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Meningoencephalitis and systemic infection by Acanthamoeba sp. in cattle in Brazil

Larissa L Souza1, Bruno S Rezende1, Rayane C Pupin1

  • 1Anatomic Pathology and Molecular Biology Laboratories, Faculty of Veterinary Medicine and Animal Science, Federal University of Mato Grosso do Sul, Campo Grande, MS, Brazil.

Journal of Veterinary Diagnostic Investigation : Official Publication of the American Association of Veterinary Laboratory Diagnosticians, Inc
|July 15, 2026
PubMed

Insights

Acanthamoeba species caused fatal meningoencephalitis and multisystemic disease in Brazilian cattle. This study details four cases, marking the first report of such infections in cattle.

Area of Science:

  • Veterinary Pathology
  • Parasitology
  • Neurology

Background:

  • Free-living amebas like Acanthamoeba, Balamuthia mandrillaris, and Naegleria fowleri are known pathogens in humans and animals.
  • Acanthamoeba infections can cause severe neurological and systemic disease.

Purpose of the Study:

  • To report and characterize two cases of meningoencephalitis and an outbreak of multisystemic disease caused by Acanthamoeba sp. in cattle from Central-Western Brazil.
  • To document the clinical, gross, and histopathological findings of these novel Acanthamoeba infections in cattle.

Main Methods:

  • Clinical case descriptions and necropsy findings.
  • Histopathological examination of central nervous system (CNS) and other affected organs.
  • Immunohistochemistry and PCR with sequencing for Acanthamoeba spp. identification.

Main Results:

  • Four cattle (two adults, two calves) presented with acute neurological signs and died or were euthanized.
  • Gross pathology revealed malacia and cavitation in the brain and spinal cord, with nodules in kidneys and lungs in some cases.
  • Histopathology confirmed multifocal necrosis, granulomatous inflammation, and amebic trophozoites/cysts in the CNS and other organs, with Acanthamoeba spp. confirmed by IHC and PCR.

Conclusions:

  • Acanthamoeba sp. caused severe meningoencephalitis and multisystemic disease in cattle.
  • These findings represent the first documented cases of Acanthamoeba-associated encephalitis and systemic disease in cattle.
  • Highlights the potential of Acanthamoeba as a pathogen in bovine health.
Keywords:
AcanthamoebaBrazilbraincattleencephalitissystemic infection

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