The topic of Public Health and horses encompasses the study of interactions between equine populations and human health systems. It involves examining the transmission of zoonotic diseases, which are diseases that can be transferred between animals and humans, as well as the role of horses in the epidemiology of such diseases. This field also considers the impact of equine-related activities on public health, including injuries and environmental effects. Research in this area often explores preventive measures, management strategies, and policies to mitigate health risks associated with horses. This page compiles peer-reviewed research studies and scholarly articles that investigate the intersection of equine and public health, focusing on disease transmission, risk assessment, and health management strategies.
Hendricks KJ, Adekoya N.To provide data on the magnitude and patterns of animal related on-farm injuries to youth in the United States. Methods: A survey of 26,000 farm households conducted for the National Institute for Occupational Safety and Health by the United States Department of Agriculture in 1998. Methods: Youth younger than 20 years of age. Results: There were an estimated 6,438 animal related on-farm injuries to youth in 1998. 70% occurred to farm residents; 69% were work related. Males accounted for 64% and approximately 41% occurred to those younger than 10; 37% involved horses and 31% cattle. Most horse...
Krebs JW, Mondul AM, Rupprecht CE, Childs JE.During 2000, 49 states, the District of Columbia, and Puerto Rico reported 7,364 cases of rabies in nonhuman animals and 5 cases in human beings to the Centers for Disease Control and Prevention, an increase of 4.3% from 7,067 cases in nonhuman animals reported in 1999. Ninety-three percent (6,855 cases) were in wild animals, whereas 6.9% (509 cases) were in domestic species (compared wth 91.5% in wild animals and 8.5% in domestic species in 1999). Compared with cases reported in 1999, the number of cases reported in 2000 increased among bats, dogs, foxes, skunks, and sheep/goats and decreased...
Chambers TM, Holland RE, Tudor LR, Townsend HG, Cook A, Bogdan J, Lunn DP, Hussey S, Whitaker-Dowling P, Youngner JS, Sebring RW, Penner SJ....Flu Avert IN vaccine is a new, live attenuated virus vaccine for equine influenza. We tested this vaccine in vivo to ascertain 1) its safety and stability when subjected to serial horse to horse passage, 2) whether it spread spontaneously from horse to horse and 3) its ability to protect against heterologous equine influenza challenge viruses of epidemiological relevance. For the stability study, the vaccine was administered to 5 ponies. Nasal swabs were collected and pooled fluids administered directly to 4 successive groups of naïve ponies by intranasal inoculation. Viruses isolated from th...
Becker K, Keller B, von Eiff C, Brück M, Lubritz G, Etienne J, Peters G.Staphylococcal food poisoning (SFP) caused by enterotoxigenic staphylococci is one of the main food-borne diseases. In contrast to Staphylococcus aureus, a systematic screening for the enterotoxins has not yet been performed on the genomic level for the coagulase-positive species S. intermedius. Therefore, the enterotoxigenic potential of 281 different veterinary (canine, n = 247; equine, n = 23; feline, n = 9; other, n = 2) and 11 human isolates of S. intermedius was tested by using a multiplex PCR DNA-enzyme immunoassay system targeting the staphylococcal enterotoxin genes sea, seb, sec, sed...
Savill MG, Murray SR, Scholes P, Maas EW, McCormick RE, Moore EB, Gilpin BJ.Rhodococcus coprophilus, a natural inhabitant of herbivore faeces, has been suggested as a good indicator of animal (as opposed to human) faecal contamination of aquatic environments. However, conventional detection methods limit its use for this as they require up to 21 days to obtain a result. In this paper an optimised method for extracting R. coprophilus DNA from faecal samples is described. PCR and 5'-nuclease (TaqMan) PCR methods were developed to allow the detection and enumeration of R. coprophilus in faecal samples within 2-3 days. Both PCR methods targeted the 16S rRNA gene, producin...
Gimsing S.Occupational injuries are notifiable in Denmark. Hitherto, occupational injuries caused by riding and horse handling have not been reported. Methods: This retrospective study comprises all cases reported to the National Working Environment Authority during the period 1992-1999. Results: There were 634 occupational accidents, and 43% of the victims were below the age of 25 years with a four-in-one female preponderance. In contrast, there were only three cases of occupational disease. Conclusions: Occupational diseases ought to be much more common than suggested by these few reported cases. Resp...
