The great mosquito debate: Kill them

I have strong feelings about mosquitoes — and they aren’t positive. These insects cause more disease and death than any other animal on the planet. Getting rid of them would be a blessing.

The Bill and Melinda Gates Foundation estimates that mosquitoes kill 725,000 people a year, far more than the 475,000 who are killed by other humans. All other animals are in a completely different league. Granted, these numbers aren’t exact, but they do offer perspective on the huge impact of these tiny creatures.

Wherever there are mosquitoes, there are mosquito-related diseases. These include malaria, dengue, chikungunya, Zika, yellow fever, West Nile virus disease, and others. The burden of disease and death is greatest in sub-Saharan Africa and parts of South America and Asia, where the climate is conducive to year-round mosquito activity and breeding.

From the public health viewpoint, there’s nothing good about mosquitoes. People say, “They feed birds.” In a lecture I gave recently to the National Institutes of Health, I wasn’t completely joking when I said “Give the birds bird feed, and get rid of mosquitoes.”

Eliminating mosquitoes would save lives and prevent suffering around the world. However, I do not think that is possible. Everyone with whom I have spoken who knows a lot about mosquito biology says it would be technically impossible to eradicate mosquitoes from the face of the Earth.

But we can control them. In some parts of the world, this has resulted in dramatic decreases in malaria and other mosquito-borne diseases.

In the 1950s, Brazil embarked on an aggressive program to control mosquitoes that carry malaria parasites. It included spraying DDT in homes and around mosquito breeding grounds. The program led to a significant decline in malaria. But when the program was stopped in the 1970s, largely because of environmental concerns over the use of DDT, mosquitoes and malaria returned.

At about the same time, concerted efforts to control mosquitoes in Zanzibar reduced malaria in that country to very low levels by 1967. Then, with malaria no longer a visible threat, the country abandoned its efforts and the disease rebounded.

The experiences in Brazil and Zanzibar illustrate one of the difficulties of mosquito control — it must be sustained indefinitely.

To control mosquito-borne disease, we don’t have to go to the extreme of killing every single mosquito. Instead, we need to break the cycle of infection from mosquito to human and back again. In temperate climates, such as in much of the United States and Europe, winter provides a natural break. In places where mosquitoes are active all year, breaking the cycle is proving to be far more difficult.

However we approach controlling mosquitoes, it must be a priority for preventing death and suffering in many parts of the world.

Anthony S. Fauci, MD, is the director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.