Immunisation of bulls against trichomoniasis

SUMMARY Studies into the immunisation of bulls against infection with Tritrichomonas foetus showed that subcutaneous administration of vaccines containing killed cells of T. foetus in a mineral oil adjuvant prevented the eliminted genital infection in most bulls up to the age of 5 years. Immunisation did not effectively prevent or cure infection in bulls older than 5.5 years.     

Documentation of In Vivo and In Vitro Aerobic Resistance of Feline Tritrichomonas foetus Isolates to Ronidazole

Background: The mainstays of treatment for clinically important trichomonad infections are the 5‐nitroimidazoles. Metronidazole resistance of feline Tritrichomonas foetus is presumed because of common treatment failure, and tinidazole does not consistently eradicate infection. To date, ronidazole is the only drug demonstrated as effective for treatment of cats infected with T. foetus. Objective: To document in vivo treatment failure and identify underlying causes and in vitro conditions of resistance of feline T. foetus to ronidazole. Animals: Two intact male Abyssinians failing ≥5 courses of treatment with increasing doses of 5‐nitroimidazole drugs. An intact male Abyssinian documented to clear infection after treatment with a single course of ronidazole. Methods: T. foetus isolates were cultured from feces and tested in vitro for susceptibility to ronidazole under aerobic and anaerobic culture conditions. A urogenital nidus of T. foetus infection was investigated by culture, polymerase chain reaction, or immunohistochemical testing of urogenital specimens. Results: Resistance to ronidazole under aerobic conditions was uniquely identified in T. foetus isolated from cats with well‐documented treatment failure. Treatment failure could not be attributed to reinfection, inappropriate treatment protocol, or presence of a urogenital nidus of infection. Conclusions and Clinical Importance: Clinical resistance to metronidazole, low efficacy of tinidazole, and present documentation of in vivo and in vitro resistance to ronidazole in some cats are consistent with a high level of cross resistance of feline T. foetus to 5‐nitroimidazole drugs. Current lack of alternative drugs with clinical efficacy against feline T. foetus suggests that active investigation of other treatment approaches is warranted.     

Cytopathic effects of Tritrichomonas foetus on bovine oviduct cells

Tritrichomonas foetus is an extracellular parasite of the reproductive tract in cattle. To investigate the cytopathic effects of T. foetus in deeper parts of the reproductive tract, a bovine primary oviduct epithelial cell system (BOECs) was developed. Reproductive tracts were obtained from cows and the effect of co-incubating T. foetus with BOECs was analyzed by scanning electron, transmission electron and fluorescence microscopy. Viability tests were performed using colorimetric methods, TUNEL (Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling), fluorescein diacetate, propidium iodide, JC-1 and annexin-V. The results demonstrate that: (1) the in vitro oviduct epithelium is useful for interaction experiments with T. foetus; (2) T. foetus adheres to the BOECs as single separate cells, and later on the cells aggregate as large clusters; (3) the posterior region of the cell initiates the process of adhesion and forms filopodia and digitopodia; (4) T. foetus severely damages BOECs leaving imprints in the epithelial cells, wide intercellular spaces, and large lesions in the epithelium; and (5) T. foetus provokes bovine oviduct cell death by apoptosis and secondary necrosis. Our observations indicate the possibility that T. foetus can move through the reproductive tract to the oviduct and that infertility in cows can be mediated by an attack on the oviduct cells by T. foetus.     

Tritrichomonas foetus and Mycoplasma felis coinfection in the upper respiratory tract of a cat with chronic purulent nasal discharge

A 5‐year‐old indoor male neutered Siamese cat was presented with clinical signs of sneezing and chronic bilateral purulent nasal discharge. Multiple nasal cavity swabs were submitted for bacterial cultures, Mycoplasma felis‐DNA qPCR, and cytology. M felisqPCR was positive and cytomorphologic diagnosis was severe, acute, purulent, rhinitis with intralesional protozoal microorganisms consistent with a Trichomonas spp. Nested PCR (nPCR) confirmed the diagnosis of Tritrichomonas foetus. Systemic therapy with doxycycline for M felis and metronidazole for T foetus was started with remission of clinical signs within 2 weeks; however, symptoms relapsed shortly after therapy was discontinued. This study represents the first documented case of T foetus associated with chronic nasal discharge in a cat, which supports the hypothesis that T foetus can live in the nasal cavity. It is also the first reported case of M felis and T foetus coinfection, which indicates that with mycoplasmal feline upper respiratory tract infections, T foetus should be considered as a coinfecting agent.     

