Tick-borne rickettsial diseases: emerging risks in Europe

Ticks are currently considered the main vectors of human infectious diseases in Europe, particularly since their role in the transmission of the agent of Lyme borreliosis was demonstrated in the 1980s. In the recent years, ticks have also been shown to be the vectors of numerous emerging rickettsial diseases. Although Mediterranean spotted fever (MSF) due to Rickettsia conorii was thought for a long time to be the only tick-borne rickettsial disease prevalent in Europe, five more spotted fever rickettsiae have been described as emerging pathogens in the last decade. Further, cases of infection due to Anaplasma phagocytophilum, the agent of human anaplasmosis (previously known as human granulocytic ehrlichiosis), have been reported throughout Europe. We present here these emerging diseases and discuss other potential threat for the future.     

犬在埃立克体病研究中的作用

随着新病原及病原新的致病性不断被发现 ,埃立克体及埃立克体病已经成为预防医学和兽医学研究热点。在已经发现的 1 1种埃立克体病原中 ,有 5种可以直接感染犬 ,引起不同的犬埃立克体病 ;另外 2种为早先分别从人单核细胞埃立克体病和粒细胞埃立克体病患者中分离的病原 ,在流行区的犬体内也可以分离到。资料表明犬对许多埃立克体都极为敏感 ,犬在埃立克体及埃立克体病研究上占有重要地位。鉴于这是我国近年才发现的新病原 ,许多兽医及研究工作者不认识它 ,文章就相关埃立克体对犬的感染和所致疾病以及在流行病学上的意义进行了综述。     

Tick- and flea-borne rickettsial emerging zoonoses

Between 1984 and 2004, nine more species or subspecies of spotted fever rickettsiae were identified as emerging agents of tick-borne rickettsioses throughout the world. Six of these species had first been isolated from ticks and later found to be pathogenic to humans. The most recent example is Rickettsia parkeri, recognized as a human pathogen more than 60 years after its initial isolation from ticks. A new spotted fever rickettsia, R. felis was also found to be associated with fleas and to be a human pathogen. Similarly, bacteria within the family Anaplasmataceae have been considered to be of veterinary importance only, yet three species have been implicated in human diseases in recent years, including Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, Anaplasma phagocytophilum, the agent of human anaplasmosis (formerly known as "human granulocytic ehrlichiosis agent", E. equi and E. phagocytophila), and finally Ehrlichia ewingii, which causes granulocytic ehrlichiosis in humans. We present here an overview of the various tick- and flea-borne rickettsial zoonoses described in the last 20 years, focusing on the ecological, epidemiological and clinical aspects.     

Brucellosis: A re-emerging zoonosis

Brucellosis, especially caused by Brucella melitensis, remains one of the most common zoonotic diseases worldwide with more than 500,000 human cases reported annually. The bacterial pathogen is classified by the CDC as a category (B) pathogen that has potential for development as a bio-weapon. Brucella spp. are considered as the most common laboratory-acquired pathogens. The geographical distribution of brucellosis is constantly changing with new foci emerging or re-emerging. The disease occurs worldwide in both animals and humans, except in those countries where bovine brucellosis has been eradicated. The worldwide economic losses due to brucellosis are extensive not only in animal production but also in human health. Although a number of successful vaccines are being used for immunization of animals, no satisfactory vaccine against human brucellosis is available. When the incidence of brucellosis is controlled in the animal reservoirs, there is a corresponding and significant decline in the incidence in humans.     

Gastrointestinal Disease in Exotic Small Mammals

Exotic small mammal medicine is a relatively new specialty area within veterinary medicine. Ferrets, rabbits, and rodents have long been used as animal models in human medical research investigations, resulting in a body of basic anatomic and physiologic information that can be used by veterinarians treating these species. Unfortunately, there is a paucity of veterinary articles that describe clinical presentation, diagnosis, and treatment options of gastrointestinal (GI) disease as it affects exotic small mammals. Although there is little reference material relating to exotic small mammal GI disease, patients are commonly presented to veterinary hospitals with digestive tract disorders. This article provides the latest information available for GI disease in ferrets (Helicobacter mustelae gastritis, inflammatory bowel disease [IBD], GI lymphoma, systemic coronavirus, coccidiosis, and liver disease), rabbits (GI motility disorders, liver lobe torsion, astrovirus, and coccidiosis), guinea pigs (gastric dilatation volvulus [GDV]), rats (Taenia taeniaeformis), and hamsters (Clostridium difficile). Both noninfectious diseases and emerging infectious diseases are reviewed as well as the most up-to-date diagnostics and treatment options.     

