A cross sectional study on Dirofilaria immitis and Acanthocheilonema reconditum in sheepdogs in a western region in Iran.

Iran is one of the endemic areas of Dirofilariasis, and also one of the most important zoonotic infections. Dirofilaria immitis causes a severe and fatal disease called heartworm disease in dog. It also produces pulmonary nodules in humans. The worm is to be investigated as a potential infection of humans and animals in various provinces in Iran. In this research, the samples were studied with modified Knott's test and molecular method. The results of the modified Knott's test method indicated that 14.00% of sheepdogs were infected with filarial microfiler. The microfilers were characterized with basic morphological features, the length of the infective larva and tail ending. There was an estimated prevalence of 4.45% for Dirofilaria immitis and 9.55% for Acanthocheilonema reconditum microfiler. To verify the differential diagnosis, molecular method was performed using PCR with Dirofilaria specific primers for amplification of ITS2 locus. Gene locus sequencing results of D. immitis and sequence alignment recorded in GeneBank showed 97.00% similarity, and relatively 98.00% similarity was observed in A. reconditum. The results of the molecular method confirmed the result of modified Knott's test method. Low infection with D. immitis was observed the region, probably due to the fact that the annual temperature and precipitation in this area were not suitable for the proliferation of the vector mosquitoes. In general, there was less infection in the region compared to regions with relatively similar climatic conditions. Hence, the results suggested that alternative diagnostic tests are required to determine the occult infections.