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.
KAPLAN MM, PAYNE AM.In 1957 the World Health Organization arranged a survey of horse and swine sera in a number of countries in order to gain information on the role and importance of animals in the epidemiology of influenza. The veterinary services of the countries concerned were requested to obtain blood specimens from these animals, if possible both before and after the human pandemic of Asian influenza. This paper reports on the results of haemagglutination-inhibition and complement-fixation tests performed on these sera in WHO Influenza Centres and other collaborating laboratories.It is apparent from these r...
Sosa-Portugal S, Dale L, Devaney J, Sharp A, Malalana F, Timofte D.The "ESKAPE" bacteria include a group of organisms known for their multidrug resistance and potential association with nosocomial infections in human and veterinary hospitals. Objective: This study aimed to evaluate the effectiveness of steam cleaning in reducing the number of ESKAPE organisms on environmental surfaces from the stables of an equine veterinary referral hospital. Methods: Environmental sampling was performed at two timepoints (pre- and post-steam cleaning) on smooth metallic doors and rough rubber stable walls. Microbiological culture targeted ESKAPE organisms and Escherichia co...
Martins ALM, Estevam LGTM, Freire MA, Lima ACVMDR, de Oliveira FCB, Dutra-Rêgo F, Carvalho GML, Ribeiro VM, Paz GF.Equine leishmaniasis is a widespread disease in Brazil, mainly caused by Leishmania (Viannia) braziliensis, with occasional cases involving Leishmania (Leishmania) infantum. This study reports a mixed infection in a 6-year-old mare from rural Itabirito, Minas Gerais, Brazil. The mare exhibited nodular cutaneous lesions on all limbs but had no other health issues. Skin and bone marrow samples were collected and analyzed using parasitological and molecular methods targeting the hsp70 gene and ITS1 region. Both L. (V.) braziliensis and L. (L.) infantum were identified, confirming a mixed infectio...
Khan A, Jose-Cunilleras E, Hyde E, Olajide E, Polo MC, Goehring LS.Equid alphaherpesvirus 1 (EHV-1) remains a major concern for the equine industry, with recent outbreaks at international equestrian events highlighting the need for improved surveillance during competitions. Objective: To investigate EHV-1 and -4 presence in shared airspaces and environmental surfaces in direct contact with horses at international equestrian events; and to evaluate air sampling as a surveillance alternative to individual horse testing. Methods: Cross-sectional field study. Methods: Air (37) and surface samples (205) were collected from temporary stabling facilities across six ...
Durán MC, Suazo M, Maturana A, Vargas MP, García A, Ahumada C, Pezoa A, Goehring LS, Lara F.Equine herpes myeloencephalopathy (EHM) is a neurological disease in horses caused by Equine herpesvirus type 1 (EHV-1). It is a serious condition, often resulting in severe neurological deficits, and can be fatal. In this report, we discuss the first outbreak of EHM in Chile (clinical signs, epidemiology, diagnosis, and control measures). A total of 567 polo horses were kept at the facility: 58.4% mares, 41.6% geldings, and stallions. Mean age was 9.7 ± 0.132 years. Thirteen horses showed clinical signs of EHV-1, eight had fevers (1.4%), and eleven developed EHM (1.9%). Only six of the eleve...
Equestrian sports play a significant economic role in the horse industry. In recent years, numerous equine viruses have emerged, among which are equine Pegiviruses and the re-emerging Equine coronavirus (ECoV). These viruses are distributed globally and primarily cause subclinical infections with unknown morbidity, even if ECoV can occasionally induce febrile and diarrheic episodes. To broaden the data on the Italian equine population, a study was conducted to assess their prevalence in two distinct horse populations belonging to the Carabinieri Corps (CC) and the Italian Army (IA) of the Ital...
