Molecular Study of Dirofilaria immitis and Dirofilaria repens in Dogs from Tunisia

Dirofilaria immitis and Dirofilaria repens are mosquito-borne nematodes which infect primarily dogs as their main definitive hosts. They cause cardiopulmonary (D. immitis) or cutaneous (D. repens) dirofilariasis in canids and other carnivores and can accidentally be transmitted to humans where they can induce a variety of clinical outcomes depending on organ localization. Dirofilaria spp. infection in dogs was assessed using molecular methods (PCR and sequencing) to identify the different Dirofilaria species occurring in 200 dogs from Northern and Central Tunisia. The overall molecular prevalence of Dirofilaria spp. was 17.5% (35/200). The prevalence of D. immitis (14.5%) was significantly higher than for D. repens (3%). Molecular prevalence of D. immitis was significantly higher in suburban compared to urban and rural regions. There was no difference in molecular prevalence of D. immitis or D. repens according to the dogs' (sex or use). Dirofilaria immitis amplicons (accession numbers KR676386) fall into the same clade with D. immitis from China, India and Taiwan. Comparison of the partial sequences of D. repensITS2 rDNA gene (KR676387) revealed 99.6% similarity with D. repens reported in dogs from USA. It had also 97.6% similarity with D. repens from mosquitoes in Czech Republic. High dog parasite burdens should motivate both medical doctors and veterinarians to consider these frequent infections.