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.
Souza CE, Pinter A, Donalisio MR.Brazilian spotted fever (BSF) is a disease transmitted by ticks for which the etiological agent is Rickettsia rickettsii. The present essay evaluates the risk factors associated with the transmission of cases of BSF in the time period between 2003 and 2013 in the Piracicaba river basin, state of São Paulo. Methods: This essay presents a retrospective study to identify the factors associated with the transmission of cases of BSF among all suspected cases identified by the System for Epidemiological Surveillance of São Paulo (CVE). After the description of temporal distribution (onset of sympt...
Li H, Dong GD, Liu JM, Gao JX, Shi YJ, Zhang YG, Jin YM, Lu K, Cheng GF, Lin JJ.Schistosomiasis japonica is a major public health problem in China. Domestic animals play a major role in the transmission of Schistosoma japonicum to humans. To better understand the epidemiology of schistosomiasis japonica in domestic animals in the mountainous areas of China, we performed a 5-year longitudinal study of schistosomiasis in cattle and horses in Yunnan Province from 2009 to 2013. We also performed a concurrent drug-based intervention study in three settlement groups in Yunnan Province aimed at developing an effective means of controlling transmission in this region. The prevale...
Davis EG, Bello NM, Bryan AJ, Hankins K, Wilkerson M.Protection from infectious disease requires antigen-specific immunity. In foals, most vaccine protocols are delayed until 6 months to avoid maternal antibody interference. Susceptibility to disease may exist prior to administration of vaccination at age 4-6 months. Objective: The aim of this investigation was to characterise immune activation among healthy foals in response to a multivalent vaccine protocol and compare immune responses when foals were vaccinated at age either 90 or 180 days. Methods: Randomised block design. Methods: Twelve healthy foals with colostral transfer were blocked fo...
Khatibzadeh SM, Gold CB, Keggan AE, Perkins GA, Glaser AL, Dubovi EJ, Wagner B.To compare antibody responses of horses naturally infected with West Nile virus (WNV) and those vaccinated against WNV, to identify whether vaccination interferes with the ability to diagnose WNV infection, and to determine the duration of antibody responses after vaccination. Methods: Sera from horses naturally infected with WNV (n = 10) and adult WNV-naïve horses before and after vaccination with a live canarypox virus-vectored vaccine (7) or a killed virus vaccine (8). Methods: An established WNV IgM capture ELISA was used to measure IgM responses. Newly developed capture ELISAs were used ...
Sedlák K, Zelená H, Křivda V, Šatrán P.The West Nile virus (WNV) is an important mosquito-borne flavivirus occurring around the world. Occasionally found in Central Europe, the virus spread massively through whole Hungary between 2008 and 2009. The aim of our study was to determine the recent prevalence of the WNV infection in horses in the Czech Republic. Methods: Overall, 2349 serum samples, collected from healthy unvaccinated adult horses in the Czech Republic between 2011 and 2013, were tested. A commercially available competitive ELISA kit (cELISA) was used for this purpose and positive samples were confirmed by virus neutrali...
Ye C, Yan W, Xiang H, He H, Yang M, Ijaz M, Useh N, Hsieh CL, McDonough PL, McDonough SP, Mohamed H, Yang Z, Chang YF.Animal leptospirosis is one of the most common zoonotic diseases in the United States and around the world. In a previous study, we applied four recombinant antigens, rLipL21, rLoa22, rLipL32 and rLigACon4-8 of Leptospira interrogans (L. interrogans) for the serological diagnosis of equine leptospirosis (Ye et al, Serodiagnosis of equine leptospirosis by ELISA using four recombinant protein markers, Clin. Vaccine. Immunol. 21:478-483). In this study, the same four recombinant antigens were evaluated for their potential to diagnose canine leptospirosis by ELISA. A total of 305 canine sera that ...