Gimsing S.A previous estimate has indicated that horse activities in Denmark account for about 5750 non-fatal and 1-2 fatal accidents every year. Many are preventable, as they are caused by carelessness. A description of the accident pattern is important. Methods: The European Home and Leisure Accident Surveillance System (EHLASS) has included data on horse-related accidents since 1989. All 8662 accidents in the period, 1989-1999, were studied. Death certificates from 11 fatal cases during the same period were obtained from the National Board of Health. Results: The annual total number of riding acciden...
Barros AT.Once a month, from June 1992 to May 1993, collections of tabanids on horse were conducted in the Nhecolândia, Pantanal State of Mato Grosso do Sul, Brazil. Tabanid catches using hand nets were conducted from sunrise to sunset at grassland and cerradão (dense savanna) habitats. A total of 3,442 tabanids from 21 species,12 genera, and 3 subfamilies were collected. Although species abundance varied seasonally depending on habitat, no habitat specificity was observed for the most abundant species. In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, while 1,817 (52.8%...
Miyazaki S, Fukumura M, Yoshioka M, Yamanaka N.From 1997 to 1999, 29 cases of disorders were detected in cattle and horses that had been fed ryegrass straw imported from the U.S.A. These animals showed symptoms resembling ryegrass staggers and the clinical signs disappeared after removal of the straw. Endophytic hyphae were detected in the seeds of all straw samples that were responsible for the clinical cases. Lolitrem B concentrations in the straw ranged between 972 and 3740 ppb. Ergovaline concentrations were between 355 and 1300 ppb. Even though the concentrations of lolitrem B were lower than the toxic threshold proposed by Oregon Sta...
Hullinger PJ, Gardner IA, Hietala SK, Ferraro GL, MacLachlan NJ.To compare seroprevalence of antibodies against equine arteritis virus (EAV) in horses residing in the United States with that of imported horses. Methods: Serologic survey. Methods: Serum samples from 364 horses on 44 equine operations in California and 226 horses imported from various countries. Methods: Serum samples were collected from each imported horse and from up to 20 horses on each operation. For resident horses, the number of sampled horses on each operation was determined on the basis of the number of horses on the operation. Samples were tested for antibodies against EAV by use of...
Iba K, Wada T, Kawaguchi S, Fujisaki T, Yamashita T, Ishii S.To investigate the demographic details and patterns of injuries related to horse handling, we reviewed 637 horse-related injuries in 581 stable- or stud-workers in a representative area of thoroughbred stabling in Japan. We found that (1) injuries occurred most frequently in a group of a relatively young workers, with a seasonal variation; (2) the principal mechanism of injury was kicks, which accounted for 39.2% of all injuries, including 11 serious and one lethal visceral injuries; (3) the upper half of the body was more frequently involved than the lower half; and (4) the peripheral bones (...
Ostlund EN, Crom RL, Pedersen DD, Johnson DJ, Williams WO, Schmitt BJ.After the 1999 outbreak of West Nile (WN) encephalitis in New York horses, a case definition was developed that specified the clinical signs, coupled with laboratory test results, required to classify cases of WN encephalitis in equines as either probable or confirmed. In 2000, 60 horses from seven states met the criteria for a confirmed case. The cumulative experience from clinical observations and diagnostic testing during the 1999 and 2000 outbreaks of WN encephalitis in horses will contribute to further refinement of diagnostic criteria.
Faye D, Pereira de Almeida PJ, Goossens B, Osaer S, Ndao M, Berkvens D, Speybroeck N, Nieberding F, Geerts S.In a study of the prevalence and incidence of trypanosomosis in horses and donkeys in two regions of the Gambia, surveys were carried out at Niamina east and Bansang south with a high and low to moderate tsetse challenge, respectively. Eleven horses and 67 donkeys were sampled monthly from August 1997 to September 1998. Blood samples were examined for trypanosomes using the buffy-coat (BC) method and polymerase chain reaction (PCR). Three primer sets were used, specific for either Trypanosoma vivax (TVW), Trypanosoma congolense (GOL) or Trypanosoma brucei (ORPHON5J). The BC results showed that...
