PREVALENCE OF BABESIA SPP., EHRLICHIA SPP., AND TICK INFESTATIONS IN OKLAHOMA BLACK BEARS ( URSUS AMERICANUS )

A novel genotype of Babesia microti-like group in Ixodes montoyanus ticks parasitizing the Andean bear (Tremarctos ornatus) in Ecuador

Babesia species (Piroplasmida) are hemoparasites that infect erythrocytes of mammals and birds and are mainly transmitted by hard ticks (Acari: Ixodidae). These hemoparasites are known to be the second most common parasites infecting mammals, after trypanosomes, and some species may cause malaria-like disease in humans. Diagnosis and understanding of Babesia diversity increasingly rely on genetic data obtained through molecular techniques. Among hard ticks, several Ixodes species are known vectors of Babesia microti-like species in the Northern Hemisphere. Recently, Ixodes and Amblyomma ticks have been recorded parasitizing the Andean bear (Tremarctos ornatus) in Ecuador. Previous reports have suggested babesiosis in a fatal case of this threatened bear species in that country. This study aimed to detect Piroplasmida DNA in hard ticks collected from Andean bears at two sites in Ecuador. This species plays a critical role as an ecological engineer and a seed disperses, contributing significantly to the maintenance and health of Andean ecosystems. Twelve ticks screened with conventional PCR and Piroplasmida DNA was amplified from one Ixodes montoyanus tick collected from a free-living female Andean bear at Llanganates National Park. Two Babesia sequences were characterized: one for the 18 S ribosomal rRNA gene and another for the cytochrome c oxidase 1 gene. Phylogenetic analyses for both loci placed these sequences within the B. microti-like clade. This study reports a novel B. microti-like genotype identified in an I. montoyanus parasitizing a female Andean bear, contributing to the knowledge of the diversity of this group in South America. Given their conservation status, future epidemiological surveillance of Babesia and other tick-borne infectious agents in Andean bears is needed.

Survey for Babesia spp. in wildlife in the eastern United States

Babesia is a diverse genus of piroplasms that parasitize the red blood cells of a wide variety of mammals and avian species, including humans. There is a lack of knowledge on the Babesia species of carnivores and mesomammals in the eastern United States and the potential impacts of these species on the health of humans and domestic animals. We surveyed 786 wild mammals in the eastern United States by testing blood, spleen, and heart samples with PCR targeting the 18S rRNA region of apicomplexan parasites. We also performed PCR targeting the cytochrome c oxidase subunit 1 (cox1) region of each unique clade identified with 18S rRNA sequencing. We found a high positivity of Babesia spp. infection in raccoons (Procyon lotor), foxes (Vulpes vulpes and Urocyon cinereoargenteus), and striped skunks (Mephitis mephitis), and low positivity in Virginia opossums (Didelphis virginiana). No Babesia infections were detected in coyotes (Canis latrans), black bears (Ursus americanus), groundhogs (Marmota monax), muskrats (Ondatra zibethicus), or mink (Neovison vison). Skunks carried a diverse number of strains including a potential novel species of Babesia related to B. gibsoni, a strain closely related to a B. microti-like species known to cause disease in river otters, as well as a separate B. microti-like strain. Raccoons primarily carried B. microti-like strains, though there was a high diversity of sequences including Babesia lotori, Babesia sensu stricto MA230, and Babesia sp. 'Coco.' Foxes exclusively carried B. vulpes. In addition to Babesia spp., a high positivity of Hepatozoon spp. infection was found in mink, while low positivity was found in raccoons and muskrats. Wildlife in the eastern United States carry a diverse range of Babesia species including several novel strains of unknown clinical significance.

Description and molecular characterisation of Babesia ailuropodae n. sp., a new piroplasmid species infecting giant pandas

BACKGROUND

Babesia spp. are protozoan parasites that infect the red blood cells of domesticated animals, wildlife and humans. A few cases of giant pandas (a flagship species in terms of wildlife conservation) infected with a putative novel Babesia sp. have been reported. However, comprehensive research on the morphological and molecular taxonomic classification of this novel Babesia sp. is still lacking. This study was designed to close this gap and formally describe this new Babesia sp. infecting giant pandas.

METHODS

Detailed morphological, molecular and phylogenetic analyses were conducted to characterise this Babesia sp. and to assess its systematic relationships with other Babesia spp. Blood samples from giant pandas infected with Babesia were subjected to microscopic examination. The 18S ribosomal RNA (18S rRNA), cytochrome b (cytb) and mitochondrial genome (mitogenome) of the new Babesia sp. were amplified, sequenced and assembled using DNA purified from blood samples taken from infected giant pandas. Based on the newly generated 18S rRNA, cytb and mitogenome sequences, phylogenetic trees were constructed.

