Angiostrongylus cantonensis Infection in Brown Rats (Rattus norvegicus), Atlanta, Georgia, USA, 2019-2022.

Rat lungworm (Angiostrongylus cantonensis), a zoonotic parasite invasive to the United States, causes eosinophilic meningoencephalitis. A. cantonensis harbors in rat reservoir hosts and is transmitted through gastropods and other paratenic hosts. We discuss the public health relevance of autochthonous A. cantonensis cases in brown rats (Rattus norvegicus) in Atlanta, Georgia, USA.

Toxocara canis seropositivity in different exposure groups in the Khyber Pakhtunkhwa province of Northwest Pakistan.

Human toxocariasis is a highly prevalent zoonosis worldwide but is underreported in most countries. This study was conducted to evaluate Toxocara canis seropositivity in different exposure sub-groups located in the Mardan, Swabi, and Nowshera districts of the Khyber Pakhtunkhwa province of Northwest Pakistan. A total of 400 blood samples were collected from males 15 years of age and older with no animals, with livestock, with dogs and/or cats living in the house, and from butchers and veterinarians or para-veterinarians. Serum was tested using a commercial ELISA kit for detection of IgG antibodies against T. canis. Proportion seropositive was presented for each group and differences between groups were evaluated using the chi-square or Fisher's exact test as appropriate. Possible risk factors obtained through administration of a questionnaire were also evaluated for each sub-population. Overall T. canis seroprevalence was 14.2%, with a significant difference found between the seroprevalence of individuals with no animals (5.0%; 5/100), individuals with dogs and/or cats living in the household (8.0%; 8/100), individuals with livestock (18.0%; 18/100), veterinarians or para-veterinarians (24.0%; 12/50), and butchers (28.0%; 14/50) (p < 0.001). Significant differences in seropositivity by income bracket, education level, and working in the fields were found for some sub-groups. Study findings demonstrate that certain sub-populations, in Northwest Pakistan, may be at greater risk of T. canis infection. Development and implementation of targeted preventive strategies may, therefore, be needed.

Autochthonous Thelazia callipaeda Infection in Dog, New York, USA, 2020.

We report a case of autochthonous infection of the eye worm Thelazia callipaeda in a dog in the northeastern United States. Integrated morphologic identification and molecular diagnosis confirmed the species. Phylogenetic analysis suggested introduction from Europe. The zoonotic potential of this parasite warrants broader surveillance and increased awareness among physicians and veterinarians.

Subcutaneous and cardiopulmonary dirofilariasis in a dog.

Canine subcutaneous dirofilariasis is rare and typically caused by Dirofilaria repens. An adult male, intact, mixed breed dog from South Carolina, USA, was examined because of physical trauma to the right maxilla. The dog died during hospitalization and was submitted for necropsy. Gross post-mortem changes included approximately 150 adult nematodes morphologically consistent with Dirofilaria spp. in the pulmonary artery, right atrium, and right ventricle. Histologically there was widespread proliferative pulmonary endarteritis with intraluminal nematodes morphologically consistent with Dirofilaria spp. Four similar nematodes were present in the subcutaneous tissue of the left medial thigh and tibial area. These nematodes were located within the fascia and skeletal muscles. They were surrounded by epithelioid macrophages and multinucleated giant cells, with some lymphocytes and plasma cells, and areas of mineralization (interpreted as mineralized cross sections of nematodes). Nematodes were morphologically identified as D. immitis. Subcutaneous dirofilariasis caused by D. immitis occurs when migrating nematode larvae develop into adults in the subcutaneous and skeletal muscle tissues. Key clinical message: Subcutaneous dirofilariasis in dogs is rare and most often associated with Dirofilaria repens. This case highlights the pathology findings of subcutaneous D. immitis in a dog.

