Malaria Flashcards
What are the 4 major species of malaria?
Plasmodium falciparum, P. vivax, P. ovale, P. malariae
What is the vector of malaria?
Female Anophales mosquito
Describe the life cycle of malaria
- Sporozoites transmitted from anophales mosquito during blood meal
- Sporozoites invade hepatocytes and multiply into merozoites
- Merozoites invade erythrocytes and mature into trophozoite (ring form)
- Trophozoite divide into multi-nucleated shizont
- Shizont bursts releasing new merozoites, can either go through asexual cycle again or can differentiate into male and female gametocytes
- Gametocytes are taken up by mosquito and progress through stages to become sporozoites in the proboscis
Which stages of the life cycle cause disease?
Asexual blood stages (destruction of erythrocytes)
What makes P. falciprum more severe?
Var genes encode protein expressed on infected erythrocytes surface that causes endothelial adhesion and microvascular obstruction in brain and other organs (cerebral malaria)
What species of malaria cause uncomplicated malarial disease?
Any four species
What species of malaria cause the most severe malarial disease?
Plasmodium falciparum
What is the clinical presentation of uncomplicated malaria?
- Periodic fever paroxysms every 48 hours
- Headache, myalgia, backache, cough, diarrhea, abdominal pain
- Anemia, hepatomegaly, jaundice
What are lab signs of uncomplicated malaria?
Anemia, thrombocytopenia, normal to low white blood cell count
What is the clinical presentation of severe malaria due to P. falciprum?
Cerebral malaria (altered consciousness, seizures common, rapid onset) Severe anemia (hemoglobin <5 gm/dL)
What is the clinical presentation of severe malaria due to P. vivax?
Splenic rupture, chronic anemia
Mostly SE Asia, West Pacific, and South America (African lack Duffy antigen to allow P. vivax invasion)
Ability to relapse, no sequestration
What is the clinical presentation of severe malaria due to P. malariae?
Nephrotic syndrome in African children
Which species of malaria remain dormant in the liver and can reactivate?
P. vivax and P. ovale (OVer and OVer)
How is the diagnosis of malaria made?
- Giemsa stained blood smear
- Rapid antigen test
What is the function of thin smear v. thick smear?
Thick smear - detects malaria
Thin smear - determines species based on morphology
What are downsides to the rapid antigen tests?
- Sensitivity decreases with low parasitemia and non-falciparum infection
- Can’t differentiate P. falciparum from mixed infections
- May remain positive after treatment
What are major clinical clues to suspect malaria?
Any fever in potentially exposed person (travel to malaria endemic country recently)
- Incubation usually 1-4 weeks
Signs of severe malaria
Mental status altered Acidotic breathing Renal, hepatic, cardiac dysfunction, shock Anemia Hypoglycemia
Treatment for uncomplicated P. falciparum malaria
Artemether-lumefantrine
Atovaquone-proguanil (Malarone)
Mefloquine
Chloroquine
Treatment for P. vivax, ovale and malariae
Primaquine (make sure G6PD activity is good) to treat hypnozoites in liver
Chloroquine for shizonts in blood
Treatment for severe malaria
IV quinine or quinidine Supportive care - Treat hypoglycemia - Monitor anemia and cardiac-respiratory status - Antipyretics - Anticonvulsants if needed
Is malarial anemia due to iron deficiency?
NO, do not give iron!
Due to peripheral hemolysis, bone marrow suppression, inflammation.
