Endemic bancroftian filariasis in Thailand: detection by Og4C3 antigen capture ELISA and the polymerase chain reaction.

Lymphatic filariasis, mainly caused by Wuchereria bancrofti and Brugia malayi, has been targeted for elimination by the World Health Organization by the year 2020. To achieve this goal, highly sensitive and specific diagnostic tests are necessary for close monitoring and evaluation of the control program. We employed an ELISA to detect the Og4C3 antigen and a polymerase chain reaction-based assay for diagnosis of W. bancrofti infection, among the Thai-Karen population in Tak province, Thailand. We found that this endemic area had a microfilarial rate of 10 per cent, while the antigen assay could detect cases about two fold as many (23%). The repeated PCR for the detection of Ssp I of W. bancrofti was positive in 12 per cent of the population under this study. Our data emphasize the need for using highly sensitive and specific assays for assessment of the real burden of the disease.

Lymphatic filariasis caused by Brugia malayi in an endemic area of Narathiwat Province, southern of Thailand.

Lymphatic filariasis caused by Brugia malayi is highly prevalent in Narathiwat province of Thailand. The World Health Organization has aimed to eliminate the disease globally by the year 2020. To achieve the goal, assessment of the real disease situation should be integrated as part of the control program. The preliminary data for long-term study of the disease situation in this endemic area is necessary for the elimination program of lymphatic filariasis. By using the conventional microscopic method, the microfilarial rate of B. malayi in an endemic area of Narathiwat province was 1.38 per cent. The microfilarial densities ranged from 17 microfilariae/ml to 1,250 microfilariae/ml median = 50. The highest prevalence was found in the age group > 45-60 (4.69%). The lowest microfilarial rate was in the age group < or = 15 (0.37%). The infection in males was about three fold the number in females. A PCR-based method was employed to detect a B. malayi-specific Hha I repetitive DNA sequence with high specificity and sensitivity. The PCR assay will be useful in assisting the elimination program of lymphatic filariasis in control and monitoring the disease in Thailand.