Seroprevalence of Feline Heartworm in Spain: Completing the Epidemiological Puzzle of a Neglected Disease in the Cat

Abstract

Feline heartworm is a vector-borne zoonotic disease caused by Dirofilaria immitis. It is a cosmopolitan disease that is continuously expanding. Spain is considered an endemic country; however, although there are many published studies in dogs, feline heartworm has been poorly studied in this country. Thus, the objective was to analyze the exposure to D. immitis throughout Spain to complete the epidemiological map in the feline species. For this, 6,588 feline serum samples were analyzed for the presence of D. immitis antigens and antibodies against D. immitis and Wolbachia. The results were analyzed according to sex, age, breed, habitat, origin (owned or shelter cats), presence of clinical signs, use of preventive, location and climatology. The results showed a prevalence of 0.5% and a seroprevalence of 9.4%. The highest antibody seroprevalences were reported in the Canary Islands and the Balearic Islands (19.2 and 16%, respectively), as well as in the autonomous communities located on the Mediterranean coast (9.2–11.2%). Seropositive cats were found in both indoor and outdoor cats, and from 6 months of age. Furthermore, only 5.8% of cats received regular prophylactic treatment. The results show that feline dirofilariasis is widely distributed throughout the national territory and corroborate that, where infected dogs are present, there are cats exposed to the parasite. It is necessary to implement efficient awareness and prophylaxis measures to control the incidence and expansion of feline heartworm in Spain.

Microfilaremic infection in canine filariosis in Colombia: a challenge in morphological and molecular diagnostics

“…In addition, we also found significant differences by socioeconomic level, which may be because of a non-uniform number of samples at all levels and variation in the administration of ectoparasiticides. A higher prevalence rate of parasitic infection was reported in animals in which ectoparasiticides were not administered, as other authors have reported ( 22 , 27 , 28 , 46 , 56 , 57 ).…”

“…The Woo and Knott techniques could generate false-negatives because of low parasitemia, interactions of a single sex of parasites, immaturity of the parasites, ectopic location of the adult worms, and application of microfilaricides, leading to a decrease in the sensitivity of the tests to identify the presence of filariae (46,(48)(49)(50)(51)(52)(53)(54)(55). This is where the identification of antibodies and circulating filarial antigens in blood becomes important (9,16,40,54,(56)(57)(58). Commercial tests for the detection of only circulating antigens of D. immitis in dogs and cats are available in Colombia, with sensitivities and specificities versus necropsy of over 94 and 100% respectively, allowing identification of dogs without microfilaremia and in which even a single adult worm is present (10,28,40).…”

Current Risk of Dirofilariosis Transmission in the Iberian Peninsula (Spain and Portugal) and the Balearic Islands (Spain) and Its Future Projection under Climate Change Scenarios

“…Spain and Portugal have traditionally been considered endemic countries, although not all areas of the Iberian Peninsula have been studied [5]. In Spain, the prevalence of D. immitis in dogs is 6.47% [13], and the seroprevalence in cats is 9.4% [14]. In the case of Portugal, published studies in dogs provide prevalence values ranging from 0.9% to 27.3%, being higher in the south [15][16][17][18][19][20].…”

Human Subcutaneous Dirofilariasis Behind a Blepharoconjunctivitis: A Case Report and Review of the Literature

“…Sporadic human infections have also been reported. Moreover, seroprevalence studies indicate that the rate of infection in humans is almost similar to that in canids and felines in endemic areas, suggesting that a significant portion of human infections are asymptomatic or self-limiting [5][6][7][8][9].…”