El Nino could trigger dengue epidemic in South-east Asia

Current phenomenon is set to be among most intense in 20 years, say researchers

A boy covers his nose while a worker fumigates outside a residential area in Paranaque city, metro Manila, on Sept 26, 2015.
A boy covers his nose while a worker fumigates outside a residential area in Paranaque city, metro Manila, on Sept 26, 2015.PHOTO: REUTERS

MIAMI • The weather phenomenon known as El Nino could lead to an epidemic of dengue fever cases in South-east Asia, international researchers said.

Cases of dengue fever have been shown to rise along with the ocean warming trend, which occurs some years but not others.

The current El Nino, which has already begun and is forecast to last into next year, is expected to be among the most intense in 20 years, researchers say.

"Large dengue epidemics occur unexpectedly, which can overburden the healthcare systems," lead author Willem van Panhuis, assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health, said yesterday. "Our analysis shows that elevated temperatures can create the ideal circumstance for large-scale dengue epidemics to spread across a wide region."

Researchers analysed 18 years of monthly dengue surveillance reports across South-east Asia, according to the study published in the Proceedings Of The National Academy Of Sciences, a peer-reviewed US journal.

They found trends among the total of 3.5 million reported cases in eight countries.

During the last particularly strong El Nino season, in 1997 and 1998, "dengue transmission was very high, matching up perfectly with high temperatures that allowed mosquitoes to reproduce faster and spread dengue virus more efficiently", said the study.

The higher temperatures in the tropics and subtropics were brought on by El Nino, moving warm sea water temperatures in the eastern Pacific towards the west.

Dengue fever is caused by a mosquito-borne virus in the tropics and subtropics, causing nearly 400 million infections each year.

Symptoms can include fever, severe pain, headache, nausea, vomiting and skin rashes. In some patients, the infection can be fatal.

There is no vaccine to prevent dengue and no medical treatment other than acetaminophen.

The World Health Organisation says the global incidence of dengue has grown dramatically in recent decades, and about half of the world's population is now at risk.

Several South-east Asian countries have reported a dramatic surge in dengue fever cases this year. Vietnam reported some 32,900 cases in the first nine months of this year, almost double that of the same period last year, which recorded 18,800 cases. Last month alone, there were more than 10,000 cases of dengue fever, including six fatalities.

Myanmar also saw a spike in cases across the country, particularly in flood-struck regions.

For the first nine months of this year, the Ministry of Health recorded 35,993 cases, almost three times as high as last year, reported The Myanmar Times. The ministry added that the number of cases this year thus far has been the highest since the government began keeping records in 1965.


A version of this article appeared in the print edition of The Straits Times on October 07, 2015, with the headline 'El Nino could trigger dengue epidemic in South-east Asia'. Subscribe