Clostridia as agents of zoonotic disease

Clostridia are not normally considered to be zoonotic pathogens, although many species affect both humans and domestic animals. Three cases in which organisms occur, possibly via direct or indirect transmission, in both food animals and humans are considered here. Strains of Clostridium perfringens that produce enterotoxin (CPE) are typically transmitted to humans in contaminated, improperly handled foods. Pathogenesis is based upon action of CPE in the intestine, and disease is usually self-limiting. Infection of domestic animals by CPE-producing C. perfringens is uncommon. C. perfringens type C is best known as a pathogen of neonatal domestic animals, which acquire the infection from the dam. The course may be peracute, and prevention by vaccination of the dam is universally advocated. Humans consuming meat contaminated with type C may develop enteritis necroticans, with segmental hemorrhagic and necrotic jejunitis, which must usually be treated by bowel resection. Clostridium difficile is a pathogen of both humans and domestic animals. Examination of retail meats by bacteriologic culture has revealed genotypes of C. difficile that in many cases are identical to those from food animals and diseased humans. Transmission, food animals to foods to humans, has not been documented.     

新生隐球菌病研究进展

隐球菌是条件致病性深部真菌,易发于细胞免疫功能受损的人群.新生隐球菌是隐球菌属的重要致病菌,属环境腐生菌,可从土壤和鸽粪中分离到,并被认为是人和动物最主要的传染源.医学方面,近年来由新生隐球菌引起的感染有逐渐增多的趋势,主要引起人的脑膜炎和肺炎.动物医学方面,可引起马的呼吸道病、牛羊的乳腺炎.鸽是隐球菌的自然宿主,但并不引起发病.该文从隐球菌病的病原特征、分类、毒力因子、致病性等生物学特性进行了概述,并对人和动物新生隐球菌病的传染和流行的基本环节、发病机制、临床表现、防治等方面的研究进展进行了综述.     

The ecology and pathobiology of Clostridium difficile infections: an interdisciplinary challenge

Clostridium difficile is a well recognized pathogen of humans and animals. Although C. difficile was first identified over 70 years ago, much remains unknown in regards to the primary source of human acquisition and its pathobiology. These deficits in our knowledge have been intensified by dramatic increases in both the frequency and severity of disease in humans over the last decade. The changes in C. difficile epidemiology might be due to the emergence of a hypervirulent stain of C. difficile, ageing of the population, altered risk of developing infection with newer medications, and/or increased exposure to C. difficile outside of hospitals. In recent years, there have been numerous reports documenting C. difficile contamination of various foods, and reports of similarities between strains that infect animals and strains that infect humans as well. The purposes of this review are to highlight the many challenges to diagnosing, treating, and preventing C. difficile infection in humans, and to stress that collaboration between human and veterinary researchers is needed to control this pathogen.     

Cryptococcus neoformans granuloma in the lung and spinal cord of a free-ranging cheetah (Acinonyx jubatus). A clinical report and literature review

A 6-year-old, male, wild-born, free-ranging cheetah (Acinonyx jubatus) was evaluated for acute onset of progressive lameness in the right hind limb. Survey radiographs were unrewarding and myelography indicated an intramedullary compressive mass at the L3-L4 region. A fine needle aspirate of the lesion indicated the presence of Cryptococcus organisms. Necropsy confirmed the presence of granulomas (cryptococcoma) in the lung and the spinal cord (meningomyelitis) caused by Cryptococcus neoformans var. gattii. Cryptococcus neoformans is a yeast-like organism that is a potential pathogen to many species. Initial infection is thought to be of respiratory origin and then it commonly disseminates systemically from the nasal cavity or lungs to the skin, eyes and central nervous system in particular. The cheetah tested negative for both feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV), as have all the previously reported cheetah cases. C. neoformans is a non-contagious, opportunistic organism and is the most common systemic mycoses in domestic cats and the cheetah.     

