Day-biting mosquitoes that can spread deadly dengue and yellow fever diseases have been found for the first time in southeast Fresno.
The Fresno Mosquito & Vector Control District stepped up trapping this month when the Aedes Aegypti mosquito was found in Exeter in Tulare County and Arvin in Kern County, said Tim Phillips, district manager.
District workers placed 120 traps in the city. One of the traps, on Clovis Avenue between Belmont and Tulare avenues, contained immature mosquitoes, Phillips said.
"We didn't need a microscope to see them," he said. "There were about 30."
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Testing showed they were the A. aegypti, a potential carrier of dengue, yellow fever and chikungunya fever -- tropical diseases with symptoms that include fever, severe headaches and body aches. In extreme cases, the diseases can lead to death.
The mosquitoes in Fresno were found about three miles from locations in Clovis where they were found initially last year and continue to spread this year. Madera was the first to detect the mosquitoes last year and continues to trap mosquitoes this year.
Typically, the mosquito likes hot, humid tropical areas, like the southeastern U.S., Mexico and Central and South America. Yale researchers said last month they believe the mosquitos found in the Valley probably hopped rides on planes or trains to get to California from the Southeast.
So far, there have been no cases of the A. aegypti mosquito carrying diseases reported in the San Joaquin Valley.
But people traveling outside the U.S. to infected areas can be bitten, become infected and return to the States. Mosquitoes here can bite an infected human, become infected and spread the disease. In 2013, there were 124 imported cases of dengue fever reported in California, according to the Yale researchers.
Spraying for the mosquito has not been as successful as hoped, Phillips said, and the public's help is needed to eliminate sources of standing water in yards that can be breeding grounds.
"We don't want this mosquito," Phillips said, "but I don't know if we're going to stop it."
The Consolidated Mosquito Abatement District is trying to determine the extent of the A. aegypti infestation in Clovis. Workers know it is spreading, and they are looking for sources of breeding, which could include everything from drainage pipes to flower pots. "Anything that can hold water is a potential source for the mosquitoes," said Steve Mulligan, district manager.
And while Valley mosquito control districts battle to stop the A. aegypti mosquito, Mulligan and Phillips said they also must contend with night-biting mosquitoes that carry West Nile virus.
"It's been a very active year for West Nile virus in Fresno County," Mulligan said. So far, 38 people in the county have been infected, he said. Statewide, more than 300 people have fallen ill.
Most people infected with West Nile have no symptoms or minor flu-like complaints, but some people experience severe neurological problems.
The message for the public, Mulligan said: Check yards for sources of standing water, report neglected swimming pools, report mosquito infestations -- and avoid mosquito bites by wearing protective clothing or insect repellent.
"In the past, we always said protect yourself when you are outside between dusk till dawn," he said. "Now we have to say the key is when you are out and you notice mosquitoes, use repellent whether it's at day or night."
To prevent exposure to mosquito bites and West Nile virus:
• Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. DEET can be used safely on infants and children 2 months of age and older.
• Wear protective clothing and repellent if outside at dawn and dusk when mosquitoes are most active. Make sure doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.
• Eliminate or drain all sources of standing water where mosquitoes can lay eggs. Report neglected swimming pools to mosquito and vector control agencies.
To report mosquitoes and neglected pools:
• Consolidated Mosquito Abatement District: (800) 821-1577;www.mosquitobuzz.net
• Fresno Mosquito & Vector Control District: (559) 268-6565;www.fresnomosquito.org
• Kings Mosquito Abatement District: (559) 584-3326;www.kingsmosquito.net
• Madera Mosquito & Vector Control District: (559) 662-8880;www.maderamosq.org
• Delta Vector Control District: (559) 732-8606;www.deltavcd.com
• Tulare Mosquito Abatement District: (559) 686-6628
• Dead birds and squirrels that may be infected with the West Nile virus can be reported by calling (877) 968-2473 or by filing an online report at the California West Nile website atwww.westnile.ca.gov