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Topic:Disease Transmission
Disease transmission in horses refers to the spread of infectious agents such as bacteria, viruses, fungi, and parasites among equine populations. These pathogens can be transmitted through various routes, including direct contact, vector-borne transmission, or environmental exposure. Factors influencing disease transmission include horse density, management practices, and biosecurity measures. Understanding the mechanisms and conditions that facilitate the spread of diseases is essential for developing effective prevention and control strategies. This page compiles peer-reviewed research studies and scholarly articles that investigate the modes of transmission, risk factors, and management practices related to infectious diseases in horses.
Probable paratuberculosis in a Sicilian ass. A presumptive diagnosis of paratuberculosis was made in a Sicilian ass on the basis of a history of chronic diarrhea and weight loss, pasture exposure to a heifer with paratuberculosis confirmed by bacterial culture of feces, postmortem identification of granulomatous inflammation of the intestine containing acid-fast organisms, the absence of acid-fast organisms in extraenteric tissues, and the absence of exposure to tuberculosis. The literature on paratuberculosis in equids is reviewed. The potential for cross-species transmission is emphasized. Justification for consideration of Mycobacteri...
Attempted transmission of Ehrlichia risticii, causative agent of Potomac horse fever, by the ticks, Dermacentor variabilis, Rhipicephalus sanguineus, Ixodes scapularis and Amblyomma americanum. Dermacentor variabilis, Rhipicephalus sanguineus, Amblyomma americanum, and Ixodes scapularis ticks were investigated for their ability to transmit Potomac horse fever. Larval and nymphal ticks were exposed to Ehrlichia risticii by feeding on mice inoculated with the organism. Molted exposed ticks were then allowed to feed on susceptible ponies or mice. No evidence of transmission, either clinically or by detection of antibodies to E. risticii in mice or ponies, was observed for any tick species examined.
Zoonotic cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis associated with domestic animals in Venezuela and Brazil. After outbreaks of cutaneous leishmaniasis in Solano State, Venezuela, 5% of the population had parasitized ulcers while after similar outbreaks in Mesquita, Rio de Janeiro State, Brazil, 9% had the disease. In these foci children, including some under six years of age, were affected. There was no significant difference in the occurrence of the disease according to sex or type of employment. In Solano, 3% of dogs and 28% of donkeys had parasitized lesions, while in Mesquita these indices were 19.8% and 30.8% respectively. The parasite from man, dogs and equines was identified as Leishmania (Vi...
Comparative features of retroviral infections of livestock. Retroviral infections of livestock have become of increasing importance due to their usefulness as comparative models for human retroviral infections and their effects upon animal health and marketability of animals and animal products nationally and internationally. This paper presents a perspective on the retroviruses of economic concern in veterinary medicine with emphasis on the importance of understanding the modes of virus transmission and the species specificity of the viruses. The retroviruses reviewed include the oncovirus, bovine leukosis virus, and the lentiviruses, equine infectiou...
Equine infectious anemia: prospects for control. Equine infectious anemia has been managed in most countries by the imposition of testing and quarantine regulations. In the United States, about 700,000 of the more than 7,000,000 horses are tested annually. As long as the status of greater than 90% of the horse population remains unknown and horses are transported and congregate in a relatively unrestricted manner, EIA will continue to exact its toll. Therefore, it is incumbent on the scientific community to continue to develop and refine practical and sensitive diagnostic tests for EIA which will be used in an expanding market, to reduce the...
Epidemiology of Potomac horse fever: an investigation into the possible role of non-equine mammals. A serological study of antibodies to Ehrlichia risticii was carried out on 10 species of wild and domestic mammals found on or near 21 horse farms in an area of the USA in which Potomac horse fever is endemic. No antibodies were found in 133 peridomestic rodents (Norway rats and house mice), nor in 108 wild rodents (white-footed mice and meadow voles) captured on farms. Three of the six domestic animal species examined, cats, pigs and a goat, showed serological evidence of exposure to E risticii. Seropositive animals were detected on three of the 21 premises. The eight seropositive cats (of 48...
White-footed mice: tick burdens and role in the epizootiology of Potomac horse fever in Maryland. One hundred ten white-footed mice (Peromyscus leucopus) were captured on horse farms in south-central Maryland, examined for ticks, and tested for specific antibodies to Ehrlichia risticii, the causative agent of Potomac horse fever. Peromyscus leucopus were consistently infested with immature American dog ticks (Dermacentor variabilis), with monthly prevalences as high as 80%. Sera from all 97 P. leucopus tested for antibodies to E. risticii were negative. This indicates that P. leucopus is not a reservoir of E. risticii, and suggests that immature D. variabilis do not acquire E. risticii in ...
Clinical Leptospira interrogans serogroup Australis serovar lora infection in a stud farm in The Netherlands. A Leptospira interrogans serogroup australis serovar lora infection in a stud farm is reported. During three successive years (1984-1986) clinical leptospirosis with a severe often rapid, fatal course was seen in 12 foals. Clinical examination revealed severe respiratory distress, depression and pyrexia. Other symptoms were diarrhea (2), jaundice (1), and an unsteady gait (1). Morphological characteristics of the disease were massive pulmonary haemorrhage and haemorrhagic-thrombotic or extracapillary glomerulonephritis with tubulonephrosis and interstitial oedema. In most foals high or increas...