Prevalence of bovine campylobacteriosis in indigenous cattle of three states in Nigeria

Summary A survey of bovine campylobacteriosis in breeding bulls and cows was carried out in the states of Kaduna, Kano and Borno. Six hundred and eighty nine cattle composed of 585 and 104 breeding bulls and cows respectively were sampled.Campylobacter fetus subsp.venerealis was isolated from 12 bulls whileCampylobacter fetus subsp.fetus was isolated from three of them. Campylobacter fetus subsp.fetus was isolated fromfour cows while Campylobacter fetus subsp.venerealis was isolated from one cow. The overall prevalence of campylobacteriosis in the three states was 2.9% (20/689). The result of the study identifiesCampylobacter fetus subsp.venerealis as the agent of enzootic infertility in Nigeria and suggests that it may be a significant problem.

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Resumen Un estudio sobre la prevalencia de campilobacteriosis en reproductores machos y hembras bovinos se llevó a cabo en los estados de Kaduna, Kano y Borno. Seiscientos ochenta y nueve animales, compuestos de 585 y 104 toros reproductores y vacas respectivamente, fueron examinados.Campylobacter fetus subsp.venerealis fue aislado de 12 toros, mientras queC. fetus subsp.fetus, se aisló de tres de ellos.C. fetus subsp.fetus se aisló de cuatro vacas, mientras queC. fetus subsp.venerealis, se aisló de una vaca. La prevalencia general de campilobacteriosis en los tres estados fue de 2.9% (20/689). El resultado de este estudio identifica alC. fetus subsp.venerealis, como el agente de infertilidad enzoótica en Nigeria, y sugiere que este puede ser un problema significativo.

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Résumé Une enquête sur la campylobactériose bovine a été menée sur du bétail reproducteur dans les états de Kaduna, Kano et Borno au Nigeria. Elle a porté sur 689 bovins dont 585 taureaux et 104 femelles.C. foetus subsp.veneralis a été isolé sur 12 taureaux etC foetus subsp.foetus sur 3 d'entre eux.C. foetus subsp.foetus a été décelé sur 4 vaches tandis queC. foetus subsp.foetus ne 1'a été que sur une seule. L'a prévalence globale de la maladie dans les 3 états représente 2,9 p. 100, soit cas sur 689 examinés. Cette enquête a permis d'identifierC. foetus subsp.veneralis comme étant responsable d'une infertilité enzootique au Nigeria. Elle indique que cette affection peut constituer un important problème.

     

Improved cultural methods for Tritrichomonas Foetus

As modified Plastridge's medium (MPM) for Tritrichomonas foetus is usually not available in small or remote laboratories and is time consuming to prepare, a simplermedium was devised for cultivation of the organism. Foetal calf serum (FCS) alone (heated at 65°C for 30 min) and commercial medium 199/10% FCS were found to be at least equivalent to fresh MPM for this purpose. Alternatively, basal or complete MPM was effective for cultivation of T. foetus after storage for at least 6 months at ?20°C. A simple rapid method for obtaining pure cultures of T. foetus without sub-cultivation is also described.     

Tritrichomonas foetus infection,a cause of chronic diarrhea in the domestic cat

Tritrichomonas foetus is a very intriguing trichomonad protozoan with respect to its varied choice of residence in the different host species. It is an obligate parasite of the reproductive and the gastrointestinal tract of bovine and feline host respectively, leading to trichomonosis. Bovine trichomonosis is a sexually transmitted disease whereas feline trichomonosis is a disease with a purported fecal-oral route of spread. Further, the trichomonad is a commensal in the nasal passages, stomach, cecum and colon of swine host. Advances have been exponential in understanding the trichomonad biology and specifically feline trichomonosis since late 1990s and early 2000s when T. foetus was soundly determined to be a causative agent of chronic diarrhea in the domestic cat. It is a challenging task, even for a skilled investigator not to mention the busy clinical veterinarian, to keep up with the vast volume of information. Here we comprehensively reviewed the trichomonad biology, clinical manifestations, pathogenesis, host immunity, world map of distribution, risk factors, diagnosis and treatment. Risk factors associated with T. foetus-positive status in the domestic cat include young age, purebred, history of diarrhea, co-infections with other enteral pathogens. In addition, molecular similarity of bovine and feline isolates of T. foetus in DNA sequence was concisely discussed. The data presented serve as an information source for veterinarians, and investigators who are interested in biology of T. foetus and feline trichomonosis.     

