Protozoa are single-celled eukaryotic organisms that can interact with horses in various ways, including as parasites. In equine health, protozoal infections can lead to significant diseases, such as equine protozoal myeloencephalitis (EPM), which is caused by the protozoan Sarcocystis neurona. These organisms can affect the central nervous system and other bodily systems, leading to a range of clinical symptoms in horses. Understanding the life cycle, transmission, and impact of protozoa is important for managing and preventing infections. This page compiles peer-reviewed research studies and scholarly articles that explore the biology, pathogenesis, and diagnostic approaches related to protozoal interactions in horses.
Mackay RJ, Tanhauser ST, Gillis KD, Mayhew IG, Kennedy TJ.To evaluate the effect of intermittent oral administration of ponazuril on immunoconversion against Sarcocystis neurona in horses inoculated intragastrically with S neurona sporocysts. Methods: 20 healthy horses that were seronegative for S neurona-specific IgG. Methods: 5 control horses were neither inoculated with sporocysts nor treated. Other horses (5 horses/group) each received 612,500 S neurona sporocysts via nasogastric tube (day 0) and were not treated or were administered ponazuril (20 mg/kg, PO) every 7 days (beginning on day 5) or every 14 days (beginning on day 12) for 12 weeks. Bl...
Soltane R, Guyot K, Dei-Cas E, Ayadi A.1,001 faecal samples were obtained from 89 sheep (lambs and adult), 184 goats, 190 horses, 178 rabbits, 110 camels, 200 broiler chicken and 50 turkeys housed in farms from different localities in Tunisia. All samples were analysed for Cryptosporidium oocysts by microscopic examination of smears stained by modified Ziehl Neelsen technique. The parasite was detected in ten lambs and adult sheep (11.2 %) and nine broiler chicken (4.5 %). Molecular characterization, performed in four animals, identified C. bovis in three lambs and C. meleagridis in one broiler chicken. This work is the first repor...
Elitsur E, Marsh AE, Reed SM, Dubey JP, Oglesbee MJ, Murphy JE, Saville WJ.Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days ...
Rashid HB, Chaudhry M, Rashid H, Pervez K, Khan MA, Mahmood AK.The present work was conducted to study the comparative efficacy of two anti-protozoan (babesicidal) drugs on the recovery and health of horses. A total of 80 horses, showing typical clinical symptoms of the disease, were selected for this study; the presence of babesiosis was confirmed through blood smear examination. These animals were divided into two groups i.e. A and B. Horses of Group A, were treated with diminazene diaceturate, while horses of Group B were treated with diminazene aceturate. Efficacy of the drugs was determined by the reversal of clinical signs and a negative blood smear...
Langan RC, Gotsch PB, Krafczyk MA, Skillinge DD.Ulcerative colitis is a chronic disease with recurrent symptoms and significant morbidity. The precise etiology is still unknown. As many as 25 percent of patients with ulcerative colitis have extraintestinal manifestations. The diagnosis is made endoscopically. Tests such as perinuclear antineutrophilic cytoplasmic antibodies and anti-Saccharomyces cerevisiae antibodies are promising, but not yet recommended for routine use. Treatment is based on the extent and severity of the disease. Rectal therapy with 5-aminosalicylic acid compounds is used for proctitis. More extensive disease requires t...
Hu J, Brooks M, Fuller AL, Armstrong P, McDougald LR.Cultured Histomonas meleagridis cells were readily agglutinated in vitro by horse serum at concentrations as low as 5%, although clumping was more rapid and prominent at 15% or higher. For observation of clumping, the cultured organisms were washed twice in Hanks balanced solution (HBSS) by centrifugation (1,000 x g for 15 min) and filtered through glass wool. The test sera were added and the mixture incubated in a Petri plate or 24-well culture plates at r.t. for 15-30 min. Formation of clumps was time- and concentration-dependent. Gentle agitation hindered agglutination at low serum concentr...
de Oliveira Lima AN, da Silva Santos S, Herrera HM, Gama C, Cupolillo E, Jansen AM, Fernandes O.The protozoan Trypanosoma evansi is described as presenting high morphological and genetic similarities among the isolates despite its biological heterogeneity and wide geographical distribution. PCR amplification of the internal transcribed spacers of the ribosomal gene in combination with the coding region of the 5.8S ribosomal subunit further submitted to restriction enzymes digestion were carried out in DNAs extracted from 41 T. evansi strains isolated from horses, dogs, coatis and capybaras from two distinct regions of the Brazilian Pantanal. We also used one T. evansi isolate from Africa...
