infections, like tuberculosis. The absence of strategies to prevent mother to child transmission (vertical transmission) is another factor. Both of these are linked with the inability of governments and/or people to afford the required drugs.

A programme to help prevent vertical transmission is now in place in Jamaica where one in 100 pregnant women are HIV infected, and one child so infected is born every week. There is free voluntary testing of pregnant women. Women found positive are given two tablets of Nevirapine at the onset of labour, and the child a single dose of the drug within the first 72 hours of its life. Breast-feeding is discouraged in these mothers, since the virus may be passed on in this way, and mothers are provided with a substitute formula. The programme started in four parishes and is being extended to cover the entire island. Vertical transmission has been reduced considerably in the industrialized countries by providing drug assistance for the mothers. We can do the same.

Question 11

The social cost

Answer 11

One enormous challenge associated with the AIDS epidemic is the plight of children of parents with the disease, whether or not the parents are alive or the children are left as orphans. A second is our economic inability to treat and care for patients properly. A third is the adverse effect the epidemic is having on our economy from three angles:
* The enforced reduction of our labour force leading to decreased productivity.
* The burden it creates on our health systems: UWI/CAREC estimates are that some 3.5% of our gross national product could be spent on AIDS over the next 20 years, and we still shall not have spent enough.
* The effect it will have on our tourism and foreign investment: We are perhaps the most tourist-dependent region in the world, and tourism is very sensitive to disease.

Question 12

Preventing AIDS – what needs to be done

Answer 12

The emphasis has to be on preventing the disease. Public understanding of the disease and how it is spread is not good enough at present. As with the nutrition-related diseases, the situation calls for aggressive educational programmes. These need to be geared to reach all ages and levels, but especially the young. In the Caribbean, sexual activity sometimes starts at the ages of 10 and 11 so school populations below and above these ages need to be targeted. School dropouts and street children must also be reached.

Further research is also needed, but this is not likely to be very successful if cases are not reported. HIV/AIDS, by law, is a notifiable disease only in Jamaica, St Lucia, and Belize. Perhaps this should be standard throughout the region. Should there be mandatory testing of rapists as happens in the Bahamas and Bermuda? These are issues that must be addressed at the level of the policymakers. The presence of a CARICOM-led task force on HIV/AIDS which has developed a Caribbean Regional Strategic Plan of Action for HIV/AIDS, 1999–2004 is evidence of some recognition at the policy level of the seriousness of the situation.

As the director of the Medical Research Foundation in Trinidad is reported to have pointed out very recently, the HIV virus is the cause of AIDS, but is not the cause of the pandemic. It has spread rapidly because of certain contributing factors (Mackoon, 2001). We need to publicise and eliminate these factors if we are to succeed in stemming the spread of the disease.

Question 13

Non-communicable diseases

Answer 13

Non-communicable diseases include a wide range of disorders. They include the so called “human-induced” or self-inflicted diseases such as lung cancer and alcoholism, inherited diseases, mental illness, nutritional disorders, and metabolic disorders, some of which are also linked to nutrition. There are no rigid boundaries between the different groups. Non-communicable, nutrition-related diseases such as diabetes, heart disease, and hypertension along with cancer, now rank as the leading cause of death in the region. Between 1984 and 1691989, 24–57% of all deaths in the region were due to these diseases. Malnutrition and infectious diseases accounted for only 2% to 7% of deaths over the same period.

Question 14

Nutrition related diseases

Answer 14

Some of these nutrition-related diseases are influenced by hereditary factors. They seem to “run in families” (see Session 3.2, The Basis of Inheritance), although the disease itself is not inherited. The precise genetic linkages are not known but such families seem to be predisposed to developing the disease.
Diabetes, hypertension, and heart disease all fall into this group. What they also share in common is that they can be prevented, delayed or controlled by changes in lifestyle such as diet, exercise, and stress relief and abstention from smoking and excessive use of alcohol. It is important to note that changing lifestyle after being diagnosed with any of these diseases is not nearly as effective as taking preventive measures.

Question 15

Diabetes mellitus- pt 1

Answer 15

In diabetes mellitus, blood levels of glucose (the simple sugar that our bodies use as a source of energy) are higher than normal, because the body either does not produce, or does not use insulin efficiently. Insulin is a hormone (secretion of a gland that goes directly into the blood stream) produced by special cells in the pancreas. Insulin promotes the uptake of glucose from the blood into cells for use or storage, thereby lowering blood sugar. Blood sugar levels between 70 and 110 milligrams per decilitre are considered normal. In most persons the level rises after a meal, but goes back to normal after about two hours. This does not happen naturally in diabetics. Excess stays in the blood, unavailable to the cells that need it, and is excreted in the urine. In persons with Type I (insulin dependent diabetes mellitus (IDDM)) the insulin-producing cells in the pancreas have been destroyed. These diabetics develop the disease at an early age, usually before 30. To survive, they must take insulin injections. Not many people have this type of diabetes. Most diabetics have Type II (non-insulin dependent diabetes mellitus (NIDDM)). In these diabetics, normal levels of insulin may be secreted but the cells that should, do not respond to it. Some young people have this type of diabetes but it tends to develop in older age groups. Type II diabetes may be controlled by a diet and exercise regimen, or by using oral drugs along with this. In some cases, it may become necessary to use insulin.

Question 16

Diabetes mellitus pt 2

Answer 16

Diabetes may cause several long-term complications. Heart attacks and strokes are more common. Damage to the blood vessels of the eye can cause poor vision. Poor blood supply to, and damage to the nerves of the skin reduce sensitivity, making injuries more likely, and wounds heal slowly. More women than men have diabetes. This may be linked with the fact that more women than men are obese, obesity being an important risk factor.
-The high rates of diabetes and its complications exert a heavy toll on hospital services in the Caribbean. The estimated cost of medication, treatment in hospital for amputations of infected limbs, eye disease, and other related services for diabetics is in excess of US$30 million annually. A study recently co-ordinated by the Commonwealth Caribbean Medical Research Council (CCMRC) showed that in Trinidad’s Port-of-Spain General Hospital, diabetic patients occupied approximately 26,659 bed days per year. This cost the hospital over US$1.8 million
-. In Trinidad and Tobago, the average cost of one diabetic admission was calculated as approximately US$516. This sum would cover the cost of treating up to nine diabetics in a government primary care setting for one year. We can only imagine what it will cost 10 years from now if preventive action is not taken seriously. Many of these admissions would be avoided with better preventive management in these primary health care settings (cited in Henry et al., 1997, from Gulliford et al., 1995).