Steinbach F, Westcott DG, McGowan SL, Grierson SS, Frossard JP, Choudhury B.Equine arteritis virus (EAV) is the causative agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids, which is notifiable in some countries including the Great Britain (GB) and to the OIE. Herein, we present the case of a persistently infected stallion and the phylogenetic tracing of the virus strain isolated. Discussing EAV occurrence and phylogenetic analysis we review features, which may aid to harmonise and enhance the classification of EAV.
van den Hurk AF, Hall-Mendelin S, Webb CE, Tan CS, Frentiu FD, Prow NA, Hall RA.In 2011, a variant of West Nile virus Kunjin strain (WNVKUN) caused an unprecedented epidemic of neurological disease in horses in southeast Australia, resulting in almost 1,000 cases and a 9% fatality rate. We investigated whether increased fitness of the virus in the primary vector, Culex annulirostris, and another potential vector, Culex australicus, contributed to the widespread nature of the outbreak. Methods: Mosquitoes were exposed to infectious blood meals containing either the virus strain responsible for the outbreak, designated WNVKUN2011, or WNVKUN2009, a strain of low virulence th...
Sánchez-Matamoros A, Sánchez-Vizcaíno JM, Rodríguez-Prieto V, Iglesias E, Martínez-López B.African horse sickness (AHS) is one of the most important vector-borne viral infectious diseases of equines, transmitted mainly by Culicoides spp. The re-emergence of Culicoides-borne diseases in Europe, such as the recent bluetongue (BT) or Schmallenberg outbreaks, has raised concern about the potential re-introduction and further spread of AHS virus (AHSV) in Europe. Spain has one of the largest European equine populations. In addition, its geographical, environmental and entomological conditions favour AHSV infections, as shown by the historical outbreaks in the 1990s. The establishment of ...
Gallusová M, Qablan MA, D'Amico G, Oborník M, Petrželková KJ, Mihalca AD, Modrý D.Rural areas of Romania, particularly the localities covering Danube Delta, are still not sufficiently explored in terms of epidemiological aspects, despite the large density of domestic animals living in close contact with people and natural environment of the Danube Delta Biosphere Reserve. Between 2010 and 2012, a survey on equine piroplasmids species was performed in this area, using a total of 178 horses, 15 donkeys and 177 dogs from 18 localities inside and outside the Danube Delta. None of the sampled hosts showed any clinical symptoms typical for equine piroplasmoses. A 25.4% overall pr...
Ayinmode AB, Oluwayelu DO, Sule WF, Obebe OO.Toxoplasma gondii (T. gondii), an obligate intracellular protozoan parasite is a known etiological factor of reproductive problems and encephalomyelitis in animals and humans. This study investigated the seroprevalence of T gondii infection in recreational horses in two metropolitan cities of southwestern Nigeria. Serum samples were randomly collected from a total of 157 horses in Lagos and Ibadan. Samples were assayed for the presence of T gondii antibodies using the Modified Agglutination Test (MAT). A total of 22 (14%) of the 157 sampled horses were positive for T gondii antibodies by MAT w...
Teixeira WF, Felippelli G, Cruz BC, Maciel WG, Fávero FC, Gomes LV, Buzzulini C, Prando L, Bichuette MA, Lopes WD, Oliveira GP, Costa AJ.With the aim of studying the endoparasite fauna of horses from the Formiga city, located in center-west region of the state of Minas Gerais, 25 animals that were naturally infected with helminths were evaluated. By means of parasitological necropsies, different endoparasites were found. The subfamily Cyathostominae presented the highest incidence, followed by Trichostrongylus axei, Oxyuris equi, Triodontophorus serratus, Strongyloides westeri, Strongylus edentatus, Habronema muscae, Parascaris equorum, Probstmayria vivipara, Strongylus vulgaris, Gasterophilus nasalis, Anoplocephala magna and A...
Equine influenza in England and Scotland, Significant numbers of outbreaks of equine herpesvirus 1 neurological disease in the USA, Summary of surveillance testing, April to June 2014. These are among matters discussed in the most recent quarterly equine disease surveillance report, prepared by Defra, the Animal Health Trust and the British Equine Veterinary Association.
Hughes K.Cases of Hendra virus infection in horses in Australia have been seen regularly since the virus was first isolated in 1994. Kristopher Hughes, associate professor of equine medicine at Charles Sturt University in Australia, gives an overview of how knowledge of the virus has developed in the past 20 years.
