Equine viral infections in Argentina: a ten-year overview based on laboratory results

Introduction

Viral infections are a threat to the equine industry(1,2). In this work, we summarized the information on viral diseases of horses in Argentina in 2013-2023.

Materials and Methods

Samples of 687 abortions, 172 neurological cases, 76 outbreaks of respiratory disease and 95 cases of diarrhea in foals; and 1874 nasopharyngeal swabs (NS) from horses in the pre-export quarantine; plus 547 semen from the pre-import quarantine, were submitted for virological studies. Serum for Equine Arteritis Virus (EAV; n: 44853) and West Nile Virus (WNV; n: 9867) serology were submitted from pre-import/export quarantine and surveillance programs. Virological diagnosis was performed by virus isolation and PCR, while seroneutralization and ELISA were used for EAV and WNV serology, respectively. Tests were conducted following the recommendations of the World Organization for Animal Health(3).

Results

Equid herpesvirus 1 was detected in 5% (33/687) of the abortions and in 2% (4/172) of the neurological cases. Rabies virus (antigenic variant 3) and Equine Infectious Anemia were the etiology of two other neurological cases. For respiratory disease, Equid herpesvirus 4 was registered in 17% (13/76) of the cases, and Influenza virus (EIV), only in 2018, in relation to the outbreak in Argentina. Abortions and NS from respiratory cases resulted negative for EAV. Rotavirus A was detected in 38% (36/95) of the diarrhea cases. All NS from pre-export horses resulted negative to EIV. EAV was only detected in one semen straw (0.2%) from the pre-import quarantine. As for serology, 2% (782/44853) of the samples resulted positive for EAV, being these horses either related with the 2010 EAV outbreak in Argentina, or vaccinated, or imported as vaccinated. No new EAV positive horses were detected after August 2010. No samples tested positive for WNV.

Conclusions

This data emphasize the importance of etiological diagnosis to implement control measures and the benefits of surveillance programs.

References

1. Timoney P. Infectious diseases and international movement of horses. In: Sellon D, Long M, editors. Equine Infectious Diseases. 2nd ed. St. Louis, MO, USA: Saunders Elsevier; 2014. p. 544–50.
2. Sellon D, Long MT. Viral Diseases. In: Sellon D, Long MT, editors. Equine Infectious Diseases. Second. 2017. p. 132–256.
3. World Organization for Animal Health. WOAH Listed Diseases and Other Diseases of Importance. In: Manual of diagnostic tests and vaccines for terrestrial animals [Internet]. 2023. Available from: https://www.woah.org/es/que-hacemos/normas/codigos-ymanuales/acceso-en-linea-al-manual-terrestre/