Question 17

Hypertension/blood pressure

Answer 17

is a condition in which the pressure of the blood in the arteries is persistently abnormally high. Mostly, the cause is not known, but excess fat in the diet, long-term smoking, excessive alcohol intake, and obesity seem to be among the contributory factors.

Question 18

Hypertension expanded

Answer 18

-When we check our blood pressure, we measure the pressure of the blood against the walls of a large artery. Two figures are recorded. The higher is taken when the heart contracts (systole) and the other when it relaxes between beats (diastole). For example, a reading of 120/80 (mmHg) means that the systolic pressure is 120, and the diastolic 80 mmHg. Blood pressure differs with age, activity and time of day. Normal figures for an adult range between about 120/80 mmHg and 130/85 mmHg, but the characteristic is very individual. Persistently higher readings may suggest to the doctor a need for monitoring, depending on the individual and other factors.
- A diet with severely reduced salt intake is believed to improve the condition, as does exercise and measures to relieve stress. A low-fat diet is often recommended as well. Various kinds of drugs are used to control blood pressure; some are expensive and others have unpleasant side effects in some people.
-Studies on Caribbean populations show that on average, 30% of adults have hypertension, compared to 12–15% of adults over 35 years, who have diabetes mellitus. In the Bahamas the prevalence of hypertension in males increased from 8.6% in the 20–40 year old group, to 23.1% in the 40–60 age group, and 32.7% in the 60+ age group. The trend in females was similar. So the disease, whilst most common in the elderly, is not limited to this group.

Question 19

Heart disease

Answer 19

-Hypertension and heart disease are on the increase in the Caribbean. This increase parallels, as it does in other parts of the world, an increase in the quantity of fast foods, junk foods and other lifestyle changes regarded as modern. The glamorous but stressful lifestyle of the busy executive who attends numerous cocktail parties and does not get enough sleep or exercise is a recipe for developing hypertension and heart disease. At equal risk is the underpaid night watchman who eats starchy foods with lots of greasy gravies or the stressed out, overworked, overweight housewife who snacks all day. A recent report (CAREC, 2001) puts heart disease first in a list of leading causes of death in the region (strokes, diabetes, cancer and injuries are the others in that list).
He-High levels of fat in the diet are known to contribute to heart disease. Fatty deposits in the coronary artery which supplies the heart muscle with oxygen and food, can obstruct the flow of blood to the muscle. With exertion, or when the artery becomes completely blocked, the blood supply may become insufficient, causing weakening or death of the heart muscle from lack of oxygen. This is accompanied by intense pain and the weakened heart muscle may fail to pump adequate amounts of blood either to itself or to the brain and other tissues. It may then cease to function altogether. This is what has happened when someone is said to have had a massive heart attack. When small branches of the coronary artery are blocked only a part of the heart muscle is affected and a person may experience pain for a short time and have a mild heart attack. This warning is sometimes ignored. There is little data on blood cholesterol levels in the Caribbean population.

Question 20

Heart disease conclusion

Answer 20

In order to prevent these nutrition-related chronic diseases, healthy lifestyles should be acquired early in life. As a region, this depends on education campaigns based on the most recent scientific evidence. The success of these educational efforts will depend on the entire population, that is, on each one of us.

Question 21

Cancer

Answer 21

-There are probably few people in the Caribbean who have not lost a relative or friend to cancer. Although much more is known about the disease than was known 20 years ago it is still in many ways a mystery. There are many different kinds of cancer. What they have in common is that they are all uncontrolled growths that if left untreated invade normal tissues to their detriment.
-The relationship between nutrition and cancer is a complex one. The most obvious link is perhaps the occurrence of carcinogens (cancer-promoting agents) in some foods. However, these various carcinogens may only form a small part of the link between diet and cancer. Besides, not all persons exposed to them develop cancers. Research in this area is continuing but it seems likely that dietary components such as fibre, fresh fruits and vegetables, and foods such as garlic and onions, may play a protective role against the development of some cancers. Other dietary factors seem to have a negative impact. These include high intake of fat (especially saturated fat) and cured or smoked foods such as ham, bacon, pig tails, smoked herring and so on.

Question 22

Substance abuse pt 1

Answer 22

substance abuse and its related health problems fall into the category of self-inflicted diseases. Despite this, they include effects that are caused by changes in the functioning of the nervous system making them very difficult for the affected individual to control. The social and economic effects of substance abuse go far beyond those of most other diseases, for example, an increase in crime. One of their many health-related effects is their association with the spread of HIV/AIDS and other STDs.
- Many of those admitted to our psychiatric institutions are substance abusers. In addition risk-taking behaviours, motor vehicle accidents, homicides and suicides are linked to substance abuse. The most frequently abused substances in the region, in descending order of frequency are alcohol, tobacco, marijuana, cocaine, and some psychotropic drugs. The habits begin young – at school.

Question 23

Substance abuse pt 2

Answer 23

Alcohol and tobacco are socially acceptable, and this makes the temptation to use them much harder to resist. Alcohol abuse has been associated with road fatalities, violence, family disputes, sexual abuse, and poor job performance. Long term use causes liver damage that may be eventually fatal. Smoking tobacco is associated with lung cancer, heart disease, bronchitis, and emphysema. Emphysema is caused by the gradual breakdown of the thin walls of the tiny air sacs in the lungs. Eventually this results in decreased surface for gaseous exchange. People affected with emphysema show severe breathlessness and in later stages have an uncontrollable racking cough. It has also been shown that children living in homes where parents smoke have a higher incidence of diseases such as sinusitis, tonsillitis, and other bronchial diseases
-Marijuana (ganja, “herb”) is used in most Caribbean countries and has been for a long time. Its use has been associated with deterioration in mental function and with behavioural disorders (Mahy and Barnett, 1997). Smoking ganja also affects the lungs just as smoking tobacco does. However, marijuana has been shown to be of therapeutic use in some areas. One use that is well recognized is the reduction of the pressure within the eye. The extract Canasol, developed by Caribbean researchers, Manley West and Albert Lockhart, is registered and used in the treatment of glaucoma (National Commission on Ganja, Jamaica 2001).
-Many of our young people experiment with alcohol, tobacco, and marijuana, according to surveys done among them in Jamaica, Trinidad, and Belize. According to Garfield Douglas (2001) very few people begin to use alcohol and tobacco as adults – first use has occurred usually by the end of high school. He also suggests, that cigarettes, alcohol, and marijuana are likely to act as “gateways” to using other drugs like cocaine. Clearly, prevention of the larger use of drugs should focus on the young, to delay the onset of tobacco and alcohol use.

