Soe Sint San remembers being hospitalised with a severe case of dengue fever when she was around eight years old.
She caught it visiting Myanmar and was placed on a drip with high fevers.
It took her 10 days to recover.
"From what I can remember the doctor informed me that if the fever was more severe than what I had, I would have to get a blood transfusion," Ms San told the ABC.
She is now 25 years old, and the mosquito-transmitted virus remains a common concern in the Singaporean's life.
Dengue fever has been endemic in the tropical island city-state and several countries in the region for decades.
The humid climate makes Singapore the perfect breeding ground for Aedes mosquitoes, which carry the virus.
"Schools in Singapore have awareness lessons regarding dengue fever," Ms San said.
Severe dengue is a leading cause of serious illness and death in some Asian and Latin American countries, but the vast majority of cases are mild.
Singapore has been successful in reducing transmission of the virus over the past 50 years with its vector control program, which works to keep the mosquito population low.
But recently, cases have been rapidly rising.
Peak season only began on June 1, and already 2022 is shaping up to have one of the worst outbreaks on record.
Cases have increased by 285 per cent compared to the same time last year, according to the latest World Health Organization (WHO) data.
So how threatening is the situation and should locals and travellers be worried about the significant spike in cases?
What's fuelling the rise in cases?
Last month, the Minister for Home Affairs warned that Singapore was at an "emergency phase," grappling with a significant rise in cases.
Total cases in 2022 have already exceeded 13,000, according to figures from Singapore's National Environment Agency (NEA).
That's compared to a total of 5,258 infections reported throughout last year.
"The weekly number of dengue cases is expected to rise and hit another historical peak, surpassing the highest weekly figure of 1,787 cases seen in 2020, and may even exceed 2,000 in the month of June," the NEA said last week.
It is advising people to "take urgent action to break disease transmission" by removing potential mosquito breeding habitats in their homes.
The current outbreak is the largest Singapore has seen since 2020, when it recorded around 35,300 cases and 28 deaths.
Dr Leong Hoe Nam — an infectious diseases expert at Singapore's Rophi Clinic — said that, depending on herd immunity, "there are usually a few good years, and then a few bad years".
"We are the victims of our earlier successes," Dr Nam told the ABC.
Immunity is already low for the common dengue type 1 and 2 strain, and the current outbreak appears to be the rarer dengue types 3 and 4, Dr Nam said.
"[The] new strain of dengue has taken a foothold," he said.
"Singaporeans have not seen dengue 3 and 4 consistently until five to 10 years ago. So, overall, the herd immunity to these two strains [is] extremely low."
These days, less than 9 per cent of children in Singapore have contracted dengue fever by age nine.
Whereas, in neighbouring countries, this can vary from 40 to 90 per cent, Dr Nam said.
He attributes the decline to Singapore's good vector control program.
Recovery from infection is believed to provide lifelong immunity, but only for a particular strain, which means the population is now particularly vulnerable.
"This would drive numbers to the roof."
He added that it will inevitably put a strain on the hospital system which is already pressed due to COVID-19.
This year, around 10 per cent of dengue fever cases have required hospitalisation, the Ministry of Health told the ABC.
While this is slightly lower compared to previous years, the number of people presenting to emergency departments (EDs) has been increasing due to the recent surge in cases.
"They contribute to about 2 per cent of total ED attendances and admissions, but remain at a manageable level," the ministry said.
Dr Alex Cook from the National University of Singapore said warmer temperatures could also be fuelling the rise in cases.
"It's been quite hot lately in Singapore and we know temperature can influence the transmissibility of dengue … within the mosquito, the virus can replicate faster under warmer conditions," he said.
"Singapore is already a sweet spot for dengue transmission. We have the right temperature for mosquitoes to thrive year-round."
What action should individuals take?
Dengue fever is mainly transmitted by the bite of infected Aedes aegypti or Aedes albopictus mosquitoes.
It's then passed on from people to mosquito to people.
"So you're not going to spread it to your household members unless a mosquito comes and bites you and then goes on to bite your family members," Dr Cook said.
If you become ill with the virus, the fever can sometimes be accompanied by a rash, headache, joint and muscle pain, or nausea and vomiting
"Dengue does kill people, but a relatively small fraction, because the majority of people will recover with enough rest," Dr Cook said.
"However, there is a subset of people who will get a more severe disease … it's thought that, when you get a second infection with dengue, you are more likely to get severe dengue, because of a strange immunological response to getting closely related viruses."
In addition to taking measures to repel mosquitoes from the home, Dr Cook said there's good public health information that can be sent to mobile apps alerting people to outbreaks.
It gives you the chance to be better prepared by wearing long pants, long sleeves and using mosquito spray, he said.
The government still relies on vector control as the most effective way to prevent the spread of dengue.
There is only one dengue fever vaccine approved for use in Singapore and its use is limited to people aged 12 to 45 years who are living in endemic area.
The Dengvaxia vaccine can also be potentially harmful to people who have not had a previous dengue fever infection.
Australian travellers are not recommended to receive Dengvaxia for short-term stays.
Instead, the advice is to wear protective clothing and use an insect repellent that contains DEET (N,N-diethyl-m-toluamide) or picaridin.
Singapore adopts Australia's mosquito eradication program
Australia has been successful in nearly eradicating dengue fever in Far North Queensland since it began a program to rid the region of the virus in 2011.
And due to COVID-19 travel restrictions, there was a significant drop in dengue cases for 2021 and early 2022, compared to previous years.
Queensland was the launch pad for an eradication program that the World Mosquito Program (WMP) hoped would save millions of lives worldwide.
It involves introducing the Wolbachia bacterium into the region's mosquito population through a staggered breeding program.
Wolbachia has been found to reduce the transmission of dengue in the Aedes aegypti mosquito.
For the past five years, Singapore has been implementing its own program, Project Wolbachia, across high-risk areas.
In July 2021, the NEA reported that Singapore had achieved up to 98 per cent suppression of the urban Aedes aegypti mosquito population and 88 per cent fewer dengue cases at study sites.
It plans to continue expanding the project.