Ruzauskas M, Siugzdiniene R, Klimiene I, Virgailis M, Mockeliunas R, Vaskeviciute L, Zienius D.Among coagulase-negative staphylococci, Staphylococcus haemolyticus is the second most frequently isolated species from human blood cultures and has the highest level of antimicrobial resistance. This species has zoonotic character and is prevalent both in humans and animals. Recent studies have indicated that methicillin-resistant S. haemolyticus (MRSH) is one of the most frequent isolated Staphylococcus species among neonates in intensive care units. The aim of this study was to determine the presence of MRSH in different groups of companion animals and to characterize isolates according the...
Hébert L, Touzain F, de Boisséson C, Breuil MF, Duquesne F, Laugier C, Blanchard Y, Petry S.Taylorella equigenitalis is the causative agent of contagious equine metritis (CEM), a sexually transmitted infection of horses. We herein report the genome sequence of T. equigenitalis strain MCE529, isolated in 2009 from the urethral fossa of a 15-year-old Belgian Warmblood horse in France.
Bohórquez GA, Luzón M, Martín-Hernández R, Meana A.Although several techniques exist for the detection of equine tapeworms in serum and feces, the differential diagnosis of tapeworm infection is usually based on postmortem findings and the morphological identification of eggs in feces. In this study, a multiplex polymerase chain reaction (PCR)-based method for the simultaneuos detection of Anoplocephala magna, Anoplocephala perfoliata and Anoplocephaloides mamillana has been developed and validated. The method simultaneously amplifies hypervariable SSUrRNA gene regions in the three tapeworm species in a single reaction using three pairs of pri...
Ryan M, Gildea S, Walsh C, Cullinane A.More knowledge of equine influenza (EI) vaccine usage in training yards and the factors that influence serological response to vaccination are required to determine evidence-based vaccination strategies. Objective: The aim of this study was to ascertain the vaccination history of a population of Thoroughbred racehorses and identify factors that impacted on their antibody titres against EI. Methods: Observational field study. Methods: The study population consisted of 102 vaccinated Thoroughbred horses in training on a single premises. The vaccination histories recorded in their official passpo...
Aharonson-Raz K, Lichter-Peled A, Tal S, Gelman B, Cohen D, Klement E, Steinman A.With the rapid global spread of West Nile virus (WNV) and the endemic state it has acquired in new geographical areas, we hereby bring a thorough serological investigation of WNV in horses in a longstanding endemic region, such as Israel. This study evaluates the environmental and demographic risk factors for WNV infection in horses and suggests possible factors associated with the transition from endemic to epidemic state. West Nile virus seroprevalence in horses in Israel was determined throughout a period of more than a decade, before (1997) and after (2002 and 2013) the massive West Nile f...
Jiménez D, Romero-Zuñiga JJ, Dolz G.Blood samples from 181 equines from the Central Valley of Costa Rica were collected in the year 2012 to determine the presence of antibodies against selected infectious agents in horses and to determine the risk factors associated with these agents. The presence of antibodies against Equine Infectious Anemia Virus (EIAV), Equine Herpes Virus 1 and 4 (EHV-1 and EHV-4), West Nile Virus (WNV), Influenza A Virus (IAV), Equine Viral Arteritis Virus (EVAV), Babesia caballi, Theileria equi, Neospora caninum and Chlamydia abortus was determined using commercial assays, and risk factors associated with...
Paillot R.Equine influenza (EI) is a major respiratory disease of horses, which is still causing substantial outbreaks worldwide despite several decades of surveillance and prevention. Alongside quarantine procedures, vaccination is widely used to prevent or limit spread of the disease. The panel of EI vaccines commercially available is probably one of the most varied, including whole inactivated virus vaccines, Immuno-Stimulating Complex adjuvanted vaccines (ISCOM and ISCOM-Matrix), a live attenuated equine influenza virus (EIV) vaccine and a recombinant poxvirus-vectored vaccine. Several other strateg...
Aribam SD, Ogawa Y, Matsui H, Hirota J, Okamura M, Akiba M, Shimoji Y, Eguchi M.Serotyping is an important element for surveillance of Salmonella. In this study, an anti-O:4 Salmonella monoclonal antibody-based competitive enzyme-linked immunosorbent assay that could identify Salmonella infection in cow, pig, horse, and chicken was developed. This detection system can therefore be useful for a wide range of animals and for humans.