Question 24

Small summary

Answer 24

-Non-communicable disease – breakdown in the functioning of the body, cannot be transmitted from person to person.
- Types of non-communicable diseases – human induced, mental, metabolic, nutritional, and genetic disorders.
- Leading causes of disease related deaths in the region hypertension, heart disease, diabetes, and cancer.
-Incidence of hypertension and heart disease reduced by a low fat diet, increased exercise, limiting alcohol intake and smoking, and reducing stress.
-Cost of treating results of hypertension, heart disease, and diabetes is very high. Primary preventive care costs comparatively little.
-A key factor in preventive management of nutrition-related disease is education.
-Causes of cancer still not well understood. High intake of saturated fats and cured/smoked foods suspected. Some foods may contain carcinogens, others appear to be protective.
- Throughout the region (and worldwide) increased incidence of these diseases coincides with changes in eating habits away from the traditional diets.
-Substance abuse associated with increases in HIV/AIDS and other diseases.
-Substance abuse has many social effects, including destruction of family life, crime, abuse, and poor job performance.
- In all cases prevention is cheaper and more effective than attempts at cures and treating the effects.

Question 25

Food consumption trends

Answer 25

-For many years, the most important nutritional concern for the region was energy-protein malnutrition. Many children were getting neither the total calories, nor the protein supply they needed to develop properly, both before and after birth. So we focused our efforts on increasing the overall calorie and protein supply available to our country’s populations.
- Recent reports on food availability in the region suggest that we now have a sufficiency, or over-supply, of energy and nutrients to meet the nutritional needs of the population. On average, all countries in the region have available more than the 2,250 calories and 43 g protein requirement per person suggested by the Caribbean Food and Nutrition Institute (CFNI) (Figure 3.2.a).
-We achieved this increased supply largely through enhancing the availability of foods from animals, fats and oils and refined sugar. Over the past 40 years, for example, average fat availability in the region has moved from 50 g to 80 g per person per day. Caribbean populations consume far more fat than recommended by CFNI

Question 26

Food consumption trends pt 2

Answer 26

-But while we met calorie and protein needs, we ate fewer cereals, fruits, vegetables, legumes, roots, and tubers. As a result, what we now have is a very significant decline in under-nutrition rates, but 180 FD12Aan enormous increase in the incidence of chronic diseases that might more properly be thought of as related to a kind of “over-nutrition”. These diseases include diabetes, hypertension and heart disease, and some nutrition-related cancers. At the same time, iron deficiency anaemia remains a problem, especially in pregnant women and preschool children (Cajanus, 2000).
- We now face a very complex challenge. We must maintain the overall gains in nutrition levels, but make our populations more aware of how to select their diets in order to avoid or delay the chronic diseases mentioned above. To meet this challenge, we need to collect information in each territory on the factors that determine what people choose to eat. This includes availability of foods from each food group, access, patterns of consumption in different communities, and existing beliefs about food. With these findings in hand we would be able to make informed decisions and develop appropriate policies and plans to improve our nutrition status.

Question 27

In order to stay healthy we should:

Answer 27

• aim to meet those nutrient goals
• decrease our dependency on imported foods
• discourage the growing popularity of those fast foods that are high in fat, animal protein, and refined carbohydrates

Question 27

What a diet should be

Answer 27

Based on a diet supplying 2,250 calories per person per day, CFNI has recommended that staples (cereals, roots, and tubers) should supply 45% of that energy; legumes, nuts, fruits, and vegetables 25%; food from animals 15%; fats and oils 10%, and refined sugar only 5%.

Question 28

Food supply

Answer 28

-We need to ensure that food is not only available to all the people all the time, but that such food provides the nutrients needed for people’s full development, both physical and intellectual. Further, we should be able to do this on an on-going basis. What we do now should not put in jeopardy the natural resources needed to ensure future generations the same advantage. In other words, the food supply must be sustainable (available over time).
-The two most important factors that determine whether or not people do get the food they need are availability and accessibility. We noted earlier in the section that adequate calories and protein are available in the region. Whether adequate supplies of the right foods are accessible to all is another matter. The fact that some undernutrition exists side by side with obesity in the region suggests that the distribution of available food supplies needs to be examined.
-Although living conditions have improved greatly in most Caribbean countries, poverty still persists throughout the region. Food may be available but not affordable for those people living below the poverty line. In 1995 it was estimated that 38% of the total population was living in poverty. Levels varied throughout the region – ranging from 65% in Haiti to 5% in the Bahamas.
-The following data show differences in access to food for those who earn the least in our society. Minimum wage earners in Barbados, Belize, Montserrat, and St Kitts and Nevis in 1993–1994 needed to use between 15% and 28% of their earnings to have a well-balanced 2400 kilocalorie per day diet. In Grenada, this figure was between 43% and 34%, while in Guyana costs went from 80% in 1993 to 63% in 1994. Figures varied widely in Jamaica for the period. In December 2000 the cost of feeding a family of five adequately for one week was estimated at J$1,828 (US$40). The present minimum wage in Jamaica is only J$1800 per week.
-We also need to consider a third factor with regard to food supply. Even if food is available and accessible, is it being assimilated so that the body can use it effectively? Infestation by worms may prevent absorption or badly prepared food may inhibit the absorption of certain nutrients. If minerals that are needed in very small quantities are not being assimilated for any reason, deficiencies will continue even though enough food is being eaten.

