CSIM1.66 Malaria

Question 1

Major routes of malaria transmission

Answer 1

Mosquito - anopheles
Blood transfusion
Inoculation
Transplacentally

Question 2

List the 4 types of parasites that cause malaria

Answer 2

Plasmodium falciparum
P vivax
P ovale
P malariae

Question 3

Desceribe the life cycle of P falciparum

Answer 3

Lives in salivary gland of anopheles mosquito
Mosquito bites human, injects saliva + parasite into human

Sporozoites in blood find its way to liver

Once in liver, form “tissue shizonts” and replicate merozoites

Once shizont matures, bursts and releases merozoites into blood

One merozoites in red blood cell, becomes trophozoite and forms “blood shizont” to replicate more merozoites.

When “blood shizont” is mature, bursts to release more merozoites, haemolysing the RBC in the process - continue ad infinitum

Some become gametozoite instead and are picked up by another mosquito who drinks human blood

Mosquito who picks up gametozoites will have gametozoites in gut, where they reproduce sexually to form more sporozoites which goes to the salivary glands, ready to infect

Question 4

Explain the cyclical fever spikes in malaria

Answer 4

Fever spikes when blood shizonts release merozoites
Different species will have different release cycle

Falciparum 36 hours
Vivax and ovale 48 hours
Malariae 72 hours

Question 5

Whats the difference between falciparum and the others?

Answer 5

Vivax and ovale form hypnozoites which go to the liver and lay dormant AKA benign malaria. Can relapse after some time.

Falciparum goes to erythrocytes and cause haemolysis and symptoms. Does not relapse.

Question 6

Clinical features of malaria incl. incubation period?

Answer 6

Incubation 10-14 days

Symptoms: chills, sweats, fever, rigors, malaise, headache, myalgia, anorexia#

Can become cerebral related; confusion, reduced GCS, fits

Anaemia is common, jaundice and hepatosplenomegaly.