A herd-level analysis of risk factors for antibodies to Sarcocystis neurona in Michigan equids

Rossano, M.G.; Kaneene, John B.; Marteniuk, J. V.; Banks, Buck; Schott, Harold C.; Mansfield, Linda S.

doi:10.1016/s0167-5877(02)00192-7

Cited by 13 publications

(5 citation statements)

References 15 publications

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“…Although several studies have investigated factors related to seroconversion or seroprevalence to agents causing EPM, 17–21,23,24 only 1 other published study has evaluated risk factors for the occurrence of clinical disease 25 and only 1 study has reported factors related to recovery and survival after presentation to a referral hospital 42 . Establishing an antemortem diagnosis for EPM has been a difficult and contentious aspect of this disease since the time of its discovery, which may be 1 reason that the epidemiology of naturally occurring disease has not been studied more.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, the consistency in findings of these 2 studies provides evidence that risk factors identified in this study truly may be causally related to the risk of EPM occurrence. Studies of factors related to seroprevalence and seroconversion in horses also have identified regional differences that may be related to the suitability of habitat for opossums or important intermediate hosts for S. neurona , or to the survivability of this agent in the environment 17–21,23,24 . Although other host factors such as age, breed, sex, or use have not been consistently associated with serologic evidence of exposure in all studies, the major biological difference between exposure or infection and subsequent occurrence of a disease such as EPM with a low incidence and seemingly long incubation period should be considered.…”

Section: Discussionmentioning

confidence: 99%

“…Although several studies have investigated factors related to seroconversion or seroprevalence, 17–21,23,24 only 1 other published study has evaluated risk factors for the occurrence of clinical disease 25 . However, the population used in this previous study consisted of hospitalized horses at 1 referral facility, which limits the ability to make valid extrapolations to other populations, especially nonhospitalized horses.…”

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confidence: 99%

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Risk Factors for Owner‐Reported Occurrence of Equine Protozoal Myeloencephalitis in the US Equine Population

Morley¹,

Traub‐Dargatz²,

Benedict³

et al. 2008

Veterinary Internal Medicne

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Background: Equine protozoal myeloencephalitis (EPM) is a serious and often fatal neurologic disease of horses, but few studies have investigated risk factors.Objectives: To evaluate operation-and individual-level factors associated with likelihood of the occurrence of EPM. Animals: Data were collected as part of a study of the US equine industry from 1,178 operations representing 83.9% of horses and 51.6% of operations with 3 horses in 28 states.Methods: Probability-based sampling was used to enroll representative operations in a cross-sectional study. Interviews were conducted to collect information regarding health and management of horses. A nested case-control study was used to investigate risk factors among individual horses. Interview data were combined with climate data, human population density, and opossum regional ecology categories. Data were analyzed using logistic regression to identify risk factors for the occurrence of EPM.Results: Owners reported that 95% of EPM cases included in this study were diagnosed by veterinarians. Variables associated with EPM occurrence on premises included opossum regional ecology, reported exposure to small wildlife, climate, terrain, housing, choice of bedding material, method of storing feeds, equine stocking density, and primary use of horses. Among individual horses, age was most strongly associated with disease risk. Associations also were identified with sex, breed, primary use, and participation in competitions.Conclusions and Clinical Importance: Because the risk of EPM occurrence on operations is closely tied to factors that impact exposure to opossums, their feces, and their environment, controlling these exposures may be important in preventing the occurrence of EPM.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Risk Factors for Owner‐Reported Occurrence of Equine Protozoal Myeloencephalitis in the US Equine Population

Morley¹,

Traub‐Dargatz²,

Benedict³

et al. 2008

Veterinary Internal Medicne

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“…Opossums have also been involved in the transmission of parasites of concern to farm animals. This is the case of D. virginiana , the definitive host of Sarcocystis neurona , a protozoan parasite known to cause severe and fatal neurologic disease in horses (Rossano et al 2003 ). The above-mentioned examples are among the few studies investigating the importance of opossums in the epidemiology of parasitic diseases to domestic animals.…”

Section: Opossums As a Source Of Parasitic Infections To Domestic Animalsmentioning

confidence: 99%

Didelphis spp. opossums and their parasites in the Americas: A One Health perspective

et al. 2021

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Medium sized opossums (Didelphis spp.) are among the most fascinating mammals of the Americas, playing important ecological roles (e.g., dispersal of seeds and control of insect populations) in the environment they inhabit. Nevertheless, as synanthropic animals, they are well adapted to human dwellings, occupying shelters within the cities, peripheral areas, and rural settings. These marsupials can harbor numerous pathogens, which may affect people, pets, and livestock. Among those, some protozoa (e.g., Leishmania infantum, Trypanosoma cruzi, Toxoplasma gondii), helminths (e.g., Ancylostoma caninum, Trichinella spiralis, Alaria marcianae, Paragonimus spp.) and arthropods (e.g., ticks, fleas) present substantial public health and veterinary importance, due to their capacity to cause disease in humans, domestic animals, and wildlife. Here, we reviewed the role played by opossums on the spreading of zoonotic parasites, vectors, and vector-borne pathogens, highlighting the risks of pathogens transmission due to the direct and indirect interaction of humans and domestic animals with Didelphis spp. in the Americas.

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“…EPM is a neurological disease that imposes a serious burden on the horse industry in the United States, for which there is no effective vaccine. Seroprevalence rates of S. neurona among horses can reach very high levels, such as 60% in Michigan (Rossano et al 2003) and 89.2% in Oklahoma (Bentz et al 2003). Even though a large percentage of horses are exposed to this parasite, the actual incidence of EPM in horses is very low $1% (MacKay et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Sarcocystis neurona major surface antigen gene 1 (SAG1) shows evidence of having evolved under positive selection pressure

Elsheikha

Mansfield

2004

Parasitol Res

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The major surface antigen gene 1 (SAG1) is conserved among members of Sarcocystidae and may play an important role in parasite pathogenesis. Additionally, generation and selection of different antigenic variants of SAG1 has the potential for inclusion in a subunit vaccine or in the development of a diagnostic assay. In this study, patterns of nucleotide polymorphism were used to test the hypothesis that natural selection promotes diversity in different parts of SAG1 of Sarcocystis neurona. Nucleotide and amino acid sequence analysis of SAG1 from multiple S. neurona isolates identified two alleles. Sequences were identical intra-allele and highly divergent inter-alleles. Also, phylogenetic reconstruction showed sequences clustering into two clades. Tajima's and Fu and Li's neutrality tests indicated that selection is more likely to be acting on SAG1. Moreover, a sliding window analysis based on the ratio of silent substitutions to amino acid replacements provided strong evidence that two short segments in the central and 3' domain of SAG1 have been under positive selection in the divergence of the two alleles, suggesting that it may be important for the evasion of host immune responses and would be a suitable target for vaccine development.

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A herd-level analysis of risk factors for antibodies to Sarcocystis neurona in Michigan equids

Cited by 13 publications

References 15 publications

Risk Factors for Owner‐Reported Occurrence of Equine Protozoal Myeloencephalitis in the US Equine Population

Risk Factors for Owner‐Reported Occurrence of Equine Protozoal Myeloencephalitis in the US Equine Population

Didelphis spp. opossums and their parasites in the Americas: A One Health perspective

Sarcocystis neurona major surface antigen gene 1 (SAG1) shows evidence of having evolved under positive selection pressure

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