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Topic:Infectious Disease
Infectious diseases in horses encompass a range of illnesses caused by bacteria, viruses, fungi, or parasites. These diseases can affect various systems within the equine body, leading to symptoms that range from mild discomfort to severe systemic illness. Common infectious diseases in horses include equine influenza, strangles, equine herpesvirus, and West Nile virus. These diseases can be transmitted through direct contact with infected animals, contaminated surfaces, or vectors such as insects. Understanding the mechanisms of transmission, pathogenesis, and immune response is essential for effective prevention and control. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, diagnosis, treatment, and management of infectious diseases in horses.
[Pharmacological effects of ivermectin, an antiparasitic agent for intestinal strongyloidiasis: its mode of action and clinical efficacy]. Ivermectin is an oral semi-synthetic lactone anthelmintic agent derived from avermectins isolated from fermentation products of Streptomyces avermitilis. Ivermectin showed a concentration-dependent inhibitory effect on motility of a free-living nematode, Caenorhabditis elegans (C. elegans). There exist specific binding sites having a high affinity for ivermectin in the membrane fraction of C. elegans, and a strong positive correlation was detected between the affinity for these binding sites and the suppressive effect on motility of C. elegans in several ivermectin-related substances. These re...
Acquired resistance of horses to Amblyomma cajennense (Fabricius, 1787) ticks. Acquired immunity of horses to larvae, nymphs and adults of the Amblyomma cajennense tick was evaluated through three consecutive experimental infestations of tick-bite naïve hosts. Data from these infestations were compared to those from field-sensitized horses and donkeys. It was observed that tick-bite naïve horses developed a low level of resistance after two infestations as shown by a significant decrease in larval yield and a tendency for lower engorged weight of nymphs during third infestation. Ticks fed on field-sensitized horses had a similar biological performance to that observed ...
Recent advances in molecular epidemiology and detection of Taylorella equigenitalis associated with contagious equine metritis (CEM). In the present review article, recent molecular advances relating to studies with Taylorella equigenitalis, as well as the recently described second species of the genus Taylorella, namely Taylorella asinigenitalis, have been described. Molecular genotyping of T. equigenitalis strains by pulsed-field gel electrophoresis (PFGE) after digestion with the suitable restriction enzyme(s) enabled the effective discrimination of strains, thus allowing the examination of the scientific mechanism(s) for its occurrence and transmission of contagious equine metritis (CEM). Alternatively, polymerase chain ...
Babesia bovis merozoites invade human, ovine, equine, porcine and caprine erythrocytes by a sialic acid-dependent mechanism followed by developmental arrest after a single round of cell fission. Babesia bovis infections have only been observed in bovine species in contrast to Babesia divergens that also can infect humans, sheep and rodents. Using an in vitro assay that assesses invasion of erythrocytes by free merozoites after a 1-h incubation period, it was shown that specificity is not determined by host-specific interactions associated with invasion. Human erythrocytes were invaded more efficiently than bovine erythrocytes whereas erythrocytes of sheep, pigs and horses were invaded only slightly less efficiently. In contrast, goat erythrocytes were refractory to efficient invasion....
Digenetic trematodes, Acanthatrium sp. and Lecithodendrium sp., as vectors of Neorickettsia risticii, the agent of Potomac horse fever. Neorickettsia (formerly Ehrlichia) risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in the secretions of freshwater snails and in aquatic insects. Insectivores, such as bats and birds, may serve as the definitive host of the trematode vector. To determine the definitive helminth vector, five bats (Myotis yumanensis) and three swallows (Hirundo rustica, Tachycineta bicolor) were collected from a PHF endemic location in northern California. Bats and swallows were dissected and their major organs examined for trematodes and for N. risticii DNA...
Lyme borreliosis. Despite more than 25 years' experience with Lyme borreliosis, much remains to be learned about this complex zoonosis. Practicing veterinarians, particularly those in the northeastern and upper midwestern states, where Lyme borreliosis is highly endemic, should be familiar with the ecologic features and typical clinical signs of Lyme borreliosis. Interpretation of signs and serologic test results should be made with consideration of the regional prevalence of Lyme borreliosis and the animal's opportunity for exposure to infected Ixodes spp. The availability of recently marketed topical acaracid...
Post-entry restriction of retroviral infections. Pathogenic retroviruses have driven the evolution of several dominant-acting mechanisms able to block infection and protect the host. These are exemplified by the mouse gene Fv1, which encodes a Gag-like protein able to protect against murine leukemia virus (MLV) infection. The block is saturable, occurs after reverse transcription and is directed against the viral capsid gene. Several other mammalian species are also able to block MLV infection with the same capsid specificity. A human gene with this activity has been named Ref1. Recently, primates have been shown to restrict a variety of ret...
Screening for West Nile virus infections of susceptible animal species in Austria. Avian mortality and encephalomyelitis in equines are considered good indicators for West Nile virus (WNV) activity. We retrospectively tested 385 horse sera for WNV antibodies and looked for WNV nucleic acid and/or WNV antigen in paraffin embedded tissues from 12 horses with aetiologically unresolved encephalomyelitis and 102 free-living birds of different species which had been found dead. With the exception of four horses originating from eastern European countries investigated on the occasion of transit through Austria, all horse sera were negative. Nested RT-PCR of the horse tissues yielde...