Infection and blood transfusion: a guide to donor screening

In recent years, blood-component therapy has become more accessible in veterinary practice. As with human medicine, care must be taken to minimize the risk of disease transmission from donor to recipient. Determining the appropriate diseases to screen for is complicated by regional variations in disease incidence, the existence of chronic carrier states for some diseases, the difficulty in screening-test selection, and testing cost. The feline diseases considered include retroviral infections, feline coronaviruses, ehrlichiosis (Ehrlichia canis-like), anaplasmosis (Anaplasma phagocytophilum), neorickettsiosis (Neorickettsia risticii), hemoplasmosis (Mycoplasma hemofelis and M. hemominutum, previously feline hemobartonellosis), and cytauxzoonosis (Cytauxzoon felis). The canine diseases considered in this paper include babesiosis (Babesia canis and B. gibsonii,) ehrlichiosis (E. canis and E. ewingii), anaplasmosis (A. phagocytophilum), neorickettsiosis (N. risticii var. atypicalis), leishmaniasis (Leishmania donovani complex), brucellosis (Brucella canis), hemoplasmosis (M. hemocanis, previously canine hemobartonellosis), and bartonellosis (Bartonella vinsonii).     

6th International Conference on Emerging Zoonoses

The 6th International Conference on Emerging Zoonoses, held at Cancun, Mexico, 24-27 February 2011, offered 84 participants from 18 countries, a snapshot of current research in numerous zoonoses caused by viruses, bacteria or prions. Co-chaired by Professors Heinz Feldmann and Jürgen Richt, the conference explored 10 topics: (i) The ecology of emerging zoonotic diseases; (ii) The role of wildlife in emerging zoonoses; (iii) Cross-species transmission of zoonotic pathogens; (iv) Emerging and neglected influenza viruses; (v) Haemorrhagic fever viruses; (vi) Emerging bacterial diseases; (vii) Outbreak responses to zoonotic diseases; (viii) Food-borne zoonotic diseases; (ix) Prion diseases; and (x) Modelling and prediction of emergence of zoonoses. Human medicine, veterinary medicine and environmental challenges are viewed as a unity, which must be considered under the umbrella of 'One Health'. Several presentations attempted to integrate the insights gained from field data with mathematical models in the search for effective control measures of specific zoonoses. The overriding objective of the research presentations was to create, improve and use the tools essential to address the risk of contagions in a globalized society. In seeking to fulfil this objective, a three-step approach has often been applied: (i) use cultured cells, model and natural animal hosts and human clinical models to study infection; (ii) combine traditional histopathological and biochemical approaches with functional genomics, proteomics and computational biology; and (iii) obtain signatures of virulence and insights into mechanisms of host defense response, immune evasion and pathogenesis. This meeting review summarizes 39 of the conference presentations and mentions briefly the 16 articles in this Special Supplement, most of which were presented at the conference in earlier versions. The full affiliations of all presenters and many colleagues have been included to facilitate further inquiries from readers.     

Diagnosis of canine monocytotropic ehrlichiosis (Ehrlichia canis): An overview

Canine monocytotropic ehrlichiosis (CME), caused by the rickettsia Ehrlichia canis, an important canine disease with a worldwide distribution. Diagnosis of the disease can be challenging due to its different phases and multiple clinical manifestations. CME should be suspected when a compatible history (living in or traveling to an endemic region, previous tick exposure), typical clinical signs and characteristic hematological and biochemical abnormalities are present. Traditional diagnostic techniques including hematology, cytology, serology and isolation are valuable diagnostic tools for CME, however a definitive diagnosis of E. canis infection requires molecular techniques. This article reviews the current literature covering the diagnosis of infection caused by E. canis.     