Elsheikha HM, Mansfield LS.Sarcocystis neurona is an important protozoal pathogen because it causes the serious neurological disease equine protozoal myeloencephalitis (EPM). The capacity of this organism to cause a wide spectrum of neurological signs in horses and the broad geographic distribution of observed cases in the Americas drive the need for sensitive, reliable and rapid typing methods to characterize strains. Various molecular methods have been developed and used to diagnose EPM due to S. neurona, to identify S. neurona isolates and to determine the heterogeneity and evolutionary relatedness within this specie...
Bruhn O, Regenhard P, Michalek M, Paul S, Gelhaus C, Jung S, Thaller G, Podschun R, Leippe M, Grötzinger J, Kalm E.Defensins are a predominant class of antimicrobial peptides, which act as endogenous antibiotics. Defensins are classified into three distinct sub-families: theta-, beta-, and alpha-defensins. Synthesis of alpha-defensin has been confirmed only in primates and glires to date and is presumably unique for a few tissues, including neutrophils and Paneth cells of the small intestine. Antimicrobial activities of these peptides were shown against a wide variety of microbes including bacteria, fungi, viruses and protozoan parasites. In the present study, we report the characterization of the equine a...
Gillingwater K, Büscher P, Brun R.The animal pathogenic protozoan, Trypanosoma evansi, leads to a wasting disease in equines, cattle and camels, commonly known as Surra. It is extensively distributed geographically with a wide range of mammalian hosts and causes great economical loss. Trypanosoma equiperdum causes a venereal disease called Dourine in horses and donkeys. Chemotherapy appears to be the most effective form of control for T. evansi, whereas infections caused by T. equiperdum are considered incurable. Due to emerging drug resistance, efficient control of T. evansi is severely threatened, emphasising the urgent need...
Kinde H, Read DH, Daft BM, Manzer M, Nordhausen RW, Kelly DJ, Fuerst PA, Booton G, Visvesvara GS.This article describes amebic infections in 4 horses: granulomatous amebic encephalitis caused by Balamuthia mandrillaris and Acanthamoeba culbertsoni and systemic infections caused by Acanthamoeba sp. The former infection occurred in 1 of 4 horses spontaneously without any underlying conditions; the latter amebic infection was perhaps "opportunistic" considering the visceral involvement by this protozoan in association with Aspergillus sp. and/or Escherichia coli and Pseudomonas sp. The clinicopathologic findings and demonstration of the amebic organisms using immunohistochemical techniques, ...
Kornilova OA.Endobiotic ciliates of native Yakut horse are investigated. 57 ciliate species have been found. From 17 up to 43 species of ciliates have been revealed in each host specimen. The specimens of Alloiozona trizona Hsiung, 1930 and Triadinium caudatum Fiorentini, 1890 were present in 100 % of the horses. The endemic genus and species of allantosomides, Strelkowella urunbasiensis Kornilova, 2004, has been found in 11 horses. Allantoxena japonensis (Imai, 1979) and Cycloposthium ishikawai Gassovsky, 1919 being recorded previously in Japan only were found for the first time in Russia. The species Cyc...
Rüegg SR, Torgerson PR, Doherr MG, Deplazes P, Böse R, Robert N, Walzer C.Piroplasmosis has been identified as a possible cause of mortality in reintroduced Przewalski's horses (Equus ferus przewalskii) in the Dsungarian Gobi (Mongolia). A cross-sectional and a longitudinal study were conducted in a representative sample (n = 141) of the resident domestic horse population and in 23 Przewalski's horses to assess the prevalence of Theileria equi and Babesia caballi. Piroplasms were detected in blood by light microscopy in 6.7% (95% confidence interval [CI]: 3.6-12.2%) of the domestic horse samples. Antibody prevalence was 88.6% (95% CI: 82.4-92.9%) for T. equi and 75....
Villalobos EM, Ueno TE, de Souza SL, Cunha EM, do Carmo Custódio de Souza Hunold Lara M, Gennari SM, Soares RM.A study of the association between the presence of serum antibodies against Neospora spp. and fetal loss was performed using serum samples of horses submitted to the laboratory for the detection of antibodies to Equine Herpesvirus-1 and Equine Infectious Anemia Virus. The sera submitted for equine infectious anemia testing were from horses declared healthy and those submitted for the detection of antibodies to Equine Herpesvirus-1 were from mares with late clinical signs of reproductive disorders or males living in close contact with diseased mares. For the detection of Neospora spp. infection...