Question 29

Deficiency problems

Answer 29

Problems with deficiency diseases seem, for the most part, to be localized. In Jamaica, for example, high prevalence of marginal vitamin A deficiency, wasting, and anaemia varied in different regions (CFNI, 1998). Data from nutrition risk mapping, also in Jamaica, suggest that rapid urbanization and the consequent stress on infrastructure, together with poverty, are associated with the presence of some pockets of persistent malnutrition. In countries with indigenous populations, there is some evidence of greater prevalence of nutrition deficiency among those groups.

Question 30

Energy-protein malnutrition (EPM)

Answer 30

means just what it says – a deficiency in the diet of the calories and protein needed for good health.

Question 31

Energy-protein malnutrition (EPM)-example

Answer 31

-Children are particularly prone to this type of malnutrition, as Dr. Cicely Williams of Westmoreland, Jamaica, discovered. Dr. Williams, who qualified in 1923 with the first group of women admitted to Oxford University Medical School, found in her work in Ghana (then the Gold Coast), West Africa, that many children had symptoms she had noticed in Jamaican children while she was growing up. They had swollen bellies, diarrhoea, fever, and were very weak and listless. She discovered that giving children a diet rich in protein and calories could reverse the condition.
-She therefore called the condition protein-energy malnutrition (PEM), and the disease it produced kwashiorkor, the term used in West Africa (meaning the disease the old baby gets when the new one comes – in other words when the baby is weaned). In the Caribbean, we also see “mirasmi” babies – babies with marasmus, which is another way in which this type of malnutrition shows itself.
-Much research into this type of malnutrition has taken place since Dr. Williams’ original discovery. Whereas the original emphasis in treatment was on the protein in the diet, more emphasis is now being placed on the energy aspect.
-Throughout the region, the incidence of EPM has declined significantly over the past 25 years. Since the late 1980s and early 1990s, levels of undernutrition in pre-school children have declined to less than 5% in nine countries. Rates between 5 and 10% have been reported in six others, and only one country had a level higher than 10% (cited in Henry et al., 1997, p.192: original source Sinha D. 1995). Severe forms of EPM like kwashiorkor and marasmus are no longer a problem, but chronic low level EPM remains. It shows up as stunting, the child’s height being below the average for healthy children of the same age.
- Food and nutrition surveys show this decline in EPM. In Grenada, surveys conducted by the Food and Nutrition Council showed a decline in undernutrition in children 3–5 years old, from 39.6% in 1985 to 8% in 1990. Hospital data from Jamaica, 1994, showed that 2.3 % of the 0-59 month old admissions were diagnosed with EPM, as compared to 5% in 1993. (National Survey by the Planning Institute of Jamaica).
-The survey also showed that the 0–5 months and 6–11 months age groups had the largest proportion of admissions for malnutrition 38.8% and 50.8% respectively. This is surprising since EPM levels tend to increase with age between ages 0 to 5 years. The feeling is that, as the Ghanians observed, this is associated with poor weaning practices. The figures suggest a need to re-emphasise the importance of breastfeeding.

Question 32

Iron deficiency

Answer 32

-Iron deficiency anaemia affects between 6 and 65 % of pregnant women throughout the countries. The Turks and Caicos Islands (65%), Guyana and Belize (52%) and Jamaica (51%) register the highest proportions of pregnant women so affected. National surveys carried out in five countries by CFNI, indicate that among children under 5 years old, between 34 and 57 of every hundred have this type of anaemia. Among adults (15–60 years) in Guyana, 42% were anaemic. Among this group, females were more than twice as likely to be affected as males. -These deficiency levels are believed to result from insufficient iron in the diet and inability to use what is taken in. To reduce these deficiencies four strategies have been adopted: iron supplementation, dietary modification, iron fortification, and the control of intestinal parasites. In Jamaica, for example, since 1984 flour fortified with iron has been available. Barbados, Belize, Grenada, Guyana, and St Vincent and the Grenadines also currently have iron fortification programmes.
-All English-speaking Caribbean countries have in place iron supplementation programmes aimed primarily at pregnant women and infants. Their impact is not yet clear. Infrequent and delayed (late in pregnancy) attendance at clinics and unwillingness to follow the programme have been problematic.

Question 33

Vitamin A deficiency

Answer 33

CFNI surveys over the period 1996–1998 have identified vitamin A deficiency in small sections of the population in Antigua, Dominica, Guyana, Jamaica, and St Vincent. Severe deficiency was identified in less than 1.3% of the population. Marginal deficiency was, however, identified in 1.1% – 10.6% of preschoolers, school children, and pregnant women. The picture in Jamaica was noticeably different, with 58.1% of children 1–4 years old, 18.8% of school children, and 33.6% of pregnant women recorded as marginally deficient in this vitamin (CFNI, 1997a, b; 1998).

Question 34

Iodine Deficiency

Answer 34

Iodine deficiency is not generally regarded as a problem in the Caribbean. However a study done in Guyana identified levels of 42.8% in pregnant women and 27.6% of female children, and 26.1% of male children 5–14 years old. In 3.9% of the female and 2.5 % of male children, the deficiency was regarded as severe (CFNI, 1997b). Iodine can be supplied as iodized salt. The latter is available in most countries.

Question 35

Problems of nutrient over-intake and choice Obesity

Answer 35

-We have already noted that there is more than enough food calories available in the region to satisfy our nutritional needs. We now need to be concerned, not by undernutrition but overnutrition. The real cause for concern is no longer how much we eat but what we eat, that is, the type of nutrients consumed. The trend towards more animal, fatty, and refined foods, including sugar-based types, is not good. In addition, as the region “develops”, we have adopted a more sedentary lifestyle. These are important contributors to obesity.
-Even casual observation suggests that much obesity is present in the Caribbean. Recent studies of obesity among adults of 20+ years suggest that some 30–32% are overweight, and 19–21% are obese (CFNI unpublished data). When does overweight become obesity? World Health Organization (WHO) standards categorize persons with Body Mass Indices (BMI) of 25 and over as overweight. Among these, persons with a BMI 25 to 29 are regarded as pre-obese and persons with BMI 30 and over are regarded as obese. Within countries, geography, level of education, and gender seem to be associated with differences in obesity. Females consistently show higher proportions of obesity than males as shown by studies done in Dominica, Guyana, Trinidad, and Jamaica. Among Jamaicans, overweight is more frequently associated with lower education levels. More rural residents than urban are pre-obese but there seem to be no urban/rural differences at higher levels of BMI. In Trinidad, however, more rural residents are obese, compared with residents in the city or towns.
-Several studies worldwide have suggested that obesity is the major link to the development of nutrition-related chronic diseases which now rank as the leading cause of death in the region.

