Mon, Aug 27, 2007 - Page 2 News List

Kaohsiung at risk for type-three dengue

By Angelica Oung  /  STAFF REPORTER

An epidemiological study of more than 2,000 Kaohsiung City residents suggests that the population of the city could be more at risk from type-three dengue fever, the most prevalent type in Southeast Asia, a Centers for Disease Control (CDC) researcher said.

There are four strains of the dengue fever virus, type one to type four, said Huang Chih-hsiung (黃智雄), a researcher at the CDC's laboratory research division.

More than a quarter of the city's residents sampled in the study tested positive for dengue fever antibodies, showing that they had contracted the disease at least once before, Huang said. The elderly are even more likely to have been previously infected, with 65 percent of those above 65 testing positive for dengue antibodies.

"In our study we found that type-one antibodies are the most prevalent, followed by type two antibodies," Huang said. "Since those with antibodies of a particular type of dengue are immune from future infections of that type, this makes type three dengue fever the most likely culprit for any future epidemics."

Type-three dengue fever is also the type that is most prevalent in Southeast Asia, Huang said.

A prior infection increases one's risk of dying from dengue, he said.

"No matter what type of dengue fever, it is very unlikely for someone to fall seriously ill the first time they get the disease," said Chou Ming-yuan (周明淵), the chief physician of the infectious disease section at Cheng Hsin rehabilitation medical center.

"However, if the patient falls ill from another of the four types of dengue fever, this secondary infection is much more dangerous," Chou said.

While the body has immunity from the dengue type that causes the original infection, the immune system reacts to all dengue infections as if it is dealing with the original type, leaving the body more vulnerable to one of the other types, Chou said.

"Individuals who are re-infected with dengue are much more likely to develop the more serious dengue hemorrhagic fever, a potentially deadly condition," Chou said.

Chou declined to answer whether a third bout of the disease from yet another dengue type would be more dangerous still.

"I haven't seen anyone that unlucky yet," Chou said. "Two infections are rare enough."

Although the study is interesting to epidemiologists seeking to further their understanding of dengue fever and track future trends in the disease, Chou said that his advice for the public is still the same.

"The most important task in dengue fever remains mosquito control," Chou said.

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