​Swords and lances, arrows, machine guns, and even high explosives have had far less power over the fates of nations than the Typhus louse, the Plague flea, and the Yellow Fever mosquito - Hans Zinsser

We fear mosquitoes because of their roles as vectors of disease. Mosquitoes transmit many diseases, many of them endemic to the United States. The best known mosquito-borne diseases are malaria and yellow fever. Lesser known but frequently occurring in the Americas are dengue and the encephalitides. Mosquito-borne diseases affect about one-fifth (one billion people) of the world's population every year. Mosquito-borne diseases are a growing threat throughout the Americas due to the decline of vector control programs. For the first time in nearly 50 years endemic cases of dengue fever and malaria are in the United States. Improvements in world transportation now allow a person infected with a disease to be on a different continent each day. This enables mosquito-borne diseases to travel from one nation to the next, increasing the potential for transmission to U.S. residents. The vectors of all major mosquito-borne disease continue to thrive in the United States. Mosquito-borne diseases have been at very low levels for one very good reason - mosquito control programs. The United States has the most intensive and efficient mosquito control effort in the world. This has decreased the threat of disease transmission in the U.S.. Recently, however, a large number of individuals have immigrated to the United States from nations with vector-borne diseases. Many of these immigrants are arriving illegally without being screened for disease. As a result, some of them may serve as a reservoir for diseases such as malaria and dengue.

E-Mail Michael Cantwell, Maryland Department of Agriculture Mosquito Control​