SINGAPORE - The Zika virus strains for locally transmitted cases and that of a case imported from Brazil in May are different, the authorities said on Thursday (Sept 8).
The Zika virus strain found in the recent cases at the Aljunied Crescent/Sims Drive cluster is similar to strains of the virus circulating in South-east Asia since the 1960s, it was announced at a briefing by the Ministry of Health's National Public Health Laboratory (NPHL) and A*Star's Bioinformatics Institute (BII) on Thursday.
The virus subsequently spread to French Polynesia in 2013 and to Brazil in 2015, they said.
On the other hand, the virus strain from a case imported to Singapore in May was similar to strains currently found in South America.
While both virus strains are of the Asian lineage, analysis suggests that the locally transmitted virus strain belongs to an earlier varietal, and was not recently imported from South America.
These were the findings of the NPHL and BII after sequencing the virus from the first imported case in May and two recent cases in Singapore.
There is no evidence to suggest that the different strains are linked to differences in severity or type of disease, researchers said at the briefing on Thursday.
"While there was no link established between microcephaly and Zika until the Brazil outbreak, we have to assume it is possible, hence the precautions that pregnant women are advised to take," said Dr Raymond Lin, head of the National Public Health Lab.
The findings will help with tracking the global spread and evolution of the Zika virus.
The sequences from the analyses will be put on public databases for the benefit of scientists elsewhere and for the World Health Organisation.