Dirofilariose sous-cutanée et cardio-pulmonaire chez un chien. La dirofilariose sous-cutanée canine est rare et généralement causée par Dirofilaria repens. Un chien de race mixte, mâle adulte intact, originaire de la Caroline du Sud, aux États-Unis, a été examiné en raison d'un traumatisme physique au maxillaire droit. Le chien est décédé pendant l'hospitalisation et a été soumis à une nécropsie. Les changements post-mortem macroscopiques incluaient environ 150 nématodes adultes morphologiquement compatibles avec Dirofilaria spp. dans l'artère pulmonaire, l'oreillette droite et le ventricule droit. Sur le plan histologique, il y avait une endartérite pulmonaire proliférative généralisée avec des nématodes intraluminaux morphologiquement compatibles avec Dirofilaria spp. Quatre nématodes similaires étaient présents dans le tissu sous-cutané de la cuisse médiale gauche et de la région tibiale. Ces nématodes étaient situés dans le fascia et les muscles squelettiques. Ils étaient entourés de macrophages épithélioïdes et de cellules géantes multinucléées, avec quelques lymphocytes et plasmocytes, et des zones de minéralisation (interprétées comme des coupes transversales minéralisées de nématodes). Les nématodes ont été identifiés morphologiquement comme D. immitis. La dirofilariose sous-cutanée causée par D. immitis survient lorsque les larves de nématodes en migration se développent en adultes dans les tissus musculaires sous-cutanés et squelettiques.Message clinique clé :La dirofilariose sous-cutanée chez les chiens est rare et le plus souvent associée à Dirofilaria repens. Le cas présent souligne les trouvailles pathologiques associées à la présence sous-cutanée de D. immitis chez un chien.(Traduit par Dr Serge Messier).

FATAL FASCIOLOIDES MAGNA IN A LESSER SPOT-NOSED GUENON (CERCOPITHECUS PETAURISTA).

A 4-yr-old male intact lesser spot-nosed guenon (Cercopithecus petaurista), housed at a North American zoological facility, presented with acute lethargy, inappetence, and mild neurologic signs. Physical examination revealed hemorrhagic pleural effusion in the right hemithorax. This guenon's condition improved over several days but then deteriorated, and the guenon presented with lethargy and weakness. A hemorrhagic pleural effusion was identified within the left hemithorax. The guenon developed respiratory and cardiac arrest while anesthetized. Gross examination revealed tract formation in the liver, adhesions of the liver to the diaphragm, hemorrhagic thoracic and abdominal effusion, and a single trematode within the right hemithorax. Morphologic features and species identification by PCR confirmed that the parasite was Fascioloides magna. Histologic examination revealed tract formation in the liver associated with biliary hyperplasia, fibrosis and hepatic necrosis, severe bile peritonitis, and pleuritis. This is the first report of an infection by F. magna in a primate.

Coyotes as Reservoirs for Onchocerca lupi, United States, 2015-2018.

The Onchocerca lupi nematode infects dogs, cats, and humans, but whether it can be spread by coyotes has been unknown. We conducted surveillance for O. lupi nematode infection in coyotes in the southwestern United States. We identified multiple coyote populations in Arizona and New Mexico as probable reservoirs for this species.

Rodents of Senegal and their role as intermediate hosts of Hydatigera spp. (Cestoda: Taeniidae).

Hydatigera (Cestoda: Taeniidae) is a recently resurrected genus including species seldom investigated in sub-Saharan Africa. We surveyed wild small mammal populations in the areas of Richard Toll and Lake Guiers, Senegal, with the objective to evaluate their potential role as intermediate hosts of larval taeniid stages (i.e. metacestodes). Based on genetic sequences of a segment of the mitochondrial DNA gene cytochrome c oxidase subunit 1 (COI), we identified Hydatigera parva metacestodes in 19 out of 172 (11.0%) Hubert's multimammate mice (Mastomys huberti) and one out of six (16.7%) gerbils (Taterillus sp.) and Hydatigera taeniaeformis sensu stricto metacestodes in one out of 215 (0.5%) Nile rats (Arvicanthis niloticus). This study reports epidemiological and molecular information on H. parva and H. taeniaeformis in West African rodents, further supporting the phylogeographic hypothesis on the African origin of H. parva. Our findings may indicate significant trophic interactions contributing to the local transmission of Hydatigera spp. and other parasites with similar life-cycle mechanisms. We therefore propose that further field investigations of rodent population dynamics and rodent-borne infectious organisms are necessary to improve our understanding of host-parasite associations driving the transmission risks of rodent parasites in West Africa.

