Field application and evaluation of a rapid immunochromatographic test for detection of Plasmodium falciparum infection among the inhabitants of Lao PDR.

Field application and evaluation of a rapid immunochromatographic test (ICT) for detection of Plasmodium falciparum infection were performed in 13 villages in a southern province of Lao PDR in 1999. More than 2,000 inhabitants, accounting for 61.8% of the total estimated population, were examined. Malaria infection was confirmed in all villages surveyed by ICT and microscopic diagnosis. The positive rates of P. falciparum malaria by microscopy ranged from 9.7% to 59.2% (mean 27.2%), whereas by ICT they were from 11.6% to 64.5% (mean 29.8%). The positive rates by ICT were generally higher in 8 out of 13 villages. However, a significant difference between the positive rates by microscopy and ICT was not observed in all villages. Plasmodium falciparum infection was actually confirmed by microscopy in 84.1% of specimens that tested positive by ICT. The results by ICT were consistent with those of the microscopic diagnosis, the discrepancy of the results was less than 10% (141/2,066). The ICT was falsely-positive in 4.7% and falsely-negative in 2.1% of the test cases. These results showed the efficacy of ICT not only in the diagnosis of the respective cases, but also in the mass-examination in the field.