PETALING JAYA, June 25 — Questions are abound over the shift in dengue pattern leaving the Health Ministry with more questions than answers.

Its deputy director-general (medical) Datuk Dr S. Jeyaindran said based on the ministry’s observations over the past six months, dengue patients were now having symptoms not usually associated with the virus — in some cases, their organs failed.

“The symptoms are severe liver failure, brain infection and some have some form of heart rhythm disturbances,” he said.

“This is something new to us because about 10 to 12 years ago, we were talking about hemorrhagic fever, where people bleed from the mouth and stomach.

“A few years ago, we identified a dengue shock syndrome. Now, it’s multi organ failure. The question is, why?”

The reason behind this is yet to be determined but Dr Jeyaindran offered several possibilities.

“One possibility is that the virus has gone through an antigenic shift, meaning it has changed itself, resulting in the manifestation of the disease.”

He said there was a possibility of people having dengue and not know it.

“Over the years, dengue was so prevalent. Now, if you test your blood and you are aged between 30 and 40, there is a 50 per cent chance of being positive for dengue serotypes — meaning you had dengue but didn’t know it, or you actually had dengue.”

“There are 80 to 90 per cent of those aged between 55 and 60 who have some form of dengue infection, with or without their knowledge.”

Dr Jeyaindran said the ministry was working together with the Institute for Medical Research and various hospitals in the country to collect and analyse data on the dengue virus.

“Those who come in with severe dengue, their blood samples are taken with consent and if they have liver involvement, or brain infection (meningitis), then we would also like to test the tissues to identify the virus, to see if there are any changes in the virus or why it lead to liver failure. We know patients with dengue would get some form of hepatitis but it does not progress to liver failure. So the question is why do some patients progress and some recover?”

He said Singapore and Thailand faced the same situation and research findings were shared among them.

Dr Jeyaindran said this particular dengue virus had affected five per cent of the total number of dengue patients.

He said the cases occurred sporadically all over the country, which made it difficult for the ministry to determine the origins of the virus, adding it was important for people to take proactive measures to avoid getting infected.

“There was a study conducted by Universiti Malaya where a large number of people saying they think they would not get dengue. The truth is, you will never know if you are going to be one of the five per cent. Prevention is better than cure.”