Vector-Borne Diseases

Billions of people around the world, including Americans, are at risk from viruses and bacteria transmitted by mosquitoes, ticks, fleas and other vectors. The most widely known vector-borne diseases in the U. S are West Nile virus, Lyme disease and Rocky Mountain spotted fever. Dengue virus, a major health problem in Puerto Rico, infects as many as 400 million worldwide each year, some fatally. As rapid global travel and changing land use increase, the risk of rare or new vector-borne pathogens to emerge and cross borders also increases. For example, West Nile virus, which was unknown in the U. S before 1999, infected 5,674 Americans in 2012.

Prevention/Control Difficulties

Vector-borne diseases are especially difficult to predict, prevent or control. Only a few have vaccines. Mosquitoes and ticks are notoriously difficult to reach and often develop resistance to insecticides. Adding to the complexity, almost all vector-borne pathogens are zoonoses, meaning they can live in animals as well as in humans.

Vector-borne diseases are among the most complex of all infectious diseases to prevent and control. Not only is it difficult to predict the habits of mosquitoes, ticks and fleas, but most vector-borne viruses or bacteria infect animals as well as humans. West Nile virus (WNV), which is primarily a disease of birds, is a good example.

Public Health Impact

Vector-borne diseases are major public health concern. Lyme Disease causes over 300,000 estimated human illnesses annually in the U.S. Tick-borne rickettsial diseases, such as Rocky Mountain spotted fever (RMSF), ehrlichiosis, and anaplasmosis, are responsible for over 4,000 U.S. cases each year, including some that result in death. Dengue fever causes millions of cases worldwide, including thousands of cases in Puerto Rico each year. DVBD uses information about the number of cases, and when and where they occur, to aid health departments and other partners to reduce cases, save lives, reduce suffering, and reduce the financial impact to the public.

We also cover less common day, but often deadly threats. Yersinia pestis causes the ancient disease plague. Focal plague outbreaks occur in the southwestern U.S., and it is a significant health threat in Africa and Asia. We work with public health officials in Uganda to improve diagnosis, treatment and prevention-learning lessons that could help us respond to natural and bioterrorist uses of plague.