RESULTS

Morphologically, the Babesia sp. from giant pandas exhibited various forms, including round to oval ring-shaped morphologies, resembling those found in other small canine Babesia spp. and displaying typical tetrads. Phylogenetic analyses with the 18S rRNA, cytb and mitogenome sequences revealed that the new Babesia sp. forms a monophyletic group, with a close phylogenetic relationship with the Babesia spp. that infect bears (Ursidae), raccoons (Procyonidae) and canids (Canidae). Notably, the mitogenome structure consisted of six ribosomal large subunit-coding genes (LSU1-6) and three protein-coding genes (cytb, cox3 and cox1) arranged linearly.

CONCLUSIONS

Based on coupled morphological and genetic analyses, we describe a novel species of the genus Babesia, namely, Babesia ailuropodae n. sp., which infects giant pandas.

Hematological and plasma profiles and ticks and tick-borne pathogens in wild Formosan black bears (Ursus thibetanus formosanus)

BACKGROUND

The endangered Formosan black bear (Ursus thibetanus formosanus) is the largest native carnivorous mammal in Taiwan. Diseases, poor management, illegal hunting, and habitat destruction are serious threats to the survival of bear populations. However, studies on the impact of diseases on bear populations are limited. Therefore, this study aimed to establish a database of the hematological and plasma profiles of free-ranging Formosan black bears and investigate the occurrence of ectoparasites, blood parasites, and vector-borne pathogens.

METHODS

Formosan black bears were captured in Yushan National Park (YNP) and Daxueshan Forest Recreation Area (DSY) in Taiwan. Blood samples were collected from each bear for hematological analysis and plasma biochemistry using a hematology analyzer. Parasites and pathogens were detected using a thin blood smear with Wright-Giemsa staining and polymerase chain reaction (PCR) assay. Additionally, macroscopic ectoparasites were collected from bears to detect blood parasites and other pathogens. Moreover, the relationships between the bear variables (sex, age, and occurrence of parasites or pathogens), ectoparasites, and infectious agents were also analyzed.

RESULTS

In all, 21 wild bears (14 in YNP and 7 in DSY) were captured and released during the satellite tracking studies. Hematological analysis and plasma biochemistry indicated significant differences in white blood cells (WBC), segments, creatine kinase (CK), and lactate dehydrogenase (LDH) levels between foot snare and culvert-captured bears. Additionally, there were significant differences in total plasma protein (TPP), creatinine, Ca2+, Mg2+, and K+ levels between male and female bears. Moreover, pathogen-infected bears had significantly higher erythrocyte sedimentation rate (ESR; 30 min and 1 h) and globulin levels than uninfected bears. In total, 240 ticks were collected from 13 bears, among which eight adult tick species were identified, including Haemaphysalis flava, Haemaphysalis hystricis, Amblyomma testudinarium, Ixodes ovatus, Dermacentor taiwanensis, Haemaphysalis longicornis, Ixodes acutitarsus, Amblyomma javanense, and nymphs belonging to Haemaphysalis spp. PCR revealed that 13 (61.90%) and 8 (38.10%) bears harbored Hepatozoon ursi and Babesia DNA, respectively. Among the ticks examined, 157 (65.41%) and 128 (53.33%) samples were positive for H. ursi and Babesia, respectively.

CONCLUSIONS

To the best of our knowledge, this is the first study to establish a database of the hematological and plasma profiles of wild Formosan black bears and investigate ectoparasite infestation and Hepatozoon and Babesia spp.

INFECTION

In conclusion, these findings may serve as a reference for monitoring the health and population of locally endangered bears.

Heat Treatment Augments Antigen Detection of Dirofilaria immitis in Apparently Healthy Companion Dogs (3.8% to 7.3%): Insights from a Large-Scale Nationwide Survey across the United States

BACKGROUND

Heartworm disease (HWD) is a vector-borne disease caused by the filarial nematode Dirofilaria immitis. Low antigen levels caused by immune complex formation preclude HWD diagnosis. Heat treatment is an immune complex dissociation technique used to enhance antigen detection. Only a few studies have reported the benefits of heat treatment in nationwide surveys.

METHODS

To investigate the impact of heat treatment on the seroprevalence of HWD in companion dogs in the USA, serum samples (n = 3253) were analyzed for D. immitis antigen (DiroCHEK®, Zoetis) without and with heat treatment of the samples.

