During a typical spring, health departments across the country would be preparing for mosquito season. Biologists would search for stagnant pools of water where the insects breed, carefully counting the number of mosquito larvae and adults and identifying the types of species present. Then, depending on the severity of the mosquito outbreak, they would apply pesticides to keep the insects and the illnesses they spread at bay.
But this year, vector control programs—institutions dedicated to protecting communities from diseases transmitted by mosquitoes, ticks, and other pests—are experiencing significant cutbacks due to COVID-19. Some have lost necessary staff, while others have had procedures completely shut down for the foreseeable future.
This means that the management of viruses like West Nile, eastern equine encephalitis, and dengue fever may be insufficient in states across the U.S., including Texas, Michigan, Ohio, and Florida. “Although I understand the limitations during these unprecedented times, it does seem short sighted to stop funding vector control and surveillance,” says Angelle Desirée LaBeaud, a professor of pediatric infectious diseases at Stanford University School of Medicine. In fact, cutting vector control and surveillance can put locals in harm’s way and add significant strain to health departments this summer.
According to a 2018 Centers for Disease Control and Prevention publication, disease cases from mosquito, tick, and flea bites tripled from 2004–16. It also said that nine new germs spread by mosquitoes and ticks had been found in the United States since 2004. Researchers have long expressed concern that climate change may expand mosquitoes’ range, therefore exposing more people to the diseases they carry.
Some states have already experienced unusual spikes in mosquito-borne viruses. For example, in 2019, Michigan saw 10 human cases of eastern equine encephalitis, an extremely rare and deadly mosquito-borne virus, resulting in six deaths. It was the largest outbreak in state history—typically, Michigan sees zero to three cases per year. Even with these trends, according to the CDC, 84 percent of vector control programs in the United States are not fully prepared to handle the spread of these diseases, and they require additional resources.
But as COVID-19 continues to devastate the nation and the reopening of states generates new viral hot spots, funding for many other disease programs remains inadequate. This isn’t a new problem—since the 2008 Great Recession, local and state health departments have lost nearly one-quarter of their workforce. Today, it’s estimated that public health departments would need an annual infusion of $4.5 billion to operate at full capacity, with COVID-19 only making this deficient more apparent. In a recent poll of 20 vector control programs by the National Association of County and City Health Officials, an organization that represents the country’s nearly 3,000 local health departments, 40 percent of respondents indicated that they had seen a moderate to severe level of disruption to their operations as a result of the pandemic.
This is the case in central Ohio’s Delaware General Health District, which lost three sanitarians (employees who specialize in health and safety) right before the pandemic and is now on a hiring freeze. As a result, the county won’t be able to fill the sanitarian positions or hire an intern this summer to help trap mosquitoes and apply pesticides. Typically, the team collects mosquitoes across the entire county—which spans almost 460 square miles, an area about the size of Los Angeles—four nights per week. But now, because of staffing limitations, the area it covers each night will be significantly reduced.
The state’s public health laboratory has also paused testing for West Nile, the most common mosquito-borne disease in the United States. “Due to the pandemic, the state of Ohio is in a hiring freeze and therefore have not been able to hire the staff needed to do the collection and the testing,” Ohio Department of Health press secretary Melanie Amato wrote in an email. “We still hope we can do testing, but start late. We have no timeframe of when that will possibly be.” This means employees in Delaware County’s health department won’t be able to confirm whether the mosquitoes in its region are carrying West Nile, thus forcing them to make an educated guess of where to apply pesticides. “That’s a hard decision to make sometimes,” says Dustin Kent, the vector control program manager. (So far this year, the state hasn’t seen any West Nile cases.)
Florida’s mosquito control program in St. John’s County has also suffered major rollbacks. Along with postponing its mosquito surveillance and cutting back on staff, the team at the Anastasia Mosquito Control District has not been able to release sterilized male mosquitoes back into the wild to help reduce the insect population. Called the sterile insect technique, this work is key in controlling the spread of diseases including Zika, yellow fever, and dengue. Scientists are particularly concerned about dengue fever, which was thought to be eliminated in the United States from 1934 to 2009 but is now considered to be one of the most common mosquito-borne diseases in Florida and infected 16 people last year.
Some health departments are also worried about how these viruses will impact COVID-19 surveillance. “Symptoms of West Nile can be rather nonspecific and mimic things like the flu,” says Nina Dacko, the vector control supervisor in Tarrant County, Texas. Because COVID-19 can also present with flu-like symptoms, patients may assume they have the coronavirus and self-isolate instead of getting tested for West Nile. “We could completely miss a West Nile outbreak going on,” says Dacko, whose county has experienced cutbacks in disease testing at their regional laboratory due to the pandemic.
For all health departments, the most effective way to stop the spread of mosquito-borne diseases is through public education. Individuals in areas susceptible to mosquito outbreaks must keep their screens closed during the summer, drain any standing water on their property to prevent mosquito breeding, and remember to use insect repellent while outside. With many other resources being stripped away, health departments must continue educating their communities, says Kent: “There’s a public value to it.”