Passamonti F, Vardi DM, Stefanetti V, Marenzoni ML, Prato S, Cévese P, Coletti M, Pepe M, Casagrande Proietti P, Olea-Popelka F.Early diagnosis and prevention of Rhodococcus equi pneumonia in foals represent important goals for equine clinicians. Recent protocols for diagnosis and treatment of Rhodococcosis in foals typically rely on a multimodal approach based on sonographic evidence suggestive of pyogranulomas, sonographic abscess scores and laboratory findings including plasma fibrinogen concentrations, blood biochemistry testing and platelet and leukocyte counts. The aim of this study was to assess the utility of weekly testing of serum amyloid A (SAA) and plasma fibrinogen concentrations in foals to achieve early ...
Ben Said M, Belkahia H, Héni MM, Bouattour A, Ghorbel A, Gharbi M, Zouari A, Darghouth MA, Messadi L.The aim of the present study was to determine the seroprevalence of Anaplasma phagocytophilum in 343 well maintained horses belonging to 11 horse stables located in northern Tunisia with indirect immunofluorescence test. Overall, 16.3% (56/343) of tested animals were positive. Anti-A. phagocytophilum antibodies were present in horses located in all studied governorates except the governorate of Ben Arous. Nine horse stables out of 11 contained positive animals, the seroprevalence of each one varied from nought to 50%. Seroprevalence varied according to gender, breed and type of activity, contr...
Wang XF, Wang S, Liu Q, Lin YZ, Du C, Tang YD, Na L, Wang X, Zhou JH.Equine infectious anemia virus (EIAV) is a member of the Lentivirus genus in the Retroviridae family that exhibits a genomic structure similar to that of HIV-1. The S2 accessory proteins play important roles in viral replication in vivo and in viral pathogenicity; however, studies on S2 evolution in vivo are limited. This study analyzed the evolutionary characteristics of the S2 gene of a pathogenic EIAV strain, EIAVLN40, in four experimentally infected horses. The results demonstrated that 14.7% (10 of 68 residues) of the stable amino acid mutations occurred longitudinally in S2 during a 150-...
Colling A, Lunt R, Bergfeld J, McNabb L, Halpin K, Juzva S, Newberry K, Morrissy C, Loomes C, Warner S, Diallo I, Kirkland P, Broder CC, Carlile G....Obtaining statistically sound numbers of sera from Hendra virus (HeV)-infected horses is problematic because affected individuals usually die or are euthanized before developing a serum antibody response. As a consequence, test validation becomes a challenge. Our approach is an extension of OIE principles for provisional recognition and included 7 validation panels tested across multiple laboratories that provided estimates for test performance characteristics. At a 0.4 S/P cutoff, 16 of 19 sera from HeV-infected horses gave positive results in the HeV soluble G, indirect ELISA (HeVsG iELISA; ...
Richardson DW, Kohn CW.The case records of 22 foals with uroperitoneum were reviewed. The most common cause was a defect in the urinary bladder. A sex predilection for males was apparent. Clinical signs were tachycardia, tachypnea, and abdominal distention. The history pertaining to micturition was variable. Hyponatremia, hypochloremia, and hyperkalemia were marked. A reliable means of diagnosis was considered to be the demonstration of a wide disparity in serum and peritoneal fluid creatinine values. Surgical repair was successful in 11 of 18 cases, although surgical and anesthetic complications were common. Some o...
Guzmán C, Calderón A, Oviedo T, Mattar S, Castañeda J, Rodriguez V, Moraes Figueiredo LT.Venezuelan equine encephalitis virus (VEEV) is an alphavirus that causes encephalitis with a high impact on public health in Latin America. However, only in Guatemala, Trinidad and Tobago, and Mexico have found antibodies in VEEV in bats, using immunohistochemistry, the sensitivity and specificity are improved; thus, it is better for demonstrating natural infection in bats as potential hosts. This study aimed to determine the presence of VEEV in tissues of frugivorous bats. Methods: A prospective descriptive cross-sectional study with a non-probabilistic sampling was carried out in 12 localiti...