RESULTS

Compared to sera without heat treatment, heat treatment significantly increased overall prevalence from 3.8% (123/3253) to 7.3% (237/3253) (p < 10-4), expanding antigen detection from 32 to 39 of the 48 states and Washington District of Columbia included in this study.

CONCLUSIONS

This study represents the largest nationwide survey of HW antigen detection in dogs in the US applying heat treatment to canine sera. The heat treatment used herein has the advantage of requiring a low volume of serum, making it optimal for use in routine diagnosis. Heat treatment should be used routinely by reference laboratories and veterinary clinics in patients with a negative initial test.

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.

Detection of Borrelia miyamotoi and Powassan Virus Lineage II (Deer Tick Virus) from Odocoileus virginianus Harvested Ixodes scapularis in Oklahoma

Odocoileus virginianus (white-tailed deer) is the primary host of adult Ixodes scapularis (deer tick). Most of the research into I. scapularis has been geographically restricted to the northeastern United States, with limited interest in Oklahoma until recently as the I. scapularis populations spread due to climate change. Ticks serve as a vector for pathogenic bacteria, protozoans, and viruses that pose a significant human health risk. To date, there has been limited research to determine what potential tick-borne pathogens are present in I. scapularis in central Oklahoma. Using a one-step multiplex real-time reverse transcription-PCR, I. scapularis collected from white-tailed deer was screened for Anaplasma phagocytophilum, Borrelia burgdorferi, Borrelia miyamotoi, Babesia microti, and deer tick virus (DTV). Ticks (n = 394) were pooled by gender and life stage into 117 samples. Three pooled samples were positive for B. miyamotoi and five pooled samples were positive for DTV. This represents a minimum infection rate of 0.8% and 1.2%, respectively. A. phagocytophilum, B. burgdorferi, and B. microti were not detected in any samples. This is the first report of B. miyamotoi and DTV detection in Oklahoma I. scapularis ticks. This demonstrates that I. scapularis pathogens are present in Oklahoma and that further surveillance of I. scapularis is warranted.

Tick abundance and life-stage segregation on the American black bear (Ursus americanus)

Tick abundance and diagnosed cases of tick-borne diseases have been increasing in the United States. American black bear (Ursus americanus) populations have also been increasing in the eastern United States. As a competent host of several species of ticks and a mammal capable of traveling long distances, the role of black bears as hosts for ticks requires further evaluation. Ectoparasite surveys were conducted on black bears in Pennsylvania to evaluate tick presence, abundance, spatial distribution, and association with Sarcoptes scabiei, the etiological agent of sarcoptic mange, on bears to better understand their role in tick ecology and to improve on-host surveillance techniques. Tick burden was evaluated using standard area sampling (10.16 × 10.16 cm squares) on pre-designated body regions on black bears from June 2018–December 2019. In total, 278 unique individual black bears were evaluated, with all ticks identified as Ixodes scapularis (n = 1976; 76.7% adults, 23.3% immatures). Tick presence differed by body region on bears, with the highest percentage of tick observations located on bear ears and muzzle. Ticks also partitioned on black bears by life-stage, with immature ticks primarily recorded on the lower extremities of bears and adult ticks primarily recorded on the front-quarters of bears. This includes the first known record of I. scapularis larvae parasitizing black bears, and observations of all three mobile life-stages concurrently parasitizing bears. Tick abundance was also statistically significant dependent on season, with the highest abundance of ticks recorded in spring and lowest abundance in fall. Adult ticks were less likely to be present on bears with mange. These data reveal the important role black bears may serve in tick ecology and dispersal as all three mobile life-stages of I. scapularis were found parasitizing a mammal capable of traveling far distances in a region with high numbers of Lyme disease cases.

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First record of Ixodes scapularis larvae parasitizing black bears.

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All three I. scapularis mobile life-stages concurrently parasitizing black bears.

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I. scapularis life-stage segregation on black bears.

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Standardized tick survey findings can be used to improve on-host surveillance.

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Bears with sarcoptic mange less likely to have adult ticks present.

