187 - 190 Ng K L.pmd

This study was conducted to investigate the low prevalence of Dirofilaria immitis in dogs in Johor Bahru as reported by veterinary practitioners, using wet blood mount, Knott’s Concentration Test and two heartworm antigen test kits (IDEXX Canine SNAP® 4Dx and RapiGEN®). This study also compared the two test kits used and determined the microfilaria species. Blood were collected from 100 owned dogs and 50 stray dogs in Johor Bahru via cephalic venipuncture. A thick blood smear was done and examined for samples that were positive for microfilaria species identification. The overall prevalence of D. immitis in dogs in Johor Bahru was 1.33% (2/150) and the microfilaria identified was D. immitis. The prevalence of heartworm in owned and stray dogs in this study was 1% and 2% respectively. With only one false negative result from RapiGEN® test kit, comparing the sensitivity between the two test kits could not be achieved. The low prevalence of D. immitis found in this study confirmed anecdotal evidence that prevalence of dirofilariasis is indeed low in Johor Bahru. Additionally, we speculate that dirofilariasis in dogs might be considered as an indicator of vector availability. Heartworm disease is of considerable economic importance affecting canine population around the globe. It is caused by the parasitic worm, Dirofilaria immitis, in arteries of the lungs of affected animals and occasionally in the right side of the heart (American Heartworm Society, 2007). Mosquitoes are the intermediate host for D. immitis. Currently more than 70 species of mosquitoes have been recorded to transmit D. immitis. The type of mosquito present depends on locality and different species have different feeding habits (Kittleson, 1998). In Malaysia, the common species are Armigeres sp., Culex sp. and Aedes sp. (Vythilingam et al., 2005). Johor Bahru city is located at the southernmost tip of peninsular Malaysia, neighbouring Singapore and about 250km south from the densely populated Klang valley which includes the city of Kuala Lumpur. Most studies on heartworm in dogs were done in the Klang valley. Limited information is available in the literature on the occurrence and prevalence of heartworm disease in Johor Bahru. Most dog owners in Johor Bahru do not put their dogs on heartworm prevention programme (personal communication, Dr Tan Check Nam, Global Pets Clinic, Johor Bahru). This practice which differed from that in Klang valley initiated our interest to investigate the anecdotal