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In P.
falciparum infection, the parasite density can be very high, particularly in
non-immune individuals. High parasite count
above 5% is considered as hyperparasitemia and is a form of severe falciparum malaria. The
parasite count can go up to 50% or 500000/m l. High parasitemia and presence of schizonts
of P. falciparum in the peripheral blood are associated with a higher mortality.
Partially immune children, however can tolerate high parasitemia (20-30%) without clinical
symptoms.
Patients with
hyperparasitemia may not have any specific clinical features and therefore it is very
important to do a peripheral smear examination for parasite count in all cases of
falciparum malaria. Some patients may have significant anemia, jaundice, prostration etc.
Management: Patients with
hyperparasitemia should be treated with parenteral antimalarials, even if they can take
oral medications. Artemisinin derivatives may be especially useful in these patients. The
parasite count should be monitored once every 12 hours to assess the response to therapy.
Adequate hydration should be maintained.
If the parasite count is above 10%, exchange transfusion may be beneficial. It can reduce the
parasitemia more rapidly than chemotherapy alone and in addition could remove harmful
metabolites, toxins, cytokines and other mediators and may also restore normal red cell
mass, platelets, clotting factors, albumin and other depleted substances. However, the
procedure carries its own risks of electrolyte disturbances, hypocalcemia, cardiovascular
problems, blood-borne infections and infection of the intravenous line. There are also
reports of ARDS developing with this procedure. However, the procedure may still be
tried in patients who are severely ill, not responding adequately to antimalarial therapy
and who have a parasite count of >10%. Newer drugs like artemisinin which clear
parasitemia rapidly may obviate the need for exchange transfusion.
Hyperpyrexia:
High body temperature above 105°F (40.5°C) is common in falciparum
malaria. Hyperpyrexia is more common in children and may be associated with convulsions,
delirium and coma. Temperature above 42°C may cause permanent severe
neurological sequelae. In pregnant women, high temperature can result in fetal distress or
fetal loss.
Treatment involves administration of
antipyretics like paracetamol (15 mg/kg body weight), tepid sponging and fanning.
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