Immune response to fungal infections

The immune mechanisms of defence against fungal infections are numerous, and range from protective mechanisms that were present early in evolution (innate immunity) to sophisticated adaptive mechanisms that are induced specifically during infection and disease (adaptive immunity). The first-line innate mechanism is the presence of physical barriers in the form of skin and mucous membranes, which is complemented by cell membranes, cellular receptors and humoral factors. There has been a debate about the relative contribution of humoral and cellular immunity to host defence against fungal infections. For a long time it was considered that cell-mediated immunity (CMI) was important, but humoral immunity had little or no role. However, it is accepted now that CMI is the main mechanism of defence, but that certain types of antibody response are protective. In general, Th1-type CMI is required for clearance of a fungal infection, while Th2 immunity usually results in susceptibility to infection. Aspergillosis, which is a disease caused by the fungus Aspergillus, has been the subject of many studies, including details of the immune response. Attempts to relate aspergillosis to some form of immunosuppression in animals, as is the case with humans, have not been successful to date. The defence against Aspergillus is based on recognition of the pathogen, a rapidly deployed and highly effective innate effector phase, and a delayed but robust adaptive effector phase. Candida albicans, part of the normal microbial flora associated with mucous surfaces, can be present as congenital candidiasis or as acquired defects of cell-mediated immunity. Resistance to this yeast is associated with Th1 CMI, whereas Th2 immunity is associated with susceptibility to systemic infection. Dermatophytes produce skin alterations in humans and other animals, and the essential role of the CMI response is to destroy the fungi and produce an immunoprotective status against re-infection. The resolution of the disease is associated with a delayed hypersensitive response. There are many effective veterinary vaccines against dermatophytoses. Malassezia pachydermatis is an opportunistic yeast that needs predisposing factors to cause disease, often related to an atopic status in the animal. Two species can be differentiated within the genus Cryptococcus with immunologic consequences: C. neoformans infects predominantly immunocompromised hosts, and C. gattii infects non-immunocompromised hosts. Pneumocystis is a fungus that infects only immunosupressed individuals, inducing a host defence mechanism similar to that induced by other fungal pathogens, such as Aspergillus.     

Cryptococcosis in seven horses

The clinical, radiographic and post-mortem findings in 6 horses with cryptococcal pneumonia and one horse with an abdominal cryptococcal granuloma are described. In pulmonary cryptococcosis, the lesions were either diffuse and multiple, with bilateral lung involvement, or localised mainly to the dorsocaudal region of one lung. The cases of diffuse multiple cryptococcosis were thought to be associated with haematogenous spread of the fungus after gastrointestinal infection and dissemination from regional lymph nodes. The localised form of the disease was thought to have been associated with inhalation of cryptococci. In all cases of pulmonary cryptococcosis, encapsulated yeast-like organisms were demonstrated in Wright's-stained sediment of tracheal washes. In the horse with the abdominal granuloma, cryptococci were present in a fine needle aspirate sample. Isolates of Cryptococcus neoformans var gattii were recovered from 2 of the 5 horses in which cultures were attempted. In addition to a history of previous illness that may have predisposed to infection, most horses in this report had been in areas in which Eucalyptus camaldulensis, or the closely related E rudis, were growing. In humans, an epidemiological relationship between E camaldulensis and infection with C neoformans var gattii has been suggested. Cases of equine cryptococcosis carry a poor prognosis and treatment was not attempted in any of these cases.     

Identification of genotypes of Cryptosporidium parvum isolates from a patient and a dog in Japan

Cryptosporidium parvum (C. parvum) is recognized as a significant pathogen in humans and animals, primarily as a cause of diarrheal illness. Recent genetic and biological studies indicate that C. parvum is not a single species but composed of genetically distinct multiple genotypes. Thus, it is valuable to distinguish between genotypes in the epidemiology of Cryptosporidium infection in humans and animals. Although C. parvum has been detected in humans and animals in Japan, the genotype of isolates remains unclear because identification has been performed only by conventional microscopy. We report herein the genotypes of C. parvum isolates distinguished by the polymerase chain reaction (PCR)-based diagnostic method. C. parvum isolates, originally obtained from a patient and a pet dog, were found to have cattle and dog genotypes, respectively.     