Historical biogeography among species of Varestrongylus lungworms (Nematoda: Protostrongylidae) in ungulates: episodic expansion and host colonization linking Eurasia and North America.

Varestrongylus lungworms (Nematoda: Protostrongylidae) include 10 nominal species that parasitize wild and domesticated artiodactyles. Eight species are endemic to the western Palearctic and Eurasia, whereas two are limited in distribution to the Nearctic. Complex host associations, primarily among Cervidae and Bovidae (Caprinae), and biogeography were explored based on direct comparisons of parasite and host phylogenies to reveal the historical development of this fauna. Diversification among Varestrongylus species has an intricate history extending over the Pliocene and Quaternary involving episodic processes for geographic and host colonization: (1) Varestrongylus has origins in Eurasia with independent expansion events into bordering ecozones; (2) cervids are ancestral hosts; (3) the caprine-associated V. pneumonicus is basal and a result of an independent host colonization event; (4) secondary diversification, linked to sequential and independent host colonization events, occurred within cervids (V. sagittatus + V. tuvae; V. alpenae; and V. capreoli, V. alces + V. eleguneniensis); (5) at least two additional host colonization events into caprines occurred, followed or not by diversification (V. qinghaiensis + V. longispiculatus; V. capricola, respectively); (6) two independent events of geographic expansion into North America from Eurasia with cervids in the late Pliocene and early Pleistocene are postulated (V. alpenae, V. eleguneniensis). Comparisons based on phylogenetic hypotheses derived from comparative morphology and molecular inference for these nematodes are consistent with the postulated history for coevolutionary and biogeographic history. Episodes of geographic and host colonization, often in relation to rapid shifts in climate and habitat perturbation, have dominated the history of diversification of Varestrongylus.

Varestrongylus (Nematoda: Protostrongylidae), lungworms of ungulates: a phylogenetic framework based on comparative morphology.

Varestrongylus Bhalerao, 1932 comprises ten valid lungworm species infecting wild and domestic ungulates from Eurasia and North America. Here, we present a phylogenetic hypothesis for the genus based on morphological characters in a broader context for the family Protostrongylidae and discuss species relationships and aspects of character evolution. Phylogenetic analysis of 25 structural attributes, including binary and multistate characters, among the 10 species of Varestrongylus resulted in one fully resolved most parsimonious tree (61 steps; consistency index = 0.672, retention index = 0.722, and consistency index excluding uninformative characters = 0.667). Varestrongylus forms a monophyletic clade and is the sister of Pneumostrongylus, supporting recognition of the subfamily Varestrongylinae. Monophyly for Varestrongylus is diagnosed by six unequivocal synapomorphies, all associated with structural characters of the copulatory system of males. Varestrongylus pneumonicus is basal, and sister to all other species within the genus, which form two subclades. The subclade I contains V. sagittatus + V. tuvae and V. qinghaiensis + V. longispiculatus. Subclade II contains V. alpenae, V. capricola, V. capreoli, and V. eleguneniensis + V. alces. Both subclades are diagnosed by two unambiguous synapomorphies. Highlighted is the continuing importance of phylogenetic assessments based on comparative morphology as a foundation to explore the structure of the biosphere across space and time.

Onchocerca lupi Nematodes in Dogs Exported from the United States into Canada.

