Disease

Question 1

What is an infectious disease?

Examples?

Answer 1

A disease caused by pathogenic microorganisms (such as bacteria, viruses or fungi) that are spread directly or indirectly from one person to another
Influenza, malaria, HIV/AIDS, TB, cholera

Question 2

What is a non-infectious disease?

What affects the risk of developing these diseases?

Answer 2

A non-communicable disease that is not caused by pathogens.

Diet, environment, lifestyle, age, gender, genes - asthma, diabetes, cancer, stroke, cystic fibrosis

Question 3

What is a communicable disease?

Answer 3

A disease that spreads from host to host - pathogens passed from person to person or from animal to person cause these diseases.

Question 4

What is a non-communicable disease?

Answer 4

A disease that cannot spread between people because it is non-infectious or non-contagious.
Caused by lack of physical activity, smoking, poor diet, exposure to air pollution, genetic defects, age and gender.

Question 5

What is a contagious disease?

Answer 5

An infectious disease caused by bacteria and spread by direct physical contact or indirect contact

Question 6

What is a non-contagious disease?

Answer 6

Diseases not due to disease-causing organisms but caused by genetics, diet, lifestyle or environment

Question 7

What are endemic diseases?

Answer 7

Diseases that exist permanently in a geographical area or in a specific human group - disease not necessarily present at a high level of occurrence but it can always be found in the population, e.g. malaria is endemic in many parts of Africa

Question 8

What are epidemics?

Answer 8

Disease outbreaks that spread rapidly through the population of a geographical area affecting a large number of people at the same time (e.g. 2013 ebola epidemic)

Question 9

What are pandemics?

Answer 9

Epidemic disease outbreaks that spread worldwide, for example when a new virus emerges for which most people do not have pre-existing immunity (e.g. H1N1 flu virus, 2009-10)

Question 10

What is the distribution of malaria?

Answer 10

90% deaths in Africa - greatest risk in the tropics - greatest numbers in DRC and Nigeria
Endemic in 95 countries
Global distribution influenced by climatic factors, especially temperature but also humidity and rainfall - anopheles mosquito thrives in warm, humid conditions where there is stagnant water, in which it lays its larvae
Risk much lower in areas of high altitude, aridity or during a cold season and where there has been successful intervention
Tropics all year round, spreads further from equator seasonally

Question 11

What is malaria caused by and what are the symptoms?

Answer 11

Infectious but non-contagious disease caused when female Anopheles mosquito acts as a vector and takes a blood meal from an infected person and then injects the parasite (plasmodium) when taking a blood meal from an uninfected person.
Affects liver cells and erythrocytes causing fever and fatigue

Question 12

What are vectors?

Answer 12

Living organisms such as mosquitos and ticks that can transmit infectious diseases between humans or from animals to humans

Question 13

What is HIV?

Answer 13

Human Immunodeficiency virus - communicable disease that is infectious and contagious.
The virus attacks the immune system, including t helper cells (a type of white blood cell) and leaves the infected person especially vulnerable to other infections (AIDS).

Question 14

What is the global distribution of HIV?

Answer 14

Significant variation globally, but a particularly high proportion in sub-Saharan Africa (e.g. Zambia and South Africa)
1.1 million people died from HIV-related causes in 2015 (WHO)
Lower percentages of HIV-affected adults in more developed country where research, drugs and education programmes are readily available.

Question 15

How is HIV transmitted?

Answer 15

Body fluids, e.g. blood, breast milk and semen
Risk of infection increases through unprotected sex, sharing contaminated needles (when injecting drugs or receiving unsafe blood transfusions.

Question 16

What is tuberculosis?

Answer 16

An infectious and highly contagious communicable disease, spread by transmission of mycobacterium tuberculosis through the air (via inhalation of droplets from coughs and sneezes of infected people)
It affects the lungs, damaging lung tissue and causing respiratory problems

Question 17

What is the global distribution of TB?

Answer 17

1.8 million died from TB in 2015 - 95% in low and middle income developing countries
New cases greatest in subsaharan Africa, especially south of the equator.
Incidence of TB is worldwide, although 60% of worldwide deaths in 2015 were in 6 countries, including China, Indonesia, and Nigeria.
Poor communities with overcrowding and dense populations and poorly ventilated houses particularly vulnerable.
Limited health access is significant adverse factor - areas affected by civil unrest or war.
HIV increases risk of death from TB (0.4 HIV related TB deaths in 2015)

Question 18

What is malnutrition?

