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Mosquitoes, allergies a growing concern amid recent storms

Posted at 5:07 PM, Mar 23, 2019
and last updated 2019-03-23 20:07:00-04

SAN DIEGO (KGTV) -- For most San Diegans, recent rainfall is a welcomed change, but a recent abundance of storms may have some unintended consequences for the county.

One expert says recent rain is already triggering allergies while at least one county department is wondering what the impact will be on San Diego’s mosquito population.

Rain may affect mosquito populations

Chris Conlan, Supervising Vector Ecologist for San Diego County, says it’s a bit too early to predict this year’s mosquito population.

“It depends on several circumstances, not just the rainfall alone,” Conlan said.

According to Conlan, warm temperatures and the timing of the rainfall also play a major role.

“If there’s a lot of standing water still lying around when the warm weather kicks on, then yeah, that could mean that we get a slightly buggier start to the spring than what we would have liked.”

Mosquitoes only breed in standing water. When San Diego gets a lot of rain, Conlan says areas that usually have standing water are flowing, minimizing the risk of mosquitoes breeding.

“In very dry years you could still have mosquito problems because then, areas that might have otherwise been flowing, are now becoming stagnant.”

Dry years in San Diego have actually been some of the worst for West Nile, Conlan said. “We’ve had some of our worst West Nile years during drought. It’s not entirely dependent on the rain.”

Conlan says it’s too early in the season to know whether or not an increase in this year’s mosquito population is on the horizon.

“It’s a little early to start making predictions. My crystal ball is in the shop at the moment,” Conlan said.

Conlan says in a normal year, mosquito season starts in April and ends in October or November.

Though it’s unclear when this year’s mosquito season will begin, the county is urging everyone to take action by making sure there’s no standing water around their homes and in backyards.

“If it can hold water it can probably breed mosquitoes,” Conlan said.

One thing the county is keeping a close eye on are several new species of mosquitoes that have the capability to transmit new tropical diseases.

The mosquitoes are fairly new here and have only been in the county for about four years, Conlan said.

Further research is needed to determine exactly why the mosquitoes have all of a sudden decided to call San Diego home.

“(The new mosquitoes) now bring the unfortunate opportunity for things like say Zika or Dengue to go ahead and potentially be transmitted here.”

Conlan says, though no human transmission of such diseases have happened yet in San Diego County, the more people can do to mitigate the risk, the better.

“What we don’t want to see is for people to let their guard down and then have some places where those mosquitoes become very locally abundant.”

“If that were to occur, it would raise the possibility that, if someone were to return from a trip infected with one of these diseases, those mosquitoes could pick it up and transmit it to someone who hadn’t gone anywhere.”

Conlan said the new breeds, known as aedes mosquitoes, are very happy to call small containers in backyards home.

“The more people can do to keep that water from being there, the less of a chance we’re going to have of mosquito problems in people’s backyards,” Conlan concluded.

Allergies expected to be worse

Another concern amid all the rain is increased allergies.

Dr. Dana Ger, the Clinical Director for Scripps Health Express said the clinics have already been seeing cases of allergies.

"In San Diego, who knows when it’s spring, who knows when it’s fall” Ger said jokingly.

Ger said the recent moisture has brought with it allergies throughout the county.

According to Ger, the moisture does more than just cause plant growth. Clouds and rain also force pollen closer to the ground, affecting people’s allergies.

Allergy season may be off to a bad start, but it could get much worse. “We anticipate that it could get pretty bad,” Ger said.

“One of the concerns is that people who have mild allergies absolutely could have worse allergies and, as with any year, people who had mild allergies in prior years, allergies can increase.”

Ger recommends that people who are unsure what to do about their allergies see their doctor. Click here for a pollen forecast.