West Nile Virus Cases in Sacramento County

West Nile Virus (WNV) is transmitted to humans and animals by the bite of an infected mosquito.

To date in 2013, West Nile Virus has been detected in 31 California counties.  Two recent cases were treated by Hunter Stallion Station Equine Veterinary Clinic that sadly required the horses to be euthanized.  Both had unknown vaccination history.

For the latest national data, view this USGS map on the U.S. Department of Interior website.

On August 16, 2013, the California Department of Food and Agriculture (CDFA) Animal Health Branch confirmed two additional cases of West Nile Virus; a one year old unvaccinated Andalusian colt in Sacramento County and a four year old Morgan mare of unknown vaccination status in Placer County. Both horses are recovering.

For 2013, a total of eight (8) horses have been confirmed positive for WNV. The positive horses were located in Kern, Placer, Riverside, Sacramento(3) and Stanislaus(2) Counties. Four of the eight positive horses were euthanized.

Please make sure your horses have been vaccinated to ensure maximum protection against the West Nile Virus, and take precautions to protect you and your family as well.

The risk of serious illness to most people is low. However, some individuals – less than 1 percent – can develop a serious neurologic illness such as encephalitis or meningitis. People 50 years of age and older have a higher chance of getting sick and are more likely to develop complications. Recent data also indicate that those with diabetes and/or hypertension are at greatest risk for serious illness.  In late July of 2013, an elderly resident in Glenn County was the first confirmed human case of West Nile virus infection. The person was hospitalized, but is now recovering.

The California Department of Public Health recommends that individuals prevent exposure to mosquito bites and West Nile virus by practicing the “Three Ds”:

1. DEET – Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. The CDPA states that DEET can be used safely on infants and children 2 months of age and older.

2. DAWN AND DUSK – Mosquitoes bite in the early morning and evening so it is important to wear proper clothing and repellent if outside during these times. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

3. DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.

Early diagnosis and treatment will enhance your horse’s chance of survival.  Look for the following signs and report them to your veterinarian immediately:

  • Flulike symptoms
  • Depression
  • Fine and coarse muscle and skin twitching
  • Hypersensitivity to touch and sound
  • Changes in attitude and awareness
  • Drowsiness
  • Abnormal gait, driving or pushing forward, often without control
  • Asymmetrical weakness or ataxia

The equine mortality rate can be as high as 30-40%, however, studies have shown that the WNV vaccine has a substantial effect on preventing disease. The American Association of Equine Practitioners (AAEP) recommends vaccinating all foals and horses against WNV.

Take steps to reduce horses’ exposure to mosquitoes:

  • Reduce mosquito breeding grounds by eliminating sources of stagnant or standing water, such as buckets, abandoned pools, and water troughs
  • Add a few drops of mineral oil to water troughs to create a film on top of the water that can keep the mosquito larvae out
  • Stall horses during peak mosquito periods (i.e., dawn and dusk)
  • Use equine-approved mosquito repellants and/or protective horse gear such as fly sheets, masks, and leg wraps
  • Mosquitoes cannot fly into strong wind, so place fans inside the barns or stalls
  • Turn off incandescent bulbs inside stables at night and place incandescent bulbs far away from the stables to attract the mosquitoes.

Contact your veterinarian today to make certain your horse’s WNV vaccine is current.  Taking these precautions will help protect your horse and you!