Answer 18

Shortage of proteins and essential vitamins caused by an unbalanced diet

Question 19

What is one of the UN health targets in Sustainable Development Goal 3?

Answer 19

Ending the TB epidemic by 2030

Question 20

What is diabetes?

Answer 20

A non-communicable disease that can lead to heart, blood vessel, eye, kidney and nerve damage.
Approx 90% of people with diabetes have type 2
Type 2 caused by excess body weight, physical inactivity, age, smoking and poor diet

Question 21

What is the global distribution of diabetes?

How can it be reduced?

Answer 21

422 million cases worldwide in 2014
Prevalent in North America, east and southeast Asia, lower in most of Africa.
4 million in UK
Number of cases is rising more rapidly in low and middle income countries - increase in overweight and obesity in developing countries

Tackling obesity through education and establishing good eating habits and encouraging physical activity from an early age

Question 22

What is CVD?

Answer 22

Cardiovascular disease - range of disorders of the heart and blood vessels. Non-communicable diseases that cannot be passed from person to person - include high blood pressure, heart attack and stroke
Risk increased through combination of lifestyle factors (smoking, alcohol abuse, unhealthy diet, physical inactivity).
Ageing population, poverty and genetics also factors
Higher incidence where there is poor access to medical care

Question 23

What is the global distribution of CVDs?

Answer 23

17.5 million deaths per year
Prevalent in all WHO regions, often among older age groups, but also many premature deaths before age of 70.
Low and middle income countries disproportionately affected - over 80% of all CVD - due to lack of treatment available. These countries have less capacity to control and prevent CVDs, but governments are encouraged to take part in the WHO’s Global Heart Initiative
Reducing death rates through education

Question 24

What are the four types of disease diffusion?

Answer 24

Expansion - disease spread from one place to another, forming new areas of prevalence, remains in area of outbreak, possibly even intensifying there
Relocation - disease moves to new areas but does not remain in area of outbreak
Hierarchical - Disease transmitted, usually down urban hierarchy, from larger, more accessible towns to more remote, rural villages - disease spreads through structured order of places
Contagious - process by which disease spreads through direct contact with a carrier - greater chance of disease being passed on to people living near the source than further away

Question 25

What is disease diffusion and what is Hagerstrand’s model for disease diffusion?

Answer 25

Process by which a particular disease spreads outwards from its geographical source.
Primary stage - strong contrast in disease incidence between area of outbreak and more remote areas
Diffusion stage - diffusion is centrifugal - new centres of disease outbreak occur at distance from the source and this reduces the spatial contrasts of the primary stage
Condensing stage - number of new cases is more equal in all locations, irrespective of distance from the source
Saturation stage - diffusion decelerates as the incidence of the disease reaches its peak

Question 26

What are some examples of barriers to diffusion?

Answer 26

Physical barriers - mountain ranges, large maritime areas, extensive areas of aridity and climatic conditions, distance
Socioeconomic barriers - national government and international organisation strategies to tackle communicable diseases, such as medical heath checks at borders and airports, quarantine, vaccination and health education programmes

Question 27

Where is guinea worm found?

Answer 27

Stagnant water sources in central Africa

Question 28

How does rainfall affect malaria?

Answer 28

More rainfall = more stagnant pools of water for female anopheles mosquitos to lay their eggs in and breed - prevalent just after rainy season. Excess rain can wash away breeding grounds for mosquitos

Question 29

What is the temperature range in which mosquitos can breed and the plasmodium parasite develop?

Answer 29

18-40°C, ideal 27°C - more blood meals, faster rate of reproduction, increased number of eggs laid, faster rate of larvae development and parasite life cycle
Relative humidity over 60% - often increased by vegetation growth, mosquito has better chance of survival and becomes more active

Question 30

How do seasonal variations affect transmission influenza in temperate latitudes of Europe and North America?

Answer 30

Epidemics tend to peak in winter - transmission of virus more efficient at lower temperatures and and when relative humidity is low - conditions occur most often in winter seasons

Question 31

What are EIDs?

Answer 31

Emerging Infectious diseases (diseases that have emerged in the last 20 years) - either not occurred in human populations before or have occurred previously but only affected small numbers in isolated places
e.g. Zika virus, ebola virus, Lyme disease

Question 32

How has climate change or global warming affected the spread of disease?