Question 36

Dealing with the problem
Any effective strategy for dealing with the nutrition problems of the Caribbean must take into account

Answer 36

the need for an effective public health campaign, l training health professionals to use a more client-oriented approach to the care and education of their clients, and l enlightened regional and national health care policies based on up-to-date research

Question 37

Dealing with the problem
Public education

Answer 37

The following comment was made about Jamaica, but it could well be said of the whole Caribbean region:
-Many of the risk factors affecting the health of Jamaicans are either not perceived by the population as such or they are only superficially understood. These include obesity/overweight, cigarette and/or marijuana smoking, heavy alcohol intake, a fatty, high salt diet with lots of refined sugars, sedentary lifestyle, failure to adequately treat hypertension and diabetes, multiple sex partners and poor health-seeking behaviour. (Figueroa 2001)
-Only education can improve this superficial understanding. People must be taught how lifestyle factors affect health, and what steps should be taken to preserve health and well-being. Early in life, we should encourage careful attention to diet and involvement in regular physical activity. We should try to ensure that citizens with family histories of nutrition-related diseases have regular medical checks, hopefully delaying or avoiding altogether the onset of these diseases. Smoking and substance abuse should be discouraged.
-To be effective, however, the educational process must be interactive and participatory. As Garcia (1999) points out in addressing the problem of diabetes education in Cuba, conventional health care and education focuses on the illness rather than the individual. “It is assumed that doctors and nurses know everything while people with diabetes know nothing.” Patients are mere objects when this is the approach. Education has to move away from just giving information to providing positive support, based on patients’ own life experiences.

Question 38

Health-care policies

Answer 38

Some important gains have been made with respect to health-care policies. Regional governments and policymakers are conscious of the role of food and nutrition in the achievement and maintenance f good health. This issue was a key component of the Caribbean Co-operation in Health (CCH) initiative, launched by the CARICOM Ministers Responsible for Health as far back as 1986. The overall goal was to “prevent malnutrition in all its forms and prevent and control those diseases conditioned by nutrition practice and behaviour”. CARICOM Ministers at a 1991 meeting, approved the goals and targets of the CCH.

Question 39

Targets set for CARICOM countries to develop were:

Answer 39

1. National food and nutrition policies
2. Food and nutrition strategies
3. Nutritional surveillance systems
4. Programmes and activities for preventing the most prevalent nutritional disorders
5. Nutrition component to health education programmes
6. Regional policy for training in nutrition
7. Reduced health risks from food contamination

Question 40

CARICOM report-health

Answer 40

A report to the 1992 meeting of the CARICOM Ministers Responsible for Health, indicated that all countries had by then developed some form of nutritional surveillance system. Satisfactory progress was also being made in several countries in developing national food and nutrition policies, strategies, and preventive activities in relation to anaemia, EPM and obesity, as well as in the development of educational materials for use by teachers (Henry et al., 1997). Later reports out of PAHO/WHO show that this trend has continued (PAHO/WHO, 1998).
-But national plans for health care are enormously affected by economic constraints. Treatment and care costs are high, and for each individual who has a chronic disease (diabetes, hypertension or heart disease), a lifetime of such costs is often involved. Therefore, the best approach is an integrated one that emphasizes preventive and health promotion measures, while supporting treatment and care. All programmes and plans should reflect these two considerations. The aim is to cover all stages of life – pregnancy, early infancy, childhood, adolescence, and adulthood.
-For example, care and nutrition in pregnancy need special attention. These are crucial stages of growth and development. Research has shown that nutrient deficiencies during pregnancy affect the foetus and may have detrimental effects that last a lifetime. Breastfeeding needs to be actively encouraged and child growth monitored continuously even in countries where malnutrition is reduced. This will lead to early identification of those with deficiencies and those most likely to develop nutrition-related diseases (high risk). These individuals can then be targeted for treatment when it will be most effective.
-The preventive and monitoring activities suggested above should be given priority in health-care budgets. Together they cost much less per person than treating those who are already ill. We need to support policies that advocate these measures so that we can reduce expenditure on expensive equipment that can care for only a few persons at a time, after they have fallen into crisis.
-This brief treatment of the status of nutrition in the Caribbean and its associated problems raises a number of questions. Some of these are suggested below. You may think of others. They need to be considered carefully if we are to reach our goal of adequate nutrients for all and a healthy society.
-In this context, it is important to note the enormous contributions of the Caribbean Food and Nutrition Institute and the Tropical Metabolism Research Unit of the UWI to research and understanding of nutrition and its problems, and to public education in the region.

Question 41

The basis of inheritance

Answer 41

Each cell of an organism carries within it a full set of the genetic instructions that define its characteristics. These instructions (or as they are commonly called, genes) are carried on structures called chromosomes within the nucleus of each of the estimated 50 trillion cells in your body. A chromosome is a long, spiral strand of a material called deoxyribose nucleic acid (DNA). Chromosomes also have segments that regulate the activities of the chromosomes themselves. Chromosomes pass on instructions for development, growth, and general functioning, from generation to generation by means of special reproductive cells called gametes, for example, sperms and eggs. Most organisms have male and female gametes. How are the instructions passed on? This is done in two ways. The astonishing thing is that the basic mechanism is the same in all organisms.

Question 42

Cell division for growth (mitosis)

Answer 42

-For growth to take place, one cell divides into two, two into four, and so on. The new cells increase to the size of the one from which they came, before they themselves split into two again. Each new cell has the same number of chromosomes and the exact number of genes in the same order on the chromosomes as the cell from which it came (the parent cell). This number is the number for the species. This is the way cell division takes place in almost every part of your body (with one exception).
-If the cell is dividing over and over how does the number of chromosomes remain exactly the same? Before mitosis each chromosome makes an exact copy of itself to form a chromosome with two strands held together at a single point. Each strand in the double stranded chromosome is called a chromatid.

