Malaria

Question 1

Describe the malaria life cycle (9)

Answer 1

1. Mosquito transmission
   - Anopheles female bites human and injects sporozoites into the bloodstream
2. Liver stage
   - Sporozoites go to the liver to invade the hepatocytes
   - Sporozoites multiply asexually in hepatocytes –> hypnozoites –> schizont
3. Hepatocyte rupture
   - Mature liver schizont releases merozoites into the blood stream
4. Erythrocyte cell stage
   - Merozoites invade the red blood cells
   - In the erythrocyte they mature to schizonts
   - These burst and release more merozoites (fever + unwell stage)
5. Sexual stage
   - Some merozoites develop into the sexual forms called gametocytes
6. Mosquito uptake
   - New mosquito bites and ingests the gametocytes
7. Mosquito midgut
   - In the midgut the gametocytes devlop into gametes which fuse to form a zygote
8. Oocyst formation
   - The oocyst lodges onto the gut wall which then produces lots of sporozoites
9. Sporozoite migration
   - Migrate to the salivary glands ready for the next bloodmeal

Question 2

Which species of malaria can stay dormant in the liver?

Answer 2

P vivax and P ovale

Question 3

What is a var gene in malaria?

Answer 3

PfEMP1 is an example of the multiple var genes
These help malaria to evade the immune system by sticking to the walls of blood vessels and avoiding being cleared away by the spleen

Question 4

What are the 6 main principles of malaria vector control?

Answer 4

1. ITNs (Insecticide-Treated Nets)
2. IRS (Indoor Residual Spraying)
3. Intermittent Preventive Treatment
4. Seasonal Malaria Chemoprevention
5. Larval source control
6. Vaccination

Question 5

Which antimalarial drug targets the gametocyte stage?

Answer 5

Primaquine

Question 6

Which species of malaria might relapse and how do you treat it?

Answer 6

P vivax and ovale

Primaquine - except avoid in G6PD deficiency, pregnancy, infants, breastfeeding

Question 7

Which malaria species rare, commonly seen in Malaysia which can present with severe disease?

Answer 7

P knowlesi

Question 8

Malaria - diagnostics

Answer 8

Thick and thin blood smears
RDT

Lab:
Anaemia
Hypoglycaemia
Thrombocytopenia
Lactic acidosis
Jaundice
AKI
Renal failure

Question 9

Malaria treatment in severe and non-severe

Answer 9

Severe:
IV artesunate
Careful fluid balance and glucose management
Broad spectrum antibiotics (e.g. ceftriaxone)

Non-severe:
Artemisinin combination therapies (ACT)

Question 10

IV artesunate considerations?

Answer 10

Needs follow up for delayed haemolysis

Question 11

How do you manage treatment failure in malaria?

Answer 11

<28 days
Recommended 2nd line treatment is an alternative ACT

> 28 days
Consider as a new infection & treat with first line ACT

Question 12

What are some complications of malaria?

Answer 12

Cerebral malaria - impaired consciousness, retinopathy, seizures, cerebral odoema and raised ICP

Severe anaemia - especially in young children and pregnant women

ARDS
Hypoglycaemia
Lactic acidosis
Shock

Question 13

Challenges to malaria control strategies (7)

Answer 13

1. Sustainable financing
2. Drug resistance
3. Insecticide resistance including behavioural resistance
4. Diagnostics
5. Lack of community engagement
6. Climate change e.g. Anopheles stephensi in Asia very efficient in urban settings coming to Africa, affecting vector distribution and reproduction
7. National priority shifting
8. Movement population

Question 14

Malaria chemoprevention strategies (4)

Answer 14

Intermittent preventive treatment of malaria in pregnancy (IPTp):
3 doses given during pregnancy at antenatal visits

Perennial malaria chemoprevention (PMC)
Given to children in endemic areas with seasonal transmission during the usual vaccination program

Intermittent preventive treatment of malaria in school aged children (IPTsc)
Given to children aged 5-15 during school time

Post-discharge malaria chemoprevention (PDMC)
Prevention in the recovery period to allow them to recover from the complications like anaemia

Question 15

Are there malaria vaccines available?

Answer 15

Yes - RTS and R21
May be helpful in combination with other measures before high transmission seasons

Question 16

What are some strategies for malaria prevention? (6)

Answer 16

1. Indoor residual spraying
2. Insecticide treated nets
3. Larvicides
4. Attractive targeted sugar baits
5. Spatial repellents
6. Genetically modified mosquitoes

Question 17

12 severity signs in malaria

Answer 17

1. Impaired consciousness or coma.
2. Prostration (inability to sit/stand).
3. Severe anemia (Hb <5 g/dL).
4. Respiratory distress (e.g., acidotic breathing).
5. Multiple convulsions (≥2 in 24 hours).
6. Hypotension or shock.
7. Jaundice with other severe signs.
8. Hemoglobinuria (dark/red urine).
9. Pulmonary edema.
10. Abnormal bleeding or disseminated intravascular coagulation (DIC).
11. Severe hypoglycemia (<2.2 mmol/L or <40 mg/dL).
12. Acidosis (pH <7.25) or lactate >5 mmol/L.