Measles has been an uncommon disease since Singapore introduced compulsory vaccinations in 1985.
But last year, Dr Low Kah Tzay, a paediatrician at Mount Elizabeth Hospital, saw a patient with the extremely contagious disease.
He was 11 months old and had yet to be vaccinated. "He had a very high fever, rashes and seizures, and was admitted to hospital for 10 days," Dr Low said.
"His parents were not sure where he contracted the disease."
Fortunately, he recovered fully.
Most people who are infected with measles do eventually recover completely, but a small group may develop serious complications.
Vaccination is the best preventive measure against measles, which is spread through air droplets and direct contact with nasal and throat secretions. Symptoms include fever, cough, runny nose and rashes.
It is so contagious that if one person has it, nine out of 10 people around him will also be infected if they are not protected, according to the Centers for Disease Control and Prevention in the United States.
But there are parents here who still do not get their children vaccinated while some may forget to take their child for the necessary second dose.
Fourteen out of 34 measles cases reported in children here in the first 20 weeks of this year occurred because they had missed their measles, mumps and rubella (MMR) vaccination, said the Ministry of Health (MOH) recently. The children were aged one to six years old.
Herd immunity can prevent spread of disease
Half of the children infected with measles were under one year old and not yet due for their first MMR vaccination, while three were below the age of one year who had received only one dose of MMR vaccination, said MOH.
Those at high risk
Measles is highly contagious. Anyone who is not protected against it can get infected.
Those at high risk of severe illness and complications from measles include infants and children aged below five.
Adults who are not vaccinated can get measles if they come into contact with infected individuals, said Dr Low Kah Tzay, a paediatrician at Mount Elizabeth Hospital.
Measles is still common in many developing countries, particularly in parts of Africa and Asia, said the World Health Organisation.
As symptoms in adults are less severe, they may not seek medical attention, Dr Low said. They may infect children, particularly those below 12 months of age who are too young to be vaccinated.
Vaccination is not recommended for babies, who usually carry antibodies that their mothers have passed them. "These antibodies can interfere with some live vaccines, like the MMR, and prevent a proper response to the vaccine to adequately prevent infections," said Dr Chan Poh Chong, head and senior consultant, division of general ambulatory paediatrics and adolescent medicine at the National University Hospital.
Dr Chan advised adults to go for vaccinations if they have not been vaccinated before, have an unknown vaccination history or do not have documented immunity.
Those who had measles as a child or had previously received two doses of MMR do not need to be vaccinated again, he said.
In all, Singapore had 50 measles cases, up from 17 in the same period a year ago. Of the 50, 10 were foreigners while six were adults.
The MMR vaccine here is given to children in two doses - the first at 12 months of age and the second at 15 to 18 months.
"This confers almost 97 per cent protection and will protect the individual for life," said Dr Chan Poh Chong, head and senior consultant, division of general ambulatory paediatrics and adolescent medicine at the National University Hospital.
Giving the vaccine to a person who had been in close contact with someone who had measles can help to prevent it. The vaccine can be given even after a person has been infected with measles, as it can help to reduce the severity and period of infection, said Dr Chan.
"The measles incubation period can be for up to three weeks and activating the immune system early with vaccination can stop or reduce the severity of the disease," he said.
In Singapore, the data for 2014 showed that more than 95 per cent of children had their first dose of MMR at two years of age, but only 76.2 per cent had the second dose, said Dr Chan.
Those who missed the second dose would have some but not adequate protection. They risk getting infected with measles.
Measles can sometimes cause severe complications in young children , said Dr Low.
"Measles infection in children below five years old can cause complications such as pneumonitis (lung inflammation), encephalitis (brain inflammation) and keratitis (eye inflammation)," he said.
This happens in about one out of 1,000 cases, he added.
However, there are parents who refuse the MMR shots out of the mistaken belief that the vaccination can cause developmental delay and learning disorders like autism, said Dr Chan.
"Many studies have concluded that MMR does not cause autism and the benefits of preventing measles or mumps and rubella infections far outweigh any possible risk from the vaccination," he said.
Others neglect to have the vaccination as they mistakenly believe that infectious diseases occur only in other countries, said Dr Low.
Getting vaccinated against measles has widespread benefits.
"Vaccination does not just protect that individual. It ensures that he does not spread it to others," said Dr Franco Wong, family physician and associate consultant at National Healthcare Group Polyclinics.
"Therefore, the more people are protected, the fewer the opportunities for measles to spread. This is what is known as herd immunity."
If fewer children are getting vaccinated, the overall herd immunity in the population here will be reduced, said Dr Low.
"Measles, mumps and rubella infections may become common again," he said.
There may be regular outbreaks, just like dengue fever or hand, foot and mouth outbreaks.
There is only one dengue vaccine in the world and it has not been approved for use in Singapore, while there is none for hand, foot and mouth disease.
If the number of measles cases increase, there will be an increased possibility of people sustaining rare complications such as brain damage or birth defects, said Dr Low.