Komar N, Panella NA, Boyce E.We evaluated West Nile (WN) virus seroprevalence in healthy horses, dogs, and cats in New York City after an outbreak of human WN virus encephalitis in 1999. Two (3%) of 73 horses, 10 (5%) of 189 dogs, and none of 12 cats tested positive for WN virus-neutralizing antibodies. Domestic mammals should be evaluated as sentinels for local WN virus activity and predictors of the infection in humans.
Hadler J, Nelson R, McCarthy T, Andreadis T, Lis MJ, French R, Beckwith W, Mayo D, Archambault G, Cartter M.In 1999, Connecticut was one of three states in which West Nile (WN) virus actively circulated prior to its recognition. In 2000, prospective surveillance was established, including monitoring bird deaths, testing dead crows, trapping and testing mosquitoes, testing horses and hospitalized humans with neurologic illness, and conducting a human seroprevalence survey. WN virus was first detected in a dead crow found on July 5 in Fairfield County. Ultimately, 1,095 dead crows, 14 mosquito pools, 7 horses, and one mildly symptomatic person were documented with WN virus infection. None of 86 hospit...
Marfin AA, Gubler DJ.In 1999, an epidemic of West Nile virus (WNV) encephalitis occurred in New York City (NYC) and 2 surrounding New York counties. Simultaneously, an epizootic among American crows and other bird species occurred in 4 states. Indigenous transmission of WNV had never been documented in the western hemisphere until this epidemic. In 2000, the epizootic expanded to 12 states and the District of Columbia, and the epidemic continued in NYC, 5 New Jersey counties, and 1 Connecticut county. In addition to these outbreaks, several large epidemics of WNV have occurred in other regions of the world where t...
Murgue B, Murri S, Zientara S, Durand B, Durand JP, Zeller H.On September 6, 2000, two cases of equine encephalitis caused by West Nile (WN) virus were reported in southern France (Hérault Province), near Camargue National Park, where a WN outbreak occurred in 1962. Through November 30, 76 cases were laboratory confirmed among 131 equines with neurologic disorders. The last confirmed case was on November 3, 2000. All but three cases were located in a region nicknamed "la petite Camargue," which has several large marshes, numerous colonies of migratory and resident birds, and large mosquito populations. No human case has been confirmed among clinically ...
Schmidtmann ET, Lloyd JE, Bobian RJ, Kumar R, Waggoner JW, Tabachinick WJ, Legg D.The blood feeding of mosquitoes and black flies from Hereford cattle and ponies treated with commercial formulations of permethrin was evaluated using an animal enclosure trap sample system that allowed comparison of insect blood-feeding levels between treated and nontreated animals. Blood feeding of both Aedes dorsalis Meigen and A. melanimon Dyar from heifers treated with pour-on concentrate and whole body spray treatments was reduced significantly by 79-88% at 4 d posttreatment, with apparent but not significant reductions of 61-68% at 11 d posttreatment. Simulium bivittatum Malloch and S. ...
Dutra F, Schuch LF, Delucchi E, Curcio BR, Coimbra H, Raffi MB, Dellagostin O, Riet-Correa F.A disease named locally as churrío or churrido equino (i.e., equine scours) has occurred for at least 100 years in Uruguay and southern Brazil in farms along both shores of the Merín lake. This report describes cases of churrido equino and provides serologic, pathologic, and DNA-based evidence indicating that the disease is in fact equine monocytic ehrlichiosis (Potomac horse fever). Results of an epidemiological investigation conducted on an endemic farm are also presented. Clinical signs in 12 horses were fever, depression, diarrhea, dehydration, and sometimes colic and distal hind limb ed...
Duggan JM, Coates DM, Ulaeto DO.Venezuelan equine encephalomyelitis (VEE) virus is an important human and veterinary pathogen of Central and South America. The virus can cause widespread epidemics, affecting hundreds of thousands of horses, and thousands of humans. Detection of the virus early in infection and in mosquito populations may allow epidemics to be predicted such that suitable prophylaxis, such as vaccination, can be used to reduce disease severity and transmission. The sensitivity and specificity of current immunoassays, based on conventional monoclonal and polyclonal antibodies, needs to be improved for the diag...
Wells D, Krecek RC.Structured interviews using a questionnaire were conducted to gather information on socioeconomic aspects, health, nutrition, breeding and management of working equids in 3 study areas of Moretele 1 near Hammanskraal, North West Province, South Africa. The questionnaire addressed questions about the role of animals with a focus on donkeys used for work in these areas. Extension and animal health officers and donkey owners participated. The analysis highlights the use of donkeys for transport of water, wood and people; that ticks, wounds and harness sores are the conditions reported most freque...
