A survey of the prevalence of dirofilaria immitis (heartworm) infection in dogs along the Kenya coast

Abstract

Dirofilaria immitis (D. immitisi also known as heartworm is the causative agent of dirofilariasis, a major condition in the dogs which is associated with debility and deaths in severe cases. It is known to occur in dogs and other animals particularly in coastal areas all over the world. The high prevalence of this parasite in several countries has necessitated the use of regular testing and chemoprophylaxis against it. In the majority of the remaining countries however, the states of this condition in dogs have not been published. Information on prevalence is important for setting up monitoring and control programmes of any disease, in any particular area. In the case of the Kenya coast, no work has been done to give an indication of the prevalence of D. immitis despite several anectodal reports suggesting its existence there. This survey was therefore carried out with the primary objectives being (i) to determine the prevalence of D. immitis in dogs residing at the Kenyan coast (ii) to examine factors that may predispose dogs to heartworm infection (iii) to determine the occurrence of other filarids in the same dogs and (iv) to recommend appropriate control measures. A total of 830 dogs of mixed breed and sex, aged above 6 months were selected from ten areas situated along the Kenya coast and examined for heartworm and other filarial infections by parasitological and serological methods and also by necropsy. In this survey, the prevalence rate of D. immitis was found to be 17.3 %. Another filaria species, Dipetalonema reconditum, which is nonpathogenic to dogs was found to exist with D. immitis in examined dogs in almost equal proportions. It was concluded from the results, that D. immitis is an important veterinary pathogen in the Kenyan coast and that its prevalence there warrants efforts to design appropriate control measures. In the view of this, routine annual testing of resident dogs for heartworm infection followed by chemotherapy in positive cases and also the use of regular chemoprophylaxis are recommended for the whole coastal area of Kenya.