Comparison of thick films, in vitro culture and DNA hybridization probes for detecting Plasmodium falciparum malaria.

Using blood from volunteers with sporozoite induced malaria, a comparison was made of the sensitivity and specificity of Giemsa stained thick film examination, in vitro culture, and 4 different DNA probes for detecting parasitemia. Between 9 and 13 days after sporozoite inoculation, patent parasitemia (4-550 parasites/microliters) was detected by thick film examination of 0.5 microliters blood in 7 volunteers. Cultures of 1 ml blood obtained 7 days after sporozoite inoculation were positive in all volunteers who eventually developed patent parasitemia. The DNA hybridization probes detected parasites in only 5-28% of smear- or culture-positive samples.