Pathogenicity of a recently isolated strain of Tritrichomonas foetus in mice

The pathogenicity of a recently isolated strain of T. foetus in mice was studied. The parasite produced local abscesses 3 days post subcutaneous inoculation (p.i.) in albino mice. The abscesses in mice, inoculated with large numbers (4 × 10⁶) of organisms, continued increasing in size until the 14th day. Some absceses ruptured between day 11 to 14 p.i., while others formed a point. Secondary abscesses were also found in some mice. the abscesses in mice, inoculated with small numbers (1 × 10⁶) of organisms reached their maximum on the 5th day and decreased thereafter. All the abscesses had motile trichomonads with no bacterial contamination. The trichomonads, inoculated intraperitoneally in mice, persisted in that cavity till day 5 or 6 p.i., but did not multiply. Subcutaneous inoculations appear to be more reliable than the intraperitoneal ones for studies on pathogenicity. The comparison of present observations with those using a similar model and T. foetus or other trichomonads, suggests that the strain of T. foetus employed was of low pathogenicity.     

Isolation and Characterization of Large Marine Bacteriophage (Myoviridae), VhKM4 Infecting Vibrio harveyi

Abstract

The causative agent responsible for vibriosis in tropical fish aquaculture, Vibrio harveyi, has become a major bacterial pathogen. Studies suggest that this bacterium has developed resistance to antibiotics commonly used in aquaculture. In view of this situation and the requirement for the proposed postantibiotic era, bacteriophage therapy seems to be a promising control strategy for fish vibriosis. In this study, a lytic Vibrio phage VhKM4 belonging to a member of large, marine Myoviridae was successfully isolated. It exhibited bacteriolysis to both V. harveyi VHJR7 and V. parahaemolyticus ATCC 17802. The latent period of the VhKM4 phage was recorded at 60 min. It also recorded average burst size of approximately 52 plaque-forming units per infected cell. A strong bacteriolytic activity at low multiplicity of infection of 0.01 indicates the effectiveness of this large marine myovirid against fish pathogenic strain of V. harveyi VHJR7.

Received June 16, 2016; accepted October 7, 2016 Published online February 6, 2017     

Controversies in therapy of infections caused by Rhodococcus equi in foals

Pneumonia caused by Rhodococcus equi is one of the most important causes of disease and death in foals. R. equi can also be cultured from a large variety of extrapulmonary sites of infection. In the absence of an effective vaccine, ultrasonographic screening for early detection of pulmonary lesions has become routine practice at many farms endemic for pneumonia caused by R. equi. Consequently, the most frequently recognised form of R. equi infection at such farms is a subclinical form in which foals develop sonographic evidence of peripheral pulmonary consolidation or abscessation without necessarily manifesting clinical signs. Evidence exists that not all foals with ultrasonographic lesions will progress to develop clinical signs, and treating a large proportion of foals based on subclinical ultrasonographic findings has been linked to emergence of macrolide‐ and rifampin‐resistant R. equi at a horse farm. Selectively treating only those foals with larger lesion scores and monitoring foals with daily physical inspections and weekly thoracic ultrasonography offers an approach that could decrease antimicrobial drug use without significantly increasing mortality. Current evidence continues to support the combination of rifampin with a macrolide (azithromycin, clarithromycin or erythromycin) for treating clinical infections caused by R. equi despite recently described pharmacological interactions between these drugs. When infection with a macrolide‐resistant isolate is confirmed, limited effective alternatives exist.     

