Differentiation of Brugia malayi and Brugia pahangi by PCR-RFLP of ITS1 and ITS2.

Lymphatic filariasis has been targeted by the World Health Organization for elimination by the year 2020. Malayan filariasis, caused by Brugia malayi, is endemic in southern Thailand where domestic cats serve as a major reservoir host. However, in nature, domestic cats also carry B. pahangi infection. In addition to chemotherapy and vector control, control in reservoir hosts is necessary to achieve the elimination of the disease. Therefore, differentiation between B. malayi and B. pahangi in the cat reservoir will help the lymphatic control program to monitor and evaluate the real disease situation. It is difficult to differentiate these two Brugia species by microscopic examination. The technique is also time-consuming and requires expertise. We employed the polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) technique of internal transcribed spacer regions, ITS1 and ITS2, of ribosomal DNA (rDNA) to differentiate B. malayi from B. pahangi species. Among the restriction enzymes tested, only the PCR product of ITS1 digested with Ase I could differentiate B. malayi from B. pahangi. This PCR-RFLP technique will be useful for lymphatic filariasis control programs for monitoring and evaluating animal reservoirs.

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.