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West Nile Virus in horses and human in New Mexico

Season's first cases of West Nile Virus (WNV)  have been reported in New Mexico. Two horse and one human case has been confirmed.

New Mexico public health officials are warning of elevated concerns over a West Nile Virus (WNV) outbreak as the first cases of equine illness related to the disease have been reported, one case each in Bernalillo and San Juan Counties. Both horses had to be euthanized.

Health officials says in addition to animal WNV, one human case has been confirmed; a 45-year-old woman in San Juan County woman became ill with last week and is currently being treated and expected to recover. The identity of the woman is being withheld.

These incidents are cause for concern and officials are advising residents of the state to be aware of the dangers that WNV poses to the public and to horse owners.

One of the horses resided at a property in Albuquerque’s South Valley area and reportedly exhibited signs of the WNV infection early last week. Officials say the animal had not been vaccinated against the disease. The case comes two months into New Mexico’s monsoon season, which has given rise to larger populations of mosquitoes.

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Traditionally, August and September are the optimum months for the spread of West Nile Virus. Both horses and humans are likely targets for the virus.

National Weather Service officials say July brought the heaviest rains on record to parts of New Mexico, including Bernalillo and surrounding counties. Officials say because of the heavy rains they are warning area residents and horse owners that the days and weeks ahead could be especially problematic for proliferation of the virus.

"We encourage all Bernalillo County residents, including those in unincorporated parts of the county, to report mosquito problems by calling 311," said Dr. Paul Smith, a manager for the City of Albuquerque Environmental Health Department.


Dangerous disease

Last year New Mexico had over two dozen reported cases of WNV from which at least two people eventually died of complications associated with the infection.

"Annual vaccination of horses for West Nile virus, conscientious mosquito control, application of mosquito repellant to body and clothing, and minimizing horse exposure during peak mosquito feeding periods will all decrease the risk of infection" says New Mexico State Veterinarian Dr. Ellen Mary Wilson, whose office is located with the New Mexico Livestock Board.

West Nile is a type of virus known as a flavivirus. Researchers believe West Nile virus is spread when a mosquito bites an infected bird and then bites a person or animal, such as a horse, capable of contracting it. Though it was first identified in 1937 in Uganda in eastern Africa, it was first discovered in the United States in the summer of 1999 in New York. Since then, the virus has spread throughout the United States and has become an annual issue for birds, horses, and humans in 47 states from coast to coast.

Mosquito management is key

Officials say that one of the key ways to minimize risk of infection with WNV for both human and equine is to eliminate as many water-holding containers as possible since mosquitoes lay their eggs there. This includes places where water can accumulate from rainfall—old tires and unprotected rain collection barrels—and also regularly changing out water in birdbaths, wading pools, pets’ water bowls, and drinking troughs. Officials advise ensuring all water collection containers such as barrels are tightly screened. In addition, it is advisable to wear long, loose fitting clothing and use repellants.

The Centers for Disease Control and Prevention (CDC) recommends using only insect repellants containing DEET, Picaridin, oil of lemon eucalyptus, or IR3535 for use on skin, and permethrin for use on clothing.

Fortunately, most human cases of WNV are not very serious for healthy individuals, but the very young and old and those with problems associated with compromised immune systems are at high risk.


"People infected may have some fever and body aches and they just won't feel well once infected with the virus," says Dr. Cedric Spak, an infectious disease specialist at Baylor Dallas Hospital. "Someone with the more simple form of the virus, or West Nile Fever, may miss a few days of work or school but should recover quickly.”

He says many people contract WNV and do not realize they have had it. Spak says some are conditions which put certain people in a higher risk of developing a far more serious form of WNV known as neuroinvasive West Nile Virus, which can invade the central nervous system and may prove fatal. Symptoms for the neuroinvasive virus can include headaches and other flu-like symptoms.

Spak says a fever higher than 102 degrees and a sense of confusion or disorientation are key signs of the more serious strain of the virus and victims should seek immediate medical attention if they suspect they have been infected.

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