Molecular detection of apicomplexan protozoa in Hokkaido brown bears (Ursus arctos yesoensis) and Japanese black bears (Ursus thibetanus japonicus)

Many tick-borne pathogens (TBPs) are present in wildlife. The objective of this study is to reveal the role of wild bears in maintaining TBPs. A total of 49 brown bears (Ursus arctos yesoensis) from Hokkaido, and 18 Japanese black bears (Ursus thibetanus japonicus) from Tochigi, and 66 Japanese black bears from Nagano were examined by two molecular methods, reverse line blot (RLB) hybridization, and nested PCR. A total of 5 TBPs (Hepatozoon ursi, Babesia sp. UR2-like group, Cytauxzoon sp. UR1, Babesia sp. UR1, and Babesia microti) were detected from bear blood DNA samples. B. microti was detected from blood DNA samples of Japanese black bear for the first time, with the prevalence of 6.0% (5/84). Out of detected pathogens, H. ursi, Babesia sp. UR2-like pathogens, and Cytauxzoon sp. UR1 were considered as three of the most prevalent TBPs in bears. The prevalence of H. ursi were significantly higher in Japanese black bear (0% vs 96.4%) while that of Babesia sp. UR2-like group was higher in Hokkaido brown bears (89.8% vs 40.5%). The prevalence of Babesia sp. UR1 were significantly higher in Japanese black bears from Tochigi (44.4%), comparing with those from Nagano (18.2%). The prevalence of the detected TBPs were significantly higher in adult bears, comparing with those in younger bears. The present study suggests that Japanese bear species contribute in the transmission of several TBPs in Japan. The expanding distribution of bears might cause the accidental transmission of TBPs to humans and domestic animals.

Canine heartworm and heat treatment: An evaluation using a well based enzyme-linked immunosorbent assay (ELISA) and canine sera with confirmed heartworm infection status

Heat treatment of serum has demonstrated improved detection of Dirofilaria immitis antigen in sera of sheltered dogs without knowing the true infection status of the animals and in dogs confirmed experimentally to be infected with heartworm. Utilizing archived sera with necropsy confirmed heartworm infection status (n = 665) and a micro-titer well based ELISA antigen assay, this study evaluated how the composition of heartworm infections affects antigen test results pre- and post-heat treatment, determined subsequent changes to the antigen test sensitivity and specificity, and application of optical density values. The composition of heartworm infections present in dogs with sera initially testing antigen negative consisted of infections by dead 1/34 (2.9 %), immature 10/34 (29.4 %), male only 7/34 (20.6 %), female only 5/34 (14.7 %), and mixed sex infections 11/34 (32.4 %) with 2-62 heartworms of which 6 were microfilaremic. The composition of heartworm infections remaining antigen negative post-heat treatment consisted of infections by dead 1/14 (7.1 %), immature 9/14 (64.3 %), male only 2/14 (14.3 %), and mixed sex infections 2/14 (14.3 %) with 6 and 62 heartworms of which 1 was microfilaremic. The overall sensitivity for all infections, mature heartworms, and mature females before heat treatment were 86.9 %, 90.7 %, and 93.3 % and after heat treatment sensitivity increased to 94.6 %, 98.4 %, and 99.2 % respectively. A decrease in specificity from 97.8%-96.1% was observed following heat treatment of heartworm negative sera. Optical density values for the varying infection intensities present in this study clearly indicate that result intensity is not reflective of the number of heartworms present. This study provides additional context for interpreting post-heat antigen results for dogs originating from animal shelters, demonstrates diagnostic utility of optical density, and highlights the need for improved heartworm diagnostics.

Zoonoses and potential zoonoses of bears

Captive and free-ranging wild bears can carry and transmit several zoonotic pathogens. A review of nearly 90 years of scientific publications concerning confirmed and potential zoonotic diseases that can be present in any of the eight species of bears in the world was conducted. The findings were organized amongst the following disease sections: bacterial, viral, protozoal, mycotic, helminth and arthropod-borne. The most commonly reported pathogens of concern were of parasitic (Trichinella, Toxoplasma) and bacterial (Francisella, Brucella) origin.

Detection and Prevalence of Babesia spp. in American Black Bears (Ursus americanus) from Eastern and Western North Carolina, USA

Blood samples collected from American black bears (Ursus americanus) in eastern and western North Carolina, US, were analyzed for piroplasms. Piroplasmids were detected in 17% (23/132) of the animals surveyed. We detected a Babesia spp. previously identified in North American raccoons (Procyon lotor) and a maned wolf (Chrysocyon brachyurus); prevalence was 22% (14/64) and 13% (9/68) in the mountain and coastal black bear populations, respectively. The presence of the same Babesia species in black bears, raccoons, and a maned wolf suggests piroplasms may not be host specific.