Answer 32

Global warming has had the effect of extending geographical areas in which vector-borne diseases are developing. Lyme disease is expected to spread northwards in the USA and possibly into Canada during the twenty-first century.
Shorter term - el nino increased rainfall and tropical cyclones - increased flooding - increased transmission of diseases such as malaria and cholera
Some diseases reemerge where they were previously eradicated (e.g. dengue fever in Florida) due to increasing temperature.

Question 33

What are zoonotic diseases?

Answer 33

Disease transmitted between animals and humans, e.g. rabies, malaria, swine flu

Question 34

What ratio changes as countries develop?

Answer 34

Ratio of communicable to non-communicable diseases
(shift from former to latter with increasing development)

As life expectancy increases, the major causes of death and disability in general shift from communicable, maternal and perinatal ones to chronic, non-communicable ones

e.g. in UK shift from cholera, smallpox and typhoid to heart disease, strokes and cancer (vaccinations, improved nutrition and sanitation, effective public health policy

Question 35

What are the stages of the epidemiological transition model?

Answer 35

Age of pestilence and famine
Age of receding pandemics
Age of degenerative and man-made diseases
+ age of delayed degenerative diseases (delayed by modern technological and medical improvements)

closely associated with demographic and socio-economic transitions that accompany development

Question 36

How can poor diets affect prevalence of diseases in LIDCs?

Answer 36

Lead to malnutrition and undernutrition, and deficiency of essential nutrients and vitamins, e.g. rickets (vit D deficiency), scurvy (vit C deficiency) - increases susceptibility to infections

Question 37

What is UNICEF?

Answer 37

United Nations International Children’s Emergency Fund

Question 38

What does increasing global mobility do for the spread of communicable disease?

Answer 38

Contributes to diffusion of communicable diseases but also enables international organisations such as the WHO to organise more rapid responses to disease outbreaks

Question 39

What is sustainable development goal 3?

Answer 39

Good health and well-being

Question 40

What are Millennium Development Goals 4 and 6?

Answer 40

Reducing infant mortality

Malaria control

Question 41

What other things does UNICEF do?

Answer 41

Cooperates with WHO CSOs and local communities to operate the Integrated Management of Childhood Illnesses strategy
Combats HIV/AIDS through education programmes , helping to prevent mother-to-child transmission
Financial and technical support
Healthcare and nutrition through immunisation, prevention and control of malaria, eradication of guinea worm disease
Rapid response in emergencies (shelter, fresh water, medicines, micronutrients to prevent malnutrition, insect-treated nets in malaria-infested areas

Question 42

What is SARS?

Answer 42

Severe Acute Respiratory Syndrome - viral respiratory illness of zoonotic origin, spread by close person-to-person contact and through air via respiratory droplets when an infected person coughs or sneezes
Pandemic spread in 2002-3 in 37 countries and over 8,000 reported cases, 774 deaths, many in Hong Kong. Infected people spread the disease via air travel internationally

Question 43

What are positive effects of physical barriers on mitigation?

Answer 43

Limits spread as population movement is restricted
Restricts disease vector habitats
Reduced risk of infection due to lack of outside contact for isolated villages in rural peripheries, in mountain valleys or within tropical rainforest
Diseases occurring within isolated communities are more likely to be contained

Question 44

What are negative effects of physical barriers on mitigation?

Answer 44

Restricting movement of medical assistance and emergency aid in the event of an outbreak
Delay of humanitarian response following natural hazards - e.g. earthquake may cause landslides, blocking roads or airports
Excess water as a result of river flooding or monsoonal rain - breeding grounds for vectors and waterborne diseases
Restricted movement of aid workers, medicines and fresh water into affected areas
Lack of outside contact for isolated communities, which may reduce immunity and mean takes longer for information on disease outbreak to reach organisations who can help to mitigate it

Question 45

How does the WHO attempt to mitigate pandemic influenza?

Answer 45

Global Influenza Programme (GIP):
assessment of risk, to devise responses and recovery actions based on surveillance and monitoring of previous outbreaks
Encouragement and advice for every country
Guidance on treatment of patients, strains for vaccine production, establishing education programmes
Plans for high-density populations including public health advice regarding social distancing, hand hygiene and household ventilation

Question 46

What is morphine, what are its growing conditions and what is it used for?

Answer 46

Dried latex from seed pods of opium poppy
Warm and humid conditions with clear sunny days and temperatures of 30-38°C.
Susceptible to frost and wet weather. Deep clay loam, well-drained soils rich in humus. pH6-8