Dengue identified as a threat to the USA: Will it now become an international priority?

21 Jan 2008

Paul Chinnock

Source: National Institute of Allergy and Infectious Diseases, USA (see original article)

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Dengue virus has largely been confined to certain countries in the tropics and subtropics, but a high-profile commentary from experts at the US National Institute of Allergy and Infectious Diseases has drawn attention to its rising incidence in the USA.

The commentary, which appeared in January in the Journal of the American Medical Association, was written by Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and David. Morens, Dr Fauci’s senior scientific advisor. They say that dengue has become a problem along the US-Mexico border and in Puerto Rico. The disease occurs sporadically and has had a relatively small impact on the United States so far. However, the two scientists note that efforts to control populations of the mosquitoes that transmit dengue have fallen short of their goal.

Drs. Fauci and Morens call for more research to understand and combat dengue saying that: “Widespread appearance of dengue in the continental United States is a real possibility. Worldwide, dengue is among the most important reemerging infectious diseases with an estimated 50 to 100 million annual cases…[and] 22,000 deaths.” Public health officials need to take the threat seriously, the scientists assert, because no specific treatments or vaccines for dengue are available. To fight the disease, they say, “The formidable challenges of understanding dengue pathogenesis and of developing effective therapies and vaccines must be met.”

Tropical diseases rarely attract the level of spending, either for research or for control programmes, that is devoted to conditions that are a problem in developed countries. The spread of any disease into new geographical zones is of great concern, but if the rise of dengue as a problem in the US boosts research efforts there could be benefits for people in countries where the disease has long been a problem.

Dengue is caused by any of four related viruses transmitted to humans by the mosquitoes Aedes albopictus and Aedes aegypti. First seen in the United States in 1985, Ae. albopictus has been found in 36 states, while Ae. aegypti has been found in several southern states. Experience elsewhere in the world shows that where these mosquitoes go, the disease usually follows. Most people infected with a dengue virus have no symptoms or a mild fever. Those who do get sick sometimes experience minor bleeding, such as from the nose or gums, and frequently develop a high fever, severe headache, pain behind the eyes and in joints and muscles, and a rash. Sometimes the disease leads to leakage of blood plasma out of the circulatory system and into tissues, causing blood pressure to drop. This condition often can be reversed by giving patients fluids and electrolytes. With proper treatment, case fatality rates for severe dengue can be less than 1 percent. If left untreated, however, the person may become unresponsive, slip into a coma and possibly die. Early diagnosis and treatment of dengue are critical to preventing shock and death. The severe forms of dengue disease have been defined by the World Health Organization as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS).

Reference

1. Morens DM, Fauci AS (2008). Dengue and Hemorrhagic Fever: A Potential Threat to Public Health in the United States. JAMA 299(2):214-6.