Horse in Verona tests positive for EEE: All about mosquito-borne viruses in New York

A horse in the Town of Verona has tested positive for Eastern equine encephalitis, a virus carried by mosquitoes that can also infect people.

The Oneida County Health Department announced the county’s first EEE equine case on Thursday.

It follows an announcement from Madison County Public Health that it found out on Monday that a horse in the Town of Sullivan had died of EEE.

“Do what you can to avoid exposure to mosquitoes,” Oneida County Public Health Director Daniel Gilmore said in a statement. “There is no human vaccine for EEE so taking measures to reduce mosquitoes around your home and reduce the chances of being bit by mosquitoes is important.”

Horses, though, can get vaccinated.

Although human cases of EEE are uncommon, it can cause life-threatening complications, including inflammation of the brain. Symptoms include a sudden, high fever, muscle aches and a headache that increases in severity.

EEE in the state

As of August 3, the state had only seen one case of EEE in a horse —in St. Lawrence County — and no human cases of the virus, which can cause encephalitis, or inflammation of the brain, according to a weekly mosquito surveillance report the New York State Department of Health posted on August 13 with the latest statewide data.

And EEE had only been detected in three mosquito pools —groups of up to 50 mosquitoes collected and tested together — across the state as of August 3, two in Onondaga County and one in Oswego County.

The state health department also tracks cases of EEE in goats and emus, but no cases have been reported in the state so far this year.

Mosquito surveillance

Not all counties in the state conduct mosquito surveillance. But it is conducted in Oneida, Madison, Onondaga and Oswego counties. And Madison County officials said the county would step up its surveillance program, given the recent horse death, by adding another mosquito trap in the Town of Sullivan.

Surveillance is also conducted in three western New York counties (Chautauqua, Cattaraugus and Erie), in the three southernmost Hudson Valley counties, in all five counties in New York City and on Long Island.

West Nile virus

EEE is not the most common mosquito-borne virus found in New York. West Nile Virus is found much more often, although the vast majority of infected mosquito pools are found downstate.

Rockland County put out a release on July 31 warning residents that it had seen a big jump in infected mosquitoes with half of the pools tested over the previous two weeks coming back positive for West Nile.

And New York City issued a health advisory on July 17 noting that West Nile had turned up in 325 mosquito pools since the first on June 5, the earliest the virus has ever been found in the city. West Nile activity usually peaks in August and September.

So far this year, West Nile virus has been found in 157 mosquito pools outside New York City, including two in Onondaga and three in Oswego counties, and 703 in the city, according to the state health department.

There have not been any cases, though, in people or in horses. However, there have also been three presumptive viremic donors in the state this year, meaning blood donations — presumably from infected donors without symptoms — tested positive for West Nile.

Not everyone infected with West Nile Virus gets sick, but people age 50 and older and people with compromised immune systems run a higher risk of developing serious illness, health officials said.

Other mosquito-borne illnesses

The state also tracks four more mosquito-borne infections: chikungunya virus, dengue virus, Zika virus and malaria. There have been no cases of chikungunya or Zika this year.

There have been 56 human cases of dengue fever —including one in Onondaga County — and 29 cases of malaria — including three in Oneida County and two in Onondaga County — so far this year.

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But none of the cases of dengue or malaria were contracted from New York State mosquitoes, the health department has determined. They were all related to travel to areas with infected mosquitoes.

That is despite the fact that the invasive Aedes albopictus mosquito, or Asian tiger mosquito, which is known to transmit chikungunya, dengue and dirofilariasis (an infection of parasitic roundworms) is already established in 10 downstate counties (with Orange being the northernmost), according to the state health department.

But the Aedes aegypti, or yellow fever, mosquito, known to transmit not just yellow fever, but also Zika, dengue and chikungunya, has not been found in New York, the health department said.

Staying safe

Health officials urged the same precautions no matter which mosquito-borne diseases might be present in an area:

• Try not to go outside around dawn and dusk when mosquitoes are most active.

• Use insect repellant outdoors and wear long pants, long sleeves, shoes and socks.

• Dump any standing water in your yard and change water in bird baths at least twice a week.

• Repair or replace any broken screens in your home.

• Use larvicides in small areas in your backyard where water tends to pool. In Oneida County, the health department offers them at the environmental health office on the fourth floor of the Adirondack Bank Building, at 185 Genesee Street in Utica.

• If you have horses, talk to your veterinarian about EEE and West Nile vaccines. Also, change the water in horse troughs and buckets frequently.

This article originally appeared on Observer-Dispatch: Horse in Verona tests positive for EEE: All about mosquito-borne viruses in New York