Evaluation of serology as a tool for malaria surveillance in East Champaran District of Bihar, India.

The indirect immunofluorescence test was evaluated as a tool for malaria surveillance. The population of 12 villages in the East Champaran District of Bihar with a low annual parasitic index and a low annual blood examination rate was surveyed in order to confirm the low endemicity of malaria in these villages. Two specimens of blood, one taken during the pre-transmission season and one taken during the post-transmission season, were collected for parasitological and serological studies. The paired samples showed no parasite positivity in the study population in both surveys. All the villages had very low serological titres. However, the presence of malaria antibodies in the zero to five years age group (the sentinel group) indicated that malaria transmission occurred in the study area at a very low level. The seropositivity and the geometric mean titre were lower in the pre-transmission season than in the post-transmission season, but the overall reduction in geometric mean titre, which was very low throughout the study, was not statistically significant. The study emphasizes the importance of serological tests in malaria surveillance.