Even though California has not recorded a human case of West Nile Virus so far this year, state health officials are warning that the presence of the disease is increasing and that it is just a waiting game on when it will reach the human population.
The California Department of Public Health is reporting increased activity of the virus across the state and is investigating numerous suspect cases in humans. The CDPH reported that a Los Angeles County resident has symptoms consistent with West Nile Virus disease. Initial tests on that patient indicate a probable West Nile virus diagnosis, which requires further testing for confirmation.
"Californians should take every possible precaution to avoid mosquito bites," said CDPH Director and State Public Health Officer Dr. Karen Smith. "Simple steps, like applying repellent, wearing long-sleeved shirts and pants in the early morning and evening, and draining standing water near your home can help to prevent bites from infected mosquitoes."
To date in 2016, West Nile Virus has been detected in mosquitoes and birds in 30 California counties.
Approximately 600 dead birds and 896 mosquitoes sampled in California this year have been found to harbor the virus. At the beginning of July the CDPH was reporting West Nile virus activity in 23 counties, with 433 mosquito samples and 372 dead birds testing positive for the virus.
In Stanislaus County there have been 48 mosquito samples and four dead birds testing positive for the virus. Two of the four dead birds were located in Turlock. One was found in a neighborhood bordered by North Avenue, E. Tuolumne Road, N. Denair Avenue and N. Olive Avenue. The second dead bird was found in a neighborhood near E. Monte Vista Avenue and Amerthyst Way.
The other two dead birds were found in Ceres and Patterson.
Most often, West Nile Virus is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread West Nile Virus to humans and other animals when they bite, according to the Centers for Disease Control.
Approximately one in five people who are infected with West Nile Virus will develop symptoms such as fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. Less than one percent will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues). About 10 percent of people who develop neurologic infection due to West Nile Virus will die, according to the CDC. People over 50 years of age and those with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and organ transplants, are at greater risk for serious illness.
There are no medications to treat or vaccines to prevent West Nile Virus infection. People with milder illnesses typically recover on their own, although symptoms may last for several weeks or months. In the neuroinvasive forms, patients can suffer severe and sometimes long-term symptoms.
A 2015 CDC report indicates that for every one diagnosed case of West Nile Virus another 150 people have the disease and are either undiagnosed or misdiagnosed.
In the United States, most people are infected from June through September, and the number of these infections usually peaks in mid-August, according to the Centers for Disease Control. Seasonal outbreaks often occur in local areas that can vary from year to year. In Stanislaus County West Nile Virus typically starts to appear in April or May and will continue to have a presence through October. The weather can also be a significant factor in West Nile Virus outbreaks. The CDC reported higher number of cases during periods of abnormally high temperatures.
Mosquitoes like to breed in stagnant water, preferring weedy areas that provide cover. The lagoons at dairy farms make for perfect breeding grounds, but so do flooded fields, uncared for swimming pools, urban catch basins, overwatered lawns, and pretty much anything that holds water and allows it to stagnate. The area's mosquito abatement districts have been conducting aerial photography to locate potential mosquito breeding sites and rely on residents to report neglected swimming pools and ornamental ponds.
The California Department of Public Health recommends that individuals prevent exposure to mosquito bites and West Nile virus by practicing the "Three Ds:"
DEET - Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.
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.
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.
Reporting and testing of dead birds is an important step in preventing West Nile Virus. A confirmed case of the virus in dead birds or mosquito samples helps to identify areas that need treatment to reduce mosquito activity. To report a dead bird, call the California State hotline at 1-877-WNV-BIRD or report it online at www.westnile.ca.gov. Birds of particular interest are crows, ravens, magpies, jays and raptors (hawk or eagle).
To report mosquito-breeding problem areas, Stanislaus County residents should contact one of the two mosquito abatement districts that serve the county. For Stanislaus County addresses north of the Tuolumne River, residents should call the Eastside Mosquito Abatement District at 522-4098 (www.eastsidemosquito.com) and all others should contact the Turlock Mosquito Abatement District at 634-1234 (turlockmosquito.org).