EEE Virus Outbreak: After Wolves Die From Eastern Equine Enchephalitis at a Zoo, Vets Urge Owners to Protect Their Pets

There has been a spike in both human and animal cases of Eastern equine encephalitis virus recently, which has killed three people in Connecticut and caused the death of two Mexican gray wolf pups at Binder Park Zoo, Michigan. This has sparked concern that the disease could spread to family pets and vets are now urging owners to take precautions.

Eastern equine encephalitis virus, otherwise known as EEEV, is native to the eastern part of the United States which is spread by infected mosquitoes. First identified in 1938, the virus can cause brain inflammation which can be fatal in up to 30 percent of human cases and 90 percent of cases in horses, according to Jessica Romine, a veterinarian at BluePearl Specialty and Emergency Pet Hospital in Southfield, Michigan.

"There has been an uptick in both human and animal cases recently, with 5-8 human cases per year reported from 2013-2018, but so far in 2019 there have been 19 human cases, 12 in Massachusetts, 3 in Rhode Island, and 4 in Connecticut this year," Romine told Newsweek. "There have been 33 animal cases this year in Michigan alone, and 9 in Massachusetts, the majority being horses."

Many animals can become infected with EEEV but in most cases they will not exhibit symptoms. The ones which are most at risk of getting sick are, in general, species that are not native to the eastern United States, such as horses, camelids, and non-native birds.

"This year cases have been confirmed in horses, goats, deer, and wolves, with multiple other species having been infected in previous years including emus, opossums, and llamas, as well as domestic dogs," Romine said.

At the moment, EEEV remains extremely rare in dogs and cats, however, the death of the two wolf pups in Michigan has raised concerns for canine exposure. At present a vaccine is available for horses, but not for humans, cats, dogs and other species. Animals which spend most of their time outdoors are at higher risk of contracting EEEV, as are puppies.

What steps can you take to minimize the risk of the disease to your pets?

"The disease can only be transmitted through the bite of an infected mosquito, so affected animals are not directly infectious to people or other animals," Romine said. "Therefore, the most important step is to limit exposure to mosquitoes as much as possible."

The vet recommends taking the following precautions to limit your pet's exposure to mosquitoes:

  • Keep dogs inside during the time of high mosquito activity from dusk to dawn.
  • Remove standing water, for instance rid flower pots of water accumulation and remove any containers in which water can collect.
  • Remove piles of decomposing leaves, lawn clippings, and manure.
  • Check screens and repair any holes.
  • Avoid turning on lights outdoors during the evening and overnight; mosquitoes are attracted to light.
  • Apply mosquito repellents approved for animal use. Read the product label before using and follow all instructions carefully, particularly, when it comes to cats.

It is important to note that human mosquito repellents are generally not approved for use on dogs or cats. DEET—the most effective repellent for humans—is actually toxic to these animals when ingested. Furthermore, some ingredients which are safe for humans and dogs, can be toxic to cats.

"The most commonly encountered toxins are pyrethroids such as permethrin or pyrethrin, used in many human and dog mosquito repellants and which should never be used in cats," Romine said.

"They can cause severe neurologic problems such as tremors, seizures, and hyperthermia. There are several natural products available, but it is always best to check with your veterinarian before use, as many natural mosquito repellents contain essential oils that can be toxic. Cats are much more sensitive to even dilute essential oils than humans or dogs," she said.

What are the signs of EEEV in animals?

The incubation period of the virus—or in other words, the time between exposure and the development of symptoms—is about 3-7 days in horses and 4-10 days in humans. The incubation period for canines is also similar.

Once symptoms of the disease appear, they can progress very rapidly with neurological affects appearing within just one or two days. Below are some of the characteristic symptoms of EEV in animals:

  • Fever;
  • Loss of appetite;
  • Weakness;
  • Uncoordinated movement;
  • Head pressing;
  • Circling;
  • Convulsions/Seizures;
  • Irritability; and
  • Blindness.

If you notice any of these signs in your pets, contact your local veterinarian immediately.

With winter approaching, cooler temperatures will reduce the risk of contracting diseases spread by mosquitoes. However, Romine urges pet owners to "remain vigilant" because the insects can still survive indoors and in other protected areas.

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Stock photo: Vets are urging pet owners to take precautions against EEEV. iStock