Equine tapeworm infections: Disease,diagnosis and control

Equine tapeworm infection has gained increasing attention over the past few decades and a number of research studies have already been published. These focus primarily on the most common of the 3 tapeworm species, Anoplocephala perfoliata, although some new information has also been generated for the other two species, Anoplocephala magna and Anoplocephaloides mamillana. The preponderance of research studies have focused on development and validation of diagnostic techniques for tapeworm detection and the role of these parasites in equine gastrointestinal disease. Several diagnostic techniques have been found useful for diagnosis of A. perfoliata but each has its strengths and weaknesses. Egg counting techniques have been modified to achieve acceptable to good diagnostic performance but the trade‐off is often a more time‐consuming method. Validation studies indicate that these methods can reliably detect tapeworm burdens above 10 worms. Several enzyme‐linked immunosorbent assays (ELISAs) have been developed and made commercially available. These can generate useful information about tapeworm exposure on the herd level but are less reliable for individual diagnosis. Unfortunately, none of the available diagnostic techniques are useful for evaluating anthelmintic treatment efficacy. Coproantigen testing may find use as a future diagnostic modality but further characterisation is required. The large body of scientific evidence supports an association between A. perfoliata infection and certain types of equine colic, although some discrepancy exists between studies. Tapeworm surveillance and control should be considered as part of the overall parasite control strategy. When properly used, the currently available diagnostic tools can guide the veterinarian to make strategic decisions regarding tapeworm control.     

Leptospirosis: An important infectious disease in North American horses

North American horses are commonly exposed to Leptospira organisms. Leptospira Bratislava is the most common infecting serovar but this serovar has not been confirmed to cause clinical disease in North American horses. Leptospira Pomona type kennewicki is responsible for most of the clinical diseases (leptospirosis) in North American horses. Leptospirosis is most commonly associated with diseases of the placenta and fetus, the kidneys and the eyes in horses. In-utero infections in pregnant mares may result in abortion, neonatal illness or birth of an antibody positive healthy foal. Acute renal failure in younger horses and recurrent uveitis in adult horses are other well documented clinical syndromes of leptospirosis. Abortions, neonatal disease and acute renal failure are caused by a subacute infection, while horses with Leptospira associated recurrent uveitis develop ocular disease months or years after the initial Leptospira infection. Diagnosis of Leptospirosis is made by a combination of antigen or antibody testing methods. Mares that abort following Leptospira infection have no additional clinical signs at the time of abortion but may shed the offending Leptospira spp. in the urine for several weeks. Antibiotic treatments are sometimes used in hopes of decreasing Leptospira shedding in infected horses or prophylactically in exposed pregnant mares but documentation of efficacy is lacking. Horses with Leptospira - associated acute renal failure can be successfully treated with antibiotics and supportive care. Recurrent uveitis is commonly associated with leptospirosis in North American horses and although horses may have chronic intraocular infection triggering an immune disease, systemic antimicrobial therapy has not been effective in eliminating the organism from the eye. An equine approved Leptospira Pomona type kennewicki vaccine is now available in North America.     

A cross-sectional study of Tritrichomonas foetus infection among healthy cats at shows in Norway

Background

In recent years, the protozoan Tritrichomonas foetus has been recognised as an important cause of chronic large-bowel diarrhoea in purebred cats in many countries, including Norway. The aim of this cross-sectional study was to determine the proportion of animals with T. foetus infection among clinically healthy cats in Norway and to assess different risk factors for T. foetus infection, such as age, sex, former history of gastrointestinal symptoms and concurrent infections with Giardia duodenalis and Cryptosporidium sp.

Methods

The sample population consisted of 52 cats participating in three cat shows in Norway in 2009. Samples were examined for motile T. foetus by microscopy, after culturing and for T. foetus-DNA by species-specific nested PCR, as well as for Giardia cysts and Cryptosporidium oocysts by immunofluorescent antibody test (IFAT).

Results

By PCR, T. foetus-DNA was demonstrated in the faeces of 11 (21%) of the 52 cats tested. DNA-sequencing of five positive samples yielded 100% identity with previous isolates of T. foetus from cats. Only one sample was positive for T. foetus by microscopy. By IFAT, four samples were positive for Giardia cysts and one for Cryptosporidium oocysts, none of which was co-infected with T. foetus. No significant associations were found between the presence of T. foetus and the various risk factors examined.