Langley RL, Hunter JL.To better understand the extent of animal-related fatalities in the workplace. Methods: This study utilized Census of Fatal Occupational Injuries files from the US Department of Labor for the years 1992-1997 to describe the events surrounding human workplace fatalities associated with animals. Results: During the 6-year time period, 350 workplace deaths could be associated with an animal-related event. Cattle and horses were the animals primarily involved, and workers in the agricultural industry experienced the majority of events. Many deaths involved transportation events, either direct coll...
Jose-Cunilleras E, Hinchcliff KW.Listeria monocytogenes rarely causes disease in horses
(Emerson and Jarvis 1968; McCain and Robinson 1976; Clark et
al. 1978; Welsh 1983; Wallace and Hathcock 1995; Larochelle et
al. 1999; Wilkins et al. 2000). It is described as a cause of
abortion, septicaemia in equine neonates, mature horses and
ponies and neurological disease in a foal (Emerson and Jarvis
1968; McCain and Robinson 1976; Clark et al. 1978; Welsh
1983; Wallace and Hathcock 1995; Larochelle et al. 1999;
Wilkins et al. 2000). Most cases of listeriosis in other species
arise from the ingestion of contaminated food and...
Hesselmar B, Aberg B, Eriksson B, Aberg N.In this 5-year follow-up study we compared the prevalence of allergic rhinoconjunctivitis, eczema, and sensitization, in relation to several background factors, in two Swedish regions (Göteborg and Kiruna). In Göteborg, a city on the southwest coast, the climate is mild and humid. Kiruna is a town north of the Arctic Circle. Questionnaire replies and results of interviews were collected from all 412 7-8-year-old children of a population-based sample (203 in Göteborg and 209 in Kiruna); in addition, 192 children from Göteborg and 205 from Kiruna were skin-prick tested for sensitization to c...
Fleming PR, Crompton JL, Simpson DA.The aim of this study was to highlight the neuro-ophthalmological dangers associated with horse riding, and working around horses, and the importance of wearing adequate headgear to protect the rider from neuro-ophthalmic injuries. It raises the questions of whether the current laws regarding helmet use are satisfactory, and whether helmets currently used are of an adequate standard. Methods: The records over a 20-year period of one neuro-ophthalmologist in Adelaide were reviewed producing 22 patients with neuro-ophthalmological sequelae of head injuries as a result of horse-related accidents....
Kaiser A, Meier HP, Straub R, Gerber V.Equine Infectious Anemia (EIA) is a reportable, eradicable epizootic disease caused by the equine lentivirus of the retrovirus family which affects equids only and occurs worldwide. The virus is transmitted by blood, mainly by sanguivorous insects. The main symptoms of the disease are pyrexia, apathy, loss of body condition and weight, anemia, edema and petechia. However, infected horses can also be inapparent carriers without any overt signs. The disease is diagnosed by serological tests like the Coggins test and ELISA tests. Presently, Switzerland is offi cially free from EIA. However, Switz...
Hancock K, Zajac AM, Elvinger F, Lindsay DS.Equine protozoal myeloencephalitis is the most important protozoan disease of horses in North America and is usually caused by Sarcocystis neurona. Natural and experimentally induced cases of encephalitis caused by S. neurona have been reported in raccoons (Procyon lotor) and raccoons are an intermediate host for this parasite. A 3-yr-long serological survey was conducted to determine the prevalence of agglutinating antibodies to S. neurona in raccoons collected from Fairfax County, Virginia, a suburban-urban area outside Washington, D.C. Samples from 469 raccoons were examined, and agglutinat...
Murray MD, Snowdon WA.The distributions of the following feral animals are given -- cattle, buffalo, pig, goat, deer, camel, horse, donkey, fox, dog and cat -- and the native dingo. The possible role these and the native rodents, marsupials and monotremes would play should an exotic disease of livestock enter Australia is discussed. It is considered that feral animals would be important in creating foci from which the disease would spread.
