Epidemiology Flashcards
what are the causative agents of malaria?
P. falciparum, P. malariae, P. ovale, P. vivax and P.knowlesi. Of these, P. falciparum and P. vivax are the most prevalent, and P. falciparum is the most dangerous, with the highest
rates of complications and
mortality.
What is the reservoir of malaria?
Humans are the only resorvoir for most cases ( this is one important element that Malaria was chosen for eradication).
–P. knowlesi has
recently been recognized to be a
cause of significant numbers of
human infections. P. knowlesi is a species that naturally infects
macaques living in Southeast Asia (zoonnotic).
What are the modes of transmission of malaria?
- Vector transmission: Infected female anopheles mosquitoes.
- Direct transmission: malaria may be induced accidentally by hypodermic intramuscular and intravenous infections of blood or plasma e.g., blood transfusion, malaria in drug addicts.
- Congenital malaria: congenital infection of the newborn from an infected mother
(Transplacental).
What is the incubation period for malaria?
Varies with species
average 2 week up to one month ( Fever occuring less than a week from exposure is not Malaria)
What is the period of communicability for malaria?
Not commuicable directly except through blood
Describe malaria distribution in egypt
Situation in Egypt:
There is a possibility
of introduction of
cases coming from
outside of Egypt
especially from Sudan
through cruise boats
and other commerce in
between
What are the risk factors of malaria?
a) Age: Any age. But Newborn are more resistant to malignant Malaria due to high HbF
b) Race and genetic factors:
* Plasmodium falciparum is mild in races with high case rate of HbS hemoglobinopathies e.g. (Sickle cell trait) [black race].
*Also Black Africans show resistance to P vivax in case of absent Duffy factors in RBCs
c) Pregnancy:
*increase the risk of malaria among women
*increase the risk of premature labor, SB and abortion and congenital malaria
General prevention of malaria
- Health education (especially for
travelers): - Remaining in well-screened
areas. - Using mosquito nets.
- Wearing clothes that cover most
of the body. - Mosquito repellents like N,N
diethyl-m-toluamide (DEET ) - Pyrethrum spray in living and
sleeping areas. - Importance of
chemoprophylaxis. - Environmental sanitation
* Vector control
* International Measures : Disinsectization of aircraft before
departure from endemic areas
and upon arrival if necessary.
Specific prevention (Travelers to chloroquine sensitive areas)
–Travelers to chloroquine
sensitive areas:
(All of Africa is choroquine
resistant)
Drug: Chloroquine
Dosage:
a. Weekly dosage.
b. Start 1-2 weeks
before travel, during
stay till 4 weeks after
leaving.
Contraindication
-Epilepsy, Psoriasis
-Can be given in
pregnancy
Specific prevention (Travellers to chloroquine resistant areas)
–Travellers to chloroquine
resistant areas
Drug: Mefloquine
Dosage
a. Weekly dosage.
b. Start 1-2 weeks before
travel , during stay till 4
weeks after leaving.
Contraindications
1. Patient with
seizures.
2. Heart arrhythmias.
3. Pregnancy
specific prevention (In case
mefloquine resistance)
Doxycycline
Dosage
a. Daily dosage.
b. Start 1-2 days before
travel, during stay till 4
weeks after leaving.
Contraindications
1. Children <8 years*
2. Pregnancy and lactation
Atavaquone + proguanil
Dosage
a. Daily dose
b. Start 1-2 days before
travel, during stay till 7
days after leaving
Contraindications
Pregnancy and lactation
specific prevention (In case of P
ovale or vivax prophylaxis and
in situations of long stay)
Primaquine
Dosage
a. Daily dose
b. Start 1-2 days before
travel, during stay till 7
days after leaving
Contraindications
1. G6PD deficiency
(normal function must
be assured before giving
the drug)
2.Pregnancy
what are the malaria precautions regarding children?
Children are not advised to go to malarious areas as the
pediatric formulas may be not available and dosage
calculation may be difficult
what is standby treatment?
it is self administered treatment that can be taken for travellers when no medical attention is
available or for use under medical supervision after a
confirmed malaria diagnosis
what are some control procedures for malaria?
A) Measures to cases:
1- Notification: Local health
authority-→WHO.
2- Isolation: Blood precautions.
3- Disinfection
4- Treatment:
- B) Measures to contacts:
Listing of all sharing blood
(addicts)
what factors enhance iron absorption?
1) Gastric HCl aids in ferric ion reduction to ferrous
2) Vitamin C
3) Phytic acid, oxalates and phosphates
4) Low iron stores and increased erythropoietic activity
5) Infancy, adolescence and anemia - Increased demand
What factors inhibit iron absorption?