Chinyere CN, Ajaebili AC, Peter-Ajuzie IK, Galadima HB, Daodu OB, Fatola OI, Okolo CC, Alaba BA, Akinniyi OO, Omoniwa DO, Edeh ER, Olorunfemi AB....African horse sickness (AHS) is a severe, infectious arthropod-borne disease of equids caused by the AHS virus (AHSV). It is endemic in Sub-Saharan Africa, and several sporadic outbreaks of the disease have been reported in Nigeria in the past 5 decades. Following a recent outbreak of the disease in Lagos State, this study was conducted to investigate the prevalence of (AHSV) antibodies in apparently healthy horses and some selected wildlife sampled in four geographical regions of Nigeria. Using a competitive enzyme-linked immunosorbent assay, 575 serum samples collected from horses in five ...
Mukhanbetkaliyev Y, Yessembekova G, Mukhanbetkaliyeva A, Akmambayeva B, Kadyrov A, Uskenov R, Bostanova S, Ashirbek A, Korennoy F, Abdrakhmanov S.Equine herpesvirus 1 (EHV-1) is one of the most dangerous viral diseases affecting ungulates, and is characterized by a wide range of clinical manifestations in horses, including rhinopneumonia, abortion, neonatal death, and myeloencephalopathy. It is well known for causing mass abortions in mares and respiratory diseases in young animals. Once introduced into a horse breeding farm of any type, EHV-1 tends to establish as a persistent infection. The disease is reported on nearly all continents and causes substantial annual economic losses to horse breeding operations. In Kazakhstan, 34 EHV-1 o...
Nemoto M, Kawanishi N, Kamei R, Furusho K, Kawauchi K, Yabuuchi Y, Oue Y, Uchida Y, Nishiura H, Reedy SE, Chambers TM, Li F, Bannai H, Yamanaka T....In April and May 2025, outbreaks of equine influenza occurred for the first time in 17 years in Japan. Equine influenza virus (EIV) of the H3N8 subtype was mainly detected in heavy draft horse populations in Kumamoto Prefecture and the Tokachi area of Hokkaido. In total, 10 EIVs were isolated from infected horses and then were used for genetic and serological analyses. Phylogenetic analysis of all eight genes revealed that all Japanese isolates were clustered with the Florida sublineage clade 1 (Fc1) viruses and were closely related to North American Fc1 viruses detected in 2024-2025. The resu...
Whitlock F, Newton R, King S, Ionescu AM, Higgins S.With the geographical distribution of West Nile virus expanding, there is growing concern about the potential for an incursion to the UK. Here, Fleur Whitlock, Richard Newton, Simon King, Andra-Maria Ionescu and Sara Higgins provide a timely reminder of key aspects of the virus' biology.
Wickenden H, Lightbody KL, Peczak N, Stevens KB, Pollard D, Blake DP, Austin CJ, Matthews JB, Fox MT.Anoplocephala perfoliata is the most common equine tapeworm infection. This parasite is found at the small/large intestinal junction and has been associated with colic. The cestode has an indirect lifecycle involving oribatid mite intermediate hosts, though little is known of its epidemiology. This study aimed to monitor seasonal fluctuations in pasture oribatid mite numbers and the presence of Anoplocephala spp. DNA in mite samples collected from three equine premises in the UK. Exposure to infection in resident horses was assessed by measuring tapeworm-specific salivary antibodies. The data ...
Vitale V, Bindi F, Bertelloni F, Sala G, Cingottini D, Bonelli F, Sgorbini M.Bacterial contamination of intravenous catheters in hospitalized horses may pose risks for both patient care and public health due to potential antimicrobial resistance and zoonotic transmission. This prospective clinical study aimed to evaluate the incidence of catheter contamination in equine patients admitted to a Veterinary Teaching Hospital between 2020 and 2021. All horses requiring intravenous catheterization were included, and data were collected on patient signalment, clinical status, duration of catheterization, treatments, and outcomes. Two catheter types were used: 5 cm polytetrafl...