The Onchocerca lupi nematode is an emerging helminth capable of infecting pets and humans. We detected this parasite in 2 dogs that were imported into Canada from the southwestern United States, a region to which this nematode is endemic. We discuss risk for establishment of O. lupi in Canada.

Can immunosuppressive therapy facilitate the diagnosis and affect the clinical signs of canine scabies? A retrospective study of 79 cases.

BACKGROUND: Scabies infestation is one of the most pruritic dermatoses of dogs. It is often misdiagnosed and dogs are treated with immunomodulatory drugs (IMD) to relieve pruritus. HYPOTHESIS/OBJECTIVES: The primary goals of this study were to determine the impact of IMD on skin scraping results, pruritus level and extent of skin lesions, and to evaluate whether disease duration is associated with positive skin scrapings and contagion. ANIMALS: Seventy nine dogs with a final diagnosis of scabies. METHODS: Inclusion in this retrospective study required a positive skin scraping for scabies or a clinical response to an acaricidal treatment trial. RESULTS: The average pruritus score of dogs that received IMD (8.71) was significantly higher than those that did not (7.43; P = 0.03). However, there were no significant differences in either the rates of positive skin scrapings (79.6% versus 59.1%; P = 0.13) or the mean number of body sites affected (3.8 versus 3.4; P = 0.30) between dogs that received IMD and those that did not. Neither skin scraping status nor duration of clinical signs were correlated with a report of contagion within the household. CONCLUSION/CLINICAL IMPORTANCE: IMD was associated with a significant increase in the pruritus level, but not with the mean number of lesional body sites. Dogs exposed to IMD had a 20.5% higher rate of positive skin scrapings. This difference could be clinically relevant and lack of statistical significance may indicate an underpowered study.

Apparent tick paralysis by Otobius megnini in a cat.

In this study, we report a rare case of tick paralysis in a cat induced by Otobius megnini infestation. An 11-month-old female cat was admitted to a private veterinary clinic in Luling Texas, USA presenting with depression, tachycardia, and flaccid paralysis of the entire body. The four recovered ticks were morphologically and molecularly identified as O. megnini nymphs. Following initial tick removal and treatment with 0.1% milbemycin oxime in the ear canal on the first day of hospitalization, and additional tick removal and topical selamectin treatment on the second day of hospitalization the animal gradually improved. The recovery of the cat after tick removal supports the diagnosis of tick toxicosis. While tick antiserum is not available in North America, prevention of tick infestation and tick-induced paralysis can be effectively accomplished using repellent collars and the compliant use of other ectoparasiticide products year-round.

Investigation of Factors Associated with Subclinical Infections of Giardia duodenalis and Cryptosporidium canis in Kennel-Housed Dogs (Canis lupus familiaris).

Giardia duodenalis and Cryptosporidium spp. are zoonotic protozoal pathogens, spread by a fecal-oral route, which can infect a wide range of hosts including but not limited to dogs and humans. Giardia was recently estimated to be present in 37% to 50% of kennel-housed dogs. Cryptosporidium infections in kennel-housed dogs have been reported in 7% to 21% of the population. The goal of this study was to define demographic factors and fecal scores associated with positive screening test cases of Giardia and Cryptosporidium in kennel-housed laboratory dogs in the state of Texas. Fecal samples were collected from 153 clinically normal laboratory dogs at an academic research facility and a local laboratory dog supplier. We used 3 diagnostic tests evaluated in parallel to determine test positivity to each organism: a human point-of-care coproantigen test, a direct immunofluorescent assay, and an in-house polymerase chain reaction. Dogs were significantly more likely to test positive for Giardia (45%) than Cryptosporidium (7%) (P < 0.01). Dogs that were 18 mo of age or younger had 3 times the odds (P = 0.009) of subclinical Giardia infection compared with older dogs. We found no significant relationship between age and Cryptosporidium prevalence. Dogs with hard feces (fecal score 1-2) at the time of screening had 0.34 times lower odds ( P = 0.049) of testing positive for Giardia than dogs with normal feces, but no statistically significant relationship was found between fecal score and Cryptosporidium -positive test status. With these findings, we demonstrated the value of considering age and fecal score when choosing which dogs to screen for subclinical Giardia. Additional studies with larger sample sizes should be conducted to determine the relationship between age and fecal score and subclinical Cryptosporidium infection.

