(Agencies)
Updated: 2008-01-19 15:13

A severe achy-joint fever spreading in Asia via mosquitoes could easily reach more countries in the region and potentially take hold in Europe and the United States, World Health Organization experts warn.

The fever, called chikungunya, is ravaging parts of Indonesia, sickening people with rashes, vomiting, headaches and joint pain so intense it is often too painful for victims to sit or stand.

"It's enormously disruptive ... the outbreaks are very abrupt and intense," said Michael Nathan, a mosquito-borne disease expert at the WHO in Geneva. "Lots and lots of people are seeking help all at the same time and services struggle to cope with that."'

Singapore reported eight suspected cases this week, the first time the virus has spread locally, according to a Ministry of Health statement. Officials were scouring the area to destroy mosquito breeding grounds, and tests were conducted to ensure no one else was infected, it said. Taiwan also detected three cases in travelers from Indonesia, two in December and another earlier last year.

Nearly 300 people in northern Italy were sickened in 2007 after an infected traveler came from India, the first time an imported case of the tropical disease sparked a local outbreak in Europe.

Although rarely fatal, the virus can lead to death in patients with other underlying health conditions and is especially hard on the elderly.

Symptoms are similar to dengue fever, another mosquito-borne disease, but joint and muscle pain is typically more intense and longer lasting with arthritis-like aches reported months or even years after infection. Dengue is considered more dangerous because it can cause internal bleeding that leads to death.

Chikungunya was first identified in Tanzania in the early 1950s and has caused periodic outbreaks in Asia and Africa since the 1960s. In 2005, the Indian Ocean island of Reunion, popular with French tourists, was devastated by the disease, with up to a third of the population sickened.

Researchers from the University of Texas discovered a mutation occurred during that outbreak, which allowed the disease to be spread efficiently by the Asian tiger mosquito. Previously, the Aedes aegypti, or yellow fever mosquito, was the main transmitter.

The tiger mosquito can survive in cooler climates, giving it a much wider geographic range, including Europe and North America. The virus could spread if an infected traveler is bitten and carries it into a new territory where other tiger mosquitoes can pass it on. The disease has shown up in the United States nearly 40 times but has never triggered an outbreak.

"With international travel being easy and fast, it is easy for the virus to be imported into a new region," said Stephen Higgs, co-author of the University of Texas findings published last month in the Public Library of Science journal PLoS Pathogens.

Health experts also say climate change is helping the virus spread because warmer temperatures are allowing mosquito-borne diseases, including malaria and dengue fever, to expand into areas that were previously too cold for breeding.

Warmer weather can also shorten mosquito life cycles, potentially doubling the number of insects born in one week, said Erna Tresnaningsih, director of animal-borne diseases at Indonesia's Ministry of Health.

"We'll have more mosquitoes, which need a shorter time to mature and will immediately seek the blood they need to breed," she said.

Chikungunya resurfaced in India in 2006, catching health officials off guard with its quick spread.

"Initially, we thought there would be 1,000 or 10,000 cases maximum, but in 2006 alone we had 1.4 million suspected cases," said Chusak Prasittisuk, a vector disease expert at WHO's Southeast Asia regional office in New Delhi. "It spread from two or three states to 17 states in India."