April showers bring ... mosquito season, officials say

If you haven’t done your spring cleaning yet, you might want to add cleaning the pool and draining out flooded flower pots to the list.

Mosquito season in Merced County is coming early this year, officials are warning, and the best way to avoid the nuisance – and the viruses some carry – is to be proactive and eliminate standing water.

Crews with Merced County Mosquito Abatement District conducted their first surveillance this week and are gearing up for a mosquito season anticipated to be unlike any in the past.

Allan Inman, manager-entomologist at the abatement district, said West Nile virus could show up as early as May. And, it’s only a matter of time until biologists find invasive species that carry Zika.

“We anticipate it’s going to be a bad year,” he said.

After the last flood year in 1997, the district anticipated the 1998 mosquito and disease season would be worse, Inman said. But, the opposite occurred. The district didn’t receive emergency funding, and there wasn’t a major increase in mosquito populations or disease.

Although the past winter was abnormally wet, Inman says other factors are at play that make it different from 1997-98.

“The difference is, in 2017, we’re coming off of six years of drought,” he said. “Every year is different in mosquito control. You never know what you’re going to have.”

During the drought, two types of mosquitoes that are West Nile vectors were prevalent – the Culex tarsalis and the Culex pipiens complex. Those mosquitoes prefer the clean water on the West side of the county, Inman said.

With all the rain that showered the Valley this winter, there will be more types of water, particularly more standing water. The flood water will attract a different kind of mosquito, one that Inman said is a long-distance flyer and an aggressive biter.

“It’s not necessarily a high disease vector,” he said, “but they are a nuisance.”

With the Zika mosquitoes – the Aedes aegypti and Aedes albopictus – found in Fresno and Madera counties, Inman said it’s likely they are here in Merced but haven’t been found.

Since 2013, human cases of West Nile in Merced County were reported only once in 2014 and once in 2015. No West Nile cases were reported in 2016. Since 2015, there have been three cases of Zika in Merced County, state public health data shows.

The abatement district recently received a $35,000 grant from the California Department of Public Health to partner with UC Merced and search for the Zika mosquitoes. The money also will be used to buy a specific type of trap.

If West Nile shows up earlier in the season, Inman will apply for disaster funding from the Federal Emergency Management Agency.

Until then, he will wait until it’s time to deploy trucks on the ground and planes in the air to spray for mosquitoes.

“We’ve set the stage to pull the trigger very quickly if we need to,” he said.

In the meantime, residents can help prevent West Nile by cleaning pools early and eliminating any standing water from the winter storms.

Said Inman: “That’s crucial this year.”

This story was originally published April 7, 2017 at 5:47 PM with the headline "April showers bring ... mosquito season, officials say."