[Anthrax in Chad: a zoonosis that still exists today]. An epidemic of human and animal anthrax raged in Chad mainly in the Department of Chari Baguirmi from September to December 1988, infesting more than 50% of donkeys and horses. 716 human cases have been reported, with 88 deaths. Thanks to a geographical distribution of animal and human prevalence, one sees immediately the interdependency between sanitary state of live-stock and public health. An unusual means of transmission from donkey to donkey by insects as the vector is suggested to explain the intensity of animal epidemics. Two strains of B. anthracis were isolated and described. Systemat...
The association between weather, frenzied behaviour, percutaneous invasion by Strongyloides westeri larvae and Rhodococcus equi disease in foals. Episodes of frenzy lasting approximately 30 minutes were observed among horses confined to enclosures surfaced with sand or soil. The probability of sighting these episodes increased by a factor of three when within 24 hours there was 0.2mm or more of rain, a maximum air temperature between 16.7 - 26.6 degrees C and a soil temperature of 16.3 - 23.9 degrees C at 30 cm. High egg counts of Strongyloides westeri appeared in faeces four to five days later and persisted for several days. Rhodococcus equi was recovered from all soil samples, and from the faeces of 76% of mares and 82% of foals. The ...
Association between serum esterase (Es) type and starting proportion in Swedish Trotters: further observations. A study was carried out to attempt to explain the basis of the association between the Es locus and starting proportion in Swedish Trotters which had been observed previously. The effect of Es genotype on starting proportion has diminished among horses born in the late 1970s. There are indications that the incidence of leg lesions varies between Es genotypes. If this is true, it is possible that the decreasing effect of the Es locus on starting proportion is due to the environmental changes which have been made at race tracks in the early 1980s to reduce the strain on the legs of the trotters....
Non-isotopic immunoassay drug tests in racing horses: a review of their application to pre- and post-race testing, drug quantitation, and human drug testing. We have introduced large scale non-isotopic immunoassay testing into pre- and post-race drug testing in racehorses. The technologies utilized are Particle Concentration Fluorescence Immuno Assay (PCFIA) and the one-step Enzyme Linked Immuno Sorbent Assay (ELISA). These technologies are rapid, inexpensive, and highly effective. On introduction into post-race testing in the Western United States, these ELISA tests exposed several previously undetected patterns of drug abuse. The drugs detected were buprenorphine, oxymorphone, mazindol, sufentanil and cocaine. This led to the suspension of a larg...
Susceptibility of cats to infection with Ehrlichia risticii, causative agent of equine monocytic ehrlichiosis. Eight adult cats were inoculated IV (n = 6) or SC (n = 2) with Ehrlichia risticii-infected P388D1 (continuous murine macrophage) cells or with E risticii released from P388D1 cells. Three additional cats were inoculated with organism-free P388D1 cultured monocytes, and 1 cat, which served as a medium control was inoculated with balanced salt solution. Clinical signs of illness were observed in the IV inoculated cats from which E risticii was isolated. One cat developed intermittent diarrhea between postinoculation days (PID) 8 and 18, and the other cat developed lymphadenopathy, acute depressi...
A propagating epizootic of equine infectious anemia on a horse farm. An epizootic of equine infectious anemia (EIA) involved 35 horses on a farm in south Georgia. During a 126-day period, 21 of these horses became seropositive for EIA. After the initial diagnosis in July, the horses were tested every 7 to 10 days. At least one additional horse was found to be seropositive on each testing day. As soon as they were determined to be seropositive, the horses were removed from the herd and sent to slaughter. The removal of the seropositive horses, however, did not stop the epizootic. We believe the initial infection was from a 7-year-old stallion that recently had b...
California serogroup virus infections in Wisconsin domestic animals. A serologic survey and experimental virus transmission studies were done to assess the role of domestic animals as amplifier hosts of La Crosse (LACV) and Jamestown Canyon (JCV) viruses. Serum from 319 cows, 88 dogs, 122 equines, 47 swine, 10 goats, and 4 cats were tested for neutralizing antibody to LACV, JCV, trivittatus (TVTV), and snowshoe hare (SSHV) viruses. Antibody prevalences of LACV, TVTV, and SSHV were less than 10% in all species. Antibody to JCV was detected in all species except cats. Prevalence ranged from 10% in goats and swine to 29% in dogs. No age-associated trends in JCV pr...
Factors influencing the ingestion of Onchocerca cervicalis microfilariae by Culicoides variipennis (Diptera: Ceratopogonidae). Culicoides variipennis were fed under controlled conditions on two ponies that exhibited seasonal changes in Onchocerca cervicalis microfilarial (mf) skin density and skin distribution. The seasonal changes did not radically affect mf ingestion. Flies were fed on the umbilicus of infected ponies by two methods: individual feeding in consecutive order at the same site, or by mass feeding. Linear regression analysis indicated that ingestion of microfilaria was independent of feeding time and engorged weight. In the individual feeding data, there was a trend toward an increased ingestion of mf as...
