Approach to the seroprevalence of heartworm disease in ferrets (Mustela putorius furo) in the endemic area of the Canary Islands

Abstract

Heartworm disease is a zoonotic and vector-borne disease in which canids act as the definitive hosts. There are other types of less adapted hosts such as domestic cats and ferrets. In the ferrets, susceptibility to infection is similar to that observed in domestic dogs, and natural infection appears to be related to canine prevalence in an endemic area. Although several case reports of cardiopulmonary heartworm in ferrets have been published, the factors that determine actual infection are still unknown. In addition, diagnostic tests in ferrets are the same as those used in infected dogs and cats, with no specific diagnostic tests on the market. The detection of microfilariae has only been reported in half of the cases and is due to the low number of living adults. The objective of this work was to study the seroprevalence of Dirofilaria immitis in ferrets on the island of Gran Canaria and Tenerife (Canary Islands). A total of 106 privately owned ferrets were used and information on their clinical findings, habitat and geolocation was recorded. Blood samples were obtained from all ferrets and subjected to three different diagnostic tests: the Knott technique to visualize circulating microfilariae, commercial immunochromatographic test for antigen detection and ELISA technique for the detection of circulating antibodies against D. immitis. As positive controls, sera from ferrets with heartworms by ultrasound and positivity in the antigen test were used. As negative controls, ferrets with all these negative tests were used, as well as the Knott test. The results showed that, using the antigen test, the prevalence was 0.9% (1/106) and using the Knott technique it was 5.66% (6/106). On the other hand, the ELISA technique developed for this study showed that the seroprevalence was 10.38% (11/106). Our results show, for the first time, the presence of seropositive ferrets on the islands of Gran Canaria and Tenerife, hyperendemic areas for heartworm disease. These results imply the possibility of including this serological test in the diagnosis in ferrets. More studies are necessary to help the efficiency in the diagnosis, as well as to implement preventive measures in these hosts.