The importance of Campylobacter jejuni to the meat industry: a review

Campylobacter jejuni is a microorganism that only recently has been implicated in gastroenteritis in humans. As appropriate methods used for detection of the bacterium have been developed, the rates of illness caused by the pathogen were found to approach or surpass those attributed to Salmonella. Substantial evidence has been gathered to document that the route for human infection is through the ingestion of adulterated food and drink. Some slaughter animals harbor this potential pathogen among the intestinal flora and, consequently, transfer of the organism to carcasses and to the resulting meat products does occur. The most frequently implicated meat is poultry, with an incidence of recovery of C. jejuni from the store-bought poultry meat reported to be at least 50%. Red meat from slaughter animals have also yielded this bacterium from carcasses, but at lower incidence levels. Foodborne disease has been associated most frequently with the ingestion of raw milk, but poultry, hamburger, and other foods have all been implicated as potential sources. However, cause and effect relating the presence of C. jejuni in meat and human gastroenteritis has not been demonstrated. Additional research is needed to determine whether C. jejuni isolated from meat causes gastroenteritis and whether all strains of the organism are virulent. Recognition of C. jejuni as a potential meatborne pathogen by the meat industry is necessary, and appropriate sanitary practices to prevent passage of the organism through meat products should be implemented.     

Serotypes and mating types of clinical isolates from feline cryptococcosis in Japan

Most isolates of Cryptococcus neoformans (teleomorph: Filobasidiella neoformans) from human patients and from environmental materials in Japan have been identified as serotype A mating type a by the seroagglutination test and mating experiments. A PCR method using the mating type alpha allele-specific primer of the STE12 gene and the serotype- and mating type-specific primers of the STE20 gene for identification of C. neoformans has been developed. Using the PCR method, conserved strains and clinical isolates from feline cryptococcosis were examined for serotype and the mating type. The results showed that all clinical isolates examined were identified as serotype A, MATalpha, indicating that feline cryptococcsis cases in Japan are caused by C. neoformans serotype A, MATalpha, as is the case in humans.     

Clinical characteristics and predictors of mortality for Cryptococcus gattii infection in dogs and cats of southwestern British Columbia

Since 1999, Cryptococcus gattii has emerged as an important pathogen of humans and animals in southwestern British Columbia. Historically thought to be restricted to the tropics and subtropics, C. gattii has posed new diagnostic and treatment challenges to veterinary practitioners working within the recently identified endemic region. Clinical reports of canine and feline cryptococcosis caused by C. gattii diagnosed between January 1999 and December 2003 were included in this case series. The most common manifestations of disease were respiratory and central nervous system signs. Multivariate survival analysis revealed that the only significant predictor of mortality was the presence of central nervous system signs upon presentation or during therapy. Case fatality rates in both species were high. Further investigation into effective treatment regimes is warranted.     

Seminal vesicle and coagulating gland growth induced by intraperitoneal inoculation of fungi in mice

The effect of fungi on the growth of body organs in mice was investigated. Single, intraperitoneal injections of yeasts (Cryptococcus albidus, Saccharomyces cerevisiae, Schizosaccharomyces octosporus) or molds (Aspergillus niger, Geotrichum candidum, Mucor haemalis) induced an increase in the mass of seminal vesicles and coagulating glands independent of whole body weight changes in mice.     

Cryptosporidium infection in dogs in Osaka,Japan

Cryptosporidium parvum is a zoonotic pathogen composed of genetically distinct but morphologically identical genotypes. Recent molecular study indicates that dogs may transmit the cattle genotype, which is known to be pathogenic to humans. Although large-scale studies of Cryptosporidium infection in dogs have been performed in several countries, the isolates were not accurately identified because of the lack of a method for molecular analysis. It is important to identify the isolates harbored in dogs, which come in close contact with humans, in order to control human cryptosporidiosis. The aim of the present study was to calculate the prevalence of Cryptosporidium infection in dogs in Osaka city, Japan, and to characterize the isolates molecularly. The prevalence was determined to be 9.3% (13/140) by PCR. All isolates were found to be Cryptosporidium canis (previously known as the dog genotype), which is thought to be non-pathogenic in humans, based on the sequencing of diagnostic fragments. These results indicate that PCR-based diagnostic methods are a useful tool for the diagnosis and molecular epidemiology of Cryptosporidium infection in dogs, and that dogs living in Osaka are not a significant reservoir for human cryptosporidiosis. It is unclear why C. canis is dominant in dogs. Further study is required to understand this partial parasitism.     

