SINGAPORE is fighting the biggest outbreak of locally transmitted malaria it has seen in possibly more than a decade. Over the past five weeks, at least 15 people have been infected with malaria locally, with the latest case only known yesterday.
The last time there was an outbreak was in 2006, when 13 people caught the disease locally.
Of greater concern is the apparent spontaneous emergence of the parasitic infection in two distinct locations - Sungei Kadut/Mandai in the north and Jurong Island in the south-west.
Like dengue, which is endemic here, malaria is a mosquito-borne disease. But it is more severe and deadly, said Dr Lim Poh Lian, a senior infectious disease consultant at the Communicable Disease Centre (CDC).
Symptoms of malaria include fever, headache, chills and vomiting. They usually appear between 10 and 15 days after the mosquito bites, although the parasites have been known to lie dormant for up to a year.
If untreated, the malarial parasites could burst red blood cells, leading to seizures and ultimately death.
But 'malaria can be treated and cured', said Dr Lim. Patients are given one medicine to get rid of the parasites in their blood, and a different one to get rid of any that may lie dormant in their liver.
Singapore has been malaria-free since 1982 - with no sustained local transmissions - though it still sees between 100 and 300 imported cases a year. These are people who are sick here, after getting infected overseas. They are quickly isolated to prevent the disease from spreading here.
There have been isolated cases of local transmissions - when an Anopheles mosquito bites someone with malaria and passes it on to another person - but these are usually just a handful a year.
This time, five people on Jurong Island became ill between May 3 and May 25, while 10 people in the north started falling ill from May 16.
The only resident infected is a full-time national serviceman. The rest are foreign workers living in dormitories. None have travelled recently.
Dr Lim said the majority of patients were found to have the same strain of malarial parasite, Plasmodium vivax, the most common of five strains in this part of the world, and not the one causing the most severe illness.
She added that there is no need to get paranoid over this, since the National Environment Agency (NEA) is 'on top of the situation'.
NEA has up to 50 people in each area where the infected people live, actively seeking out and destroying mosquitoes.
This includes chemical fogging at night - when the Anopheles is most active - for three consecutive nights, followed by using a 'light trap' which attracts mosquitoes, to see if there are any still around.
The NEA said it has found different types of Anopheles mosquitoes at the two sites - but these have not been known to transmit malaria here.
A Health Ministry spokesman said doctors have been alerted 'to be vigilant' in looking out for possible malaria sufferers who have been near these two locations.
MOH has also asked the employers to refer any other sick workers to the CDC. The spokesman added: 'We are also conducting active case detection among workers at the area.'
Although no breeding sites have been found near the workers' living quarters, the NEA spokesman added: 'The dormitory operators are not letting up on their efforts and are equipping their residents with mosquito netting and mosquito repellent as a precautionary measure.'
Dr Lim's advice to people living near these areas is to use such repellents and wear long pants and socks, since the legs are a favourite feeding zone for mosquitoes.
