Malaria Flashcards
(31 cards)
What is malaria?
A protozoan parasite that can infect humans
It is passed to humans via mosquitoes
Which mosquitoes transmit the protozoa to humans?
- Species
- Male or female
Anophales species
Female mosquitos
Name the types of parasitic protozoa that cause malaria?
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Describe the lifecycle of the malaria protozoa?
Mosquito bites human infecting them with protozoa (called sporozoites at this stage)
Multiply inside hepatocytes (called merozoites at this stage)
Hepatocytes rupture, merozoites released into bloodstream
Taken up by RBCs, they continue to multiply
Rupture the RBCs
Once in the blood, protozoa can be passed on to the next mosquito that bites that person,
This mosquito will then bite someone else, infecting them
Which is the most hazardous protozoa?
Plasmodium falciparum
Which protozoa(s) can result in a chronic illness?
Plasmodium malariae
Which protozoa(s) ca relapse?
Plasmodium vivax and ovale
How does the protozoa infection cause so much damage?
Ruptures hepatocytes: liver dysfunction
Ruptures erythrocytes: anaemia and release of pyrogens which cause fever
RBCs infected with protozoa adhere to endothelium of small vessels = vascular occlusion = organ damage
Why does fever occur in malaria?
Rupture of the RBCs by the protozoa causes release of pyrogens
Pyrogens cause pyrexia
Which organs are worse affected in malaria?
Liver
Gut
Kidney
Brain
How can P. vivax and ovale cause relapsing malaria?
The protozoa remain latent/dormant in the liver
Incubation period of protozoa?
10-14 days in all except malariae which can be 18 days to 6 weeks
Clinical features of malaria?
Severe headache Fever Tachycardia Rigors Cough Diarrhoea + vomiting Hepatosplenomegaly Anaemia
Cyclical cold/fever/sweating stages
What are some severe complications of malaria?
Cerebral malaria: when RBCs infected with protozoa cause occlusions in the brain
Blackwater fever: dark brown-black urine caused by severe intravascular haemolysis
Clinical features of cerebral malaria?
Diminished consciousness Confusion Convulsions Coma Death
Some people are protected against some types of malaria. How?
Sickle cell trait, i.e. carrier of gene but not affected
- protection against P. falciparum
Duffy blood group negative RBCs are resistant to P. vivax
Diagnosis of malaria?
Thin and thick blood films
3 separate films are usually needed
Look for protozoa
Calculate % RBCs affected
Management of malaria?
Depends on type!
Complicated F. infection
- IV quinine
- IV artesunate
Uncomplicated F. infection
- quinine PO
- doxycycline
Non-F infection
- Chloroquinine PO
P. vivax + ovale
- Primaquine used to clear dormant infection
Which protozoa is IV quinine used for?
Complicated falciparum infection
Which protozoa is IV artesunate used for?
Complicated falciparum infection
Which protozoa is PO quinine used for?
Uncomplicated falciparum
Which protozoa is PO doxycycline used for?
Uncomplicated falciparum
Which protozoa is chloroquinine used for?
Non-falciparum
Which protozoa is primaquinine used for?
Dormant P. vivax and ovale
