Making the correct decision to protect public health is not always easy. Take, for example, the case of eastern equine encephalitis (EEE). EEE is a rare but serious viral disease transmitted by mosquitoes. The disease is uncommon in humans but extremely dangerous: half of infected patients die, usually within 2 to 10 days after the onset of symptoms. Spraying with pesticides can kill mosquitoes and lower the risk of someone catching EEE, but pesticides carry their own risks. Deciding whether or not to spray an area takes careful consideration, including weighing the risks and benefits.

In the United States, roughly 12 to 17 cases of EEE are reported each year. The virus infects birds that live in freshwater swamps and can be spread from bird to bird by mosquitoes that feed on the birds. As the name implies, the disease is found in the eastern region of the country and was first identified in horses. If a mosquito infected with the virus bites a horse or human, the animal or person can become sick. The first symptoms of the disease are high fever, stiff neck, headache, and lack of energy. These symptoms show up 3 to 10 days after a bite. The most dangerous complication is inflammation (or swelling) of the brain, called encephalitis. In encephalitis cases, the disease quickly progresses and patients could fall into a coma within a week. There is no treatment for the disease, and people who survive will often be permanently disabled.

Because EEE is so deadly and spreads so easily, public health officials keep a close watch on the disease. They regularly test mosquitoes and track cases in humans and animals. If officials determine that an area is at risk for an outbreak, they may consider nighttime aerial spraying of a pesticide that targets mosquitoes. Small aircraft are equipped with spray tanks that dispense very fine droplets of the poison. The droplets stay aloft and kill adult mosquitoes on contact.

Organic farmers like Ron Maribett in the video argue that pesticide spray contaminates pesticide-free farms like his. And other residents in sprayed areas may wonder if the pesticide used will affect their health. These concerns are valid, and public health officials weigh them all before deciding to spray. The U.S. Environmental Protection Agency (EPA), which has evaluated the pesticides used in aerial spraying, says that they do not pose an unreasonable risk to birds or mammals if used properly. However, the pesticides are considered highly toxic to fish and bees. Therefore, they are not to be sprayed near open bodies of water or in sensitive environments such as wetlands. Surface drinking water supplies, certified organic farms, fish hatcheries, and limited endangered species habitats are also avoided. Despite the EPA’s approval and the aerial spraying guidelines, the practice remains controversial.

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