Conclusions

T. foetus was found to be a common parasite in clinically healthy cats in Norway.     

A Critical Review and Meta‐Analysis of the Efficacy of Whole‐Cell Killed Tritrichomonas foetus Vaccines in Beef Cattle

This review assesses the efficacy of whole cell Tritrichomonas foetus vaccine to prevent and treat trichomoniasis in beef cattle. Three databases were searched in June 2012. Eligible studies compared infection risk, open risk, and abortion risk in heifers or infection risk in bulls that received vaccine compared with no vaccine. Study results were extracted, summary effect measures were calculated, and the quality of the evidence was assessed. From 334 citations identified, 10 were relevant to the review . For heifers, there was limited evidence of moderate quality to assess the impact of vaccination on infection risk (RR, 0.89; P = .16; 95% CI, 0.76–1.05; 6 randomized and 4 nonrandomized studies; 251 animals) and open risk (RR, 0.80; P = .06; 95% CI, 0.63–1.01; 6 randomized and 5 nonrandomized studies; 570 animals). The quality of the body of work describing the impact of vaccination on abortion risk was low (summary RR, 0.57; P = .0003; 95% CI, 0.42–0.78; 3 randomized and 2 nonrandomized studies; 176 animals). The quality of evidence was very low for duration of infection (mean difference, ?23.42; P = .003; 95% CI, ?38.36 to ?7.85; 2 randomized and 3 nonrandomized studies; 163 animals). Although the summary effect measures suggest a benefit to vaccination, due to publication bias the effect reported here is likely an over estimate of efficacy. For bull‐associated outcomes, the evidence base was low or very low quality.     

Campylobacteriosis in dogs and cats: a review

Campylobacter species are commonly isolated from faecal samples collected from dogs and cats, with the most prevalent species being C. upsaliensis, C. helveticus, and C. jejuni. Although the majority of dogs and cats are subclinically infected, some will develop mild to moderate enteritis. Immature animals, animals from intensive housing backgrounds, and animals with concurrent disease are especially predisposed to infection and the development of clinical signs. Bacterial culture methods applied in diagnostic laboratories remain biased to C. jejuni and C. coli detection, but molecular methods to diagnose Campylobacter spp. infections in dogs and cats have become widely available and can aid rapid and accurate diagnosis. Multilocus sequence typing has also been developed for subtyping different strains and has been used in epidemiological investigations. In the majority of cases, clinical signs are self-limiting and antimicrobial treatment is not warranted. Campylobacter spp. isolated from dogs and cats have shown resistance to commonly used antimicrobials, so antimicrobial therapy should only be administered where this is justified. Contact with dogs and cats is a recognised risk factor for human campylobacteriosis, thus people living or working in close contact with cats and dogs should be made aware of the zoonotic organisms these animals can shed.     

Experimental Transmission and Pathogenicity of a Viral Erythrocytic Infection in Sea Bass Dicentrarchus labrax

Abstract

The experimental transmission of a viral erythrocytic infection (VEI) in sea bass Dicentrarchus (=Morone) labrax of the Mediterranean is reported. Transmission procedures included the intraperitoneal inoculation of healthy fishes with blood and hematopoietic tissue extracts from VEI-affected fishes, direct contact between VEI-affected and unaffected fishes, and rearing of fishes in unfiltered, nonirradiated seawater that had been used for holding VEI-affected fishes. Successful transmission of the infection was achieved in all experimental conditions, as ascertained by the presence of inclusion bodies in Giemsa-stained blood cells and subsequently confirmed by indirect immunofluorescent staining. Transmission of VEI by the inoculation of filtered cell-free extracts from affected tissues confirmed not only the infectious character of the disease but also its viral etiology. Two different patterns of effects on the hematological variables were observed: an erythroblastic polycythemia occurred 3 months after infection, whereas a moderate anemia appeared after 5–6 months. Fish growth was also negatively affected by VEI. Sea bass infected with VET were found to be more susceptible to bacterial challenge infection with Vibrio anguillarum isolate AO 18 than were control fish; the V. anguillarum dose that was lethal to 50% of the test fish was lower for VEI-affected fish, and their cumulative mortality in the bacterial challenge was higher. The injection of cyclophosphamide produced immunosuppression in unaffected sea bass and an increase in the level of infection in VEI-affected fishes; these results suggest the role of the immunological status of the host sea bass in the development of VEI.     

Sample collection factors affect the sensitivity of the diagnostic test for Tritrichomonas foetus in bulls

The current diagnostic test for Tritrichomonas foetus involves the culture of collected preputial or vaginal samples. In an earlier study, which evaluated sampling tools for use with bulls, it was observed that the sensitivity of the diagnostic test was higher for 2nd samples collected from the right side of the prepuce than it was for samples collected 1st from the left side. The study described in this paper was conducted to evaluate which of these factors was responsible for the effect on diagnostic sensitivity. Twenty-nine bulls infected with T. foetus were repeatedly sampled in a 2-factor cross-over design. Samples taken from the right side of the prepuce were 4 times as likely to be positive as samples taken from the left side (P = 0.03). Other factors did not have a significant effect on the outcome of the diagnostic test. Unexpected factors may affect the sensitivity of the diagnostic test for T. foetus.     