Romaniuk K, Reszka K, Lasota E.On the turn of July and August the prevalence and intensity of internal parasites of cattle, deer, and primitive Polish horses were estimated. It was determined, that all groups of animals were infected with parasites. The prevalence and intensity of infection were diversified and depended on the animal species, breed, age, and even sex. For instance, dairy cows of lowland black-and-white breed were six times stronger infected than Polish red breed, despite using the same pasture and the same cowshed. Nematodes and coccidia were present in calves using small, frequently wet, calf-runs and at h...
Samper JC, Tibary A.Bacterial, viral and protozoal infections may cause severe reproductive losses. The present paper reviews the risk factors, clinical signs and preventive measures for the most important venereal or potential sexually transmitted diseases in horses. The stallion and use of semen for artificial insemination represent major risk factors for the transmission of bacterial contaminants of the penis, including Streptococcus equi subspecies zooepidemicus, Pseudomonas aeruginosa and Klebsiella pneumoniae, known to cause endometritis and infertility in the mare. The role of the stallion in disease trans...
Okubo K, Wilawan P, Bork S, Okamura M, Yokoyama N, Igarashi I.Ethylene glycol bis (beta-aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) is a chelating agent capable of binding to positively-charged metal ions, including a calcium-ion (Ca2+). Here, we demonstrated the inhibitory effect of the chemical on the in vitro asexual growth of the equine protozoan parasites, Babesia caballi and Babesia equi. The growth of both B. caballi and B. equi was significantly inhibited in the presence of EGTA (IC50=1.27 and 2.25 mM, respectively). Under microscopical observation, increased percentages of extracellular merozoites in the total parasites were detected in bot...
Dirikolu L, Karpiesiuk W, Lehner AF, Hughes C, Woods WE, Harkins JD, Boyles J, Atkinson A, Granstrom DE, Tobin T.Diclazuril is a triazine-based antiprotozoal agent which may have clinical application in the treatment of equine protozoal myeloencephalomyelitis (EPM). In this study, the use of the sodium salt diclazuril to increase the apparent bioavailability of diclazuril for the treatment and prophylaxis of EPM and various other Apicomplexan mediated diseases is described. In this study, diclazuril sodium salt was synthesized and administered to horses as diclazuril sodium salt formulations. The absorption, distribution, and clearance of diclazuril sodium salt in the horse are described. Diclazuril was ...
Murphy JE, Marsh AE, Reed SM, Meadows C, Bolten K, Saville WJ.Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease of horses caused primarily by the protozoal parasite Sarcocystis neurona. Currently available antemortem diagnostic testing has low specificity. The hypothesis of this study was that serum and cerebrospinal fluid (CSF) of horses experimentally challenged with S neurona would have an increased S neurona-specific IgM (Sn-IgM) concentration after infection, as determined by an IgM capture enzyme linked immunoassay (ELISA). The ELISA was based on the S neurona low molecular weight protein SNUCD-1 antigen and the monoclonal an...
Lindsay DS, Mitchell SM, Yang J, Dubey JP, Gogal RM, Witonsky SG.Horses are considered accidental hosts for Sarcocystis neurona and they often develop severe neurological disease when infected with this parasite. Schizont stages develop in the central nervous system (CNS) and cause the neurological lesions associated with equine protozoal myeloencephalitis. The present study was done to examine the ability of S. neurona merozoites to penetrate and develop in equine peripheral blood leukocytes. These infected host cells might serve as a possible transport mechanism into the CNS. S. neurona merozoites penetrated equine leukocytes within 5 min of co-culture. I...
Locatelli-Dittrich R, Dittrich JR, Richartz RR, Gasino Joineau ME, Antunes J, Pinckney RD, Deconto I, Hoffmann DC, Thomaz-Soccol V.Antibodies to Neospora sp. and Toxoplasma gondii were measured in mares and precolostral foals from a farm in Parana State, Brazil. An indirect fluorescent antibody test (IFAT) was used to determine specific antibodies. Three sampling points, 2003, 2004 and at parturition were included in the study, but not all horses are represented at a parturition time point. In 2003, antibodies to Neospora were detected in 17 mares (47%) at 1:50 dilution and in 5 mares (13.8%) at 1:100 dilution. In 2004, antibodies to Neospora were found in 11/36 (30%) horses with titers of 1:50 and in 6 mares (16.6%) at 1...
