Health Officials Offer Tips to Prevent Mosquito Bites As Season Starts


Preventing Mosquito Bites

With mosquito season near, County officials reminded people Tuesday that they need to dump out standing water and protect themselves from mosquitoes if they want to stay safe from illnesses like West Nile virus and Zika.

County Supervisor Greg Cox and Chris Conlan, a supervising vector ecologist with the County’s Vector Control Program, held the County’s annual mosquito-prevention kickoff event Tuesday afternoon at Olivewood Gardens and Learning Center in National City.

“The most important message we want to get out today,” Cox said, “is that you can help prevent these diseases. All you have to do to help fight mosquitoes and disease is follow the County’s ‘Prevent, Protect, Report’ mantra.

“Prevent mosquitoes from breeding,” Cox said, “by dumping out standing water inside and outside homes. Protect against mosquitoes by wearing insect repellent and proper clothing. And report mosquito activity and dead birds to County Vector Control.”

The County has held the annual mosquito prevention kickoff for nearly 15 years and reiterated its main messages Tuesday — that mosquitoes can breed in the smallest amounts of water.

That means backyard items such as toys, flower pots, rain gutters, tarps, holes in trees, even bottle caps, can become mosquito breeding grounds.

While the overwhelming majority of people who get infected by both West Nile virus and Zika never suffer any symptoms at all, both diseases have potentially dire consequences. In rare instances, West Nile virus can make people extremely ill and even kill them. Zika has been linked to a severe birth defect. Pregnant women who become infected with Zika can have babies with microcephaly, which leaves infants with smaller brains and skulls.

West Nile virus is spread by native Culex mosquitoes after they bite an infected bird or animal.

Two species of invasive Aedes mosquitoes first found in San Diego County in 2014 and 2015 are potentially capable of transmitting Zika and tropical diseases like dengue and chikungunya — but only if they first bite an infected person.

Because those tropical diseases do not exist naturally in San Diego County, invasive Aedes mosquitoes could only transmit Zika and tropical diseases if they first bit a person who contracted the disease elsewhere — travelers returning home infected from abroad.

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To date, no invasive Aedes mosquitoes have tested positive for Zika or other tropical diseases in San Diego County or California.

Cox said the County’s Vector Control Program works hard to protect residents from mosquitoes — using helicopters to drop granular larvicide that is harmless to people and pets but kills mosquito larvae on 48 local waterways, hand-treating other areas, giving out free mosquito-eating fish and educating the public.

San Diego County escaped relatively unscathed by West Nile virus and Zika in 2017. Last year, just two San Diego County residents tested positive for West Nile virus and no one died. And the County did not have to hand-spray any neighborhoods as they did in 2016 to keep invasive Aedes mosquitoes from coming into contact with County residents who became infected with Zika while traveling abroad.

But West Nile virus, Zika and other mosquito-borne diseases are still a threat. In Los Angeles County last year, 264 people tested positive for West Nile virus and 27 people died. And in San Diego County in 2016, 22 people tested positive for West Nile virus and two people died.

County Public Health officials said the threat of the Zika virus diminished slightly last year. Zika was practically unheard of before 2015, when it raced through the Western Hemisphere, prompting the World Health Organization to declare it an epidemic. In 2015 in San Diego County, just two people tested positive for Zika, having become infected while traveling.

That number skyrocketed to 83 in 2016, and County Vector Control hand-sprayed 10 neighborhoods over the course of the summer and fall to prevent invasive Aedes mosquitoes from biting infected residents and potentially spreading Zika.

In 2017, the number of traveling San Diego residents returning home to test positive for Zika dropped from 83 to 20.

Even so, Public Health officials said the public needs to remain on guard.

Dr. Sayone Thihalolipavan, the County’s Deputy Public Health Officer, said:

“People still need to be aware. They still need to protect themselves from mosquitoes. So remember to dump out all standing water inside and outside your home so mosquitoes can’t breed.”