More flu risk in tropics than previously thought

HONG KONG (Reuters) - People living in warmer climates suffer far more illness and death during flu outbreaks than previously imagined, Hong Kong researchers have found, and they urge vaccination for those most at risk, such as the elderly.

As a result, human influenza ought to be given a higher priority than is presently accorded to it in tropical and subtropical countries, said microbiologist Malik Peiris, the leader of a research team at the University of Hong Kong.

Ordinary influenza is responsible for about one million deaths worldwide each year. It has long been assumed the flu does not have a significant impact on health outside temperate regions.

But Peiris's team found that complications brought on by outbreaks of influenza in subtropical Hong Kong were similar to what is commonly found in the United States.

"During influenza outbreaks, hospital admissions increased, not just for respiratory diseases such as pneumonia but also for cardiovascular conditions and diabetes," Peiris's team wrote in a report to be published in April in the journal PLoS Medicine.

The team studied information on patients admitted to hospitals in Hong Kong between 1996 and 2000 and found influenza was responsible for 11.6 percent of admissions for respiratory disease.

It was also responsible for 1.5 percent of admissions for stroke, 1.8 percent of admissions for heart attacks and 3.5 percent of admissions for diabetes.

Hospitalization of children in Hong Kong was also marginally higher compared with figures reported in Western countries, Peiris told Reuters in an interview.

"What the study finds is that the impact of influenza, in this case, on hospitalizations in Hong Kong...is very similar to that documented in colder countries," Peiris said.

"In other words, influenza is just as big a problem, and in fact it may be even a bigger problem, in the tropics and subtropics as compared to colder countries," he said.