Epidemiology of leptospirosis: observations on serological data obtained by a “diagnostic laboratory for leptospirosis” from 1995 to 2001. Serological data on leptospira infection were reported and discussed. From 1995 to 2001, the blood serum samples of 9885 domestic and wild animals and humans, living in Northern and Central Italy, were examined by the macroagglutination test (MAT) employing bratislava, ballum, canicola, grippotyphosa, icterohaemorrhagiae, pomona, hardjo and tarassovi serovars as antigens. Considering sera with > or = 1:400 antibody titers as positive, 674 (6.81%) animals scored positive. Sheep, horses, pigs and dogs gave the highest number of positive responses, particularly against the serovar bratislava and,...
West Nile virus activity–United States, October 23-29, 2003. This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m., Mountain Standard Time, October 29, 2003.
Subpopulations of equine infectious anemia virus Rev coexist in vivo and differ in phenotype. Lentiviruses exist in vivo as a population of related, nonidentical genotypes, commonly referred to as quasispecies. The quasispecies structure is characteristic of complex adaptive systems and contributes to the high rate of evolution in lentiviruses that confounds efforts to develop effective vaccines and antiviral therapies. Here, we describe analyses of genetic data from longitudinal studies of genetic variation in a lentivirus regulatory protein, Rev, over the course of disease in ponies experimentally infected with equine infectious anemia virus. As observed with other lentivirus data, t...
Rabies DNA vaccine in the horse: strategies to improve serological responses. In order for DNA vaccines to become a practical alternative to conventional vaccines their ability to induce antibody responses in large mammals needs to be improved. We used DNA vaccination against rabies in the horse as a model to test the potential of two different strategies to enhance antibody responses in a large mammalian species. The administration of the DNA vaccine in the presence of aluminum phosphate improved both the onset and the intensity of serological responses but was not potent enough to achieve seroconversion in all vaccinated ponies. However, when the DNA vaccine was formu...
Usefulness of aerobic microbial culture and cytologic evaluation of corneal specimens in the diagnosis of infectious ulcerative keratitis in animals. To determine the diagnostic value of aerobic microbial culture and cytologic evaluation of corneal specimens in the diagnosis of infectious ulcerative keratitis (IUK). Methods: Prospective study. Methods: 48 animals (26 dogs, 13 horses, 7 cats, 1 bird, and 1 llama) with corneal ulcers. Methods: Scrapings from corneal ulcers were examined cytologically. Corneal swab specimens were submitted for microbial culture. Animals were grouped according to whether they had been receiving antimicrobials at the time of admission. Results: Of the 38 animals receiving antimicrobials, 19 had positive results ...
Empyema of the guttural pouch (auditory tube diverticulum) in horses: 91 cases (1977-1997). To identify features of guttural pouch (auditory tube diverticulum) empyema in horses and compare findings of uncomplicated guttural pouch empyema with guttural pouch empyema complicated by chondroids. Methods: Retrospective study. Methods: 91 horses with guttural pouch empyema. Methods: Medical records of horses with guttural pouch empyema were reviewed. Results: The most common owner complaint and abnormal finding was persistent nasal discharge. Chondroids were detected in 21% (19/91) of affected horses. Streptococcus equi was isolated from the guttural pouch in 14 of 44 horses; for Streptoc...
[Bacteriological findings for endodontical and apical molar dental diseases in the horse]. In most cases the diagnosis of any molar dental disease in horses is made at an advanced stage, so that permanent restoration of the diseased teeth is not feasible. Complications such as bacteraemia and septicaemia due to infections as a result of dentogenous sinusitis and following dentosurgical procedures have been described in human medicine and in veterinary medicine. Twenty patients were available for examination from the Clinic for Horses of the School of Veterinary Medicine Hannover with molar dental disease in upper or lower jaw. As a result of this disease the infected tooth had to be...
[Diagnosis of Lawsonia intracellularis using the polymerase chain reaction (PCR) in pigs with and without diarrhea and other animal species]. Lawsonia (L.) intracellularis, an obligately intracellular bacterium, causes proliferative enteropathy (PE) in swine and, occasionally, in other animals. To determine the spread of the agent among German pig herds pooled fecal samples of five animals each of clinically normal Hessian pig herds collected between november 1998 and february 1999 as well as feces (n = 1684) from individual animals representing 648 herds, sent to our laboratory by veterinarians from all parts of Germany, were tested for L. intracellularis using the polymerase chain reaction (PCR). In addition, fecal samples from di...
Disseminated pythiosis in three horses. Three cases of equine subcutaneous pythiosis with dissemination to the internal organs were investigated. The subcutaneous lesions were observed on the mammary gland, nostrils and limbs of the infected horses. Histopathological analysis of the infected tissues revealed a strong eosinophilic reaction, with macrophages, mast cells and giant cells. Sparsely septated hyphal filaments of 4-6 microm diameter were identified in the center of the eosinophilic areas. Specific fluorescent antibody against Pythium insidiosum confirmed the hyphae in the infected tissues in three examined horses. In one of...
