Wildlife & Biodiversity

COVID-19: Infection in Dutch mink farms point to ‘reverse zoonosis’

The COVID-19 outbreak has reached 12 out of 130 Dutch mink farms, according to Science 

By Rajeshwari Sinha
Published: Friday 19 June 2020

The novel coronavirus SARS-CoV-2 has begun infecting minks farms in the Netherlands, according to an article published in Science. Minks are small semi-aquatic mammals raised for their fur. 

According to the article, COVID-19 outbreak has reportedly reached 12 out of 130 Dutch mink farms.

The article suggested that the infection was a result of virus spillover from humans. It is a zoonosis in reverse — called ‘reverse zoonosis’.

Zoonosis is an infectious disease caused by a pathogen that has jumped from an animal to a human. When the pathogen is transmitted from human to animals, it is known as reverse zoonosis. The animal infected through the process may in turn re-transmit the infection to humans under some circumstances.

When the first infection of two mink farms was reported in April 2020, COVID-19-like symptoms were found in individuals working on both the farms. The symptoms for the virus were detected in minks a little later.

Researchers said the most possible explanation to the infection in mink farms is the introduction of the virus by humans and its subsequent transmission amongst other minks.

It also mentioned that since animals in mink farms remain caged separately, it was unlikely that the transmission of the virus between minks happened through direct contact. It could largely have been transmitted through indirect routes such as through feed or bedding material, infectious droplets or by contaminated dust from the bedding.

These are the initial evidences coming out of Netherlands that could be linked to reverse zoonosis during the pandemic. The infection of pet animals with SARS-COV-2 earlier suggested that human to animal transmission of the virus can occur.

While this has provided an opportunity for scientists to understand reverse zoonosis with respect to SARS-CoV-2 and how the virus jumps between species and spreads through large animal populations, the Dutch government is also concerned that the infected mink could become another viral reservoir causing new outbreaks in humans.

In order to prevent further infection spread, the minks are being culled as per government orders. Based on risk assessment studies carried out by the National Institute for Public Health and the Environment (RIVM) in Netherlands, there is, however, negligible risk of the virus being transmitted from mink to human outside mink sheds.

Literature has shown that the phenomenon of reverse zoonosis can also happen in case of other pathogens such as resistant bacteria. This cannot only add to the greater spread of bacterial infections in animals, but also involve an increased use of antibiotics to treat or prevent such infections, eventually contributing to another slow pandemic of antimicrobial resistance.

The need for appropriate farm hygiene and biosecurity measures, therefore, becomes important.

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