Multnomah County health officials warn of record year for mosquitoes

In Multnomah County, health officials say they’re seeing the biggest mosquito outbreak in a dozen years.
Published: Jul. 13, 2022 at 11:45 AM PDT|Updated: Jul. 13, 2022 at 12:14 PM PDT
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MULTNOMAH COUNTY, Ore. (KPTV) - The metro area is heading into the hottest months of summer after the wettest spring in more than 80 years, which led to perfect breeding conditions for mosquitoes.

In Multnomah County, officials say they’re seeing the biggest mosquito outbreak in a dozen years.

“This is probably at least 15,000 mosquitoes, if not more,” Bek Sudia, Multnomah County Vector Control Supervisor, said while holding a trap.

The trap was set out on Sauvie Island for 14 hours, collecting about 15,000 mosquitoes. Sudia says in a normal year they would see just 50 to 100 mosquitoes in the trap.

“This is astronomical this year,” she said.

Mosquitoes caught in traps are taken back to a lab, separated, then sent in vials to Oregon...
Mosquitoes caught in traps are taken back to a lab, separated, then sent in vials to Oregon State University for testing.(KPTV)

So far this year, Sudia says the county has trapped 40,000 mosquitoes - which is a seven-fold increase from recent years.

Mosquitoes, of course, are not just annoying, they carry viruses that can be deadly. In Oregon, the concern is the West Nile virus. There are cases of West Nile every year in southern and eastern Oregon.

Multnomah County, however, hasn’t seen a case in years and that’s in part because the county puts out as many as 125 different traps for the 25 different kinds of mosquitoes found in the area. Sudia separates them into groups, hunting down the ones that can carry West Nile, then sending them off in vials to Oregon State University for testing.

“They are known as the deadliest animal in the world,” Sudia said.

With more mosquitoes in the county this year, there is more risk. Mosquitoes kill roughly 700,000 people every year worldwide. Children and older adults are the most vulnerable to the diseases they carry.

Mosquitoes spend most of their lives in standing water. All of the recent spring rainfall created flooding in grasslands and low lying areas along the Columbia River, and the pests have been breeding like there’s no tomorrow.

Of course, some people do seem to get bitten more often than others.

“Basically, scientists have come up with it’s just you unique chemical scent. So some people just smell good to them,” said Sudia.

There are some things you can do to avoid getting bitten:

  • People who spend time outside around mosquitoes, especially in areas where the insects carry West Nile virus, should take steps to avoid being bitten. Wear long sleeves and pants and apply mosquito repellent.
  • Minimize time spent outside during dawn and dusk when mosquitoes are at their worst
  • Mosquitoes can breed in as little as an inch of water. At home, people can prevent mosquitoes from reproducing by dumping or regularly changing standing water in kiddie pools, buckets and dog bowls.
  • Repair home screens in windows and doors.
  • If you have an ornamental pond or pool, mosquitofish may help to control mosquitoes. Multnomah County residents can get free mosquitofish. Call 503-988-3464 or email to schedule a pick-up.
  • Often, if there is disease in an area, crows will start dying before mosquitoes or humans test positive. Report newly-dead crows (within 24 hours of death). Do not report crows that have clearly been hit by a vehicle or electrocuted (hint: look for burned-off feet).

July is usually the peak time for mosquitoes, but people at Vector Control say the worst is yet to come.

Clark County is also reporting a more robust mosquito season than usual.