Equine Herpesvirus 2 (EHV-2) outbreak in foals and mares.

EHV-2 is not usually associated with respiratory disease and abortion in horses but here a severe outbreak is reported from Brazil. EHV-2 has worldwide distribution. Of particular note is that some of the foals had neurological signs.
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Potential outbreak by herpesvirus in equines: detection, clinical, and genetic analysis of equid gammaherpesvirus 2 (EHV-2)
Braz J Microbiol. 2023 Jan 27.

Authors
Angélica Cristine de Almeida Campos # 1 2 , Sofia Cicolo # 3 , Cairo Monteiro de Oliveira 4 , Camila Vieira Molina 4 5 , Pedro Enrique Navas-Suárez 6 7 , Thais Poltronieri Dos Santos 8 , Vanessa Barbosa da Silveira 4 , Carla Meneguin Barbosa 4 , Raquel Yvonne Arantes Baccarin 8 , Edison Luiz Durigon # 4 , Luiz Gustavo Bentim Góes 4 5 , Carla Bargi Belli # 9 , Danielle Bruna Leal Oliveira 4 10
Affiliations

1 Department of Microbiology, Instituto de Ciências Biomédicas II da Universidade de São Paulo (ICB-II/USP), SP, 05508-000, São Paulo, Brazil. camposac@alumni.usp.br.
2 Clinical and Molecular Virology Research Team, Scientific Platform Pasteur-USP (SPPU), SP, 05508-020, São Paulo, Brazil. camposac@alumni.usp.br.
3 Department of Surgery, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo-USP, SP, 05508-270, São Paulo, Brazil.
4 Department of Microbiology, Instituto de Ciências Biomédicas II da Universidade de São Paulo (ICB-II/USP), SP, 05508-000, São Paulo, Brazil.
5 Clinical and Molecular Virology Research Team, Scientific Platform Pasteur-USP (SPPU), SP, 05508-020, São Paulo, Brazil.
6 Wildlife Comparative Pathology Laboratory-LAPCOM, Faculdade de Medicina Veterinária e Zootecnia da, Universidade de São Paulo-USP, SP, 05508-270, São Paulo, Brazil.
7 Wildlife Disease Association-WDA, Associate member, 66044-7065, Lawrence-KS, United States.
8 Department of Internal Medicine, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo-USP, SP, 05508-270, São Paulo, Brazil.
9 Department of Internal Medicine, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo-USP, SP, 05508-270, São Paulo, Brazil. cbbelli@usp.br.
10 Hospital Israelita Albert Einstein, HIAE, 05652-900, São Paulo, Brazil.

Abstract

Background: Equid herpesvirus (EHV) commonly affects horses causing neurologic and respiratory symptoms beside spontaneous abortions, meaning huge economic losses for equine industry worldwide. In foals, the virus can facilitate secondary infections by Rhodococcus equi, important in morbidity and mortality in equines. A total of five genotypes of EHV were previously described in Brazil including EHV-1, EHV-2, EHV-3, EHV-4, and EHV-5. EHV-2 genotype had only been previously described in Brazil in asymptomatic animals. We report the investigation of the dead of 11 foals in Middle-west region of Brazil showing respiratory and neurological symptoms, as well as several abortions in mares from the same farm.

Methods: Clinical and laboratory exams were performed in this case study. Lung, whole blood, serum, and plasma samples were analyzed by necroscopic and histopathologic techniques followed by molecular assays (conventional and qPCR and Sanger sequencing).

Results and conclusion: Laboratory exams revealed neutrophilia leukocytosis. Necroscopic and histopathologic findings were suppurative bronchopneumonia and ulcerative enteritis. Molecular assays point to the absence of the bacteria Rhodococcus equi and other viruses (including other EHV). The presence of EHV-2 DNA was confirmed by sequencing in serum sample from one foal. This is the first confirmed outbreak of EHV-2 causing disease in Brazilian horses with confirmed presence of the virus, and which highlight the important role of EHV-2 in equine respiratory disease and spontaneous abortions in equid in Brazil.

Keywords: Abortion; EHV-2; Foal; Herpesvirus; Horse; Neurological signs; Pneumonia.