Dengue fever - a tropical disease once confined mainly to Africa and Asia - has become a growing problem in the Americas. So far, there is no drug to treat the mosquito-borne viral disease or any vaccine to prevent the infection. Public health experts say it has the potential to become a global health problem - more costly and difficult to control than malaria.
“Dengue had been eliminated in this hemisphere for quite a while but unfortunately it got reintroduced and has been generally growing since then," said Donald Shepherd.
Donald Shepherd spoke to VOA via Skype. He and his colleagues studied the economic burden of dengue fever on the Caribbean island of Puerto Rico (a U.S. territory). Shepherd says the figure they came up with was staggering.
“The economic cost of dengue averages $40 million per year," he said. "For the moderate size that Puerto Rico is it’s a substantial amount of money.”
Dengue is a viral infection spread by the bite of a small, stripe-bellied mosquito called Aedes aegypti. Outbreaks commonly rise after heavy summer rains, which create stagnant-water breeding areas for the mosquitoes that carry the virus.
Dengue can cause high fevers, headaches, severe muscle and joint pain, lack of appetite and fatigue. And in many parts of Asia and Africa where it is still endemic, the disease can prove fatal:
“A nasty feature of dengue is something that microbiologists call 'antibodies enhancement' - such that if you have had one of the dengue serotypes and then you get another one then the second one is a more severe illness than it would have been the first time," said Shepherd.
Experts say people can usually recover from these severe bouts of dengue, even with no drugs to fight the virus. But they need to receive good medical care, especially close monitoring of bodily fluids, and proper diagnosis of dengue's high fever, -- which can be mistakenly blamed on more common causes.
Dr. Dan Stinchcomb is the chief executive officer of Inviragen, which is developing a vaccine against the multiple dengue viruses. He says developing a safe vaccine has been a significant challenge.
“Because dengue is a problem that affects different ages throughout the world. In Southeast Asia it's mainly a childhood disease, but in Central and South America and other parts of Asia it can still affect adults as well," said Stinchcomb.
Experts say because the cost of treating dengue victims is so high, it's important that affected countries strengthen their traditional disease surveillance, prevention, and control efforts - until a drug or vaccine is available to combat the virus.