Dirofilaria immitis infection in the Pelagie archipelago: The southernmost hyperendemic focus in Europe

Abstract

Dirofilaria immitis and Dirofilaria repens are mosquito‐borne filarioids of zoonotic concern, which primarily cause canine heartworm disease (HWD) and subcutaneous dirofilariosis, respectively. The geographical distribution of these nematodes is constantly changing, due to many factors such as the colonization by new invasive mosquito species, the increased movement of animals and the absence of chemoprophylactic strategies in non‐endemic regions. Although HWD has always been considered endemic in northern Italy, an increase in the prevalence of this disease has been recorded in the last decades in central and southern regions. We describe the southernmost hyperendemic European focus of heartworm disease in the Pelagie archipelagos. From June to November 2020, 157 dogs and 46 cats were sampled in Linosa and Lampedusa islands for the detection of Dirofilaria immitis and Dirofilaria repens by modified Knott's, rapid antigen and molecular tests. Mosquitoes were collected using CDC light and BG sentinel‐2 traps and aspirators, and tested for host blood meal and Dirofilaria spp. DNA. Out of 56 dogs in Linosa and 101 in Lampedusa, 33 (i.e. 58.9%) and 8 (i.e. 7.9%) were positive to D. immitis and D. repens, respectively. Three cats scored positive to D. immitis (i.e. 17.6%) in Linosa. Six mosquito species were identified, and the abdomen of a non‐engorged Aedes albopictus was positive for D. immitis and human DNA. The results suggest that D. immitis infection could spread to new previously non‐endemic territories in southern Europe, representing a real threat to animal and human health.

Zoonotic Dirofilaria immitis and Dirofilaria repens infection in humans and an integrative approach to the diagnosis

“…Our results suggest that humans living in the islands of Lampedusa and Linosa (Pelagie archipelago) are exposed to both Dirofilaria spp., overlapping the distribution of dogs (Brianti et al, 2021). In particular, while the difference in prevalence of D. immitis infection in humans (7.8%) in Linosa and Lampedusa is not statistically different, D. repens was more prevalent in Lampedusa.…”

“…Study sites have been described elsewhere (Brianti et al, 2021). Briefly, Lampedusa (20.2 sq km) and Linosa (5.4 sq km) are two small islands of the Pelagie archipelago, almost equidistant from Italian and Tunisian coasts and populated by nearly 300 and 6000 inhabitants, respectively.…”

“…Currently, hyperendemic foci of D. immitis infection in dogs are described in Apulia region (southern Italy) (Panarese et al, 2020a;Panarese et al, 2020b), as well as in the Pelagie archipelagos, with a prevalence of 58.9% for D. immitis and 7.9% for D. repens in Linosa and Lampedusa, respectively (Brianti et al, 2021). The latter finding represents the southernmost focus of the infection and triggered the scientific interest in investigating the exposure of asymptomatic patients living in a confined/close environment (i.e., Linosa and Lampedusa) where many interactions among humans, dogs and cats occur.…”

Simultaneous Exposure to Angiostrongylus vasorum and Vector-Borne Pathogens in Dogs from Italy

“…The presented results and recent analysis [ 56 ] ultimately prove that, to date, all Italian regions should be considered potentially enzootic for D. immitis and L. infantum and corroborate the changing epizootiological scenario of dog dirofilariosis in Italy, following an expansion from Northern areas southwards [ 56 , 57 ]. Hence, worthy of note is the establishment of hyperendemic foci of dirofilariosis in the extreme South of Italy, and vice versa for leishmaniosis [ 58 , 59 , 60 , 61 ].…”

Identity of Microfilariae Circulating in Dogs from Western and South-Western Romania in the Last Decade

“…Dirofilaria repens, an agent that generally causes subclinical infections, is responsible for subcutaneous dirofilariosis in dogs and it is frequently linked with the presence of adults in subcutaneous tissues, representing the main cause of human dirofilariosis. The clinical signs of this infection in dogs include pruritus, localized alopecia, or cutaneous ulceration [3][4][5][6][7][8][9].…”