Emerging arthropod-borne diseases of companion animals in Europe

Vector-borne diseases are caused by parasites, bacteria or viruses transmitted by the bite of hematophagous arthropods (mainly ticks and mosquitoes). The past few years have seen the emergence of new diseases, or re-emergence of existing ones, usually with changes in their epidemiology (i.e. geographical distribution, prevalence, and pathogenicity). The frequency of some vector-borne diseases of pets is increasing in Europe, i.e. canine babesiosis, granulocytic anaplasmosis, canine monocytic ehrlichiosis, thrombocytic anaplasmosis, and leishmaniosis. Except for the last, these diseases are transmitted by ticks. Both the distribution and abundance of the three main tick species, Rhipicephalus sanguineus, Dermacentor reticulatus and Ixodes ricinus are changing. The conditions for such changes involve primarily human factors, such as travel with pets, changes in human habitats, social and leisure activities, but climate changes also have a direct impact on arthropod vectors (abundance, geographical distribution, and vectorial capacity). Besides the most known diseases, attention should be kept on tick-borne encephalitis, which seems to be increasing in western Europe, as well as flea-borne diseases like the flea-transmitted rickettsiosis. Here, after consideration of the main reasons for changes in tick vector ecology, an overview of each “emerging” vector-borne diseases of pets is presented.     

Rocky Mountain spotted fever in dogs and its differentiation from canine ehrlichiosis

Rocky Mountain spotted fever (RMSF) or ehrlichiosis was diagnosed in dogs on the basis of specific immunofluorescent testing for each disease. Comparisons between clinical and laboratory findings were made between the 2 diseases. The incidence of RMSF tended to be more seasonal and it affected younger dogs. Purebred dogs appeared to be more susceptible to both diseases. In general, RMSF had a more rapid and severe course of clinical illness than did ehrlichiosis, but acute ehrlichiosis was difficult to differentiate from RMSF. Both diseases were characterized by fever, depression, lymphadenopathy, and signs of neurologic dysfunction; petechial hemorrhages or other signs of hemorrhagic diathesis were evident only in a small proportion of cases. Anemia, leukopenia, and thrombocytopenia were more common in dogs with ehrlichiosis, whereas those with RMSF more often had leukocytosis and thrombocytopenia. Hypoalbuminemia was found in dogs with both diseases, but those with ehrlichiosis usually had concurrent hyperglobulinemia. High serum alkaline phosphatase activity and serum cholesterol concentration, and low serum calcium concentration were more common in dogs with RMSF than with ehrlichiosis. Rising serum titers or positive direct immunofluorescence for Rickettsia rickettsii in skin biopsy specimens were used to confirm RMSF, whereas a single serum titer for Ehrlichia canis enabled detection of ehrlichiosis. In the absence of neurologic deficits and when dogs were treated with tetracycline, dogs with RMSF made a more rapid and consistent recovery than did dogs with ehrlichiosis.     

Death of a horse infected experimentally with Anaplasma phagocytophilum

A 19-year-old horse that was one of a group of six horses infected experimentally with Anaplasma phagocytophilum for a study of the pathogenesis of equine granulocytic ehrlichiosis died suddenly two days after first showing clinical signs of disease. The clinical signs and laboratory findings observed before its death were similar to all those of the other infected horses, and to previous reports of this disease. A postmortem examination revealed widespread haemorrhaging in its internal organs, and vasculitis and thrombosis in the kidneys. These changes are consistent with disseminated intravascular coagulation, which has previously been reported in human beings infected with the presumably identical agent of human granulocytic ehrlichiosis.     

Probiotic Use in Horses – What is the Evidence for Their Clinical Efficacy?

The gastrointestinal microbiota is extremely important for human and animal health. Investigations into the composition of the microbiota and its therapeutic modification have received increasing interest in human and veterinary medicine. Probiotics are a way of modifying the microbiota and have been tested to prevent and treat diseases. Probiotics are proposed to exert their beneficial effects through various pathways. Production of antimicrobial compounds targeting intestinal pathogens, general immune stimulation, and colonization resistance are among these mechanisms. Despite widespread availability and use, scientific, peer‐reviewed evidence behind commercial probiotic formulations in horses is limited. Additionally, quality control of commercial over‐the‐counter products is not tightly regulated. Although promising in vitro results have been achieved, in vivo health benefits have been more difficult to prove. Whether the ambiguous results are caused by strain selection, dosage selection or true lack of efficacy remains to be answered. Although these limitations exist, probiotics are increasingly used because of their lack of severe adverse effects, ease of administration, and low cost. This review summarizes the current evidence for probiotic use in equine medicine. It aims to provide veterinarians with evidence‐based information on when and why probiotics are indicated for prevention or treatment of gastrointestinal disease in horses. The review also outlines the current state of knowledge on the equine microbiota and the potential of fecal microbial transplantation, as they relate to the topic of probiotics.     