Characterization of experimental equine glanders. Considerable advances in understanding of the disease caused by Burkholderia mallei have been made employing a combination of tools including genetic techniques and animal infection models. The development of small animal models has allowed us to assess the role of a number of putative virulence determinants in the pathogenesis of disease due to B. mallei. Due to the difficulties in performing active immunization studies in small animals, and due to the fact that the horse is the target mammalian species for glanders, we have initiated experimental studies on glanders in horses. Intratracheal ...
Prevalence of antibodies to Neospora caninum, Sarcocystis neurona, and Toxoplasma gondii in wild horses from central Wyoming. Sarcocystis neurona, Neospora caninum, N. hughesi, and Toxoplasma gondii are 4 related coccidians considered to be associated with encephalomyelitis in horses. The source of infection for N. hughesi is unknown, whereas opossums, dogs, and cats are the definitive hosts for S. neurona, N. caninum, and T. gondii, respectively. Seroprevalence of these coccidians in 276 wild horses from central Wyoming outside the known range of the opossum (Didelphis virginiana) was determined. Antibodies to T. gondii were found only in 1 of 276 horses tested with the modified agglutination test using 1:25, 1:50, ...
Seroepidemiologic studies on Babesia equi and Babesia caballi infections in horses in Jilin province of China. The prevalence of equine piroplasmosis caused by Babesia equi and Babesia caballi in northeast China has remained unknown, although the People's Republic of China is recognized as an endemic country for the diseases. In the present study, we investigated the prevalence of equine piroplasmosis in Jilin province, a part of northeast China. A total of 111 serum samples were taken from horses in eastern Jilin, and examined for diagnosis of B. equi and B. caballi infections by the enzyme-linked immunosorbent assays with recombinant antigens, equi merozoite antigen-1 and P48, respectively. Of the 11...
A PCR-ELISA for the identification of cyathostomin fourth-stage larvae from clinical cases of larval cyathostominosis. We report the use of six oligoprobes designed from intergenic spacer region sequences to identify fourth-stage larvae (L4) of the tribe Cyathostominae. Oligoprobes were designed for identification of the following species: Cylicocyclus ashworthi, Cylicocyclus nassatus, Cylicocyclus insigne, Cyathostomum catinatum, Cylicostephanus goldi, and Cylicostephanus longibursatus. A seventh probe was designed as a positive control to identify all these members of the Cyathostominae. The intergenic spacer region was amplified by PCR using conserved primers. Initially, three oligoprobes were used in South...
West Nile virus activity–United States, September 25-October 1, 2003. This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m., Mountain Daylight Time, October 1, 2003.
West Nile virus infection of Thoroughbred horses in South Africa (2000-2001). West Nile virus (WNV) infection is endemic in southern Africa. With the recent emergence of WNV infection of horses in Europe and the USA the present study was performed to estimate the risk of seroconversion to WNV in a cohort of 488 young Thoroughbred (TB) horses. Objective: To estimate the risk of seroconversion to WNV among a cohort of South African TB yearlings sold at the 2001 National Yearling Sales (NYS) and to determine whether the risk varied geographically. Two horses were also infected with a recent South African isolate of WNV to evaluate its virulence in horses. Methods: Serum sa...
Lateral transmission of equine arteritis virus among Lipizzaner stallions in South Africa. A serological study conducted in 1995 revealed that 7 stallions at the Lipizzaner Centre, Gauteng, South Africa, were seropositive for antibody to equine arteritis virus (EAV). A Lipizzaner stallion imported into South Africa from Yugoslavia in 1981 had previously (1988) been confirmed to be an EAV carrier. Despite being placed under life-long breeding quarantine, EAV had been transmitted between stallions at the Lipizzaner Centre. Objective: To investigate the phylogenetic relationships between the strain of EAV shed in the semen of the original carrier stallion and strains recovered from the...
Small-world topology of UK racing: the potential for rapid spread of infectious agents. The topology of the network of contacts between individuals has important effects on infectious disease dynamics within a population. Here we examine for the first time a network of contacts between training yards that occurred through racing. Objective: To explore the topology of this network and to consider the effects of the network on the potential for disease transmission. Methods: Race data from one week was analysed. Contacts were defined as occurring between trainers that raced horses in the same race and hence one trainer could contact another trainer several times. A connection was s...
Severe hypertriglyceridaemia in clinically ill horses: diagnosis, treatment and outcome. Sporadic measurement of serum triglycerides in depressed and inappetant clinically ill horses revealed severe hypertriglyceridaemia without visible evidence of lipaemia on several occasions, leading to the inclusion of serum triglyceride concentrations in the routine serum biochemistry evaluation of our hospital. Since then, more cases have been identified and treated for hypertriglyceridaemia, raising questions about the prevalence, predisposing factors and significance of these findings. Objective: 1) Severe hypertriglyceridaemia without visible opacity of the serum occurs more commonly in c...