Beier RC, Norman JO.White snakeroot (Eupatorium rugosum Houtt) has been known to cause trembles in animals and milk sickness in humans since the American Revolution. It still continues to poison animals. Horses and goats are particularly sensitive to white snakeroot poisoning. Resurgence of livestock production on small farm units, and utilization of fresh raw milk may result in milk sickness; if the animals have white snakeroot exposure. The goat is the only animal with good toxicity threshold data. In other animals and humans the toxicity thresholds of white snakeroot are not known, and that until responsible t...
Science (New York, N.Y.)August 25, 1961
Volume 134, Issue 3478 565-566 doi: 10.1126/science.134.3478.565
LOWENTHAL JP, BERMAN S, GROGAN EW.Protection tests in guinea pigs indicate that vaccines prepared from virus propagated in chick embryo cell cultures are as effective as the purified whole chick embryo vaccines which are currently used for human immunization against eastern equine encephalomyelitis.
Baxter C.This is a clinician's view of the current state of veterinary dentistry at the level of the general practitioner across the different species. An indication of the work done and the hazards commonly encountered are covered. Conclusions: To increase awareness within the dental profession of the current state of veterinary dentistry.
Ebisawa I, Takayanagi M, Kigawa M.Clostridium tetani was isolated from human and animal stools at the following rates [95% confidence interval (CI)]: Human, 0% (1.5-0); horse, 1% (5-0); cow in cowshed, 4% (10-1); cow in pasture, 8.3% (17-1), calf in pasture, 0% (7-0); dog, 2% (11-0) and sheep in pasture, 25% (44-14). Quantification of C. tetani in 16 animal stools positive for the bacillus was impossible in most cases, as the number of tetanus bacilli present was not large enough for this purpose. Contaminating anaerobic and facultative anaerobic bacteria in human and animal stools, i.e., C. perfringens and Streptococcus sp., ...
Raftery AG, Gummery L, Garcia K, Mohite D, Capewell P, Sutton DGM.Equine trypanosomiasis is a neglected protozoal disease. Objective: To perform a systematic search of literature to explore: (1) In equines what is the global geographical distribution and prevalence of trypanosomiasis? In low and middle-income countries (LMICs) is trypanosomiasis more prevalent than in higher-income countries (HICs)? (2) Is trypanosomiasis infection a significant contributor to global morbidity and mortality? Methods: Systematic review and meta-analyses. Methods: Studies were identified that described naturally occurring equine trypanosomiasis worldwide following 'Preferred R...
Javed R, Taku AK, Sharma RK, Badroo GA.The aim was to determine the occurrence of in equines and their environment in Jammu (R.S. Pura, Katra), molecular characterization and to determine the antibiotic resistance pattern of . Methods: A total of 96 nasopharyngeal swab samples were collected from equines. The organism was isolated on Columbia nalidixic acid agar containing 5% sheep blood as well as on sheep blood agar and was later confirmed by cultural characteristics and biochemical tests. Molecular detection of isolates was done by gene amplification followed by virulence associated protein A () gene amplification. Antibiogra...
Allen DA, Schertel ER.Shock has been described and defined by the inciting cause. This method of categorization does little to clarify common pathophysiologic changes known to occur regardless of the etiology. Each type of shock involves different stages that are determined by the inciting cause, its duration, severity of the initial result, susceptibility of the patient, and adequacy of treatment.
Holmquist JG, Schmidt-Gengenbach J, Haultain SA.Grazing management necessarily emphasizes the most spatially extensive vegetation assemblages, but landscapes are mosaics, often with more mesic vegetation types embedded within a matrix of drier vegetation. Our primary objective was to contrast effects of equine grazing on both subalpine vegetation structure and associated arthropods in a drier reed grass (Calamagrostis muiriana) dominated habitat versus a wetter, more productive sedge habitat (Carex utriculata). A second objective was to compare reed grass and sedge as habitats for fauna, irrespective of grazing. All work was done in Sequoia...
Huxtable CR, Chapman HM, Main DC, Vass D, Pearse BH, Hilbert BJ.A severe paretic syndrome accompanied by intense neuronal lipofuscinosis is described in sheep and horses exposed to Trachyandra divaricata. This is a newly recognised toxic hazard for grazing livestock in the coastal region of the south west of Western Australia. Animals appear to become affected over a period of weeks when summer conditions induce a scarcity of alternative feed. The disease is discussed in relation to its recent documentation in South Africa where the plant is indigenous.
