Infectivity of gastropod-shed third-stage larvae of Angiostrongylus vasorum and Crenosoma vulpis to dogs

Background Metastrongyloid parasites Angiostrongylus vasorum and Crenosoma vulpis infect wild and domestic canids and are important pathogens in dogs. Recent studies indicate that gastropod intermediate hosts infected with various metastrongyloids spontaneously shed infective third-stage larvae (L3) into the environment via feces and mucus under laboratory conditions. Shed L3 retain motility up to 120 days, but whether they retain infectivity was unknown. Methods To assess the infectivity of shed L3, the heart/lungs of six red foxes (Vulpes vulpes) were obtained from trappers in Newfoundland, Canada. Lungs were examined for first-stage larvae (L1) by the Baermann technique. A high number of viable A. vasorum L1 and a low number of C. vulpis L1 were recovered from one fox; these were used to infect naïve laboratory-raised Limax maximus. L3 recovered from slugs by artificial digestion were fed to two naïve purpose-bred research beagles (100 L3/dog). L1 shed by these two dogs was used to infect 546 L. maximus (2000–10,000 L1/slug). L3 shedding was induced by anesthetizing slugs in soda water and transferring them into warm (45 °C) tap water for at least 8 h. Shed L3 recovered from slugs were aliquoted on romaine lettuce in six-well tissue culture plates (80–500 L3/well) and stored at 16 °C/75% relative humidity. Four naïve research beagles were then exposed to 100 L3/dog from larvae stored for 0, 2, 4, or 8 weeks, respectively, after shedding. Results All four dogs began shedding C. vulpis L1 by 26–36 days post-infection (PI). All four dogs began shedding A. vasorum L1 by 50 days PI. Conclusions L3 infectivity for the definitive host was retained in both metastrongyloids, indicating the potential for natural infection in dogs through exposure from environmental contamination. As an additional exposure route, eating or licking plant or other material(s) contaminated with metastrongyloid L3 could dramatically increase the number of dogs at risk of infection from these parasites. Graphic Abstract

Detection of Crenosoma spp., Angiostrongylus vasorum and Aelurostrongylus abstrusus in Gastropods in Eastern Austria

Canine and feline cardiorespiratory parasites are of utmost relevance in veterinary medicine. Key epizootiological information on major pet metastrongyloids, i.e., Angiostrongylus vasorum and Crenosoma vulpis infecting dogs, and Aelurostrongylus abstrusus and Troglostrongylus brevior infecting cats, is missing from Austria. This study investigated their occurrence in 1320 gastropods collected in the Austrian provinces of Styria, Burgenland, Lower Austria, and in metropolitan Vienna. Metastrongyloid larvae were microscopically detected in 25 samples, and sequence analysis confirmed the presence of metastrongyloids in nine samples, i.e., A. vasorum in one slug (Arion vulgaris) (0.07%), C. vulpis in five slugs (one Limax maximus and four A. vulgaris) (0.4%), A. abstrusus in two A. vulgaris (0.17%), and the hedgehog lungworm Crenosoma striatum was detected in one A. vulgaris. The present study confirms the enzooticity of major cardiorespiratory nematodes in Austria and that canine and feline populations are at risk of infection.

Cardiopulmonary parasitic nematodes of the red fox (Vulpes vulpes) in Serbia

Among the wild canids, the red fox (Vulpes vulpes) is recognised as an important reservoir species for a range of parasites, including cardiopulmonary nematodes of public health and veterinary importance. As cross-host transmission between the red fox and domestic carnivores can play an important role in the epizootiology of cardiopulmonary parasitic diseases, the aim of the present investigations was to obtain data on the geographical distribution of cardiopulmonary nematodes of the red fox. The material for examination consisted of 83 foxes which were legally hunted at different locations during a three-month period from December 2017 to February 2018. The presence of four emerging species in Europe (Angiostrongylus vasorum, Crenosoma vulpis, Dirofilaria immitis and Eucoleus aerophilus) was revealed in red foxes of Serbia. Crenosoma vulpis and E. aerophilus were detected in foxes in both the plain and the mountainous areas across the country. Dirofilaria immitis is distributed in red foxes near alluvial rivers in Vojvodina province (northern Serbia). Angiostrongylosis caused by A. vasorum was demonstrated to exist in two enzootic foci with a high percentage of infected foxes in a plain area of northern Serbia. To the best of our knowledge, C. vulpis and A. vasorum were discovered for the first time in red foxes in central Serbia. The results provide strong evidence for veterinarians to take into consideration the parasitic nematodes discovered in red foxes in the differential diagnosis of diseases of companion animals. In the context of the ‘One Health’ approach the results related to the distribution of the zoonotic species E. aerophilus and D. immitis can be useful for medical epidemiology.