Chikungunya may be as widespread as dengue

Tania Tan, Straits Times 29 Jan 08;

CHIKUNGUNYA, once a little-known disease, could eventually reach the global proportions of dengue.

Singapore has seen 11 cases of the mosquito-borne disease in its first outbreak here, with victims stricken by fever, joint pains, chills and nausea. These symptoms usually last three to 10 days.

The situation could well get worse, warned infectious disease expert Paul Herrling, the head of corporate research at Novartis Institute for Tropical Diseases here.

'There's no reason, in essence, why chikungunya could not spread like dengue has,' said Professor Herrling in an interview with The Straits Times last week.

On Saturday, Health Minister Khaw Boon Wan said he harboured little hope of wiping chikungunya out here.

The main factor working for chikungunya, said Prof Herrling, is that it is spread by the Aedes mosquito, the same insect vector that carries the viruses which cause dengue.

This mosquito is thriving. Insecticides are beginning to lose their efficacy, Prof Herrling noted, with the disease vector becoming an increasingly stubborn problem in developed countries.

High population densities and increased travel also make it easier for the disease to jump borders.

First discovered in the 1700s, dengue was once confined to parts of Asia and Africa but has now reached global proportions, he said.

Similarly, outbreaks of chikungunya had occurred largely in India since the 1950s, but recent cases have been reported in countries as as far away as Italy.

'It's an interesting case of how diseases are beginning to re-emerge,' Prof Herrling said.

However, he added that it was too early to conclude that chikungunya is here to stay.

Similarly, Associate Professor Vincent Chow, who is with the National University of Singapore's department of microbiology, agreed it is possible the disease could become a global problem.

But he cautioned Singaporeans against hitting the panic button.

'With aggressive containment measures, it's possible to nip the problem in the bud,' he said.

All the cases emerging in the past two weeks have occurred in Little India.

To stem the current outbreak, the National Environment Agency has deployed 20 officers and hired 15 private pest control operators, almost three times more people than usual, to comb the Clive Street area for mosquito breeding sites.

They have also carried out repeated fogging there.


Pulling out all stops before it digs in
Lee Hui Chieh, Straits Times 29 Jan 08;

PROVISION shop owner Ong Long Chye, 46, lives and works in 'Chikungunya Central'.

His Clive Street shophouse is just two doors away from where the first man diagnosed with the disease lived.

In the two weeks since then, 10 others have been hit in this first local outbreak of the mosquito-borne, dengue-like disease.

The 13 patients before this had caught the disease overseas, and did not spread it to anyone here.

But Mr Ong is blase about the risk he takes.

He has had blood drawn for tests by health officers; environment officers have come by almost every day to look for mosquito breeding sites.

But ask the man if he has taken precautions, such as using mosquito nets or coils, or insect repellent, and his answer is no.

His reasons: 'The Government has already taken all measures. Besides, what's there to be worried about? It won't kill. The Government is more worried than we are.'

Indeed, the authorities have pulled out all stops to stamp out the infection before it digs in and becomes part of the landscape here.

Three times more environment officers than usual have been sent to the Clive Street area to wipe out mosquitoes and their breeding grounds.

They have even combed areas in Little India beyond Clive Street, as well as MacPherson, where the latest patient lives.

Health officers have taken blood samples from 1,795 people in the area for testing.

And then patients with, or suspected to still have, the virus in their blood have been isolated in the Communicable Disease Centre (CDC). Hospitalisation shields them from being bitten again by mosquitoes which could then bite other people and spread the virus further.

This step, which has not even been taken with dengue, harks back to the time when Sars hit in 2003, when those suspected to have had contact with patients were quarantined at home.

The Ministry of Health went one step further last Monday - it vested the CDC's clinical director, Associate Professor Leo Yee Sin, with the legal powers to quarantine anyone suspected to be infected with chikungunya, to order him to be examined, give blood or other samples for tests, and to be treated.

The last time the ministry appointed an official with such powers was during Sars.

People like Mr Ong may wonder: What's the fuss about?

The authorities believe, first, the disease is not as well studied as, say, dengue. While it is not usually fatal, it has killed some people in the past three years in India and on Reunion Island in the Indian Ocean, suggesting the virus may have become more deadly.

The fact that people have died means the illness cannot be taken lightly, Prof Leo said.

Second, the environment here is right for chikungunya to take root, she added.

The Aedes mosquito which transmits the virus flourishes here, and people here have zero immunity against chikungunya.

Third, Singapore's status as a destination or stop-

over for travellers means it is likely that some from chikungunya-endemic countries, infected back home, may bring the disease here.

In fact, although investigations are on, health officials here believe the outbreak began with an infected traveller who came to Singapore, fell sick here and was bitten by mosquitoes, which then infected other people.

Fourth, dengue is already here. Last year, it hit more than 8,800 people and killed 20. Having a similar disease entrenched here will complicate diagnosis, treatment, and containment.

So it is clear the tide needs to be stemmed.

The weapons used against dengue and Sars, now taken up against chikungunya, have yielded varying degrees of success.

Contact-tracing and mosquito-busting, for example, have been used for decades on dengue, but the illness shows no sign of bowing out from here.

But while the latest patient to be diagnosed with chikungunya appears to have been infected where he worked - in another part of Little India outside Clive Street - surveillance tests of 1,700 blood samples over the last year or so indicate there are no other chikungunya infections apart from the 13 imported cases and those in this outbreak.

This suggests the virus is not widespread in the community, so there may be time yet to stop this from happening.

The government machinery that has kicked into action seems to be aimed at just that.