Scientists who studied the sequence of Singapore’s Zika virus outbreak have determined that the strain likely did not come from Brazil, the country’s Ministry of Health said this weekend.
The analysis of two patients in a local so-called “cluster” has “found that the virus belongs to the Asian lineage and likely evolved from the strain that was already circulating in Southeast Asia,” officials said in a statement on Saturday.
As of Sunday night—one week after the country received its first alert of a local Zika transmission, triggering widespread panic and fumigations in affected neighborhoods—Singapore’s total number of cases had surged to 242, according to local newspaper The Straits Times.
That included “a potential new cluster, involving one previously reported case and a new case,” the health ministry said on Sunday. It said it had “detected and destroyed” 62 different breeding habitats for the Aedes mosquito in private homes and common areas located in the Aljunied Crescent and Sims Drive area, where the nation’s first cluster of cases was identified.
Experts say it’s still too early to tell what the origin of Singapore’s Zika would mean for its anxious residents. But the new findings could inject optimism into the small city-state, where volunteers have been scrambling to stamp out mosquito breeding and retailers are working to restock their aisles with insect repellent.
The trace of the virus back to an Asian lineage could potentially imply a lower chance of pregnant Singaporeans delivering children affected by microcephaly, the birth defect associated with Zika in other parts of the world, said one expert. That defect can hinder babies’ brain development and result in abnormally small heads.
“I need to look at the data more closely. But given that it’s distanced from the Brazil virus, then certainly the likelihood of microcephaly here will be more distant,” Dr. Leong Hoe Nam, an infectious diseases specialist from Mount Elizabeth Novena Hospital, told The Straits Times.
Another infectious diseases specialist, Paul Tambyah, told the paper that Zika virus in Southeast Asia dates back to the 1960s. “This is good news because people in the region have higher chances of having built up immunity to a Southeast Asian strain,” the publication reported.