A total of 764 adult dogs were examined for microfilariae and adult worms of D immitis and 197 (25-8 per cent) were found to be infected. Direct blood examinations revealed only 47-2 per cent of the infected dogs whereas the blood serum examination detected 57-8 per cent of them. These results showed that the absence of circulating microfilariae could not be relied upon to be an accurate indication of the absence of patent heartworm infection. The average number of heartworms per dog was 5-5 with a range of one to 50.
Filarial infections in 447 cats and 68 dogs from six endemic areas of human filariasis in Peninsular Malaysia were studied as part of the study on the zoonotic transmission of subperiodic Brugia malayi infection. 20.6% of cats and 57.4% of dogs had filarial infections. Cats were infected with subperiodic B. malayi, B. pahangi, Dirofilaria repens and D. immitis. Dogs were infected with B. pahangi and D. immitis. 6.9% of the cats had subperiodic B. malayi infection. The zoonotic implications of these infections and their impact on the filariasis control programme in Peninsular Malaysia were discussed.
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.
In 3 urban areas in Selangor, Peninsular Malaysia between 1973 and 1981, blood from 4084 dogs was examined for haematozoa. The following frequencies were found: Babesia gibsoni 17.7%; microfilariae of Dirofilaria immitis 9.6%; Hepatozoon canis 1.2%; B. canis 1.1%; Ehrlichia canis 0.2%; Trypanosoma evansi 0.1%. A detailed examination of B. gibsoni infections and microfilariasis due to D. immitis with regards to monthly distribution, breed frequency, sex and age, revealed that pedigree and non-pedigree dogs were equally susceptible to Babesia and microfilariae infections.
Human dirofilariasis due to Dirofilaria (Nochtiella) repens is a common zoonotic infection in Sri Lanka. Todate 70 cases are on record, and they include 3 expatriates from Russia, England and Korea, who were undoubtedly infected in Sri Lanka. Around 30-60% of dogs are infected with D. repens in various parts of the country and the mosquito vectors are Aedes aegypti, Armigeres subalbatus, Mansonia uniformis and M. annulifera. Unlike in other countries of the old world infection is most common in children under the age of 9 years, the youngest being 4 months old and the scrotum, penis and perianal regions of male children appear to be frequent sites for the worms. Dirofilaria (Dirofilaria) immitis is not present in Sri Lanka though it is present in neighbouring countries like India, and Malaysia.