Evaluation of a novel Tc-24 recombinant antigen ELISA for serologic testing for Trypanosoma cruzi in dogs.

Chagas disease is a parasitic infection caused by Trypanosoma cruzi. Diagnosis of chronic Chagas disease in dogs relies on limited serological test options. This study used a new Tc-24 recombinant antigen ELISA on an archival set of 70 dog serum samples from multi-dog kennel environments in Texas subjected to three existing Chagas serological tests. Tc-24 ELISA produced a quantitative result and could detect anti-T. cruzi antibodies in dogs with high sensitivity and specificity. Comparing individual tests to Tc-24 ELISA resulted in strong associations and correlations, which suggest that Tc-24 ELISA is a reliable and accurate diagnostic tool for dogs with a single test.

Apparent fatal winter tick (Dermacentor albipictus) infestation in captive reindeer (Rangifertarandus).

The winter tick, Dermacentor albipictus (Ixodidae), commonly infests a wide variety of wild and domestic ungulates throughout North America. This one-host-tick infests animals from October to April, with moose (Alces alces) particularly affected. Animals highly infested may present with anemia, tick-induced alopecia, and alterations in thermoregulation, often resulting in death. Mortality from winter tick infestation has been reported in free-ranging woodland caribou (Rangifer tarandus caribou) and captive reindeer in Alberta, Canada. This historic report raises concern about mortality due to D. albipictus in a wider host range, specifically on translocated caribou. The aim of this report was to describe three cases of winter tick infestation in captive reindeer resulting in severe anemia and mortality likely due to the infestation in New Hampshire, northeastern United States (US). Additionally, ticks were screened molecularly for the detection of tick-borne pathogens. At time of necropsy, all three reindeer showed decreased nutritional status, marked submandibular edema, and had heavy D. albipictus infestation. None of the reindeer exhibited alopecia, which is a common clinical manifestation in moose that die from winter tick infestation. No pathogens were detected via qPCR screening. This report highlights the risk that captive cervids face in areas where winter tick is endemic; therefore, the adoption of preventive control measures should be encouraged to reduce the risk of tick infestation and potential death of these animals.

Development of an indirect ELISA for the serodiagnosis of canine infection by Onchocerca lupi.

Onchocerca lupi is a zoonotic filarioid parasite of dogs and cats with widespread distribution. A specific non-invasive diagnostic assay for the detection of O. lupi infections remains unavailable. This study aimed to assess the accuracy, specificity, and sensitivity of an ELISA test designed using nine peptides from two O. lupi proteins. Sera (n = 54) collected from O. lupi infected dogs from endemic areas (Portugal and USA), alongside sera from dogs positive for Dirofilaria immitis, D. repens, Cercopithifilaria bainae, and Acanthocheilonema reconditum (n = 53) from a non-endemic area for O. lupi, as well as from helminth-free dogs (n = 60), were tested. The checkerboard titration method was applied for the optimization of peptide concentrations and conjugate anti-dog dilutions. Sensitivity, specificity, and optimal cut-off values were calculated using ROC curve analysis. All peptides reacted against sera of O. lupi, with no correlation between optic density (OD) values and microfilariae (mfs) loads. Sensitivity and specificity values ranging from 85.45 to 100%, and 88.89% to 100%, respectively, were recorded for all peptides examined, with 100% specificity and sensitivity observed for peptides 40_3, 40_5, 130_3, 120_3 and 40_1, 130_5, respectively. The maximum cut-off value was observed for peptides 40_5 (0.765) and 40_3 (0.708). Testing of sera from dogs positive for other filarioids resulted in lower OD values (up to 1.565) for peptides 40_3 and 40_5 when compared with O. lupi (up to 2.929). The availability of this assay will be of value in epidemiological studies of canine O. lupi infection in both endemic and non-endemic areas, and in assessing the risk for zoonotic transmission.