Hébert L, Moumen B, Pons N, Duquesne F, Breuil MF, Goux D, Batto JM, Laugier C, Renault P, Petry S.The Taylorella genus comprises two species: Taylorella equigenitalis, which causes contagious equine metritis, and Taylorella asinigenitalis, a closely-related species mainly found in donkeys. We herein report on the first genome sequence of T. asinigenitalis, analyzing and comparing it with the recently-sequenced T. equigenitalis genome. The T. asinigenitalis genome contains a single circular chromosome of 1,638,559 bp with a 38.3% GC content and 1,534 coding sequences (CDS). While 212 CDSs were T. asinigenitalis-specific, 1,322 had orthologs in T. equigenitalis. Two hundred and thirty-four T...
Seo MG, Kwon OD, Kwak D.Lyme borreliosis is one of the most prevalent tick-borne infectious zoonotic diseases caused by spirochetes of the sensu lato group. The present study assessed the risk factors and prevalence of Lyme borreliosis in ticks parasitizing domestic and wild animals. A total of 589 ticks (329 tick pools) collected from animals were identified as , (85.7%), (10.0%), and (4.3%) using morphological and molecular methods in South Korea. In this study, the 5S-23S gene sequences of (6/329, 1.8%) were detected in ticks taken from mammals, including ticks from horses (2/147 pools, 1.4%), wild boar (1/19 ...
Al-Kass Z, Eriksson E, Bagge E, Wallgren M, Morrell JM.Although artificial insemination (AI) was developed as a means of controlling disease transmission, pathogens can still be transmitted to females in semen used for AI. In addition, bacteria can cause deterioration in sperm quality during storage. Semen becomes contaminated by the male's normal bacterial flora as it passes out of the reproductive tract but potential pathogens may also contaminate the semen. Therefore, semen samples from stallions to be used for AI are tested before the breeding season to minimize transmission of pathogens to inseminated mares. In Sweden, semen samples are teste...
Russell CL, Heesom KJ, Arthur CJ, Helps CR, Mellor PS, Day MJ, Torsteinsdottir S, Björnsdóttir TS, Wilson AD.Culicoides spp. are vectors of several infectious diseases of veterinary importance and a major cause of allergy in horses and other livestock. Their saliva contains a number of proteins which enable blood feeding, enhance disease transmission and act as allergens. We report the construction of a novel cDNA library from Culicoides nubeculosus linked to the analysis of abundant salivary gland proteins by mass spectrometry. Fifty-four novel proteins sequences are described including those of the enzymes maltase, hyaluronidase and two serine proteases demonstrated to be present in Culicoides sali...
Bolin CA, Zuerner RL.Isolates (n = 147) of Leptospira interrogans serovar pomona type kennewicki from cattle, swine, horses, and wildlife were analyzed by DNA restriction endonuclease analysis. Restriction fragment length polymorphisms were identified in DNA digested with HpaII, and the restriction fragment length polymorphisms were correlated with the host animal source of the isolates. These results will be useful in understanding the epidemiology of serovar pomona infections in livestock.
Junqueira DG, Dorneles EM, Gonçalves VS, Santana JA, Almeida VM, Nicolino RR, Silva MX, Mota AL, Veloso FP, Stynen AP, Heinemann MB, Lage AP.The present survey aimed at estimating the seroprevalence of brucellosis in working equines of cattle farms from Minas Gerais State, Brazil, and investigating risk factors associated with the infection. Serum samples from 6439 animals, including 5292 horses, 1037 mules and 110 donkeys, were collected from 1936 herds, between September 2003 and March 2004, in 848 municipalities from the state of Minas Gerais, Brazil. The prevalence of antibodies against smooth Brucella spp. found in equines from Minas Gerais State was 1.37% (95% CI: 0.97-1.78), resulting in a prevalence of herds with infected a...
