Lake County health officials warned Wednesday that the risk of mosquitoes transmitting the potentially dangerous West Nile virus has significantly increased.
The red flag comes after 32 batches of mosquitoes sampled throughout the county tested positive for the potentially fatal virus -- well above the record pace of 2005. Two birds collected in Round Lake and Long Grove also tested positive, health officials said.
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"That 32 could actually be much higher when some of the lab samples come back. Although there are not a lot of mosquitoes out, the ones that are out are the ones that could potentially carry this," said Mike Adam, senior biologist with the health department.
Adam said the numbers are tracking ahead of 2005, when 11 human cases resulting in one death occurred. No human cases in Lake County have been reported this season.
"This is kind of a significant increase compared to the past couple of years," said Leslie Piotrowski, health department spokeswoman.
Most people infected with the virus will have no symptoms but some may become ill, usually three to 15 days after the bite of an infected mosquito. In some people, particularly the elderly, the virus can cause muscle weakness, inflammation of the brain, stiff neck, stupor, disorientation, tremors, convulsions, paralysis, coma or death.
The positive batches were primarily concentrated in the southern part of the county but were widespread, Adam said.
"The only area we haven't pulled any is from the very far northwest but that's just a matter of time," he added.
Culex mosquitoes, which carry West Nile, thrive in dry conditions as breeding areas like catch basins, for example, are not getting flushed.
"These mosquitoes like decaying matter in water -- the stinkier the better," Adam said. And it doesn't take much.
"I've seen larvae in little cups of water that were left out," he added.
Residents are urged to reduce their exposure, wear repellent and report areas where mosquitoes typically breed. To report stagnant water or to learn about the virus or preventing mosquito breeding or bites, call the West Nile hotline, (847) 377-8300.