Elsheikha HM, Lacher DW, Mansfield LS.Phylogenetic analyses based on sequences of the nuclear-encoded small subunit rRNA (ssurRNA) gene were performed to examine the origin, phylogeny, and biogeographic relationships of Sarcocystis neurona isolates from opossums and horses from the State of Michigan, USA, in relation to other cyst-forming coccidia. A total of 31 taxa representing all recognized subfamilies and genera of Sarcocystidae were included in the analyses with clonal isolates of two opossum and two horse S. neurona. Phylogenies obtained by the four tree-building methods were consistent with the classical taxonomy based on ...
Ueti MW, Palmer GH, Kappmeyer LS, Statdfield M, Scoles GA, Knowles DP.The protozoan parasite Babesia equi replicates within erythrocytes. During the acute phase of infection, B. equi can reach high levels of parasitemia, resulting in a hemolytic crisis. Horses that recover from the acute phase of the disease remain chronically infected. Subsequent transmission is dependent upon the ability of vector ticks to acquire B. equi and, following development and replication, establishment of B. equi in the salivary glands. Although restriction of the movement of chronically infected horses with B. equi is based on the presumption that ticks can acquire and transmit the ...
Hoane JS, Yeargan MR, Stamper S, Saville WJ, Morrow JK, Lindsay DS, Howe DK.Neospora hughesi is a recently identified cause of equine protozoal myeloencephalitis. However, the significance of this parasite is poorly understood. An enzyme-linked immunosorbent assay (ELISA) with a recombinant form of the N. hughesi 29-kDa surface antigen (rNhSAG1) was developed for serodiagnosis of equine N. hughesi infections. Parallel ELISA analysis showed that animals immunized or infected with N. hughesi exhibited greater antibody reactivity with rNhSAG1 than with the Neospora caninum homolog, rNcSAG1. The rNhSAG1 ELISA showed 94.4% sensitivity and 95.0% specificity when compared wi...
Mullaney T, Murphy AJ, Kiupel M, Bell JA, Rossano MG, Mansfield LS.Opossums (Didelphis spp.) are the definitive host for the protozoan parasite Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis (EPM). Opossums shed sporocysts in feces that can be ingested by true intermediate hosts (cats, raccoons, skunks, armadillos and sea otters). Horses acquire the parasite by ingestion of feed or water contaminated by opossum feces. However, horses have been classified as aberrant intermediate hosts because the terminal asexual sarcocyst stage that is required for transmission to the definitive host has not been found in their tissues despite...
Traub R, Wade S, Read C, Thompson A, Mohammed H.Giardia isolates from eight horses from New York State (NY), USA and two horses from Western Australia (WA) were genetically characterized at the SSU-rDNA and triose-phosphate isomerase (TPI) genes. Phylogenetic analysis of the TPI gene provided strong support for the placement of both isolates of Giardia from horses in WA and a single isolate from a horse in NY within the assemblage AI genotype of G. duodenalis. Another two isolates from horses in NY placed within the assemblage AII genotype of G. duodenalis. Phylogenetic analysis of the TPI gene also provided strong bootstrap support for the...
Drogemuller M, Schnieder T, von Samson-Himmelstjerna G.P-glycoproteins (Pgps) are adenosine triphosphate-binding transporter proteins thought to be associated with multi-drug resistance in mammals and protozoans and have been suggested to be involved in the mechanism of ivermectin (IVM) resistance in Haemonchus contortus. Until now, resistance to IVM has not been reported in cyathostomins in horses in spite of its widespread and frequent use. Reasons for this might be differences in the molecular mechanism of the development of resistance. Based on this hypothesis, the present study was carried out to find homologues of Pgp in cyathostomins. A 416...
Elata A, Mossaad E, Satti R, Matar N, Ohari Y, Xuan X, Inoue N, Suganuma K.In Sudan, donkeys are important animals, providing transportation and income possibilities. However, the prevalence of parasites in donkeys in Sudan has not been thoroughly characterized. Accordingly, in this study, we aimed to detect selected hemoprotozoan parasites in donkeys in West Omdurman, Khartoum State, Sudan, wherein people depend mainly on donkeys for their daily life. In total, 198 blood samples collected from donkeys in a local market in West Omdurman, were screened using serological and molecular diagnostic techniques. Serologically, 52 (26.3%), 56 (28.3%), and 19 (9.6%) samples w...