Tizard IR, Harmeson J, Lai CH.The prevalence of seropositive reactions to Toxoplasma gondii was studied in farm animals, companion animals, wild rodents and birds. Of the animals tested, 17% of cattle, 65% of sheep, 45% of pigs, 9% of horses, 33% of dogs and 20% of cats were seropositive by the Sabin-Feldman dye test. In addition 11% of mice (Mus musculus), 5% of deer mice (Peromyscus), 3% of rats (Rattus norvegicus) and less than 2% of sparrows (Passer domestcus) were seropositive. All samples from short-tailed field mice (Microtus pennsylvanicus), squirrels (Sciurus carolinensis), chipmunks (Tamias striatus), meadow jump...
Sampieri F, Vannucci FA, Allen AL, Pusterla N, Antonopoulos AJ, Ball KR, Thompson J, Dowling PM, Hamilton DL, Gebhart CJ.Lawsonia intracellularis infection causes proliferative enteropathy (PE) in many mammalian species, with porcine and equine proliferative enteropathy (PPE and EPE) known worldwide. Hamsters are a well-published animal model for PPE infection studies in pigs. There is no laboratory animal model for EPE infection studies and it is not known whether there is species-specificity for equine or porcine isolates of L. intracellularis in animal models. The objective of this study was to determine whether it is possible to generate typical EPE lesions in hamsters after inoculation with an equine strain...
Shirafuji H, Kanehira K, Kamio T, Kubo M, Shibahara T, Konishi M, Murakami K, Nakamura Y, Yamanaka T, Kondo T, Matsumura T, Muranaka M, Katayama Y.A group of horses immunized with inactivated Japanese encephalitis (JE) vaccine (JE-Immune Group) and a group of non-immunized horses (Non-Immune Group) were infected with West Nile virus (WNV). After WNV infection, neutralizing (Nt) antibody (Ab) titers to WNV were higher than those to JE virus (JEV) in the Non-Immune Group, but the NtAb titers to JEV were higher than those to WNV during most of the post-challenge observation period in the JE-Immune Group. Immunoglobulin M (IgM) Abs to WNV tested positive in the Non-Immune Group but negative in the JE-Immune Group, except for in one horse. Th...
Guthrie AJ, Howell PG, Hedges JF, Bosman AM, Balasuriya UB, McCollum WH, Timoney PJ, MacLachlan NJ.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...
Britz E, Spier SJ, Kass PH, Edman JM, Foley JE.Equine infection with Corynebacterium pseudotuberculosis can manifest in several forms, including external or internal abscesses. The objective of this study was to phenotype clinical isolates of C. pseudotuberculosis and to investigate the relationship between lesion location and extent of lesions in the animals from which they were collected. One hundred and seventy-one C. pseudotuberculosis biovar equi isolates were collected from horses presenting to the University of California Veterinary Medical Teaching Hospital and two other sources in the period between September 1996 and December 201...
Uchida-Fujii E, Niwa H, Kinoshita Y, Nukada T.Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is used for bacterial identification by analyzing the spectra of isolates and comparing them against a database of reference spectra; it is known for its rapidity and accuracy. Although MALDI-TOF MS is used for identification of bacterial isolates from animals, not all animal pathogens are identified correctly. In this study, we used a commercial MALDI-TOF MS identification system to examine 3724 bacterial isolates from horses and their environments. Isolates that could not be identified with MALDI-TOF ...
James KE, Smith WA, Packham AE, Conrad PA, Pusterla N.While toxoplasmosis is not commonly considered a clinical disease of equines, previous seroprevalence studies have reported differing background rates of Toxoplasma gondii infection in horses globally. The objective of this study was to evaluate possible associations between T. gondii seroprevalence and clinical signs of equine protozoal myeloencephalitis (EPM) in horses. Using a case-control study design, 720 Californian horses with neurologic signs compatible with EPM were compared to healthy, non-neurologic horses for the presence of T. gondii antibodies (using indirect fluorescent antibody...
Holman PJ, Frerichs WM, Chieves L, Wagner GG.Culture of horse blood for Babesia caballi identified four carrier horses among nine previously infected horses. Three of the carriers had no detectable parasitemias on stained blood smears, and sera from two carrier horses were complement fixation test negative. Three cultures were continuously cultivated. Cryopreserved fourth-passage B. caballi was successfully reestablished in vitro. Blood from a 10th horse previously subinoculated with blood from a suspected carrier was cultured, with negative results.