Diversity of Anaplasma and Ehrlichia/Neoehrlichia Agents in Terrestrial Wild Carnivores Worldwide: Implications for Human and Domestic Animal Health and Wildlife Conservation

Recently, the incidence and awareness of tick-borne diseases in humans and animals have increased due to several factors, which in association favor the chances of contact among wild animals and their ectoparasites, domestic animals and humans. Wild and domestic carnivores are considered the primary source of tick-borne zoonotic agents to humans. Among emergent tick-borne pathogens, agents belonging to family Anaplasmataceae (Order Rickettsiales) agents stand out due their worldwide distribution and zoonotic potential. In this review we aimed to review the genetic diversity of the tick-transmitted genera Ehrlichia, Anaplasma and "Candidatus Neoehrlichia sp." in wild carnivores Caniformia (Canidae, Mustelidae and Ursidae) and Feliformia (Felidae, Hyanidae, Procyonidae and Viverridae) worldwide, discussing the implications for human and domestic animal health and wildlife conservation. Red foxes (Vulpes vulpes) have been identified as hosts for Anaplasma spp. (A. phagocytophilum, Anaplasma ovis, A. platys), Ehrlichia canis and "Candidatus Neoehrlichia sp." (FU98 strain) and may contribute to the maintaenance of A. phagocytophilum in Europe. Raccoons (Procyon lotor) have been reported as hosts for E. canis, A. bovis, "Candidatus Neoehrlichia lotoris" and A. phagocytophilum, and play a role in the maintenance of A. phagocytophilum in the USA. Raccoon dogs (Nyctereutes procyonoides) may play a role as hosts for A. bovis and A. phagocytophilum. New Ehrlichia and/or Anaplasma genotypes circulate in wild canids and felids from South America and Africa. While Ehrlichia sp. closely related to E. canis has been reported in wild felids from Brazil and Japan, Anaplasma sp. closely related to A. phagocytophilum has been detected in wild felids from Brazil and Africa. Red foxes and mustelids (otters) are exposed to E. canis in countries located in the Mediaterranean basin, probably as a consequence of spillover from domestic dogs. Similarly, E. canis occurs in procyonids in North (raccoons in USA, Spain) and South (Nasua nasua in Brazil) Hemispheres, in areas where E. canis is frequent in dogs. While "Candidatus Neoehrlichia lotoris" seems to be a common and specific agent of raccoons in the USA, "Candidatus Neoehrlichia sp." (FU98 strain) seems to show a broader range of hosts, since it has been detected in red fox, golden jackal (Canis aureus) and badger (Meles meles) in Europe so far. Brown (Ursus arctos) and black (Ursus americanus) bears seem to play a role as hosts for A. phagocytophilum in the North Hemisphere. Anaplasma bovis has been detected in wild Procyonidae, Canidae and Felidae in Asia and Brazil. In order to assess the real identity of the involved agents, future works should benefit from the application of MLST (Multi Locus Sequence Typing), WGS (Whole Genome Sequencing) and NGS (Next Generation Sequencing) technologies aiming at shedding some light on the role of wild carnivores in the epidemiology of Anaplasmataceae agents.

Prime detection of Dirofilaria immitis: understanding the influence of blocked antigen on heartworm test performance

Detection of circulating antigen of Dirofilaria immitis has been a mainstay of identifying heartworm infection in clinical practice for the past three decades. Several validated commercial antigen tests have very good sensitivity, specificity, and positive predictive values, especially when used in patients for which heartworm infection is likely. In some dogs and cats infected with heartworm, antigen may not be available for detection although present in the patient sample; heat pretreatment of these samples reveals the antigen, changing the false negative to positive. This phenomenon was documented in the literature in the 1980s but subsequently overlooked by the heartworm research community for many years. In this review, we provide a summary of the current understanding of the role of heat reversal in diagnosing heartworm infection. This additional diagnostic step is most important for patients in which heartworm infection is likely, such as dogs or cats in an endemic area with an inconsistent history of heartworm preventive use, or dogs with a prior diagnosis of heartworm infection that were recently treated. To illustrate the concept, we share a summary of results from canine samples tested at the state veterinary diagnostic laboratory in Oklahoma, USA in 2017 by modified Knott test and by commercial antigen test before and after heat treatment of samples; in this sample set, heat treatment changed all D. immitis microfilaria-positive but antigen-negative samples to antigen-positive. Pet dogs with a history of consistent preventive use are unlikely to become positive with heat pretreatment; for that reason, routine pretreatment of all samples tested in a veterinary practice is not recommended. We also review known causes of false negative and false positive results on heartworm antigen tests that, although uncommon, can complicate accurate diagnosis in individual patients. Together, this review provides a primer to aid understanding of strategies that can enhance accurate diagnosis of heartworm infection in veterinary practice and clinical research.