Listeric Infections in Humans and Animals in the Indian Subcontinent: A Review

Listeriosis is an important bacterial zoonosis caused by the intracellular pathogen Listeria monocytogenes. The disease has been reported in animals from the Indian subcontinent, usually in the form of sporadic cases but occasionally as outbreaks. Cases of listeriosis arise mainly from the ingestion of contaminated food. Listeriosis has been reported to cause encephalitis, abortion, mastitis, repeat breeding and endometriosis in animals. Listeric infections occur in children and women with a poor obstetric history. The epidemiological aspects and pathogenesis of listeriosis in animals and humans are not yet fully understood. This review offers comprehensive information on experimental studies and field cases in animals and on cases of human listeriosis. There are also sections on isolation from foods, diagnosis and treatment in humans and animals.     

The detection of Chlamydophila psittaci genotype C infection in dogs

Reports of canine chlamydiosis are infrequent, possibly because the pathogen is rarely considered to be a cause of disease in dogs. This report presents details of Chlamydophila psittaci infection in four bitches with recurrent keratoconjunctivitis, severe respiratory distress and reduced litter size (up to 50% stillborn or non-viable puppies) in a small dog-breeding facility in Germany. Cell culture and immunofluorescence examination of conjunctival, nasal and pharyngeal swabs revealed chlamydial inclusions. PCR and sequencing of ompA amplification products confirmed the presence of Cp. psittaci genotype C. The zoonotic potential of the pathogen was illustrated by evidence of disease in two children that lived on the premises with the infected dogs. There was circumstantial evidence to suggest infection of dogs and humans may have followed the introduction of two canaries and a parrot to the household. The persistent nature of the chlamydial infection suggests that dogs may be reservoirs of Cp. psittaci, but this putative role and whether or not dogs shed the pathogen require further investigation.     

Disease Risk Surface for Coxiella burnetii Seroprevalence in White‐Tailed Deer

Coxiella burnetii is considered a re‐emerging zoonosis in many countries. The bacterium is enzootic in livestock and wildlife in the United States, and environmental contamination is widespread. Despite the potential for exposure, the estimated prevalence of Q fever in humans and animals is not well elucidated, and reported human infections in the United States are relatively rare. Zoonotic transmission of the bacterium is usually associated with abortions in domestic ruminants, but other modes of transmission, such as contact with infected blood and/or milk during field dressing of infected wildlife, have not been thoroughly investigated. Studies of zoonotic pathogen transmission between animal reservoir hosts and humans are usually established in response to documented emergence or re‐emergence of a zoonosis in a particular locale, and, as such, the prevalence of infection in wildlife is largely unknown for many zoonotic pathogens, including C. burnetii. The objective of this study was to create a disease risk surface for C. burnetii seroprevalence in wild white‐tailed deer (Odocoileus virginianus) in New York State. Blood samples were collected from hunter‐harvested deer from across New York State in 2009 and 2010. The samples were processed and tested for the presence of anti‐C. burnetii antibodies via indirect microimmunofluorescence assays using phase II C. burnetii strain RSA439. Overall, 14.50% of the tested white‐tailed deer were C. burnetii phase II seropositive. The dual Kernel density estimation method was used to create a smoothed disease risk surface, which revealed variation in seroprevalence ranging from 0% to 32.0%. Areas of higher seroprevalence were detected in four discrete areas of Central New York and in one additional area in the southwest corner of the northern part of the state. This suggests certain locales where humans may be at increased risk for exposure to the bacterium secondary to contact with potentially infected deer.     

