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.
Findlay GM, Maccallum FO.(1) Among 3,100 persons immunized against yellow fever with virus and immune serum over a period of five years, 89 cases of jaundice have been traced.(2) The symptoms are those of a hepatitis and closely resemble those produced by common infective hepatic jaundice, cases of which have frequently been noted as occurring in the same areas.(3) The average period between the time of inoculation and the development of hepatitis is between two and three months.(4) Attention is directed to the occurrence of hepatitis in horses, usually two to three months after immunization against the viruses of hor...
Tenbroeck C, Hurst EW, Traub E.Equine encephalomyelitis of the eastern type is a disease of the late summer and fall and cases are found in greatest numbers near salt marshes. The epidemiological findings are against its transmission by contact and favor the view that it is insect borne. Although virus can be demonstrated in the blood of infected horses it is present for a relatively short time, and the possibility that the disease is not primarily an infection of horses but that it is transmitted to them from another host is considered.
Woods AC, Chesney AM.A filterable agent has been obtained from the humors and tissues of the eyes of horses suffering from active periodic ophthalmia. The intra-vitreous injection of this filtrate produced in normal horses the same clinical and pathological picture observed in the natural disease. This filtrate injected into rabbits produced a different clinical picture, but the essential pathological lesions closely resembled those found in horses. After passage of the filterable agent through six generations of rabbits, it again produced the clinical and pathological picture of the natural disease when injected ...
Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging problem in horses; however, the epidemiology of infection and colonization is poorly understood. This study evaluated factors associated with MRSA colonization at the time of admission to a veterinary teaching hospital. A case-control study evaluating historical factors was performed. Previous colonization of the horse, previous identification of colonized horses on the farm, antimicrobial administration within 30 days, admission to the neonatal intensive care unit, and admission to a service other than the surgical service were...
Karaushi H, Yoshitake A, Kanazawa Y, Watanabe N, Tokano M, Seki M, Mitsutake K.A 69-year-old woman with hypertension had undergone total arch replacement with an open stent graft 7 years prior. She was referred to our hospital for evaluation after experiencing fever (>38 °C) and cough. Chest radiography revealed a prominent aortic arch, and contrast-enhanced computed tomography demonstrated aortic arch enlargement and peri-graft fluid collection containing air. These findings indicated graft infection and prompted immediate intervention. Blood cultures grew Streptococcus equi subspecies zooepidemicus, a zoonotic pathogen associated with horses. Notably, the patient wor...
Basso RM, Cerri FM, Braga PRC, Silva ROS, de Araújo Júnior JP, Oliveira-Filho JP, Pantoja JCF, Ribeiro MG, Arroyo LG, Borges AS.Diarrhea is a significant cause of morbidity and mortality in foals. Our hypothesis is that foals with diarrhea have a greater prevalence of ≥2 organisms causing coinfections. We investigated the major microorganisms associated with diarrhea in 200 foals up to 1-y-old (100 diarrheic and 100 non-diarrheic). Fecal samples were analyzed by real-time PCR (rtPCR) for the detection of and toxin genes and , (genotyping for toxin-encoding genes), spp., , , , , , and spp. Rotavirus A and coronavirus were detected using reverse-transcription rtPCR. Fecal bacterial culture was also performed for ...
Onyiche TE, Peng TL.Potomac Horse Fever (PHF), also known as equine neorickettsiosis (EN) or equine monocytic ehrlichiosis is an acute, potentially fatal infectious disease in horses caused by the monocytotropic rickettsia bacterium Neorickettsia risticii. This obligate intracellular bacterium is maintained throughout the life cycle of digenetic trematodes which utilize multiple intermediate and definitive hosts. Research on N. risticii is scattered across multiple continents, with most studies originating from North and South America. Therefore, a systematic review is needed to consolidate global evidence, clari...
Tau RL, Marandino AE, Panzera Y, Alamos F, Vissani MA, Romera SA, Pérez R, Maidana SS.The Equid alphaherpesvirus type 1 (EHV-1) infection can have devastating economic consequences in the horse industry due to large-scale outbreaks of abortions, perinatal foal mortality, and myeloencephalopathy. The present study analyzed the genome of two isolates obtained from aborted fetuses in Argentina, E/745/99 and E/1297/07. The E745/99 genome shares 98.2% sequence identity with Ab4, a reference EHV-1 strain. The E/1297/07 genome shares 99.8% identity with NY03, a recombinant strain containing part of ORF64 and part of the intergenic region from Equid alphaherpesvirus-4 (EHV-4). The E/12...