A retrospective study of 61 cases of spontaneous canine epistaxis (1998 to 2001)

OBJECTIVES: To determine the prevalence and identify possible clinicopathologic indicators of the diseases associated with canine epistaxis. METHODS: The medical records of 61 dogs with epistaxis were reviewed. RESULTS: Systemic diseases, diagnosed in fifty-six dogs, included canine leishmaniasis in twenty-three dogs, canine monocytic ehrlichiosis in twenty-two, concurrent canine leishmaniasis and canine monocytic ehrlichiosis in six, rodenticide toxicity in two and primary immune-mediated thrombocytopenia, suspected oestrogen toxicity and systemic arterial hypertension in one dog each. Intranasal diseases were documented in the remaining five dogs, including transmissible venereal tumour in three dogs, and nasal adenocarcinoma and nasal aspergillosis in one dog each. Mucosal pallor and a generalised bleeding tendency were significantly more common among dogs with canine monocytic ehrlichiosis compared with those with canine leishmaniasis, whereas the opposite was true for peripheral lymphadenomegaly. Also, dogs with canine monocytic ehrlichiosis presented with pancytopenia more frequently compared with those with canine leishmaniasis; in the latter dogs, the median values of haematocrit, leucocyte and platelet counts and serum total protein concentrations were higher. CLINICAL SIGNIFICANCE: Canine leishmaniasis and canine monocytic ehrlichiosis are the leading causes of canine epistaxis in Greece. Mucosal pallor, bleeding tendency and pancytopenia are more likely to be indicative of canine monocytic ehrlichiosis, as opposed to peripheral lymphadenomegaly and hyperproteinaemia in canine leishmaniasis.     

我国犬埃立克体病研究现状

犬埃立克体病是由严格细胞内寄生的埃立克体所致的疾病。目前,我国已经发现的犬埃立克体病原有犬埃立克体(Ehrlichia)和扁平埃立克体(E.platy)两种。我国已发现的犬埃立克体病均为E.canis和E.platy的混合感染。临床症状包括发热、体重严重减轻、流鼻血和腹泻带血等;白细胞和血小板计数同时下降是我国犬埃立克体病的特点;严重的病犬常因广泛性出血或继发感染而死亡。犬埃立克体病的病原学诊断主要依靠镜检、血清学试验和PCR等。犬血清埃立克体抗体的调查结果表明,我国犬埃立克体病的流行与蜱活动密切相关。四环素类抗生素是治疗犬埃立克体病的有效药物。     

Canine vector-borne disease in travelled dogs in Germany--a retrospective evaluation of laboratory data from the years 2004-2008

When importing dogs from various Mediterranean countries into Western Europe canine vector-borne infections are often considered as a major issue. Several diseases including babesiosis, leishmaniosis, hepatozoonosis, canine heartworm disease or ehrlichiosis can potentially be endemic in this region and pose a potential health risk for travelling dogs. Information on such infections in travelled dogs is scarce and therefore this study has been undertaken to examine the frequency of vector-borne infections in travelled dogs from the years 2004-2008. A total of 997 samples were screened by direct and/or indirect methods. Total seroprevalence was 7.5% with individual seroprevalence for the 3 species Leishmania spp., Ehrlichia canis and Babesia canis spp. ranging from 3.1 to 4.9%. Total detection rate for pathogens by direct methods was 3.5%. Ninteen Giemsa-stained blood smears were positive for large Babesia. None of the samples screened for microfilariae by Knott's test or for Dirofilaria immitis antigen by DiroChek^® were positive. Using PCR methods Leishmania-DNA was detected in 1/42 samples but none of 59 animals screened for E. canis-DNA was positive. The prevalence values as established by indirect and direct pathogen detection are considered as rather low.     