Aural hematoma in lambs associated with Otobius megnini (Ixodida: Argasidae) infestation.

In this report we described a case of aural hematomas in three lambs associated with Otobius megnini (Ixodida: Argasidae) infestation. From April to May 2021, five 3-month-old Hampshire cross lambs presented with unilateral aural hematomas. Upon otoscopic examination, engorged soft ticks (O. megnini) were observed in the external ear canals of three of the five lambs. The remaining two lambs had lesions consistent with infestation and were in a shared environment and deemed likely to have been infected. The treatment of all animals was based on the drainage of the serosanguinous fluid through an incision in the internal space of the ear pinna. Upon physical inspection of the entire flock (n = 310), O. megnini infestation was observed in one additional animal that did not have a hematoma. Following animal and environmental ectoparasiticide treatment with permethrin, no recurrences or additional cases of aural hematomas were observed in the flock in the following two-year period. To the authors' knowledge, this is the first description of aural hematomas in lambs associated with O. megnini infestation with successful recovery after surgery and off-label acaricide treatment.

Invasion, establishment, and range expansion of two parasitic nematodes in the Canadian Arctic.

Climate warming is occurring at an unprecedented rate in the Arctic and is having profound effects on host-parasite interactions, including range expansion. Recently, two species of protostrongylid nematodes have emerged for the first time in muskoxen and caribou on Victoria Island in the western Canadian Arctic Archipelago. Umingmakstrongylus pallikuukensis, the muskox lungworm, was detected for the first time in 2008 in muskoxen at a community hunt on the southwest corner of the island and by 2012, it was found several hundred kilometers east in commercially harvested muskoxen near the town of Ikaluktutiak. In 2010, Varestrongylus sp., a recently discovered lungworm of caribou and muskoxen was found in muskoxen near Ikaluktutiak and has been found annually in this area since then. Whereas invasion of the island by U. pallikuukensis appears to have been mediated by stochastic movement of muskoxen from the mainland to the southwest corner of the island, Varestrongylus has likely been introduced at several times and locations by the seasonal migration of caribou between the island and the mainland. A newly permissive climate, now suitable for completion of the parasite life cycles in a single summer, likely facilitated the initial establishment and now drives range expansion for both parasites.

Cryptic Onchocerca species infecting North American cervids, with implications for the evolutionary history of host associations in Onchocerca.

Parasites in the genus Onchocerca infect humans, ruminants, camels, horses, suids, and canids, with effects ranging from relatively benign to debilitating. In North America, Onchocerca cervipedis is the sole species known to infect cervids, while at least 5 Onchocerca species infect Eurasian cervids. In this study, we report the discovery of a cervid-parasitizing Onchocerca only distantly related to O. cervipedis. To reconstruct the phylogenetic history of the genus Onchocerca, we used newly acquired DNA sequence from O. cervipedis (from moose in Northwest Territories, Canada) and from the newly discovered species (from white-tailed deer in upstate New York), as well as previously published sequences. Ancestral host reconstructions suggest that host switches have been common throughout the evolutionary history of Onchocerca, and that bovid- and cervid-parasitizing species have been particularly important sources of descendant species. North America cervids might therefore serve as a source for Onchocerca invasions into new hosts. Given the high density of deer populations, the potential for zoonotic infections may also exist. Our discovery of a new Onchocerca species with relatively limited sampling suggests that the diversity of Onchocerca associated with cervids in North America may be greater than previously thought, and surveys utilizing molecules and morphology are necessary.