Malaria
The 5 species of malaria parasites now known to affect humans differ in their geographic distribution:
| Plasmodium falciparum | most common in sub-Saharan Africa and Melanesia (Papua New Guinea and the Solomon Islands) | can cause rapidly progressive and severe illness and death |
|---|---|---|
| P. vivax | mainly Central and South America, North Africa, the Middle East and within the Indian subcontinent | less severe but treatment for hypnozoites which lie dormant in the liver is necessary to help prevent relapses |
| P. ovale | almost exclusively in West Africa | |
| P. malariae | mainly in Africa. | |
| P. knowlesi | on the island of Borneo and other parts of South-East Asia | can cause rapidly progressive and severe illness and death |
- Thick blood smears are more sensitive in detecting malaria parasites because the blood is more concentrated
- -ve blood smear makes diagnosis of malaria unlikely but non-immune individuals may be symptomatic at very low/indetectable parasite densities, therefore blood smears should be repeated every 12-24/24 x3 before ruling out Dx.
- Rapid antigen test also available but less sensitive
- PCR test more sensitive and specific than microscopy