Hacilarlioglu S, Bilgic HB, Karagenc T, Aydin HB, Toker H, Kanlioglu H, Pekagirbas M, Bakirci S.Equine piroplasmosis (EP), caused by and , is a tick-borne disease posing significant threats to equine health and the horse industry worldwide. Other vector-borne blood parasites, including , spp., and spp., can also infect horses; however, their prevalence remains poorly characterized in Türkiye. This study aimed to determine the molecular prevalence of , , , spp., and spp. in equids from the Western Aegean Region of Türkiye. Blood samples were collected from 388 clinically healthy equines across İzmir, Aydın, Denizli, and Muğla provinces. Species-specific PCR assays were performed...
Mège M, Bonsergent C, Viry L, Dhune M, Lecollinet S, Malandrin L.Equine piroplasmosis is a major tick-borne horse disease, caused by the intracellular development of piroplasms (Theileria equi sensu lato and Babesia caballi), with significant economic and sanitary consequences. In 2024, 203 blood samples were collected in Guadeloupe (Caribbean) from asymptomatic horses. Using an 18S rRNA nested PCR (nPCR) specific for each equine genus parasite, 79 samples tested positive for Theileria equi and 9 for Babesia caballi, resulting in respective prevalence of 38.9% and 4.4%. Three horses were co-infected. For B. caballi, 18S rRNA sequence analysis revealed the p...
Jelocnik M, Hall C, Dennis S, Mitchell K, Blishen A, Mashkour N, Anstey SI, Jenkins C, Jeffers K, El-Hage C, McMillan D, Gilkerson J.Infectious diseases significantly impact equine health and welfare, causing illness and death, and loss of productivity globally. One such disease is 'strangles', a highly contagious upper respiratory condition in horses caused by Streptococcus equi subspecies equi (SEE). Diagnostic methods for this pathogen include sensitive molecular assays and less reliable bacterial isolation and biochemical testing. However, the presence of closely related streptococci, such as Streptococcus equi subspecies zooepidemicus (SZOO), may confound diagnosis. Rapid assays for SEE are crucial for outbreak control...
McLinden LA, Kemp-Symonds JG, Daly JM, Blanchard AM, Waller AS, Freeman SL.Infection with Streptococcus equi subspecies equi (S. equi) is characterised by acute disease, with about 10% of infected animals remaining persistently infected. Clinically, infection with S. equi cannot readily be distinguished from infection caused by other respiratory pathogens, including Streptococcus equi subspecies zooepidemicus (S. zooepidemicus), equine influenza virus, and equine herpes virus. Screening protocols, with appropriate quarantining facilities, are important to detect horses infected with S. equi and avoid strangles outbreaks. Virulent strains of S. zooepidemicus can also ...
Seeger MG, de Vargas APC, Vogel FSF, Cargnelutti JF.Streptococcus equi subsp. equi (S. equi) is the etiological agent of strangles, a contagious equine disease characterized by lymph node abscess and respiratory complications. To clarify the epidemiology and virulence factors of isolates, this study demonstrated phenotypic and genotypic differences between S. equi obtained from nasal secretions and lymph node aspirates of clinical strangles cases. Additionally, circulating alleles were differentiated through sequencing of the 5' end of the seM gene. A total of 23 clinical isolates collected from horses with strangles over the past decade were a...
Badr C, Handous M, Nsiri J, ElBehi I, Arbi M, Maaroufi A, Bennour MA, Ben Osman R, Dachraoui K, Abbes M, Mahmoudi A, Khosrof I, Abrougui S, Lachheb J....West Nile virus (WNV) is an arthropod borne virus, the most widely distributed of the encephalitic Orthoflaviviruses. It can cause severe neurological symptoms in both humans and horses. It poses an emerging threat to both public and animal health. In this study, we retrospectively screened 25 suspected WNV samples collected from 2018 to 2023. Methods: A total number of 25 samples (brain tissue and blood) were collected from clinically affected horses and those already deceased across several locations in Tunisia. All samples were tested for the presence of WNV NS2A gene using qRT-PCR. Eleven ...
