Health officials in the U.S. say the tropical infection Dengue fever is in danger of spreading across the country.
Dengue fever is usually confined to tropical and sub-tropical climates but the mosquito-borne illness is becoming a much more serious problem along the U.S.-Mexico border and in Puerto Rico.
Experts at the National Institute of Allergy and Infectious Diseases (NIAID) say cases of the disease have been reported in Texas and this may be the beginning of a new trend.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, and senior scientific adviser, Dr. David Morens say the efforts to control the populations of mosquitoes that transmit Dengue have fallen short of their goal and along with a warming climate this could encourage its spread northwards.
The World Health Organization (WHO) says worldwide, Dengue is one of the most important re-emerging infectious diseases, with an estimated 50 to 100 million annual cases, 500,000 hospitalizations and as many as 22,000 deaths, mostly in children.
The experts believe Dengue fever's re-emergence is comparable to that of the West Nile virus.
West Nile virus first appeared in New York in 1999 and has now spread to the entire continental United States, Canada and Mexico and claimed the lives of at least 98 people in the United States last year.
Both viruses are carried by mosquitoes but Dengue which is caused by any of four related viruses can be transmitted by the Aedes albopictus species first seen in 1985 in the U.S. as well as the more common Aedes aegypti species.
Although most people infected with Dengue have no symptoms or just a mild fever, it can cause minor bleeding from the nose or gums.
Sometimes the disease leads to leakage of blood plasma out of the circulatory system and into tissues, causing blood pressure to drop; without treatment it can be fatal.
Severe forms of Dengue disease have been defined by the WHO as Dengue hemorrhagic fever (DHF) and Dengue shock syndrome (DSS).
The experts say the combined effects of global urbanization and increasing air travel are expected to make Dengue a growing international health problem for the foreseeable future.
NIAID allocated $33.2 million in 2007 for nearly 60 Dengue research projects, including basic research on Dengue, DHF and DSS; projects to develop vaccines, diagnostics and therapeutics for the disease; and clinical trials of vaccines.