Echinococcus Species Infections among Wild Canids in Pennsylvania, USA.

Echinococcus species are zoonotic tapeworms that can impact the health of wildlife, domestic animals, livestock, and humans. Two species of interest in North America are Echinococcus multilocularis and Echinococcus canadensis (Echinococcus granulosus sensu lato). The primary wildlife definitive hosts for E. multilocularis and E. canadensis are similar, including red foxes (Vulpes vulpes), gray foxes (Urocyon cinereoargenteus), coyotes (Canis latrans), and wolves (Canis lupus). These two Echinococcus spp. use different intermediate hosts, including small mammals for E. multilocularis and artiodactylids for E. canadensis. Although historically absent from much of the eastern US, recent reports in new US states (e.g., Virginia, Vermont, Maine, Missouri) highlight the need for Echinococcus spp. surveillance in this region. During 2019-2020, 308 gastrointestinal tracts were collected from wild canids in Pennsylvania and microscopically screened for adult Echinococcus species. Two coyotes (2/155) were co-infected with both E. multilocularis and E. canadensis as determined by molecular confirmation. No red foxes (n=137) or gray foxes (n=16) were positive. These data indicate both Echinococcus species are present in Pennsylvanian coyotes, highlighting the need to better understand the ecological and epidemiological consequences for human and animal health.

Characterization of the genetics and epidemiology of Brugia sp. in domestic dogs in Chad, Africa.

Neglected tropical diseases pose a threat to domestic animal health, as domestic animals can serve as reservoirs for certain zoonotic parasitic infections, including Guinea worm (Dracunculus medinensis) and lymphatic filariasis. Surveillance for these parasites in domestic animals is needed to understand infection prevalence and transmission cycles, with the goal of instituting appropriate interventions. The goal of this research was to report our finding of Brugia sp. infection in dogs from Chad, Africa, and to characterize the genetics and epidemiology of the parasite. During a recent Chadian canine pathogen surveillance project, we identified Brugia sp. infections in a total of 46 out of 428 dogs (10.7%) sampled at three time points in 2019-2020. We found high levels of sequence similarity to B. malayi and B. pahangi based on amplification of 18S rRNA, 5.8S rRNA, and ITS-2 regions. Phylogenetic analysis of 18S rRNA gene sequences placed the Chadian Brugia sp. in a clade with other Brugia spp. but grouped it separately from both B. malayi and B. pahangi. Analysis of Hha I sequences showed the greatest similarity with B. patei, a parasite previously reported from dogs, cats, and wildlife hosts in Kenya. Epidemiologic analysis using generalized linear regression modeling found significantly higher odds of Brugia sp. detection among dogs in villages in southern Chad compared to those in the northern region. Further, within the northern region, there were higher odds of detection in the dry season, compared to the wet season, which is consistent with the ecology of a presumably mosquito-borne parasite. The same 428 dogs were tested for Dirofilaria immitis antigen using a commercial assay (IDEXX SNAP 4Dx) at the earliest time point of the study, with 119 dogs testing positive. However, no association was noted between Brugia infection and a dog being positive for Di. immitis antigen, with only seven of the 119 Di. immitis antigen-positive dogs being Brugia-positive. This is the first report of Brugia sp. in domestic dogs in Chad and additional research is needed to definitively identify the species present, elucidate transmission, and understand potential risks to canine and human health.

Notoedric mange (Notoedres centrifera) in two species of free-ranging rabbits from Florida, USA.

Mange is a contagious skin disease caused by different mite species affecting numerous domestic and wild animals, worldwide. This report details notoedric mange in an eastern cottontail (Sylvilagus floridanus) and in a marsh rabbit (Sylvilagus palustris) from Florida, USA. Clinical examination revealed similar gross lesions including poor nutritional condition, multifocal alopecia and hyperkeratosis. Skin scrapings from both rabbits revealed numerous subcutaneous mites identified as Notoedres centrifera, a species previously only associated with rodents, primarily squirrels. Mites from both rabbits were identified based on morphology and confirmed by sequencing the internal transcribed spacer-2 (ITS-2) region. These cases emphasize the need for continued surveillance and accurate diagnostic evaluation to determine the cause and characterization of the skin disease, while distinguishing it from other potential pathogens that may manifest similarly in rabbits, such as Notoedres cati, Sarcoptes scabiei or Psoroptes cuniculi.

Copepod consumption by amphibians and fish with implications for transmission of Dracunculus species.

Parasitic nematodes in the genus Dracunculus have a complex life cycle that requires more than one host species in both aquatic and terrestrial habitats. The most well-studied species, Dracunculus medinensis, is the causative agent of human Guinea worm disease (dracunculiasis). There are several other Dracunculus species that infect non-human animals, primarily wildlife (reptiles and mammals). The classic route of D. medinensis transmission to humans is through the ingestion of water containing the intermediate host, a cyclopoid copepod, infected with third-stage larvae (L3s). However, many animal hosts (e.g., terrestrial snakes, dogs) of other Dracunculus sp. appear unlikely to ingest a large number of copepods while drinking. Therefore, alternative routes of infection (e.g., paratenic or transport hosts) may facilitate Dracunculus transmission to these species. To better understand the role of paratenic and transport hosts in Dracunculus transmission to animal definitive hosts, we compared copepod ingestion rates for aquatic species (fish, frogs [tadpoles and adults], and newts) which may serve as paratenic or transport hosts. We hypothesized that fish would consume more copepods than amphibians. Our findings confirm that African clawed frogs (Xenopus laevis) and fish consume copepods, but that fish ingest, on average, significantly higher numbers (68% [34/50]) than adult African clawed frogs (36% [18/50]) during a 24-h time period. Our results suggest that amphibians and fish may play a role in the transmission of Dracunculus to definitive hosts. Still, additional research is required to determine whether, in the wild, fish or frogs are serving as paratenic or transport hosts. If so, they may facilitate Dracunculus transmission. However, if these animals simply act as dead-end hosts or as means of copepod population control, they may decrease Dracunculus transmission.