Marcelino I, Keizer J, Monti G, Cornelissen P, Santman-Berends I, Lam JH, van der Poel WHM.Monitoring and surveillance of pathogens are crucial for safeguarding animal and public health. While passive surveillance is more common for wild and free-living animals, active monitoring improves the detection and characterisation of specific pathogens relevant to animal and public health. In the (OVP) nature reserve in the Netherlands, an active monitoring system for Heck cattle (), Konik horses () and red deer () has been in place since 1997. This study utilised the data generated from the monitoring system to estimate pathogen prevalence and to evaluate the ongoing monitoring efforts. Y...
Lobato OL, Nogueira TDS, Lima TET, Andrade FJDC, de Macedo MGG, Pereira RS, Xavier J, Amorim MR, Barbosa PP, da Rocha AS, Silva SDC, Alcantara LCJ....The cycle of the Orthoflavivirus nilense (West Nile virus - WNV) involves birds and mosquitoes, while humans and equids serve as terminal hosts. In 2014, the first human case in Brazil was confirmed in Piauí State. Objective: To investigate the presence of WNV in birds, mosquitoes, and equids in municipalities of Piauí. Methods: Collections were carried out following recommendations from the Ministry of Health of Brazil, in 11 municipalities (all with human cases or bird mortality), where biological samples were collected from birds, mosquitoes, and equids. The Viral RNA extraction was perfo...
Li C, Liu K, Wei N, Hu S, Li X, Li C.RNA viruses, a unique class of life forms, are widely distributed in nature and pose potential health risks. Monitoring the gut RNA virome in livestock is a crucial component of global health surveillance. As important companion animals, horses play a vital role in transportation and make significant contributions to various cultural and economic activities. Nevertheless, the characteristics of horse gut RNA viruses remain largely uncharted. Unassigned: In this study, we used metatranscriptome sequencing and bioinformatics methods to characterize viruses within the gut contents of 16 horses sp...
Wei W, Lan Z, Li C, Liu X, Zhang X, Wang J, Bai X, Zhou L, Wang X, Wang C, Gao J.Babesia species are tick-transmitted hemoprotozoa that infect mammals, birds, and humans, posing a significant global threat to veterinary medicine threat. In this study, the authors systematically retrieved articles on the occurrence of Babesia species in domestic herbivores in China, including ovine, bovine, and equine species, through a search in the following six databases from their inception to 4 November 2024: PubMed, Web of Science, ScienceDirect, Chinese National Knowledge Infrastructure, Wanfang Data, and VIP Chinese Journal Database. A total of 94 studies (54 high-quality studies, 4...
Fukumoto N, Shibata M, Hayashi M, Kawauchi K, Yabuuchi Y, Oue Y, Matsuyama R, Yamamoto T, Mita H, Kawanishi N, Bannai H, Tsujimura K, Yamanaka T....In 2025, an outbreak of equine influenza occurred among draft horses at Obihiro Racecourse in Hokkaido, Japan. The number of horses showing clinical signs increased dramatically in April. The proportion affected was significantly higher in 2-year-olds than in older groups. The proportion that developed fever during the outbreak was significantly higher than that observed among Thoroughbreds during the 2007 outbreak. In non-epidemic periods, the geometric mean hemagglutination inhibition antibody titer of 2-year-old draft horses was significantly lower than that of 2-year-old Thoroughbreds. The...
Aguirre Siliezar K, Datu C, Proia K, Rotstein D, Nemser SM, Tyson GH, Ragsdale JM, Wilkes RP, Baker RE, Carossino M, Del Piero F, Sasaki E, Yant P....A multi-state outbreak of equine botulism occurred between December 2022 and March 2023 in the United States. Follow-up and testing were performed on 42 horses, including 24 that died or were euthanized in the outbreak that affected ~98 horses. Affected horses had all been exposed to the same commercial feed. Clinical signs included progressive muscle weakness and tremors, recumbency, and colic. No significant gross or microscopic abnormalities were observed on autopsy. Feces and gastrointestinal content were tested for various infectious agents, including botulinum toxin; fecal samples from 2...
