The fifth dengue death in Singapore, this early in the year, has highlighted the vulnerability of senior citizens here.
Ironically, this might be because of Singapore's effectiveness at controlling dengue infections. Thirteen of the 21 dengue victims since 2013, including the 79-year-old man who died on Sunday, were aged 60 or above, and only two were younger than 45.
Singapore is considered by the World Health Organisation (WHO) to be one of the most successful nations in dengue control.
But the increase in the average age at which people are first infected has led to more older people falling ill, said a WHO report.
Older people are more likely than younger people to fall ill when infected with dengue, especially when they have not been infected before, a 2007 study found.
"We are a victim of our own successes," said Dr Leong Hoe Nam, an infectious disease specialist at Mount Elizabeth Novena Hospital.
A global study last year identified numerous factors like ethnicity, education and health, alongside age, as possible factors in the odds of dying from dengue. However, in Singapore, age is the major factor because of Singapore's dengue control, said Dr Leong.
Singapore effectively targets the virus by promptly exterminating Aedes mosquitoes where dengue cases have been reported.
Consequently, only about 1 per cent of the Aedes mosquitoes at any given dengue hot spot actually harbour the virus, compared with about 5 per cent in some countries in South-east Asia and Latin America, Dr Leong said.
Once infected, the most important way to fight the virus and lower the risk of death is to ensure adequate hydration, said doctors.
This is because the main complication in severe dengue is vascular leakage, where fluid leaks out of blood capillaries.
But elderly patients, who have weaker immune systems that may be compounded by pre-existing medical conditions like heart or kidney problems, may not be able to handle the additional water load.
The doctors explained that fluctuations in fluid balance caused by dengue and by attempts at hydration may cause heart or kidney failure as these organs are too weak to handle the changes. Dr Leong said: "The very hydration that helps fight dengue will kill these people because of system overload."
A 62-year-old dengue survivor, who wanted to be known only as Madam Yeo, said that soon after admission to hospital in January this year, she fell into a coma, with multiple organs on the brink of failure, for more than a week while doctors struggled to save her life.
"The doctors were very happy when I woke up," she added.
Dr Leong, one of the doctors who treated Madam Yeo, said a team of doctors working together is crucial in such situations.
Professor Leo Yee Sin, director of the Institute of Infectious Diseases and Epidemiology at Tan Tock Seng Hospital, said that seniors with pre-existing medical conditions, suspected to have dengue, should seek medical attention as soon as possible. Prof Leo said the hospital has a lower threshold for admitting seniors with pre-existing conditions for close monitoring of their condition and management of their fluid balance.
"Singapore is entering a different dengue era where we are seeing much older adults - many with pre-existing single or multiple chronic illnesses," she added.
"More studies to understand the different disease manifestations, and explore the latest technologies to enhance management of these individuals, are urgently needed."
Meanwhile, some residents of Jalan Tenaga, an estate of mostly HDB housing near Eunos, where the latest dengue victim had lived, are not worried. Mr Henry Cheong, 66, who works in the construction industry, said: "I always get bitten by mosquitoes, but nothing happens."
Mr Mohammad Salihin Hussen, 41, who works on miscellaneous projects, added: "Dengue isn't only here - it can be anywhere."
•Additional reporting by Audrey Tan and Rachel Agatha Oh