Is dengue vaccine safe for patients?

16 Feb 2009, 1644 hrs IST, IANS

WASHINGTON: Researchers have developed a test to determine whether vaccines against a virus that infects 100 million people annually, now ready for clinical trials, should really protect patients from infection, or would make it more dangerous for them.

"Our study shows that the new test is likely superior to the standard test in its ability to tell whether a patient's response to a vaccine is safe," said Xia Jin, associate professor of medicine at the University of Rochester Medical Centre (URMC) and co-author of the study.

Cases of tropical, mosquito-borne dengue fever have been expanding globally for more than 50 years, with nearly a third of the human population in 100 countries now at risk of infection with the four types of dengue virus.

Infection with the dengue flavivirus, which is related to West Nile Virus and Yellow Fever, annually results in an estimated half a million hospitalisation and 22,000 deaths, mostly among infants, according to WHO.

After decades of absence in the US, the disease is causing illness again along the Texas-Mexico border, experts say and add that widespread dengue infection in the continental US is a real possibility.

A typical dengue infection confines a patient to bed for more than a week with fever and severe limb pains, but most recover. In less than five percent of cases, however, dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), often deadly complications, develop just as the fever breaks.

Mostly affecting babies between five and eight months, DHF causes victims to vomit and pass blood in their feces and urine. If diagnosed quickly, patients respond to intensive hospital treatment and fluids, but mortality can reach 15 percent when undiagnosed.

DSS comes when the infection has caused so much fluid to leak out of capillaries that there is not enough blood to supply organs. As of 2008, there were no antiviral drugs designed to treat dengue and no drug candidates in late-stage development, said an URMC release.