Peer-reviewed veterinary case report
Chagas disease in a Texan horse with neurologic deficits.
- Journal:
- Veterinary parasitology
- Year:
- 2016
- Authors:
- Bryan, Laura K et al.
- Affiliation:
- Department of Pathobiology · United States
- Species:
- horse
Plain-English summary
A 10-year-old Quarter Horse gelding was brought to the Texas A&M University Veterinary Teaching Hospital because he had been unsteady and limping in his back legs for six months. Initially, the horse was treated for a condition called equine protozoal myeloencephalitis (EPM), but his health continued to decline, and he was eventually euthanized. During the examination, doctors found some reddening in a small area of his spinal cord and discovered signs of a parasite called Trypanosoma cruzi, which causes Chagas disease in humans and dogs. Although this horse showed signs of Chagas disease in his spinal cord, there was no evidence of the parasite in his heart, which is different from what has been seen in dogs and humans. This case highlights the importance of considering Chagas disease as a possible diagnosis in horses with neurological symptoms, especially in regions where the disease is known to occur. Unfortunately, despite the investigation, the horse's treatment did not succeed, leading to his euthanasia.
Abstract
A 10-year-old Quarter Horse gelding presented to the Texas A&M University Veterinary Teaching Hospital with a six month-history of ataxia and lameness in the hind limbs. The horse was treated presumptively for equine protozoal myeloencephalitis (EPM) based on clinical signs but was ultimately euthanized after its condition worsened. Gross lesions were limited to a small area of reddening in the gray matter of the thoracic spinal cord. Histologically, trypanosome amastigotes morphologically similar to Trypanosoma cruzi, the agent of Chagas disease in humans and dogs, were sporadically detected within segments of the thoracic spinal cord surrounded by mild lymphoplasmacytic inflammation. Ancillary testing for Sarcocystis neurona, Neospora spp., Toxoplasma gondii and Leishmania spp. was negative. Conventional and real time polymerase chain reaction (PCR) of affected paraffin embedded spinal cord were positive for T. cruzi, and sequencing of the amplified T. cruzi satellite DNA PCR fragment from the horse was homologous with various clones of T. cruzi in GenBank. While canine Chagas disease cases have been widely reported in southern Texas, this is the first report of clinical T. cruzi infection in an equid with demonstrable amastigotes in the spinal cord. In contrast to previous instances of Chagas disease in the central nervous system (CNS) of dogs and humans, no inflammation or T. cruzi amastigotes were detected in the heart of the horse. Based on clinical signs, there is a potential for misdiagnosis of Chagas disease with other infectious diseases that affect the equine CNS. T. cruzi should be considered as a differential diagnosis in horses with neurologic clinical signs and histologic evidence of meningomyelitis that originate in areas where Chagas disease is present. The prevalence of T. cruzi in horses and the role of equids in the parasite life cycle require further study.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/26801589/