Yeargan M, de Assis Rocha I, Morrow J, Graves A, Reed SM, Howe DK.Enzyme-linked immunosorbent assays (ELISAs) based on the SnSAG surface antigens of Sarcocystis neurona provide reliable detection of infection by the parasite. Moreover, accurate serodiagnosis of equine protozoal myeloencephalitis (EPM) is achieved with the SnSAG ELISAs by measuring antibodies in serum and cerebrospinal fluid (CSF) to reveal active infection in the central nervous system. Two independent ELISAs based on recombinant (r)SnSAG2 or a chimeric fusion of SnSAG3 and SnSAG4 (rSnSAG4/3) are currently used together for EPM serodiagnosis to overcome varied antibody responses in different...
Portella LP, Cadore GC, Sangioni LA, Pellegrini LF, Fighera R, Ramos F, Vogel FS.Sarcocystis spp., Neospora spp., and Toxoplasma gondii are Apicomplexa protozoa that can infect horses. This study aimed to investigate the occurrence of antibodies against Sarcocystis spp., Neospora spp., and T. gondii in horses slaughtered in southern Brazil. The presence of histological lesions, tissue cysts, and Sarcocystis spp. DNA in the hearts of these horses was also investigated. A total of 197 paired serum and heart samples were evaluated by serology and direct microscopic examination; 50 of these samples were subjected to histopathological and PCR analyses. Antibodies against at lea...
Dame JB, MacKay RJ, Yowell CA, Cutler TJ, Marsh A, Greiner EC.Equine protozoal myeloencephalitis (EPM) is a neurologic disease of horses caused by Sarcocystis neurona. The horse is a dead-end host for S. neurona and the definitive and intermediate hosts have not previously been identified. We hypothesized that S. neurona is actually Sarcocystis falcatula, a parasite that cycles in nature between Virginia opossums (Didelphis virginiana) and any of a variety of avian intermediate hosts. We extracted DNA from S. falcatula sarcocysts in the muscle of a brown-headed cowbird (Molothrus ater) and from schizonts in a fixed specimen of lung from a Moluccan cockat...
Romaniuk K, Reszka K, Lasota E.On the turn of July and August the prevalence and intensity of internal parasites of cattle, deer, and primitive Polish horses were estimated. It was determined, that all groups of animals were infected with parasites. The prevalence and intensity of infection were diversified and depended on the animal species, breed, age, and even sex. For instance, dairy cows of lowland black-and-white breed were six times stronger infected than Polish red breed, despite using the same pasture and the same cowshed. Nematodes and coccidia were present in calves using small, frequently wet, calf-runs and at h...
Cutler TJ, MacKay RJ, Ginn PE, Greiner EC, Porter R, Yowell CA, Dame JB.Equine protozoal myeloencephalitis (EPM) is a debilitating neurologic disease of the horse. The causative agent. Sarcocystis neurona, has been suggested to be synonymous with Sarcocystis falcatula, implying a role for birds as intermediate hosts. To test this hypothesis, opossums (Didelphis virginiana) were fed muscles containing S. falcatula sarcocysts from naturally infected brown-headed cowbirds (Molothrus ater). Ten horses were tested extensively to ensure no previous exposure to S. neurona and were quarantined for 14 days, and then 5 of the horses were each administered 10(6) S. falcatula...
The Journal of protozoologyAugust 1, 1980
Volume 27, Issue 3 288-292 doi: 10.1111/j.1550-7408.1980.tb04259.x
Simpson CF, Mayhew IG.Equine protozoal myeloencephalitis (EPM) was diagnosed in 10 horses. By electron microscopy, schizonts were found in intact host cells of the spinal cords or, more frequently, free in the extracellular spaces. Developmental stages of schizonts differed morphologically, and the late stage of schizogony was characterized by endopolygeny. These findings permitted tentative identification of the protozoon as a Sarcocystis sp. Free merozoites were present in the extracellular spaces or in cells of the spinal cord. Pericytes of capillaries were most frequently parasitized by merozoites were present ...
Elghandour MMMY, Adegbeye MJ, Barbabosa-Pilego A, Perez NR, Hernández SR, Zaragoza-Bastida A, Salem AZM.Greenhouses gas emission mitigation is a very important aspect of earth sustainability with greenhouse gasses reduction, a focus of agricultural and petrochemical industries. Methane is produced in nonruminant herbivores such as horses because they undergo hindgut fermentation. Although equine produce less methane than ruminant, increasing population of horses might increase their contribution to the present 1.2 to 1.7 Tg, estimate. Diet, feeding frequency, season, genome, and protozoa population influence methane production equine. In population, Methanomicrobiales, Methanosarcinales, Methan...
