Aedes aegypti mosquito that spreads dengue fever gets a blood meal from a human host. (James Gathany/CDC)

New research may help scientists develop better therapies to treat dengue fever, a debilitating illness that sickens millions of people in tropical and sub-tropical areas each year.

Dengue fever is spread by Aedes mosquitoes, and almost half of the world's population is at risk of infection, suggests a new study released Wednesday in the journal Nature.

The painful illness leads to 20,000 deaths worldwide each year, according to the U.S. National Institutes of Health.

Researchers have discovered that Aedes mosquitoes have dozens of areas in their cells that could be potential targets for drugs or a vaccine, the study says.

The study's authors identified about 40 "host factors" — cellular components in mosquitoes and humans that dengue virus uses to multiply inside their hosts after infecting them.

"The high prevalence, lack of an effective vaccine, and absence of specific treatment conspire to make dengue fever a global public health threat," Mariano Garcia-Blanco, of Duke University in Durham, N.C., and his co-authors wrote.

Each of the newly identified host factors is a potential target that could be used to block or slow dengue infection, Garcia-Blanco said.

"If we can find a weakness in the virus, we can design a strategy to fight it," he said in a release. "This study has helped us identify some gaps in dengue's armour."

All viruses co-opt parts of the cells they invade. But dengue viruses are thought to need more such host factors since they have little genetic material of their own, Garcia-Barco explained.

Until now, only a handful of human or mosquito dengue virus host factors had been found.

New avenues for treatment

To find the host factors, researchers painstakingly knocked out one gene segment at a time using fruit flies infected with dengue virus. That way the researchers could find what the dengue virus needs to grow efficiently.

They then infected human cells with the same virus, finding 42 dengue-specific host factors that are important for infecting humans.

It's these host factors that could serve as targets for new kinds of drugs, Garcia-Barco said.

"Their discovery should spur a better understanding of how dengue virus causes illness and open new avenues for developing specific treatments for a disease that exacts a huge global burden," said Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, which funded the research.

A couple of dengue vaccines are in development, which could be important for controlling dengue epidemics, such as the ones currently striking Brazil and Bolivia.

Currently, fluids, rest and non-Aspirin pain and fever reducers are used to treat dengue.

Last year, the WHO warned climate change means the breeding cycle of mosquitoes is shortening which allows them to multiply at a faster rate and increase the threat of diseases such as dengue fever and malaria.