Rosanowski SM, Milne H, Pearce P, McDonald N, Zobel G, McFadden A.An essential component of a timely response to a disaster event or disease outbreak is an accurate understanding of the population at risk, its location, and the owners' contact details. In equines, this can be achieved through individual identification, via microchipping, and the registration of these individuals in a centralised database. This review outlines the development by the New Zealand Equine Health Association (NZEHA) of a centralised database for equines in New Zealand, the National Equine Identification and Traceability (NEIT) system, which is built using Companion Animal New Zeal...
Vasconcelos AB, França DA, Prado ACD, Yamauchi DH, Silva ACAD, Barros IO, Valença SRFA, Lucheis SB, Bosco SMG.Pythiosis is an underestimated and neglected disease in Brazil, both in horse breeders and in horses. The molecular detection of in horses in the Brazilian Northeast represents a milestone in the epidemiology of equine pythiosis in the country. This study reports novel cases of equine pythiosis, diagnosed by molecular methods, in five states of Northeastern Brazil. Clinical samples were submitted to microbiological culture, DNA extraction, and nested-PCR for molecular detection of . The nested-PCR successfully detected in four out of five equine lesion samples, demonstrating higher sensitivi...
Al-Ebshahy E, Badr Y, El-Ansary RE, Alajmi R, El-Ashram S, Rady A, Elgendy E.The present study investigated the molecular detection and genetic characteristics of equine herpesvirus 1 (EHV-1) and EHV-4 circulating within Egyptian horse populations during 2019-2022. A total of 79 animals were sampled (54 nasal swabs and 25 aborted fetal tissues). PCR assays revealed that 24 (30.3%) and 7 (8.8%) samples were positive for EHV-1 and EHV-4, respectively. Additionally, 5 (6.3%) samples were concurrently infected with both viruses. Four EHV-1 and three EHV-4 isolates were genetically characterized based on partial sequencing of gB gene. The four EHV-1 strains displayed 100% n...
Zanilabdin M, Ilgekbayeva G, Otarbayev B, Nissanova R, Mussayeva G, Takai S, Suzuki Y, Kakuda T, Kurman S, Kassymov Y, Valiyeva B. is a facultative intracellular pathogen causing bronchopneumonia in foals; data from Central Asia are limited. We conducted a cross-sectional serological and molecular survey in horses from three regions of Kazakhstan (Kyzylorda, Almaty, Akmola). Unassigned: Sera from 312 animals (272 adults, 40 foals) on 20 farms were tested by indirect ELISA. Selected clinical samples underwent culture, PCR, and 16S rRNA sequencing. Unassigned: Overall seroprevalence was 8.3% (26/312; 95% CI 5.8-11.9). Positivity among foals was 25.0% (10/40; 95% CI 14.2-40.2) versus 5.9% (16/272; 95% CI 3.7-9.3) in adults,...
Rimayanti R, Khairullah AR, Mustofa I, Utomo B, Lestari TD, Utama S, Akintunde AO, Mulyati S, Hernawati T, Dawood AQ, Riady G, Khan IU, Rasad SD.... is a protozoan parasite that causes the sexually transmitted disease known as "dourine" in horses. This chronic illness is directly spread from one animal to another during mating. Doflein proposed the name in 1901. Despite being distributed worldwide, the broad use of artificial insemination technology over the past three decades has resulted in only a few cases being documented. The condition is typically fatal and is characterized by gradual emaciation, nervous system involvement, and edematous lesions of the genitals. The incubation period between exposure and the onset of clinical sympt...
McLachlan AD, Woolford L.Chlamydia psittaci was detected by real-time PCR in the lung, liver and kidney of an equine foetus that had aborted in South Australia in August 2023. The corresponding microscopic lesions included lymphocytic and histiocytic chorionitis, necrosis of placental villi associated with bacteria in the cytoplasm of trophoblastic epithelial cells, and multiple microgranulomas in the liver. Equine chlamydial abortion had not been diagnosed previously in South Australia. Eight days after examining the foetus and placenta, the veterinary pathologist developed fever and subsequently was admitted to hosp...