Pitel PH, Lindsay DS, Caure S, Romand S, Pronost S, Gargala G, Mitchell SM, Hary C, Thulliez P, Fortier G, Ballet JJ.Sarcocystis neurona is considered a leading cause of equine protozoal myeloencephalitis (EPM), a common infectious neurological disease in horses in the Americas. EPM-like cases associated with S. neurona peptide reactive antibodies in Western blots were recently described in Normandy, France. In this report, antibodies reacting with S. neurona merozoites were detected using an agglutination assay at titers ranging from 50 to 500 in sera from 18/50 healthy horses from two farms with a previous EPM-like case. Higher values were found in older animals. Four out of six horses which traveled or st...
Cano-Terriza D, Franco JJ, Jose-Cunilleras E, Buono F, Almería S, Veneziano V, Alguacil E, García J, Villena I, Dubey JP, Jiménez-Martín D....Toxoplasmosis, caused by the obligate intracellular protozoan Toxoplasma gondii, is a worldwide parasitic zoonosis. A cross-sectional study was carried out to determine the exposure to T. gondii in equids in Europe. Serum samples from 1399 equids (1085 horses, 238 donkeys, and 76 mules/hinnies) bred in four European countries (Italy, Spain, United Kingdom [UK], and Ireland) were collected during the period of 2013-2021. The overall seroprevalence of T. gondii was 18.9% (95% Confidence Interval [CI]: 16.9-21.0) by using the modified agglutination test (MAT) at a cut-off of 1:25. Seropositivity ...
Zhang XX, Ren WX, Hou G, Liu Q, Yu TQ, Zhao Q, Ni HB.Toxoplasmosis is caused by the protozoon Toxoplasma gondii that can infect almost all warm-blooded hosts including horses and humans. Horse meat is one of the most important meat products for human consumption. However, data on seroprevalence of T. gondii in horses intended for human consumption in Northern China is scarce. Thus, a total of 614 serum samples were collected from Jilin Province and Inner Mongolia Autonomous Region (IMAR) between 2015 and 2017, and were detected the seroprevalence for T. gondii by indirect hemagglutination assay test. In the prevalence study, the overall seroprev...
Lindsay DS, Mitchell SM, Yang J, Dubey JP, Gogal RM, Witonsky SG.Horses are considered accidental hosts for Sarcocystis neurona and they often develop severe neurological disease when infected with this parasite. Schizont stages develop in the central nervous system (CNS) and cause the neurological lesions associated with equine protozoal myeloencephalitis. The present study was done to examine the ability of S. neurona merozoites to penetrate and develop in equine peripheral blood leukocytes. These infected host cells might serve as a possible transport mechanism into the CNS. S. neurona merozoites penetrated equine leukocytes within 5 min of co-culture. I...
Moreira CJC, De Cicco NNT, Galdino TS, Feder D, Gonzalez MS, Miguel RB, Coura JR, Castro HC, Azambuja P, Atella GC, Ratcliffe NA, Mello CB.Chagas disease, infecting ca. 8 million people in Central and South America, is mediated by the protozoan parasite, Trypanosoma cruzi. The parasite is transmitted by the bite of blood sucking triatomine insects, such as Rhodnius prolixus, that had previously fed on parasite-infected vertebrate blood and voided their contaminated feces and urine into the wound. The stages of the parasite life cycle in both the insect vector and human host are well-known, but determinants of infection in the insect gut are complex and enigmatic. This paper examines the possible role of the R. prolixus gut agglut...
Pavlásek I, Hess L, Stehlík I, Stika V.The first occurrence of Giardia spp. in horses in the Czech Republic is reported. During preventive examination of 360 five-month up to 14-year horses from various parts of the region of Central Bohemia carried out from January 1993 to June 1994 in the parasitological laboratory of the State Veterinary Institute in Prague, the Giardia cysts were detected in the excrements of 18 (5%) horses, mostly 2-4 years of age, and in two foals 3 and 6 weeks old. During the period between March 1993 and June 1994, systematic and repeated observation was aimed at a group of 38 racing horses two up to four y...
de Oliveira Lima AN, da Silva Santos S, Herrera HM, Gama C, Cupolillo E, Jansen AM, Fernandes O.The protozoan Trypanosoma evansi is described as presenting high morphological and genetic similarities among the isolates despite its biological heterogeneity and wide geographical distribution. PCR amplification of the internal transcribed spacers of the ribosomal gene in combination with the coding region of the 5.8S ribosomal subunit further submitted to restriction enzymes digestion were carried out in DNAs extracted from 41 T. evansi strains isolated from horses, dogs, coatis and capybaras from two distinct regions of the Brazilian Pantanal. We also used one T. evansi isolate from Africa...
