SINGAPORE: Two patients in Singapore were infected with a listeria strain similar to an outbreak in Australia tied to rockmelons, according to a statement issued by the Ministry of Health (MOH) on Monday morning (Apr 16).
One patient has recovered while the other died for reasons not due to the listeria infection, the ministry said.
MOH said on Monday that initial epidemiological investigations were conducted immediately upon the notification of listeria cases in Singapore earlier this year.
These cases did not show a link to the Australian outbreak.
Further laboratory investigations were conducted, and two cases out of the five tested were found to be infected with a listeria strain similar to that in an outbreak in Australia.
"The Ministry of Health’s National Public Health Laboratory has since completed genetic sequence analysis on listeria bacteria strains obtained from five patients who had listeria disease this year", the ministry said.
"Two cases were found to be infected by the listeria strain ST240, which had a similar gene sequence to the listeria strain found in a patient in Australia affected by the outbreak of listeriosis in Australia this year," it added.
NO FURTHER PUBLIC HEALTH RISK: MOH
Australia's rockmelon listeria outbreak killed seven people and caused one miscarriage between Jan 17 and Apr 6, the World Health Organization (WHO) said last week.
The deaths were linked to the consumption of rockmelons contaminated with listeria. The rockmelons were exported to at least nine countries, including Singapore, the WHO said.
Singapore's Agri-Food and Veterinary Authority on Mar 8 announced a recall of all rockmelons from Australia as a "precautionary measure".
At least two consignments of rockmelons, which were traced to a specific Australian grower said to be implicated in the outbreak, were sold in Sheng Siong stores and wet markets.
In a statement on Mar 12, MOH said that one case of listeria at the Singapore General Hospital (SGH) was not linked to the consumption of rockmelons.
It added that up to Mar 12, there had been no reported cases of listeriosis linked to the consumption of rockmelons in Singapore.
MOH had also informed doctors to refer suspected cases of listeriosis for testing and treatment and to notify MOH of suspected cases.
Responding to queries from Channel NewsAsia, MOH on Monday said that the patient who had died was previously admitted at SGH, but that the cause of death was not due to the listeria infection.
"One of the cases was seen at SGH, who has passed away for reasons not due to the listeria infection. We are unable to provide more information due to patient confidentiality," MOH said.
"It is important to note that there is no further public health risk from the Australia outbreak as the risks have been mitigated through the recall of the implicated consignments in March 2018," MOH added. "We will continue to monitor the situation closely."
Listeria is a bacteria which causes listeriosis, a form of food poisoning that is treatable with antibiotics if diagnosed early.
Symptoms include fever and muscle aches, preceded by diarrhoea or other gastrointestinal symptoms that appear within 70 days after consumption of the contaminated food item.
"As the incubation period of listeria ranges from three to 70 days (typically one to four weeks), MOH has informed doctors to refer suspected cases of listeriosis for testing and treatment and to notify MOH of suspected cases," the ministry said.