- Presence of phytates (present in wheat and cereals), and tannins
(tea).
- Presence of phytates (present in wheat and cereals), and tannins
- Health status: infections and
malabsorption decrease iron
absorption.
- Health status: infections and
how is junk food related to iron deficiency?
- Junk food: may be related to iron deficiency anemia as it contains less iron and causes obesity.
Obesity increases Hepcidin Levels.
Hepcidin expression is induced by iron stores and inflammation and is suppressed by hypoxia and anemia.
High Hepcidin Levels Lower Iron Levels
what is Hepcidin?
Hepcidin is a small, cysteine-rich cationic peptide produced by hepatocytes, secreted into plasma, and excreted in urine.
what are the dietary sources of iron?
Haem iron: present in meat, fish, poultry , blood products,
liver, kidney, heart. Bio availability is high.
Non haem iron: found in varying degrees in all foods of plant
origin e.g. molases (richest source), yellow lentils, beans, dark green leafy vegetables. It is less absorbed than haem-ir
how prevalent is anemia and what are the groups at risk?
- Infants and Preschool children: more Prevalent in
Rural Areas - Adolescents
- Woman of childbearing age
particularly pregnant and
lactating women
*Anemia in Pregnancy: The
early stages of anemia in
pregnancy are often without
symptoms. However, as the
hemoglobin concentration
falls, oxygen supply to vital
organs declines, and the
expectant mother begins to
complain. Anemic mothers do not tolerate blood loss to the same extent as healthy
women (postpartum hemorrhage).
Describe the first step of the anemia control program (supplementation)
Supplementation:
* Giving Iron as medications
To: Pregnant – Lactating –
School children
The success of this step depends on:
1) Adequate population coverage of target groups
2) Effective education and motivation of recipients
3) Training of health personnel
Describe the last step of the anemia control program (fortification)
Fortification:
* Adding Iron to food
* Examples: Milk – Wheat flour
Describe the second step of the anemia control program (dietary modifications)
Dietary modifications:
It consists of 2 basic parts:
a. Correct the under-nutritional status: as when energy needs are fully met, the total iron
consumption is increased. This is a simple approach especially in rural areas.
b. Quality of iron ingested and absorbed should be improved:
- Increase ascorbic acid content of diet (eating fruits and vegetables)
- Reduce ingestion of inhibitors of absorption
- In weaning, foods prepared should be rich in Vit C and iron
- Importance of breast milk for infant (iron in breast milk is highly absorbable)
Describe the third step of the anemia control program (infection control)
Infection Control:
a. Control of viral, bacterial and parasitic infections contributes to the iron status even if there is no increase in dietary iron consumption.
b. Provision of safe water and
environmental sanitation will decrease diarrheal diseases which affects iron absorption.
c. Treatment of parasitic infestations e.g. ancylostoma, necator, giardia.
d. Sick children should be properly fed (change the wrong believes of rural families where they avoid proper nutrition to sick children: semi- starvation state)
Types of G6PD deficiency
- Type A: common in
American blacks. The
enzymatic activity is 5-15% of
the normal and leads to less
severe hemolytic attacks. - Type B: common in
Mediterranean area. The
enzymatic activity is less than
5% of normal and leads to
severe hemolytic attacks and
death may occur in severe
cases
what are the risk factors of G6PD deficiency?
- Consanguinity plays a major role in the incidence of this disease.
- It affects males more than females
- Exposures that lead to hemolytic attacks are: fava beans and certain drugs (oxidizing agents) such as:
Antipyretics (Aspirin), Anti- malarial drugs, Sulfonamides,
Chloramphenicol, and
Naphthalene.
How is G6PD deficiency prevented?
- Early diagnosis ( Genetic counseling and screening may be of value for positive family history)
- Health education of the parents of children with G6-PD disease for prohibiting the previous drugs that causes hemolysis.
- Epidemiologic surveillance
what is thalassemia?
- Thalassemia is a group of
inheritable autosomal linked
– recessive anemia due to
genetic defects and diminished synthesis of one of the hemoglobin polypeptide chains. - The most common type is
Beta thalassemia
(Mediterranean Sea anemia).
Alpha thalassemia is common
in Asia
what is beta thalassemia?
*High incidence in Arab countries in general.
-It is the most common cause of chronic hemolytic anemia in children commonly present after the 6th month of age.
- Risk Factors: consanguineous marriage
how is thalassemia prevented?
- Premarital counseling, genetic counseling, neonatal screening and screening for carrier.
- Health education about the hazards of consanguinity.
- Tertiary prevention: Rehabilitation programs