Stem cells and veterinary medicine: tools to understand diseases and enable tissue regeneration and drug discovery

New sophisticated laboratory techniques, as well as established interactions between basic science, researchers and veterinarians, have led to an exponential increase in our understanding of the animal body in health and disease. The advent of animal cloning, the identification and characterization of stem cells, and publication of the various mammalian genomes has afforded the opportunity to exploit these technologies to better understand disease and develop new therapies. In human medicine, these medical advances are already being translated into clinical practice, the promise being that previously untreatable or incurable chronic diseases will become a thing of the past. In parallel, the veterinary profession is looking to these technologies to explore novel therapies for chronic diseases, such as osteoarthritis in companion animals, and is applying these technologies to enhance food animal production. This review focuses on the emerging area of stem cell biology and explores the potential applications of stem cell technologies to veterinary medicine.     

Human and animal fasciolosis: Coprological survey in Narok,Baringo and Kisumu counties,Kenya

Fasciolosis is caused by digenean trematodes of the genus Fasciola. The principal definitive hosts are cattle, sheep and goats. Humans are infected as accidental hosts. Fasciolosis is one of the major neglected tropical diseases and is considered an emerging zoonotic infection. This study was aimed at determining the prevalence of human and domestic animal fasciolosis in selected counties in Kenya. Stool samples for Fasciola diagnosis were collected from humans and domestic animals and transported to the laboratory at Egerton University and processed using sedimentation technique and examined for the presence of eggs. A total of 272 human samples collected were all negative for Fasciola eggs. A total of 582 domestic animals (cattle [46.0%], sheep [29.9%] and goats [24.1%]) samples collected had overall prevalence of 30.9% for Fasciola infection. There was no significant differences (p > 0.05) between the prevalence of fasciolosis and origin of the animals, sex and season. There was a significant difference (p < 0.05) between the prevalence of fasciolosis and domestic animals, age and body condition. The prevalence of fasciolosis was high in two irrigation schemes which favour the breeding of intermediate host snail and grazing of animals along the irrigation canals where metacercaria of Fasciola parasites could be present on the vegetation. Although human fasciolosis was not detected in this study, the presence of animal fasciolosis can pose public health risk because of its zoonotic nature. Therefore, it is important to introduce measures which would help to reduce the exposure of animals to Fasciola infection.     

Generalized Microsporum canis dermatophytosis in six Yorkshire terrier dogs

Six Yorkshire terrier dogs with generalized, chronic dermatophytosis caused by Microsporum canis were seen over a 3-year period. Specific tests showed that they also had concurrent leishmaniosis (four cases), leishmaniosis and ehrlichiosis (one case) or diabetes mellitus (one case). Although specific therapy for these infectious diseases was instituted and the dogs were treated systemically and topically with appropriate antifungal drugs, only partial clinical resolution of the dermatophytosis was achieved. M. canis infection resolved in the dog with diabetes mellitus after stabilizing the diabetes mellitus. Although immunological studies were not performed in these cases, it is theorized that the immune disregulation caused by leishmaniosis, ehrlichiosis or diabetes mellitus may have favoured generalization of the infection and prevented favourable responses to appropriate treatment of the M. canis infection.     

New molecular biology detection methods for tick-borne infectious agents

Tick-borne zoonotic pathogens are well known in many areas all over the world. Among the tick-borne transmitted diseases in Switzerland, Lyme disease caused by Borrelia burgdorferi, ehrlichiosis caused by various species of Ehrlichia and tick-borne encephalitis caused by the tick-borne encephalitis virus (TBEV) are the most important zoonotic diseases. Early diagnosis and treatment is necessary to prevent fatal infections and chronic damage to various tissues. Due to the variety of uncharacteristic clinical signs, tick-borne diseases are not easily recognized. Diagnosis is based on clinical findings, a record of tick exposure, and direct or indirect detection of the pathogen. Here we discuss briefly the most important tick-borne infections and their diagnosis with emphasis on a new molecular diagnostic tool--the real-time TaqMan PCR--and its importance for the diagnosis of tick-borne pathogens.