Question 43

Cell division for gamete formation (meiosis)

Answer 43

In mitosis you get back exactly what you start with! A cell divides to form two exact copies of itself. Cell division for gamete formation is somewhat different, (the exception mentioned above). Gametes are reproductive structures, in our case, the male sperms and the female eggs. Remember that our body cells have 46 chromosomes. Sperms and eggs have only 23 chromosomes i.e. half the number found in body cells. There is a very practical reason for that which should be fairly obvious if you think about it. Cells with the capacity to produce gametes divide in a two-step process.
-Step 1: One cell becomes two, but each daughter cell gets one of each chromosome pair, and so has 23 unpaired chromosomes. Note that one will get the X and the other the Y chromosome (see above). This step is called a reduction division because of the halving of the chromosome number.
-Step 2: These two cells divide to become four, each with 23 chromosomes. In a male, these four cells become the gametes (sperms), half having X chromosomes and half Y.
-The process is called meiosis.. By convention, we represent this half or haploid number as n, and the full diploid number in the body cells as 2n. The haploid number of humans is 23 and the diploid number is 46, thus we have n chromosomes in our gametes and 2n in all our other body cells.
-Interestingly, in females Step 1 in meiosis starts in the ovaries of the foetus i.e. before birth, then stops. About 1 million of these “pre-eggs” survive until after birth, remaining dormant until puberty when the process restarts. Then one is selected for release at ovulation each month. In her lifetime a woman will release only some 400–500 eggs. The rest degenerate.

Question 44

Passing on the instructions to the next generation What happens to the chromosomes after fertilization?

Answer 44

When a new individual is formed, there is fusion of the male and female gametes. We say that the sperm fertilizes the egg. At fertilization both gametes join together to form a zygote with 46 chromosomes. Of this number, 23 are paternal chromosomes from the sperm and 23 are maternal chromosomes from the egg. The process of meiosis ensures that the diploid number of chromosomes (2n) remains constant from one generation to the next. Also important is the fact that sperms may have either an X or a Y chromosome. All eggs have X chromosomes. After fertilization, if the sperm had an X the child would be female. If it had a Y chromosome the child would be male. Can you complete the diagram in Figure 3.8 to show how sex is inherited? The zygote divides repeatedly by mitosis to become multicellular. We refer to it as an embryo, and later, once recognizable organs begin to form, as a foetus.

Question 45

How do chromosomes carry instructions?

Answer 45

Chromosomes contain DNA (deoxyribose nucleic acid). DNA carries the instructions for proteins to be made by the cell (cells are mostly protein). In 1952, Cambridge University scientists James Watson and Francis Crick, proposed that the DNA molecule is shaped like a double helix. The molecule is double stranded, and the two strands are twisted on each other into a spiral or helix (see Figure 3.9a, next page). Each strand is made up of alternating phosphate and sugar (deoxyribose) units. The two strands are linked together by pairs of bases, adenine (A), thymine (T), cytosine (C), and guanine (G). There are differences in the size and shape of the bases, such that adenine is always linked to thymine, and cytosine to guanine

Question 46

Amino Acids

Question 47

how these chemicals are able to carry so much information

Answer 47

The sequence of the bases on each DNA strand forms a code that directs the production of specific proteins. Each DNA strand is therefore a list of different instructions for making different proteins that the cell needs to carry out its specific functions. To understand this fully, we must first describe the structure of proteins. Proteins make up most of the cell structures, and enzymes that control what each cell does are also made of protein.

Question 48

Protein, amino acids and ribosomes

Answer 48

Each protein is made of hundreds or thousands of smaller molecules called amino acids, arranged in a particular way. A succession of three bases on the DNA strand codes for one amino acid. The sequence of these triplets, as they are called, gives the sequence for linking specific amino acids together to make a particular protein. Proteins are not made inside the cell nucleus but outside in the cytoplasm. DNA does not leave the nucleus so a messenger molecule, mRNA, copies the code from the DNA and takes it from the nucleus into the cytoplasm. Structures in the cytoplasm called ribosomes then follow the instructions and assemble the protein. A length of DNA that codes for one protein is called a gene. Genes give us our characteristics.

Question 49

How we inherit our characteristics

Answer 49

Genes are carried from parent to offspring in the gametes. So each of our body cells has two genes for each character – one gene coming from the male parent, and the other from the female parent. We can look at the inheritance of sickle cell anaemia to see how the process works. Haemoglobin is a complex protein molecule found in red blood cells. It gives the blood its red colour but more importantly, it carries oxygen around the body so cells can use glucose for energy.
-A segment of the DNA at a particular point along chromosome No. 11 of both parents codes for (determines the sequence of amino acids in) one chain of the haemoglobin molecule (it has four) (see Figure 3.10). This is the gene for the haemoglobin A protein chain (HbA).

Question 50

how sickle cell anemia is caused

Answer 50

In most people both of the genes for HbA in the maternal and paternal chromosome 11 will be identical. In the Caribbean and elsewhere, some people have a different haemoglobin. A single base pair in the entire sequence coding for HbA is different. Thus, a different amino acid is substituted into the haemoglobin chain. This slightly different haemoglobin is termed haemoglobin S (HbS), and behaves differently from normal HbA, causing sickle cell anaemia.

Question 51

How we inherit our characteristics pt 2

Answer 51

Each variant of a gene is called an allele; HbA and HbS are alleles of the Hb gene. Let us take this single characteristic – the haemoglobin molecule, and work out the possibilities for the offspring from parents with different alleles for this gene. To do this, we need to understand the terms dominant and recessive as they apply to alleles. Sometimes one allele of a gene compensates for and masks the effects of the other allele when they are present together. In this case the allele A (coding for HbA), will mask the effect of the allele S (coding for HbS), preventing its effects from showing up in a person. When this is so, we say the allele A is the dominant allele, and S the recessive allele. We call the alleles (variants of genes) in the cells, the genotype for the characteristic.
-In this case the possible combinations of genotypes for haemoglobin are AA, AS and SS. What shows up on the outside, that is, whether the person has the symptoms of sickle cell anaemia or not, is termed the phenotype. Figures 3.11 and 3.12 show how you can work out the probable phenotypes for children born to parents with certain genotypes.

