Prevalence of Dirofilaria repens in dogs in Potchefstroom and Mahikeng, South Africa

Abstract

Dirofilaria repens is a filarial nematode causing subcutaneous dirofilariosis in canids and felids, both domestic and wild. It is a mosquito-borne infection with zoonotic implications. Though previous studies have shown the presence of D. repens in domesticated dogs and cats in South Africa, there is less available evidence regarding its occurrence specifically in the North West Province, particularly among hunting and shelter dogs. The research was focused on North West Province on account of its geographical proximity to Gaborone, Botswana, where prior surveys have identified a significant prevalence of D. repens in dogs. The aim of this study was to investigate the prevalence of D. repens in dogs in the towns of Potchefstroom and Mahikeng, located within North West Province. The study focuses on dogs, as they are considered to be more competent hosts and reservoirs of the infection, in comparison to cats, and thus are a major source of D. repens for mosquitoes which then transmit infection to humans. Human cases of dirofilariasis due to D. repens have been documented in South Africa. A quantitative, correlational, cross-sectional study employing convenience and random sampling was conducted. Sheltered dogs at the Potchefstroom Animal Welfare Society (PAWS) were targeted in Potchefstroom, whereas hunting dogs kept in colonies were targeted in Mahikeng. A total of 157 animals were tested, 87 from Potchefstroom and 70 from Mahikeng. Venous blood drawn into EDTA tubes was screened for microfilariae using the membrane filtration test. No microfilariae were detected in samples from Potchefstroom. Microfilariae were detected in 14 out of 70 samples from Mahikeng. Acid phosphatase staining confirmed these positive samples to be attributed to Acanthocheilonema reconditum, which is regarded as non-pathogenic. Dirofilaria repens was not detected in this survey. Based on our findings, it can be concluded that the presence of D. repens in hunting and shelter dogs in the towns of Mahikeng and Potchefstroom, North West Province, is either absent or exhibits a low prevalence, hence hindering its detection in the current study. Future research endeavours should prioritize the broadening of sample sizes and survey locations in the province, as well as the diversification of sampling populations to include cats and mosquitoes.