Last month we addressed dengue fever’s reappearance in the United States.  Since last summer 28 cases have been reported.  Though this disease is a little known entity in the United States, it is the most common vector-borne viral disease in the world, causing an estimated 50–100 million infections and 25,000 deaths each year.  Dengue is now the leading cause of acute febrile illness in U.S. travelers returning from the Caribbean, South America, and Asia.  However, those who have not travelled abroad or do not reside close to the Mexican border have historically not been at risk.

Dengue fever often exhibits only mild symptoms, so there is an excellent chance that hundreds of other infections have gone undetected.  The virus is transmitted primarily by the Ae. Aegypti mosquito, and results in fever, chills, headache, muscle aches, nausea with vomiting, eye pain, and occasionally a spotty red rash on the trunk or legs.  The disease may be suspected when there is a drop in the body’s platelet count- the small cells responsible for blood clotting, but can only be confirmed with the detection of antibodies in the blood. There is no treatment for dengue fever, and symptoms will usually resolve spontaneously within days.  However, in a small percentage of cases, the disease may progress to cause internal bleeding with organ failure and death. 

A vaccine for dengue fever is in development, and may ultimately join vaccines for hepatitis and yellow fever as recommended inoculations for U.S. citizens travelling to tropical areas.  In the meantime, visitors returning from areas where dengue is endemic should be suspicious of possible dengue infection if experiencing flu like symptoms, and seek medical attention if a spotty red rash develops.

Photo by Koala:Bear