Question 52

Inheritance of sickle cell anemia

Answer 52

The inheritance of sickle cell anaemia represents the simplest situation. Sometimes more than two alleles (variants) for one characteristic may exist in a population. Each gamete will still have only one allele and each body cell two. For example, there are three alleles for human blood groups, A, B and O, but A and B are both dominant to O, so there are four possible blood groups (phenotypes); Group A, Group B, Group O and Group AB. How many different genotypes are possible? Some characteristics are determined by the interaction of several genes as with skin colour or height, but that is a very complex matter.

Question 53

Some genetic “accidents” and the conditions they cause Genetic “accidents” are mutations

Answer 53

Normally in nature, the DNA instructions are passed on accurately. Sometimes, however, there is an accident or mutation. For example, in meiosis the separation of the paired chromosomes may not be perfect. If for example, one pair does not separate, some of the resulting gametes will have 24 chromosomes instead of 23 and others only 22. At other times, the number of chromosomes may be right, but the molecule of DNA itself is affected. Bases may be left out, or the sequence may be changed, so that proteins with altered characteristics are formed, as in the case of HbS above.
-Any gene can undergo a mutation, and there are about 30,000 genes in humans. So, theoretically, thousands of genetic diseases are possible. But many embryos formed from gametes with genetic defects die, either before birth (in a miscarriage) or shortly after. Others live with the conditions or diseases caused by the mistakes. These conditions may show varying degrees of severity.

Question 54

Birth defects have how many chromosomes/genes?

Answer 54

Down syndrome is a whole chromosome while the others involve single genes

Question 55

Down’s syndrome

Answer 55

-The condition is named after the English physician who first described it just over 130 years ago. The cause, however, was not known until the microscope and staining technology became available. In 1959, a French physician Lejeune, showed that individuals with Down’s syndrome had three copies of chromosome 21, not two as is normal.
- In Down’s syndrome, one gamete, usually the egg, has 24 chromosomes, because during meiosis, instead of separating into different daughter cells, both maternal and paternal copies of chromosome 21 go into one daughter cell. The matching cell with 22 chromosomes has no copy. When a sperm with 23 chromosomes fertilizes the egg, the child formed has 47 chromosomes instead of 46, three copies of chromosome 21 instead of two. Embryos formed with fewer chromosomes than normal usually die.
-Individuals with Down’s syndrome show abnormalities of the face, eyelids, hands, and other body parts. Typically they are short, with relatively small skulls, and a flat, rounded face. They are mentally retarded, sometimes severely. They also tend to be susceptible to infections, especially of the respiratory tract and ears. The incidence of Down’s syndrome increases markedly with the mother’s age. Estimates given are of a risk of 1 in 2,000 at age 20, 1 in 900 at age 30, 1 in 100 at age 40, and at age 44, 1 in 40 (Taylor et al. 1997, p. 865).

Question 56

Sickle cell anaemia

Answer 56

-The mutation causing this condition is a recessive variant of the gene for making haemoglobin (Hb), situated on chromosome 11. Haemoglobin made by the allele with the mutation (HbS), differs from normal haemoglobin (HbA) by one amino acid only.
-Normal red blood cells with HbA are disc-shaped. In the lungs, Hb combines with oxygen. This it gives up to cells that need it. The red blood cells then return to the lungs where Hb picks up more oxygen. The process is continuous. To get through very small blood vessels, the red cells bend and flex. When there is not much oxygen the red blood cells with HbS change shape and become fragile and stiff. (Some of them become sickle-shaped, hence the name.) The abnormal shape slows the flow of blood and causes blockages in small vessels. This can cause tissue damage and severe pain, often in the joints and stomach.
-Normal red blood cells last about 120 days in the circulation. Those with the sickle shape seem to last only about one tenth of that time. Individuals therefore become anaemic because of the rapid and continuous breakdown of the cells. Treatment includes pain relief measures, drug therapy, and transfusions. Exposure to certain conditions can trigger these crises. In Jamaica, cold and/or wet conditions have been observed to do this. Where these triggers are known, affected individuals can avoid them.
-Sickle cell disease is present throughout the Caribbean region. An estimated 10% of the population of African ancestry, are carriers. Fortunately, the Sickle Cell Centre at the Mona campus of the University of the West Indies has for over three decades carried out extensive and world renowned research into the disease. There is an on-going programme of monitoring, treatment, follow up and education for patients. Health professionals from several other countries including the United Kingdom, Brazil, and Uganda visit to learn from the experiences the Centre provides. Staff is actively involved in sickle cell projects in these countries.

Question 57

More on sickle cell anaemia

Answer 57

-There is a common misconception that sickle cell occurs only in “black” people. The mutation causing sickling seems to be present in a large percentage of persons in populations in parts of Africa, Saudi Arabia, Italy, Greece, Turkey, and India. It is true to say, however, that in North and South America, Europe and the Caribbean, sickle cell is usually found in people of African descent. The Caribbean, in fact, has a special “connection” since the first reported case in the West was a Grenadian, studying in Chicago between 1904 and 1907.
-An interesting twist to the survival and distribution of the gene is its association with malaria. The populations mentioned above come from regions where there is a high incidence of malaria. People with the normal genotype AA tended to succumb to malaria, many of them dying. Individuals with genotype SS often died early from the complications of sickle cell disease. Those with one allele for HbS and one for HbA (genotype AS – carrying the “trait”) were found to be more resistant to malaria than those with normal haemoglobin. Persons carrying the “trait” (AS) therefore had an advantage over those without it (AA) and were protected from the scourge of malaria. These individuals lived longer and were more likely to reach reproductive age than either the sicklers or those with both normal alleles.
-If you look back at Figures 3.11 and 3.12 you should be able to see how malaria and sickle cell worked together to develop and maintain a pool of individuals of the HbS genotype. This is one instance where the mutation could be said to have had a good, as well as a bad effect. Where malaria is no longer common, we can expect a gradual reduction in sickle cell anaemia as persons with the AS genotype no longer have an advantage over others although the SS genotypes are still at a disadvantage.

Question 58

Cystic fibrosis

Answer 58

is the most common genetic defect of Caucasian children. It is caused by a mutation on the recessive allele of a gene located on chromosome 7. Individuals with cystic fibrosis carry two recessive alleles with the mutation.

