Detection of filarial nematodes in domestic cats by suing PCR-RFLP

Abstract

Lymphatic filariasis has been targeted by the World Health Organization to be eliminated by the year 2020. Malayan filariasis, caused by Brugia malayi, is endemic in India, Indonesia, Malaysia, Philippines, Sri Lanka, and the Southern Thailand where domestic cats serve as a major reservoir host. However, in nature, domestic cats also carry B. pahangi, Dirqfilaria immitis and D. repens infections. In order to assess the burden of filarial nematodes in domestic cats, we studied domestic cats in an endemic area of malayan filariasis at Pra-sang district, Surat-thani, a province in Southern Thailand. Together with Giemsa stain and acid phosphatase activity studies, we performed PCR-RFLP analysis of the first internal transcribed spacer (ITS 1) region of ribosomal DNA (rDNA). The PCR-RFLP of ITS1 with Ase I could differentiate B. malayi, B. pahangi, D. immitis and D. repens. Out of the 52 study cats, filarial parasites were identified in 3 (5.7%) cats, of which 2 (3.8%) were B. pahangi, and 1 (1.9%) D. immitis. The PCR-RFLP technique could detect two more blood samples with B. pahangi, increasing the total prevalence of filarial parasites to 9.5%. Our data suggest that the domestic cats are not an important host of B. malayi in this region of Thailand. However, D. immitis and D. repens, can cause dirofilariasis in human, a zoonotic infection. Therefore, it should be of public health concern. The high sensitivity and specificity of this PCR-RFLP method makes it valuable for large-scale epidemiological studies of filarial parasites in animal reservoir hosts, and can be applied for studies in human, as well as mosquito vectors.