SINGAPORE - More attention must be paid to seniors with dengue as they are at a higher risk of severe illness and death, Professor Leo Yee Sin, executive director of Singapore's National Centre for Infectious Diseases (NCID), said on Wednesday (June 15).

She was speaking at the fifth Asia Dengue Summit, which was organised by the Asia Dengue Voice and Action group and held at Orchard Hotel from June 13 to 15.

The event saw more than 200 clinicians, researchers, government public health leaders and policymakers from across Asia discussing dengue management strategies for the region.

Citing studies from Singapore's Environmental Health Institute at the National Environment Agency, Prof Leo noted that at least 30 per cent of those aged 60 and above here have never had a dengue infection before.

Recovery from infection by one dengue virus provides lifelong immunity against that particular virus serotype.

"So you can see there's a huge population at risk in Singapore, that's very susceptible to dengue," said Prof Leo.

She added it is also harder to diagnose an older person with dengue. Citing a study from Taiwan, Prof Leo pointed out that fewer older dengue patients show symptoms of the disease, such as fever, aches and pain as well as rashes.

Despite this, the elderly tend to be at a higher risk of needing admission to the intensive care unit for dengue, and have more co-morbidities such as hypertension and renal failure.

Elderly dengue patients also have a higher death rate, said Prof Leo, adding that their age means they are less likely to be able to withstand the toll dengue takes on them.

"We really need to look very hard at how we can better manage older (people with dengue)," she said.

Another speaker at the summit, Dr Shirin Kalimuddin, who is a senior consultant at the Department of Infectious Diseases in Singapore General Hospital, also cautioned about the potential long-term effects of dengue infection on patients.

Noting that there have not been many studies on post-dengue chronic sequelae - the persistence of symptoms more than three months after infection - Dr Kalimuddin, who is also an assistant professor at Duke-NUS Medical School, said that the burden of the disease may be underestimated.

In a study, which is still under review, Dr Kalimuddin and other researchers examined about 200 patients, about a quarter of whom had dengue infection.

They found that about three months later, some 18 per cent of them continued to report symptoms, including fatigue, headaches, and impaired memory and concentration.

They also reported functional impairment and a lower health-related quality of life.

Acknowledging that her research was done with a small sample size and other limitations, Dr Kalimuddin nevertheless said that it raised some important questions, including whether vaccines and therapeutics could be tailored towards addressing not just acute dengue, but its chronic symptoms as well.

 A third speaker at the summit, Associate Professor Somia Iqtadar from King Edward Medical University in Pakistan, warned that dengue infection during pregnancy is associated with higher maternal and perinatal mortality rates.

"There is a constellation of different problems which we can encounter if we have dengue in a pregnant female," said Prof Somia, citing increased chances of preterm labour, foetal distress and miscarriages as just some examples.

Calling for a rigorous programme specifically designed for the management of pregnant dengue patients, she said: "We need admission and timely disease management (for) infected pregnant women, because this is of utmost importance to save the life of the mother and the foetus."