Fact or fiction: Zika virus in animals

Mosquito_blog4There has been growing concern about Zika virus after several news reports have focused on the virus causing children in South America to be born with microcephaly, a condition in which a baby’s head is significantly smaller than expected, often due to abnormal brain development. Scientists have yet to confirm the link to microcephaly and have continued to stress that the disease caused by the Zika virus is generally less of an issue than other mosquito-borne viruses.

However, with all the media coverage surrounding Zika, the agriculture and pet industries have been receiving questions about whether or not animals can contract the virus. As with almost all things in biology, there is no simple answer.

Zika virus was first identified in 1947 in the Zika forest of Uganda in a monkey showing mild fever, so the short answer, therefore, is yes. The real question, however, if whether our domestic species can get AND spread Zika virus. Currently, there is only limited evidence that animals (including horses, cows, goats and ducks) can become infected with Zika. Such a study was conducted and showed that these types of animals had been exposed to Zika virus, but did not show that the animals became sick or transmitted the disease.

Currently, the only known method of transmission is through Aedes species mosquitoes. Aedes mosquitos are seen primarily in the south and eastern U.S. and bites from infected mosquitoes result in transmission from human to human. As a result of this information, mosquito control companies have seen a huge increase in interest in Aedes mosquito areas and it’s clear that mosquitoes control measures are undoubtedly one step in control of the virus. These types of measures alone, however, haven’t wiped out other mosquito-borne viruses such as Dengue fever or chikungunya.

The only animals known to develop infection remain apes and primates. Import of these animals is strictly regulated and the quarantine period they are restricted to exceeds the amount of time an animal may be able to transmit Zika to a mosquito. Most of these species already in the U.S. are under professional supervision with regular health screening, so it is unlikely that a non-human primate epidemic of Zika could ever develop.

According to the CDC, as of March 9, there were 193 identified human cases of Zika in the U.S. meaning it is not currently in a transmissible population in the nation. In fact, all of the cases were associated with travel to known Zika areas.  Puerto Rico, the U.S. Virgin Islands and American Samoa, for example, have all seen mosquito-borne infection with Zika. However, with the mosquito population and environmental temperatures in the gulf states, it is likely that at some point in the future we will see vector-borne transmission of Zika in that region.

Based on the current information, pets and farm animals within the U.S. are not believed to be at risk for developing illness from Zika virus. They are not known to exist as reservoir species or be involved in the transmission of the virus at all.  Research and time will tell if Zika is as serious a concern as the media would have us believe, but for the time being there are many other more troublesome mosquito-borne diseases to worry about.

Joe Lyman


This blog was written by Neogen’s professional services veterinarian, Dr. Joe Lyman (pictured left).

For more information on Neogen’s animal safety division, click here. 

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