• Parasites, Hosts and Diseases
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• v.36 no.4
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• pp.235-239
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• 1998

Microfilarial periodicity of Dirofilaria immitis (the dog heartworm) was determined at two hr intervals for 72 consecutive hrs in 10 naturally infected war dogs, 3-9 years old, in Korea to facilitate harvest of the microfilariae for possible use in laboratory works and to elucidate further the periodicity of the microfilaria depending on geographic location, Although the periodicity had been observed as being lowgrade nocturnal, maximal microfilarial counts were found at 21 :00 hr and minimal at 11 :00 hr, giving rise to an evident peak in fluctuation of the larval counts. This is the first record of the periodicity of the microfilariae identified as D. immitis in Korea.

• Journal of Veterinary Clinics
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• v.22 no.2
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• pp.79-83
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• 2005

Six dogs including 4 dogs living in different geographic locations of Kangwon province and 2 client-owned dogs were used to determine the periodicity of microfilariae of D. immitis using a trigonometric model. The calculated periodicity index was ranged from 25.6 to $95.5\%$ with mean of $57.6\%$, and the estimated hour of peak was approximately 21:00 hrs (range, 20:04-21:29 hrs) and minimum counts at 09:00 hrs (range, 08:04 - 09:29 hrs). Correlation coefficient between the observed and the expected count from the model varies depending on dogs, ranging from 6.4 to $49.2\%$. Based on this study, the periodicity of microfilariae of D. immitis was considered as nocturnally sub-periodic for all dogs employed. This result is in consistent with previous report in peak hour but different in minimal hour, indicating that further studies on the periodicity need to be performed to better understanding the dynamics of the periodicity and to help practitioners in the choice of the time for examination of the dogs.