Better biosecurity coordination could reduce equine flu outbreaks in South America – review

The influenza virus viewed under an electron microscope.
The influenza virus viewed under an electron microscope. Image: Centers for Disease Control and Prevention

Harmonizing quarantine and biosecurity protocols among countries in South America would likely reduce the spread of equine influenza in the region, scientists in Argentina believe.

Cecilia Olguin-Perglione and María Edith Barrandeguy, in a review published in the journal Viruses, provided an overview of equine influenza across the continent.

They said the equine flu virus has been responsible for many episodes of respiratory disease in horses in South American countries, such as Chile, Brazil, Uruguay, Argentina, Colombia and Ecuador, where the equine industry plays a critical role in generating jobs and income.

The disease is considered endemic in many countries in the region, while in others there are no cases reported.

“The fact that some South American countries have never communicated the occurrence of equine influenza could be due to the absence of the disease itself or the lack of surveillance and specialized diagnostic laboratories,” they said.

In the region, the major outbreaks have occurred within similar time periods in different countries, with analysis work indicating close genetic links.

“It is highly likely,” they said, “that the continuous movement of horses, some of them subclinically infected, among South American countries, facilitated the spread of the virus.”

They said although vaccination is mandatory in almost all of South America for mobile horses, and in areas with dense equine populations, equine flu outbreaks continuously threaten the equine industry.

“Vaccination plays a major role in controlling EI infection and disease, and particularly for horses that travel frequently, intermingle with other horses and participate in shows, sport and competition events.”

Olguin-Perglione, with the National Institute of Agricultural Technology, and Barrandeguy, with Salvador University, noted that, in the last 10 years, two main outbreaks, one in 2012 and the other in 2018, occurred in Chile, Brazil, Colombia, Ecuador, Argentina and Uruguay. They affected both vaccinated and unvaccinated horses.

“Given the importance of international transport of horses in the spread of equine influenza virus, and considering the significant economic impact that equine influenza has on the equine industry, health authorities should promote incorporating a mandatory vaccination program for highly mobile horses, and at the same time, encourage horse vaccine producer companies to incorporate updated strains of equine influenza virus.” This, they said, should be in line with recommendations of the World Organisation for Animal Health’s Expert Surveillance Panel on Equine Influenza.

Vaccine breakdown seen in some cases could be related to the fact that many of the commercial vaccines available in the region contain out-of-date strains, they said, and some even lack reliable information about immunogenicity and efficacy.

“This review highlights the importance of disease surveillance and reinforces the need to harmonize quarantine and biosecurity protocols, and encourage vaccine manufacturer companies to carry out quality control procedures and update the EIV strains in their products.”

Olguin-Perglione, C.; Barrandeguy, M.E. An Overview of Equine Influenza in South America. Viruses 2021, 13, 888.

The study, published under a Creative Commons License, can be read here

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