Holý O, Matousková I, Holý V, Koukalová D, Chmelar D.Cronobacter spp. belongs to the family Enterobacteriaceae. It is a motile (peritricha) Gram-negative non-spore forming bacterium. At present, Enterobacter sakazakii is reported as a Cronobacter spp. species with 16 biogroups. It is a ubiquitous organism whose isolation used to be associated with a contaminated powdered infant formula and feed for neonates and infants. Information about the Cronobacter spp. species incidence in the environment, its potential dissemination and its vectors, is very limited. The authors have documented incidence of Cronobacter spp. in the nostril mucous membrane o...
Diyes GCP, Karunaratne WAIP, Tomberlin JK, Rajakaruna RS.Megaselia scalaris (Loew) is a cosmopolitan polyphagous small fly with the ability of exploiting variety of ecological niches. Different life history stages act as detritivore, parasite, and parasitoid of wider spectrum of plant and animal matter under natural and laboratory conditions. Here, for the first time we present the opportunistic parasitism of M. scalaris on Otobius megnini, which act as a vector of Q fever and is capable of causing paralysis, toxic conditions, otoacariasis and otitis in humans and other animals. Tick samples from the ear canals of 14 thoroughbred horses were brought...
Kośla T, Anke M, Grün M.The breed of horses took a significant effect on the Pb content of animals with a normal Pb supply. Warm-blooded horses stored more Pb in skeleton, kidneys, liver and cerebrum than heavy horses. The sex only had the trend of influencing the Pb status. Mares with a normal Pb supply incorporated more Pb than geldings. Age only took a slight effect on the skeleton. Older horses stored more Pb in the metatarsal bone than younger ones. The Pb content of horse meat was not influenced by Pb exposure. Pb was not additionally deposited in the musculature. The Pb offer of the living area took a signific...
Bustos CP, Muñoz AJ, Guida N, Waller A, Mesplet M.Strangles is a worldwide infectious disease caused by Streptococcus equi subsp. equi that affects the upper respiratory tract of horses. Streptococcus equi subsp. equi characterisation by seM-typing is internationally used for epidemiological studies and comparison of isolates. Objective: To identify and to compare the seM-types of Argentinian isolates of Streptococcus equi subsp. equi. Methods: Investigation of bacterial isolates using molecular and phylogenetic approaches. Methods: A total of 59 Argentinian isolates of Streptococcus equi subsp. equi obtained between 2007 and 2019 were studie...
Kotelevska TM, Pryimenko NO, Dubynska HM, Iziumska OM, Koval TI, Pikul KV, Purdenko TY.West Nile Fever (WNF) is the most common arbovirus infection caused by West Nile Virus (WNV), which has been responsible for numerous epidemic outbreaks of disease among humans, birds and horses on all continents, with the exception of Antarctica, over the past two decades. On the territory of Ukraine, the earliest reports of cases of WNV circulation in humans and birds relate to the 70s of the XX century. In Poltava region WNF was first registered in 2011. Though the epidemiological and clinical patterns of WNF in Ukraine and Poltava region remain understudied, primarily due to the lack of al...
Adam E.Emma Adam of the Gluck Equine Research Center at the University of Kentucky in the USA provides an update on rotaviruses, particularly the group B equine rotavirus identified in 2021.
Whitelock RG.This paper quantifies the extent of the radiation hazard to personnel from horses undergoing scintigraphy using technetium99m methylene diphosphonate (99Tcm-MDP). From the data produced it is possible to derive safe working protocols which are comfortably within the legislated limits for whole body doses as set out in the Ionising Radiations Regulations 1985. Measurements were made of the surface and environmental activities which result from individuals undergoing scintigraphic evaluation and also from urine contaminated bedding. The use of both high and low activities in the assessment of th...
De Lange JF, Gummow B, Turner GV, Redman AR.This is the first known isolation in the Republic of South Africa (RSA) of the serovar pomona from the organs of porcine foetuses as well as from the renal lymph nodes of slaughter pigs showing chronic nephritis. In addition, the serovar pomona was isolated from the kidneys of 87.5% of the slaughter pigs examined. The success of these isolations was attributed in part to the refining of 2 existing isolation techniques which complement each other. Using the microscopic agglutination test, serum samples taken from the same farming unit showed evidence of antibodies to the serovar pomona in 89 ou...