Evaluation of practices used to reduce the incidence of bovine respiratory disease in Australian feedlots (to November 2021)

Bovine respiratory disease (BRD) has been identified as the most significant infectious disease of feedlot cattle in eastern Australia.¹ Bovine respiratory disease causes economic loss due to medication costs, mortalities, excessive feed inputs associated with increased time on feed, reduced sale prices and associated labour costs. Bovine respiratory disease is a complex multifactorial condition with multiple animal, environmental and management risk factors predisposing cattle to illness. A range of microorganisms are implicated in BRD with at least four viral and five bacterial species commonly involved individually or in combination. The viruses most commonly associated with BRD in Australia are bovine herpesvirus 1 (BHV1), bovine viral diarrhoea virus (BVDV or bovine pestivirus), bovine parainfluenza 3 virus (PI3) and bovine respiratory syncytial virus (BRSV). More recently, bovine coronavirus has been identified as a potential viral contributor to BRD in Australia.² A number of bacterial species have also been recognised as important to the BRD complex; these include Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Trueperella pyogenes and Mycoplasma bovis. Although one or more of the pathogens listed above can be isolated from clinical cases of BRD, there is no evidence that infection alone causes serious illness. This indicates that, in addition to specific infectious agents, other factors are crucial for the development of BRD under field conditions. These can be categorised as environmental, animal and management risk factors. These risk factors are likely to exert their effects through multiple pathways including reductions in systemic and possibly local immunity. For example, stressors such as weaning, handling at saleyards, transport, dehydration, weather conditions, dietary changes, comingling and pen competition might reduce the effectiveness of the immune system. Reduced immunocompetence can allow opportunistic infection of the lower airways with potential pathogens leading to the development of BRD. The objective of this paper is to critically review the evidence for management practices aimed at reducing the incidence of BRD in Australian feedlot cattle. Predisposing factors (Table 1) largely beyond the control of most feedlots, such as weather and exposure to respiratory viruses, are discussed separately, but these factors can generate indirect prevention responses that are discussed under the preventative practices categories. The current practices are classified as either animal preparation practices (Table 2) or feedlot management practices (Table 3).     

Enterohaemorrhagic Escherichia coli: A new problem, an old group of organisms Inter faeces et urinam nascimur

All mammals are colonised by Escherichia coli generally at birth and these organisms become part of their intestinal flora for the rest of their lives. New types are acquired generally by an oral route. Some E coli are pathogenic and some may have a far more enhanced ability to colonise the human intestine than most others. Recently enterohaemorrhagic E coli have emerged. They can cause a number of intestinal illnesses in humans including bloody diarrhoea and haemolytic uraemic syndrome. These organisms produce a number of virulence factors particularly the Shiga-like toxins (verotoxins). The intestines of animals may be the reservoir of these organisms for human infection, and cattle particularly have been shown to harbour them. Food, especially undercooked meat products, have been associated with a number of outbreaks throughout the world. While a certain serotype O157.H7 has been associated with many outbreaks throughout the world, other serotypes, particularly 0111.H-, have also been reported. This latter serotype appears to be more common in Australia.     

Microsporidiosis: Enterocytozoon bieneusi in domesticated and wild animals

Microsporidia are a ubiquitous group of obligate intracellular parasites that infect all major animal groups. Enterocytozoon bieneusi is the most commonly identified Microsporidia in humans and has also been reported worldwide in animals with importance in veterinary medicine (e.g. cats, dogs, horses, cattle and pigs). The identification of E. bieneusi in animals has raised the question of the importance of animal reservoirs in the epidemiology of this pathogen, and the implications of the infection with this pathogen in infected animals. Considerable genetic diversity within E. bieneusi has been found with over 90 genotypes identified based on the ITS nucleotide sequence of E. bieneusi spores recovered from the feces of infected humans and animals. Both host-adapted E. bieneusi genotypes with narrow host ranges and potentially zoonotic genotypes with wide host specificity have been identified. The information presented in this review should be useful in understanding the taxonomy, epidemiology, zoonotic potential, and importance in public health of E. bieneusi.