The role of Acinetobacter baumannii as a nosocomial pathogen for dogs and cats in an intensive care unit

Acinetobacter baumannii is a nosocomial pathogen associated with high morbidity and mortality in humans. Whereas infections with strains of Acinetobacter species have been reported in various situations, the importance of A baumannii as a nosocomial pathogen in veterinary hospitals has not been studied so far. In this retrospective case series, we describe 17 dogs and 2 cats from which A baumannii had been isolated during a 21/2-year period. In 7 dogs, A baumannii induced systemic signs of illness, whereas 12 animals showed signs of local infection. In all animals with systemic infection, and in 2 with localized infection, A baumannii contributed to the death of the animal or contributed to euthanasia; the remaining 8 dogs and both cats recovered. Molecular typing of the isolates with restriction polymorphisms of ribosomal DNA provided evidence of nosocomial spread of this pathogen and for the presence of several strains of A baumannii in the hospital environment.     

Identification of genotypes of Giardia intestinalis isolates from a human and calf in Japan

Giardia intestinalis is recognized as a significant pathogen in humans and animals, causing diarrhea. Recent molecular studies indicate that G. intestinalis is composed of genetically distinct multiple genotypes. Therefore, it is valuable to distinguish among genotypes in the epidemiology of Giardia infection in humans and animals. Although G. intestinalis has been found in humans and animals in Japan, the genotype of isolates remains unclear except for several isolates from dogs, because identification has been performed only by conventional microscopy. We report herein the genotypes of G. intestinalis isolates distinguished by a phylogenetic analysis. G. intestinalis isolates originated from a patient and a calf were found to have Assemblage B and E, respectively.     

The excretion of Cryptococcus neoformans (Sanfelice) VUILLEMIN 1894 by pet birds

A survey on taxonomy, diagnosis, distribution and pathogenicity of Cryptococcus neoformans is given. The investigation presented here concerns 1046 fecal samples of avian species, which can be kept in the living area of humans. All together only 15 strains have been isolated, 9 of which originated from the same breeder.     

Chronic Bartonellosis in Cats: What are the potential implications?

Practical relevance: Bartonellae are small, vector-transmitted Gram-negative intracellular bacteria that are well adapted to one or more mammalian reservoir hosts. Cats are the natural reservoir for Bartonella henselae, which is a (re-)emerging bacterial pathogen. It can cause cat scratch disease in humans and, in immunocompromised people, may lead to severe systemic diseases, such as bacillary angiomatosis. Cats bacteraemic with B henselae constitute the main reservoir from which humans become infected. Most cats naturally infected with B henselae show no clinical signs themselves, but other Bartonella species for which cats are accidental hosts appear to have more pathogenicity. Global importance: Several studies have reported a prevalence of previous or current Bartonella species infection in cats of up to 36%. B henselae is common in cats worldwide, and bacteraemia can be documented by blood culture in about a quarter of healthy cats. The distribution of B henselae to various parts of the world has largely occurred through humans migrating with their pet cats. The pathogen is mainly transmitted from cat to cat by fleas, and the majority of infected cats derive from areas with high flea exposure. No significant difference in B henselae prevalence has been determined between male and female cats. In studies on both naturally and experimentally infected cats, chronic bacteraemia has mainly been found in cats under the age of 2 years, while those over 2 years of age are rarely chronically bacteraemic. Evidence base: This article reviews published studies and case reports on bartonellosis to explore the clinical significance of the infection in cats and its impact on humans. The article also discusses possible treatment options for cats and means of minimising the zoonotic potential.     

Compendium of measures to control Chlamydophila psittaci (formerly Chlamydia psittaci) infection among humans (psittacosis) and pet birds, 2005

Psittacosis, also known as parrot fever and ornithosis, is a bacterial infection of humans that can cause severe pneumonia and other serious health problems. It is caused by Chlamydophila psittaci, formerly known as Chlamydia psittaci. From 1988 through 2003, 935 human cases of psittacosis were reported to the CDC and most resulted from exposure to infected pet birds, usually cockatiels, parakeets, parrots, and macaws. In birds, C. psittaci infection is referred to as avian chlamydiosis. Infected birds shed the bacteria through feces and nasal discharges, and humans become infected from exposure to these materials. This compendium provides information about psittacosis and avian chlamydiosis to public health officials, physicians, veterinarians, the pet bird industry, and others concerned with controlling these diseases and protecting public health. The recommendations in this compendium provide standardized procedures for controlling avian chlamydiosis in birds, a vital step to protecting human health. This document will be reviewed and revised as necessary.