Abstract

Objective: To analyze the epidemiology of Dirofilaria immitis (D. immitis) infection in different categories of dogs in Assam. Methods: Microscopy of blood in wet film preparation was conducted in two dog populations during 2009 and 2010, and data obtained were analyzed to investigate the infection pattern according to season, living condition, breed, sex and age of dogs. Results: Examination of 424 clinically ill dogs (hospital population) presented at the referral Teaching Veterinary Clinical Complex, Guwahati, Assam revealed 5.42% cases microfilaraemic. Clinical cases of D. immitis infection were recorded throughout the year with 9.10% as the highest record during pre-monsoon and 1.12% as the lowest in the winter. Pet dogs staying indoor showed 4.76% microfilaria positive compared to 7.95% record among working dogs with restricted outdoor activity. Breed wise, Dalmatian dogs representing 3.53% of the study population were negative to microfilaria while among the positives, Doberman showed 30.76% infection rate as the highest and 2.94% lowest record in the Labrador. Rate of infection was slightly higher in the males (5.81%) than the females (4.81%). Dogs below 2 years of age were negative to microfilaria while it was 3.70% in 2-4 years age group with a rising trend reaching 28.00% as the highest in 6-8 years age group. Examination of non-descript (street dog population) adult dogs living outdoor showed 29.54% microfilaraemic, the rate of infection being higher in males (37.50%) than the females (25.00%). Similar non-descript dogs living indoor as pets however showed only 11.11% microfilaria positive. Conclusions: The study shows endemicity of D. immitis in dogs of Assam with living condition and age as the host related important risk factors, which have significant role in its epidemiology

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