Question 59

How cystic fibrosis can be carried down

Answer 59

The gene concerned in cystic fibrosis regulates the movement of chloride ions in and out of the cells responsible for producing mucus. When the gene does not function, the mucus formed gets sticky. These abnormal secretions are produced especially in the respiratory system. Because the mucus is thick and sticky, it builds up, blocking small passages in the lungs and providing a breeding place for bacteria. The bacteria and the poisons they produce attack the surrounding tissues. This leads to repeated bouts of pneumonia and other complications. Heavy secretions of mucus in the pancreas and liver cause other problems. The pancreas develops patches of fibrous tissue, called cysts (hence the name of the disease), and the passage carrying bile from the liver to the gut may be blocked. Heavy mucus in the intestines causes digestive problems and probably obstruction. In addition, the individual may be infertile, especially the males.

Question 60

Treatment for cystic fibrosis

Answer 60

it includes giving antibiotics to control bacterial infections, and daily physical therapy to clear the respiratory passages. Treatment with an enzyme that breaks down the mucus also helps. Even with such treatment, sufferers tend to die young and without treatment, they die in infancy. Gene therapy may provide an answer for the symptoms of this disease. Some interesting research is in progress at this time.

Question 61

Huntington’s disease

Answer 61

it is the dominant allele of chromosome 4 that bears the mutation responsible. The condition causes severe mental and physical deterioration. There are uncontrolled muscle spasms, personality changes, and sometimes insanity

Question 62

Biotechnology and genetic diseases

Answer 62

-Genetic diseases are particularly distressing because we cannot cure them. We can, so far, only relieve the symptoms. Gene therapy, in which the abnormal gene is replaced by a normal one, offers some hope but its practical applications have not yet been realised. In addition, the research being done and the techniques proposed by gene therapists make some people uncomfortable. It raises many questions of ethics, some of which will be discussed in Unit 3 of this Module.
-One particularly contentious issue concerns efforts being made to improve the treatment and care of persons with defective genes. The successful treatment and survival of haemophiliacs provides a good example of the controversy. Haemophilia, the so-called bleeder’s disease, was very rare because the few individuals who inherited the condition, usually died before they reached reproductive age. Nowadays, by taking injections of certain blood products, they can live almost symptom-free lives, grow to adulthood and reproduce. Some people question the wisdom of preserving, and allowing the passage, through reproduction, of defective genes, which would normally be eliminated from the gene pool.
-It is possible to avoid passing on these diseases by receiving genetic counselling. Potential parents provide counsellors with a history of the occurrence of a particular disease in their family. Counsellors work out the probability of their having an affected child and they then decide whether to take the risk or not. Techniques now exist to examine the DNA of the couples so they can be told for sure whether they are carrying certain defects. These techniques can also detect abnormalities in the early foetus and a decision can then be made to terminate a pregnancy. Knowing about inheritance allows couples to make what they feel is the best decision but presents other ethical issues. If, in the face of the evidence, couples choose to have a child, at least they would be better prepared to deal with the consequences of the disorder.

Question 63

Quick review

Answer 63

See if you remember these terms
Gamete Mitosis DNA
Chromosome Meiosis Mutation
Gene Zygote Genetic counselling
Allele Embryo Genetic therapy

Use the following outline to review the information you have covered in this Session. Check the text for further details when necessary.
* Chromosomes are found in the nucleus of the cell. They exist in pairs; one of each pair is from each parent.
* Genes are found on the chromosomes.
* Genes control the characteristics of all organisms.
* Genes are made of DNA.
* Genes have variants called alleles.
* Chromosomes and the genes they carry are passed from one generation to the next, i.e., inherited from both parents.
* Sometimes chromosomes or genes have defects called mutations.
* Mutations cause changes in the traits that the genes control.
* Some genetic disorders are caused by inherited mutations.
* Genetic diseases cannot be cured but symptoms can be treated.
* Examples of genetic disorders include Down’s syndrome, sickle cell anaemia, cystic fibrosis, and Huntington’s disease

Question 64

Summary

Answer 64

-In Session 1 we looked at some diseases that are common in the region, both communicable and non-communicable. Communicable diseases are caused by living organisms. Many dangerous ones have been eradicated from the Caribbean by vaccination campaigns or controlled by public health measures. Dengue and tuberculosis remain problematic. The incidence of HIV/AIDS continues to increase mainly by heterosexual intercourse, putting many women and children before and after birth at risk. Treatment of HIV/AIDS is expensive; prevention is therefore very important. Substance abuse is prevalent in the region, contributing to the incidence of sexually transmitted diseases and other social problems such as crime.
-The non-communicable nutrition-related diseases, diabetes mellitus, hypertension, and heart disease, as well as cancer are the leading causes of death in the Caribbean region. There is some genetic predisposition to these diseases; nevertheless, they can be prevented or controlled by changes in lifestyle such as diet, exercise, stress relief, and abstention from smoking and excessive use of alcohol.
-Session 2 covered nutrition and nutritional disorders. Changing patterns of food consumption were discussed. There is now an over supply of energy and nutrients but these are not distributed between the different food groups, as they should be. The trend is towards increased consumption of fats, oils, and refined sugars and away from cereals, fruits, vegetables, legumes, roots, and tubers that used to constitute traditional diets. In addition, what is available is not always accessible to all citizens on an equitable basis. Consequently, deficiency diseases still exist in some areas in the region, largely due to poverty.
-EPM, iron, iodine, and vitamin A deficiencies were discussed. Problems of nutrient over-intake are of greater concern because of their links to the non-communicable diseases mentioned in Session 1. The Caribbean Co-operation in Health (CCH), an initiative of the CARICOM health ministers, shows an awareness of the nutritional problems of the region and willingness to deal with them.
-In Session 3, we dealt with genetic diseases. First we looked at how genes carried information encoded as sequences of triplets of bases on chromosomes and how these were transmitted from cell to cell during cell division and reproduction. The processes of mitosis and meiosis were described in outline. Mutations were introduced as accidents involving whole chromosomes or parts of particular chromosomes. Examples covered were Down’s syndrome, sickle cell anaemia, cystic fibrosis, and Huntington’s disease, each of which exemplified a different kind of genetic mistake. The importance of genetic counselling and the possibilities for gene therapy were discussed briefly.