Cheadle MA, Dame JB, Greiner EC.The Virginia opossum (Didelphis virginiana) is a definitive host for multiple Sarcocystis species including Sarcocystis neurona, one of the causative agents of equine protozoal myeloencephalitis (EPM), a severe, neuromuscular disease of horses. Size and morphologic characteristics of isolates of Sarcocystis shed by the opossum were examined to determine if differences were useful in discriminating between the isolates and/or species. Collections of sporocysts from 17 opossums were molecularly characterized and measured using an ocular micrometer. The mean sporocyst size of isolates of S. neuro...
Okubo K, Wilawan P, Bork S, Okamura M, Yokoyama N, Igarashi I.Ethylene glycol bis (beta-aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) is a chelating agent capable of binding to positively-charged metal ions, including a calcium-ion (Ca2+). Here, we demonstrated the inhibitory effect of the chemical on the in vitro asexual growth of the equine protozoan parasites, Babesia caballi and Babesia equi. The growth of both B. caballi and B. equi was significantly inhibited in the presence of EGTA (IC50=1.27 and 2.25 mM, respectively). Under microscopical observation, increased percentages of extracellular merozoites in the total parasites were detected in bot...
Kirkpatrick CE, Saik JE.Ciliated protozoa of several morphological types were found in the colonic tissue of 8 horses, mostly immature Standardbreds. Most of the protozoa observed appeared similar to those normally found as commensals in the equine large intestinal lumen. In all cases, organisms were located in the lamina propria; organisms were also found in the submucosa of 2 horses. The association of colonic disease with the presence of intramural ciliates was unclear.
Darien BJ, Belknap J, Nietfeld J.Two horses with cerebrospinal nematodiasis (Micronema deletrix) had signs similar to those of other neurologic diseases resulting from parasitic (fly larvae, protozoa, or other helminths) migration through the central nervous system (CNS). In one horse (horse 1), a 13-year-old Paso Fino stallion, the cerebrospinal fluid (CSF) was slightly xanthochromic (1+), with a pleocytosis (25 nucleated cells/microliter) and a normal protein level (69 mg/dl). A CSF differential cell count showed 15% neutrophils, 56% lymphocytes, 22% macrophages, 5% eosinophils, and 2% basophils. In the other horse (horse 2...
Pradella GD, Duarte CA, Escobar TA, Zuravski L, Góss GC, Skupien JA, Lübeck I.The Leishmaniases are on the top of the global list of tropical neglected diseases. The number of infected dogs in South America is estimated in millions and correlated to disease cases in humans, especially in Brazil. Equines may get infected too and can play a role in the epidemiological chain. Thus, the aim of the present study was to evaluate risk and protective factors of leishmaniasis in rural areas of the western border region of Rio Grande do Sul state, Brazil by Leishmania spp. protozoa molecular detection and serological evaluation (ELISA) in equine and canine blood samples. This wor...
Anderson JA, Alves DA, Cerqueira-Cézar CK, da Silva AF, Murata FHA, Norris JK, Howe DK, Dubey JP.Neosporosis is a common cause of abortion in cattle worldwide but is rare in horses. Here, the first case of histologically, ultrastructurally, immunohistochemically, and molecularly confirmed equine abortion caused by neosporosis is reported. Samples of lung, heart, liver, skeletal muscle, tongue, brain, and the placenta from a female fetus aborted at 280 days of gestation were fixed in formalin and submitted for diagnosis. Histologically, there was disseminated neosporosis with severe lesions in lungs, liver and the heart. Protozoal tachyzoites in all tissues reacted with polyclonal anti-Neo...
Dubey JP, Porterfield ML.Multifocal areas of necrosis and infiltrations of mononuclear cells were seen in lung specimens of an equine fetus aborted 2 months before term. Extracellular and intracellular protozoa were seen in the alveolar tissue. Individual organisms were 4 microns by 2.5 microns, and cyst-like structures were 25 microns by 18 microns. Organisms did not stain with periodic acid-Schiff or by use of the immunoperoxidase and peroxidase-antiperoxidase method for Toxoplasma gondii. Twelve days after abortion, the mare had serum antibody titer of less than 1:10 against T gondii.