Piketh G, Viljoen A, Eberhardt C.Equine encephalosis (EE) is caused by an Orbivirus from the family Sedoreoviridae and is thus similar to African horse sickness (AHS) and Bluetongue viruses (BTV). These viruses are transmitted by Culicoides midges. Equine encephalosis can infect horses, donkeys and zebras sub-clinically while only horses develop clinical disease. The vector's distribution is climate-dependent with evidence for circulation in Southern Africa, the Middle East and India. Global warming could facilitate the expansion of this distribution and consequently the potential spread into Europe should not be overlooked. ...
Linnegar B, Hoegh A, McCallum H, Peel AJ.Anthropogenic climatic and landscape change can drive behavioural shifts in wildlife and thus lead to increased risk of pathogen exposure for humans and domestic animals. While spillover research often focuses on the reservoir hosts or ongoing transmission in humans, livestock and companion animals can play important roles as bridging and amplifying hosts, facilitating the emergence of highly pathogenic diseases. Objective: To investigate the distribution and density of domestic horses in the context of their role as bridge hosts for Hendra virus and build models to study zoonotic emergence. M...
Khan MZ, Ji Y, Fan X, Liu Y, Liu W, Wang C.Equine herpesvirus (EHV) infections represent a significant global veterinary and economic challenge affecting both horses and donkeys across all inhabited continents. This narrative review comprehensively examines the nine distinct EHV species (EHV-1 through EHV-9), their taxonomic classification within Alphaherpesvirinae and Gammaherpesvirinae subfamilies, and their diverse host tropism patterns. The complex molecular pathogenesis involves sophisticated viral glycoproteins (gK, gB, gC, gH, gM, gL, gG, gD, gI, gE) that orchestrate cellular invasion, immune evasion, and intercellular transmiss...
This study presents the first investigation of West Nile virus (WNV) seroprevalence among farmed horses in Kazakhstan. In 2024, a total of 368 serum samples were collected from horses across 106 settlements in 10 regions of the Republic of Kazakhstan. Using an enzyme-linked immunosorbent assay (ELISA), antibodies to WNV were detected in 32 horses (8.7%; 95% CI: 6.2-12.0%) from six regions. Among the seropositive animals, 26 (81.25%) were females and 6 (18.75%) were males, ranging in age from 1 to 19 years. No statistically significant association between sex and the presence of antibodies to W...
Bhat S, Karunakaran S, Frossard JP, Choudhury B, Steinbach F.Equine arteritis virus (EAV) is the causative agent of equine viral arteritis, a notifiable respiratory and reproductive disease of equids that causes significant losses to the equine industry. This study presents a comprehensive analysis of two EAV outbreaks in the UK in 2019, combining virus isolation, sequencing and phylogenetic analysis to provide a holistic understanding of EAV dynamics in these outbreaks. Genetic characterization revealed that all outbreak strains were similar to viruses detected in the UK and Europe from 2004 to 2011, belonging to phylogroup D and clustering in two grou...
In 2017, Spain reported its first equine infectious anemia virus (EIAV) outbreak in 34 years, affecting three horses in two unrelated holdings in Candeleda (Ávila) and Serradilla (Cáceres), with no apparent epidemiological link between premises. Phylogenetic analysis of whole genome and the gene revealed that the Spanish EIAV strains form a distinct monophyletic clade, sharing more than 99% nucleotide identity, suggesting a common contamination event. Interestingly, these three viral strains seem to cluster with North American strains, sharing up to 80.12% nucleotide identity, notably with ...
McGilvray TA, Stevens KB, Spence KL, Rosanowski SM, Slater J, Cardwell JM.The widespread assumption that there is minimal potential for pathogen transmission between British racehorse and sport horse populations remains unverified by empirical evidence. Objective: To characterise spatiotemporal patterns of horse attendance at racing and other sport events in Great Britain in 2018. Methods: Spatiotemporal analysis. Methods: Publicly available data from British Horseracing Authority, British Dressage, British Eventing, Endurance GB, and British Showjumping events in Great Britain during 2018 were analysed. Horse attendance was summarised by discipline, month, and seas...
