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.

Brugia malayi in a naturally infected cat from Narathiwat Province, southern Thailand.

Brugia malayi-like from an infected cat from Narathiwat Province, southern Thailand was identified intensively by microfilarial morphometry, acid phosphatase activity, and adult morphology. The results indicated that both microfilarial and adult characteristics conformed to the topotypic B. malayi.