McQueary CA, Worley DE, Catlin JE.Of 22 foals from 4 localities in southwestern Montana, 59% were found to be infected with Eimeria leuckarti. Oocysts collected from feces of 4 positive horses were sporulated and subsequently administered to a 5- to 6-month-old foal. The prepatent period was 31 days and the patent period was between 5 and 10 days.
Golombieski L, Bassi das Neves G, Casa MDS, Costa GCS, Miletti LC, Saito ME, Fonteque JH.Campeiro horse is a breed locally adapted to the Santa Catarina plateau region and its main characteristic is the gait, it is known as "Marchador das Araucárias." It is a breed considered in danger of extinction, being fundamental the search for the preservation of this important genetic resource. Surra, caused by the protozoan Trypanosoma evansi, is among the diseases that affect horses. However, there are no data on the prevalence of infection in Campeiro horses. This study aimed to determine the prevalence of T. evansi in Campeiro horses, correlate hematology and serum biochemistry, and id...
Kruttlin EA, Rossano MG, Murphy AJ, Vrable RA, Kaneene JB, Schott HC, Mansfield LS.Sarcocystis neurona is the etiologic agent of equine protozoal myeloencephalitis, a neurologic disease of horses. The present study was designed to test the hypothesis that pyrantel tartrate can kill S. neurona merozoites growing in equine dermal cell culture. Sarcocystis neurona merozoites were exposed to a range of concentrations of pyrantel tartrate or sodium tartrate ranging from 0.001 to 0.01 M. Merozoites were then placed onto equine dermal cell cultures and incubated for 2 weeks to check for viability. At 1 and 2 weeks after inoculation, plaque counts were compared between treatments an...
Marzok M, Al-Jabr OA, Salem M, Alkashif K, Sayed-Ahmed M, Wakid MH, Kandeel M, Selim A. is classified as intracellular protozoa and is one of the major zoonotic parasites. Most warm-blooded intermediate hosts, including humans, are commonly infected by this parasite. The epidemiology of infection in Egyptian horses is currently poorly understood. Methods: 420 blood samples were randomly collected from horses raised in four governorates in Northern Egypt (110 each from Giza and Kafr El Sheikh, and 100 each from Qalyubia and Gharbia) to investigate the existence of antibodies against using a commercial ELISA kit, and to ascertain the risk factors for the infection. Results: the ...
Springer A, Ehrmann C, Lembcke M, Roscher K, Strube C.Equine piroplasmosis, caused by the protozoan pathogens or , is endemic in many (sub-)tropical regions worldwide, including Southern Europe. In Germany, it mainly plays a role as an imported parasitosis. Nevetherless, tick species with known vector potential for equine piroplasms occur in Germany. Thus, a long-term establishment of autochthonous cycles after introduction via infected equids or ticks cannot be excluded. In the present case, 2 horses developed clinical infection after returning from a trail riding trip to southern France. During treatment, a feeding tick was discovered on one ...
Onzere CK, Fry LM, Bishop RP, Da Silva M, Madsen-Bouterse SA, Bastos RG, Knowles DP, Suarez CE.Theileria equi is an obligate intracellular protozoan parasite that causes severe hemolytic anaemia in most equid species. Similar to other apicomplexan parasites, T. equi contains rhoptries whose contents have been implicated in host cell invasion and formation of the parasitophorous vacuole that is crucial for survival of the species within cells. Despite their importance, the composition of T. equi rhoptries and their role(s) in host cell invasion remain unexplored. To gain insight into these issues, we evaluated the expression, immunogenicity, and functional roles of two T. equi rhoptry-as...
Lindsay DS, Dubey JP.Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in the Americas. The apicomplexan protozoan most commonly associated with EPM is Sarcocystis neurona. A direct agglutination test (SAT) was developed to detect antibodies to S. neurona in experimentally infected animals. Merozoites of the SN6 strain of S. neurona collected from cell culture were used as antigen and 2-mercaptoethanol was added to the antigen suspension to destroy IgM antibodies when mixed with test sera. Mice fed sporocysts of S. speeri or S. falcatula-like sporocysts from opossums did not sero...
Mayhew IG, Greiner EC.The clinical and pathologic findings of and therapy for such protozoal diseases as equine protozoal myeloencephalitis, toxoplasmosis, sarcocystosis, pneumocytosis, cryptosporidiosis, giardiasis, besnoitiosis, and klossiellosis are discussed. Emphasis is placed on disorders that occur with greater frequency in North America and on emerging protozoal diseases affecting horses.