Elsawy BSM, Alzan HF., a recently discovered tick-borne hemoparasite infecting equids globally, has significant implications for equine health. Although it is closely related to (sharing 23% genomic divergence), it establishes an asymptomatic carrier state in persistently infected horses, creating a silent transmission reservoir. Its discovery and unique genetics justify its classification as a new taxon. A critical diagnostic challenge is that the lack of the gene in prevents its detection by the standard cELISA, emphasizing the need for species-specific tools. Although species-specific PCR assays, including ...
Shams N, Jaydari A, Khademi P, Eydi J, Sgroi G.Due to the abundance of ticks on open grassy surfaces, racetracks may represent ideal scenarios for tick-borne pathogens. Therefore, in 2024/2025 Turkmen horses (Akhal-Teke breed) and ticks collected by dragging in paddocks of Iran were screened for Anaplasmataceae using Sanger sequencing on 16S rRNA, TRP36 and dsb genes. Amongst 200 horses, 11 (5.5%) tested positive without signs/symptoms, being 8 (4%) for Ehrlichia canis and 3 (1.5%) for Anaplasma ovis; no difference in prevalence was found by gender and age (p>0.05). All ticks were identified as Hyalomma asiaticum and Haemaphysalis sulca...
K-Jánosi K, Sztojka A, Kis IE, Biksi I, Bakos Z, Kaszab E, Mag T, Albert E.In 2024, a highly fatal outbreak of equine salmonellosis occurred in a Hungarian equine referral hospital, resulting in the death or euthanasia of four out of five affected horses. () subsp. serovar Typhimurium was identified as the primary causative agent from equine faecal, reflux, and post-mortem intestinal content samples, while one case involved Coeln. Extensive environmental sampling during the outbreak also yielded multiple serovars. Whole-genome sequencing revealed a high degree of genetic relatedness among the Typhimurium isolates, confirming nosocomial transmission. The source ...
West Nile virus (WNV) circulates endemically in Romania, yet prevention of WNV infection in horses largely depends on owner-driven decisions that require accurate risk perception and veterinary guidance. A cross-sectional online survey was carried out between May and November 2025 to evaluate the knowledge, attitudes, and preventive practices (KAP) regarding WNV among 227 horse owners from various Romanian regions. In total, 67.4% of respondents had previously heard of WNV. The main transmission route was correctly identified as mosquito bites by 49.8% of participants, while 32.2% answered "do...
Firdausy LW, Fikri F, Wicaksono AP, Maslamama ST, Purnama MTE.Equine viral arteritis (EVA) is a globally widespread infectious disease affecting equids, with significant consequences for reproductive efficiency and the regulation of international equine trade. Nevertheless, despite the accumulation of numerous region-specific investigations, an integrated synthesis of global seroprevalence estimates and overarching epidemiological patterns remains insufficiently developed. Objective: To calculate the pooled global seroprevalence of EVA and to explore sources of epidemiological heterogeneity. Methods: A systematic review and meta-analysis were undertaken ...
Ehizibolo DO, Oyekan O, Mkpuma N, Haliru H, Garba I, Turaki IZ, Williams EE, Danmarwa A, Mohammed A, Muhammad MA, Abubakar M, Brown C, Faburay B.Rift Valley Fever (RVF) is a neglected vector-borne zoonotic disease of significant veterinary and public health concern in Sub-Saharan Africa. This study investigated the seroprevalence of Rift Valley Fever Virus (RVFV) exposure and associated risk factors among camels and horses marketed in northern Nigeria. A total of 1117 animals were sampled, comprising camels (812) and horses (305), across three major livestock markets (Maigatari, Maiduguri, and Illela). The overall seroprevalence was 18.8% (95% CI: 16.6-21.2%), with a striking six-fold disparity: camels showed a prevalence of 24.4% (95%...
