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West Nile virus is confirmed south of Manteca

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POSTED May 25, 2013 2:19 a.m.


The Bulletin

Five days after a Manteca woman suffered thousands of mosquito bites while stranded along the Stanislaus River, San Joaquin County officials have detected the West Nile virus.

Two mosquito samples collected along the southern border of the county contained the mosquito-borne virus.

It is the earliest detection of West Nile in the county since its first detection in 2004, according to the San Joaquin County Mosquito and Vector Control District. Last year, the first mosquito detection was June 11; the year before that July 5.

“I wouldn’t say it’s alarming,” said Aaron Devencenzi, public information officer with the District.

However, Devencenzi did indicate the presence of the West Nile virus would only get stronger as the weather warmed.

This is the fourth detection of the West Nile virus in California this year. Yuba, Fresno, Tulare and Los Angeles counties have all reported West Nile virus activity as of May 16, according to the California Department of Public Health. Yuba and Los Angeles have reported dead bird infections, while Fresno and Tulare detected the virus in mosquito pools.

The West Nile virus can cause West Nile fever (headaches, muscle pain, fatigue, nausea and vomiting) in human cases, and in severe instances, neurological disease.

People of older or younger age, as well as those with pre-existing medical conditions are most susceptible.

“It’s going to spread,” Devencenzi said. “We’re just able to put out a warning to the public that West Nile virus has been found. As the warmer weather continues into the summer, it will amplify throughout the county and the state.”

San Joaquin County’s infected samples were collected near Caswell Memorial State Park – the site of Sunday’s search-and-rescue effort for Manteca couple Scott Johnson and Tracy Crane.

The two spent the late afternoon floating the Stanislaus River – an annual spring- and summertime activity for the two – when they became lost and their raft developed a slow leak.

They managed to make it to shore near Division Road in south Manteca – a flood area – but were immediately attacked by thousands of aggressive mosquitoes. The area is west of Ripon.

Johnson called 9-1-1 at approximately 8 p.m., alerting emergency officials of their predicament. However, because of the remote nature of their location and the heavy foliage, Sheriff’s officers and Ripon Fire’s water rescue unit weren’t able to reach Johnson and Crane until midnight.

For four hours, they fought a losing battle against what is believed to be the Aedes vexans, an aggressive, hostile mosquito species. Crane suffered bites to her entire body, including her eyeball. At one point, she says, she was inhaling and coughing up mosquitoes.

The Aedes vexan does not carry the West Nile virus.

The infected samples were removed at traps near Division Road and the Manteca-Ripon city border, a stretch marked by the zip code 95366.

On Wednesday, the District saw a surge in the mosquito population in the southern part of the county. It collected 1,970 mosquitoes from its Division Road trap – 1,892 of which were the non-carrying Aedes vexan – a 9,280-percent increase over a 12-month period.

At the time, Devencenzi reported a drop in the presence of the Culex tarsalis and pipiens, both of which carry the virus.

His tone changed on Friday morning, shortly after the District’s press release was sent out.

The District responded to Friday’s discovery with a treatment on a private property in the south county – and a promise.

 “We’ll keep working at it until we get those populations down,” Devencenzi said.

The District will also increase surveillance throughout the entire San Joaquin County.

Devencenzi implores the public to protect themselves against the blood-suckers by: 1) eliminating standing water around their homes; 2) wearing layered clothing, long pants and long-sleeved shirts; 2) using repellent containing DEET; and 4) reporting infestations and dead animals to the appropriate authorities.

“It’s always important to remember to take precautions for mosquitoes, even in the colder months,” Devencenzi said. “The potential for the West Nile virus is all year long, but as the weather gets warmer the percentage increases exponentially.”

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