Parasitological, Serological and Molecular Study of Dirofilaria immitis in Domestic Dogs, Southeastern Iran

Abstract

Background: Dirofilariasis is a serious and potentially deadly condition in dogs and one of the zoonotic filarial infections, which inadvertently affects the humans. The objectives of this study were to determine the seroprevalence and the molecular identity of dirofilariasis in Kerman Province, southeastern Iran between Jul and Aug 2013.

Methods: A hundred and forty-nine domestic dogs were randomly selected and five ml blood samples were taken from each dog. One ml of anticoagulant (EDTA) was used for each test in the parasitological study (modified Knott's test) and sera samples were examined, using ELISA kit to detect Dirofilaria immitis antigen. Extracted DNA of all positive blood samples was used for molecular characterization and sequencing.

Results: Four (2.7%) domestic dogs of the total 149 domestic dogs were infected with micofilariae of D. immitis, while the serological study showed 8 (5.4%) domestic dogs were infected with D. immitis. No significant difference, however, was found between dirofilariasis infection and gender. On the other hand, a significant difference was observed between dirofilariasis infection and age (P<0.05). Based on the PCR findings, among the total specimens, 6 positive samples were characterized as D. immitis.

Conclusion: Dirofilariasis occurred when there was low endemicity in the dogs. Such dogs could be a potential source of infection for humans. These findings could help in better understanding of the epidemiological aspects of D. immitis in the southeastern parts of Iran.

Keywords: Diagnostic tests; Dirofilaria immitis; Domestic dog; Iran.

Fig. 1:

Amplification of partial cytochrome c oxidase subunit 1 in mitochondrial DNA, using primers new DirF and DirR Primers. Six positive isolates that were amplified 680 bp PCR products showed as lanes 1, 2 and 5 to 8, negative isolates (lanes 3 and 4), non-template control (lane N), molecular size marker (lane M)

Fig. 2:

A phylogenetic tree rooted by out-group (Thelazia callipaeda), inferred from partial CO1 nucleotide sequences using the Neighbor-Joining method after Kimura2 correction. Scale bar indicates the proportion of sites changing along each branch