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Health officials warn of mosquito-borne illnesses in California
killer mosquito
The California Department of Public Health is warning state residents about invasive mosquitoes that have the potential to spread viruses like yellow fever. - photo by Photo Contributed

If the threat of West Nile Virus wasn’t enough to scare people into dousing themselves with mosquito repellant, then state health officials have three new terrors to get the job done: dengue fever, chikungunya and yellow fever.

The California Department of Public Health is warning people that two more California counties have found invasive species of mosquitoes that can transmit infectious diseases.

“It is important to know these species of mosquitoes because they are not what we’re used to in California, and they can transmit diseases such as dengue fever, chikungunya and yellow fever,” said CDPH Director and Public Health officer Dr. Karen Smith. “While the risk is still low in California, infected travelers coming back to California can transmit these viruses to mosquitoes that bite them. This can lead to additional people becoming infected if they are then bitten by those mosquitoes.”

In September, the yellow fever mosquito was detected for the first time in San Bernardino and Riverside Counties.  Since 2013, when this species was first discovered in Madera, Fresno and San Mateo counties, it has been found in Tulare, Kern, Los Angeles, San Diego, Imperial, Orange and Alameda counties. Also in September, the Asian tiger mosquito was detected in Kern and San Diego counties and has expanded in regions of Los Angeles County.

The Turlock Mosquito Abatement District has been aware of the invasive mosquitoes presence in nearby counties and have been working proactively to keep it out of this area, said General Manager David Heft. In particular, the District has been working with local cemeteries, because these mosquitoes look to make their home in the water that collects in vases.

“Awareness is a big part of our effort,” said Heft. “Knowing where they prefer to breed and eliminating those conditions goes a long way.”

Yellow fever mosquitoes can lay eggs in containers holding as little as a teaspoon of water and eggs, which are laid just above the water line, can survive dry conditions for months.

Those traveling to Mexico and other Latin American countries should be aware of an increase in chikungunya cases. So far, about one-third of the 120 chikungunya cases imported into California were contracted in Mexico, with 91 percent of cases coming from Latin America. Sixty-nine imported cases of dengue have been reported in California this year, according to the CDPH.

Neither of these mosquitoes is native to California. They are known for their black-and-white stripes, biting people during the middle of the day and readily entering buildings. The more-familiar mosquitoes, including those that carry West Nile Virus, bite primarily at dusk and dawn.

Chikungunya virus and dengue fever are transmitted to people by mosquitoes. The most common symptoms are fever and joint pain, according to the Centers for Disease Control and Prevention. Other symptoms may include headache, muscle pain, joint swelling, or rash. In the most severe form, the viruses can cause hemorrhagic fevers, leading to death. Yellow fever is a similar virus and while it has no specific treatment, there is a vaccine.

“There is no vaccine or treatment for chikungunya or dengue fever.  To prevent these diseases from becoming established in California, it is important for everyone to take steps to keep these mosquitoes from spreading” Smith said. “If you notice that you are being bitten by mosquitoes during the day, or notice black-and-white striped mosquitoes, call your local mosquito and vector control agency. Your participation in mosquito surveillance greatly aids in efforts to detect new infestations.”

To prevent mosquito-borne illnesses present in California, such as West Nile virus disease, or abroad, such as chikungunya and dengue, Smith offers the following tips:

·  Apply mosquito repellents containing DEET, picaridin, IR3535, and/or oil of lemon eucalyptus to your skin and clothing.

·  Wear long sleeve shirts, long pants, socks and shoes when mosquitoes are most active.

·  Use air conditioning, and keep mosquitoes from getting into your home by having intact window and door screens.

·  Eliminate potential mosquito-breeding sources, such as water-filled containers, from around your home and where you work. Drain water that may have collected under potted plants, in bird baths and discarded tires. Check rain gutters to make sure they aren’t holding water, and clean pet water-dishes weekly.