Infected mosquito spike sparks West Nile warning in Kent Co.

Kent County

GRAND RAPIDS, Mich. (WOOD)  — The Kent County Health Department is urging people to take steps to protect themselves after finding an “unusually high” number of trapped mosquitoes testing positive for West Nile virus this year.

The health department says in the first 11 weeks of sampling this year, they collected 16,314 Culex mosquitoes, which typically carry the West Nile virus. That’s nearly six times the number of Culex mosquitoes collected during the same period last year.

Kent County Health Department Officer Adam London says of the eight pools of 50 mosquitoes sent to labs this year, 26 percent of Culex mosquitoes tested positive for West Nile virus.

“I’ve been working with West Nile virus in Michigan for over 15 years and in that time…  I don’t recall a year where we had surveillance data that was more concerning than what we have right now. So, I’m very concerned that people will get hurt this year if they don’t follow the precautionary measures that we recommend,” said London.

>>App users: Watch the health department’s news conference here.


Although there are no reported cases in Kent County so far this year, London expects that to change by late this season. 

“That virus builds over the course of the summer and that mosquito population builds over the course of the summer,” he explained. “I hate to say it, but with the number of mosquitoes that we have, with the number we have carrying the virus, I think there’s a strong likelihood probably statewide, but I can only speak for Kent County, that we’re going to see (human) cases this year.”

Dr. Mark Hall with the health department says the number of human cases of West Nile virus have been light in Kent County recently; over the past five years, only four residents reported falling ill with the virus, three of whom were sickened last year.

But if 2002 is any indication, the virus can be pervasive. That year, Kent County reported 614 human cases of West Nile virus – the most the county has ever seen since the epidemic began, according to Hall.

Last year, Michigan recorded 42 human cases of West Nile virus.


The number of people with West Nile virus may be much higher than reported, since health officials say 80 percent of people affected have no symptoms.

It’s the rest of those cases that raise concern and require doctor visits. Nearly 20 percent of those sickened with West Nile virus have flu-like symptoms, London said. Less than 1 percent of people who come down with West Nile virus suffer neurological symptoms, loss of consciousness, confusion, headaches, weakness in their arms or legs, or fever. 

Health officials say the most severe symptoms affect one out of 150 West Nile cases; Al Walczak of Grand Rapids was one of them.

The incubation period for West Nile virus is 2-14 days, meaning those sickened by it would start feeling symptoms as soon as two days after they’re bitten. 

While everyone is vulnerable to West Nile virus, health officials say people over the age of 60 years are most susceptible. 


Things that fly don’t often stay in one place, so tracking mosquitoes is no easy task.

“We’ve highlighted the zip codes where our positive trap locations are,” said Kent County Health Department Sanitarian Brendan Earl, referring to a computer screen that marks the locations of mosquito collection sites around the county. 

The county’s testing has focused on the urban areas of greater Grand Rapids, which the Culex mosquito typically favors.

“History has told us that this mosquito likes the urban environment because of catch basins, the storm sewer, because of all of those small containers that are in densely populated areas,” explained London.

Traps are placed in storm drain catch basins and adjacent areas to collect more mosquitos, giving health officials a makeshift road map to the problem.

But health officials say Culex mosquitoes and the West Nile virus they carry could be anywhere.

“We know with as many zips codes that we have, as many positive traps that we have, it’s most likely throughout Kent County,” said Earl.

When it comes to the winged West Nile carrier, London says standing water is the enemy.

“I encourage everyone today when they get home, to walk around their property, look for small containers of water, the pop cans in the bushes, the kiddie pool, maybe the toys that are back there or the bird feeder. Dump the standing water from those things. Each of those containers acts as a nursery for up to hundreds of these mosquitoes, this particular mosquito that’s especially worrying to us.”


There is no vaccine or cure for West Nile virus, but the Kent County Health Department offers tips to protect yourself:

  • Wear a mosquito repellant that contains 10 percent to 35 percent DEET.
  • Stay indoors during dusk, when mosquitoes are most active.
  • Remove standing water in your yard, which can be a mosquito breeding ground.
  • Keep your lawn and shrubs cut.
  • Wear light-colored clothing

“There is lots of evidence that suggest that mosquitoes are attracted to dark clothing. Most of the things that they feed on in the wild have dark fur, dark feathers, so avoid dark clothing,” London elaborated.

Kent County officials say they’re talking with other counties about the risk of West Nile virus this year, after working to get the word out.

“Recognize the threat that exists this year. It’s a threat that we have not seen here in Kent County. I believe this threat is also present in much of the state right now because we have experienced these dry conditions for most of the summer. Please take heed of this information and protect your family as much as possible from these mosquitoes,” London said.



West Nile virus

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