malaria

Question 1

pathophysiology

Answer 1

BASICALLY: infected erythrocytes in the liver, then in the blood

During a blood meal, an infected female Anopheles mosquito injects 8 to 15 malarial sporozoites, which rapidly enter hepatocytes. Reproduction by asexual fission (tissue schizogony) takes place to form a pre-erythrocytic schizont. This part of the life-cycle produces no symptoms. After a period of time, 30 to 40 thousand merozoites are released into the bloodstream to penetrate erythrocytes after attaching via receptors. The time period before merozoites enter the blood is designated the pre-patent period; this is between 7 and 30 days for Plasmodium falciparum, but may be much longer for Plasmodium vivax or Plasmodium ovale because of the possible development of an inactive hypnozoite stage in the liver.[23]

Most merozoites undergo blood schizogony to form trophozoites, evolving to schizonts, which rupture to release new merozoites. These then invade new erythrocytes and the 48-hour (72-hour for Plasmodium malariae and 24 hour for Plasmodium knowlesi) cycle continues, sometimes resulting in periodicity of fever. The rupture of erythrocytes releases toxins that induce the release of cytokines from macrophages, resulting in the symptoms of malaria.[24] Some merozoites mature into larger forms called gametocytes, which reproduce sexually if they are ingested by a mosquito.

The outcome of infection depends on the infecting species, the patient’s age, and the level of host immunity.[11][24] Severe disease is more commonly seen with P falciparum, with sequestration (the binding of mature trophozoites to the endothelium of small blood vessels), rosetting (the formation of clumps of infected and uninfected erythrocytes), impaired red cell deformability (in infected and uninfected erythrocytes), cytokine responses, and high levels of parasitaemia (relating to the multiple entry pathways for P falciparum into erythrocytes), which are all likely to contribute to this high mortality.

Question 2

symptoms

Answer 2

fever
headache
weakness
myalgia
arthralgia
anorexia
diarrhoea

nausea and vomiting
abdominal pain
pallor
jaundice
hepatosplenomegaly
altered level of consciousness
hypotension
anuria/oliguria

Question 3

investigationsysis

- ABG

Answer 3

• giemsa-stained thick and thing blood smears
• rapid diagnostic testing
• FBC
• clotting profile
• U&E, creatinine
• LFTs
• blood glucose
• urinalysis
• ABG