Do more mosquitoes mean more disease? Not necessarily.
After a season of heavy rainfall resulting in more bloodsuckers flying around Michigan than usual, safety from mosquito-borne viruses is as important as ever.
In light of confirmed human cases of West Nile Virus in Michigan, as well as animals contracting Eastern equine encephalitis and Jamestown Canyon virus, Michigan Department of Health and Human Service employees Kristen Finch and Emily Dinh joined Stateside to discuss public health.
Finch, a microbiologist of viral serology, studies the diseases carried around by mosquitoes, while Dinh, a medical entomologist, specializes in the field, setting traps for and collecting mosquitoes.
“I believe it was after the Fourth of July, we had our first big surge,” Finch said of this summer’s mosquito workload. “I think we all remember in Michigan how it became impossible to walk outside without getting swarmed. And our numbers reflected that. So we went from testing 50 or 60 in a week to several hundred.”
Finch, Dinh, and the rest of their MDHHS mosquito team are on the forefront of mosquito pool testing in Michigan, a relatively new practice in the state.
“I don't know exactly when it started, but it's been a centuries long practice, depending on the mosquito-borne disease you're interested in,” Dinh said.
As opposed to testing humans for these diseases (known as arboviruses, or viruses transmitted through arthropods), mosquito pool testing enables Finch and Dinh to get in front of the viruses earlier in their spread.
“[Arboviruses] circulate within the mosquito-, birds-cycle in nature for some time before the virus has circulated enough within the birds and mosquitoes to then what we call spillover into different mosquito species and animal species and humans. And so with that, we try to sample the mosquitoes because they're the first indicator of viral activity in an area,” Dinh said.
While Dinh acknowledged that the fall is typically when they start to see arbovirus infections decline, it’s still possible to contract an arbovirus “as late as October.”
“And so what I urge people to do during this time of year is that although it seems like things are cooling off, it's still warm enough for the mosquitoes to fly in the peak daytime hours. And one bite from a mosquito can give you a disease that, quite frankly, many of them don't have cures for.”
Eastern equine encephalitis, which kills 33% of humans infected with the virus, had a record outbreak for the US in 2019, leaving 39 dead.
“Sure, yeah, the numbers we see for these viruses might be small, but every single person matters.” Finch said. “And especially with the surveillance that we're doing, our hope is that we mitigate human impact and see fewer people affected by these viruses. So it's true that we don't see gigantic numbers, but when we do, it's devastating for everybody affected.”
As for mosquito safety precautions, Dinh cited bug spray for when you’re moving around outside, “thermocells” for when you’re stationary, and a helpful EPA database of effective repellents to keep handy.
“So bringing all that together, I feel really passionate about contributing to public health in this way,” Finch said. “So it feels like a small way for me to have a big impact, I guess. I guess the hope is that by completing this testing and doing these tests in a quick and efficient and effective manner, I can help people. That's really—it all comes down to helping people. That's what we're here for, you know.”