Serological investigation of malaria outbreak in Thar desert of Rajasthan.

ABSTRACT

A serological investigation by a repeat cross-sectional survey was conducted in Thar desert (Rajasthan) during and after one year of malaria outbreak to determine malaria endemicity using ELISA as a tool. The assay was based on indirect ELISA to measure antibody levels against a nonapeptide R1 (EENVEHDA-cys) derived from Pf 155/Resa and Plasmodium falciparum crude antigen. Finger prick blood samples were collected from individuals belonging to all age groups. Sera were tested at already standardized optimum dilution to detect antigen specific immunoglobulin isotype. The mean ELISA O.D. values 0.153 for anti R1 peptide and 0.162 for anti Pf antigen reflected the seronegative profile, when the focal malaria outbreak occurred in 1994. A substantial increase in antibody levels was detected in individuals after one year showing mean ELISA values for anti-R1 and anti-Pf antigens as 0.52 and 0.58 and seropositivity as 75.2% and 52% respectively. Data obtained from the present study indicate that serological survey could be done to assess the situation in case of reappearing or disappearing status of malaria in a defined population.