Jiang Z, Merits A, Qin Y, Xing G, Zhang L, Chen J, Wang N, Varjak M, Zhai X, Li D, Song W, Su S.Alphaviruses are important arthropod-transmitted pathogens of humans and livestock. Getah virus (GETV) is an arthritogenic alphavirus that causes disease in horses and piglets; it also poses a potential threat to humans. A live attenuated vaccine candidate named GETV-3ΔS2-CM1, harbouring a deletion in nonstructural protein 3 and substitutions in the capsid protein, is genetically stable and exhibits robust immunogenicity. It was shown to confer passive protection to piglets born to immunized sows. In mice, a single dose of GETV-3ΔS2-CM1 protected against infection with different strains of G...
Noh H, Cho HU, Kim SH.The genus is widely distributed and includes species with ecological and biotechnological importance. In this study, morphological and phylogenetic analyses of the ITS and LSU rDNA sequences revealed two novel species, sp. nov. and sp. nov., as well as one previously unrecorded species in Korea, , from horse dung collected in Seopjikoji, Jeju Island, Republic of Korea. sp. nov. is unique in producing conidia from conidiomata instead of teleomorphic structures, a feature not observed in any other known species of the genus. sp. nov. is morphologically distinguished by the absence of a nec...
Delling C, Helm C, Heinze P, Friedman M, Böttcher D.While the principle definitive host of the zoonotic cestode in Europe is the red fox, several rodent species act as main intermediate hosts. Among others, e.g., humans, dogs, and pigs, also horses have been described to act as aberrant hosts in highly endemic regions. Here, a case of an infection in a kulan () is described. The five years old kulan from a zoo in Slovakia was transported to an animal park in Germany. The animal had to be euthanized within a few weeks after the import due to its poor general state of health. The pathological examination revealed a nodular mass in the liver as ...
Stokes JE, Labuschagne K, Fèvre EM, Baylis M.In recent decades there has been a huge increase in the export of cut flowers from countries in Africa and elsewhere to European flower markets, with the vast majority first entering the Netherlands for local use or for export. Coincidentally, three significant livestock disease outbreaks caused by viruses associated with Africa or other tropical regions were first detected in the Netherlands (bluetongue virus serotype 8 (BTV-8), 2006, and BTV-3, 2023) and in western Germany about 200 km from the Netherlands border (Schmallenberg virus, SBV, 2011). This study aimed to determine whether Culic...
Ma W, Gao L, Wu X, Zhong L, Huang X, Yang R, Wu H, Zhu L, Ma W, Peng L, Li B, Song J, Luo S, Bao F, Liu A.Both Borrelia burgdorferi (Bb) and Anaplasma phagocytophilum (Ap) can infect humans and animals through tick-borne transmission, resulting in zoonosis. Under certain conditions, human infection can lead to Lyme disease (LD) and human granulocytosis (HGA), whereas infection in animals can cause various acute and non-specific symptoms. The combination of Bb and Ap has been reported to increase the disease severity in infected animals. In this systematic review and meta-analysis, we investigated the global diversity of Bb and Ap coinfection in animals and their prevalence and distribution regardi...
Kozak S, Merda D, Duquesne F, Breuil MF, Mawhinney I, Petry S.In 2018, a T. asinigenitalis strain (MCE663) was isolated in a Persian onager tested for contagious equine metritis (CEM) in a United Kingdom (UK) zoo. This bacterium had never been reported in the UK and Multilocus Sequence Typing described a new atypically divergent ST (ST60). Although the causative agent of CEM is the bacterium Taylorella equigenitalis, a first natural outbreak of endometritis caused by T. asinigenitalis ST70 was reported in 2019, putting its pathogenic potential into question. In this context, we aimed to further sequence the T. asinigenitalis MCE663 genome and characteriz...
Bland J, McGowan C, Bush E, Lloyd V.Zoonotic diseases have major impacts on human and animal health, as well as being ecologically significant. Lyme Borreliosis or Lyme disease, caused by infection by pathogenic members of the Borrelia genus, is among these zoonotic diseases. Serology is one of the most accessible means for indirect surveillance of pathogen presence by monitoring the presence, abundance, and type of immune response to the pathogen or pathogen-associated epitopes. Serological surveillance of wild animals is important as wild animals are the primary reservoirs of many zoonotic diseases. Similarly, serological sur...
