Studies on Canine Dirofilariasis.

Dogs with Dirofilaria immitis microfilaremia were obtained from three geographically distinct areas to determine whether divergent strains of the parasite might develop differently in the mosquito Aedes triseriatus Say. Because no significant differences were noted, results of these experiments were combined to give an overall view of development of D. immitis in Aedes triseriatus. An average of twenty microfilariae was found in the midgut and malpighian tubules of the mosquitoes 24 hours following a blood meal on an infected dog. Over a 15 day period the average number of first and second stage larvae found in the tubules was 6.5. Third stage (infective) larvae were found in the tubules commencing on the 11th day following ingestion of the blood meal. The average number was 2.7/mosquito. These larvae varied in length from 776-865 microns. Mortality of A. triseriatus utilized during these experiments was not a critical factor. (Author)