Thailand just reported two cases of newborns with Zika-related microcephaly, the first time the birth defect has been linked to the virus in Southeast Asia.
An investigation by Thailand's department of disease control determined that the mosquito-borne virus was connected to the two recent cases of microcephaly, a condition where a child is born with a small head and an underdeveloped brain. The news of these first cases in the country comes amid growing concern about the virus's prevalence there, as it's a popular destination for foreign travelers.
The unprecedented outbreak of the virus in Brazil and recent research have led experts to confirm a strong connection between Zika-infected mothers and their babies being born with the birth defect. The first cases surfaced there in May 2015.
Earlier this week Thailand revealed it was investigating four microcephaly cases to determine whether the mothers had contracted Zika during pregnancy. They ultimately found that just two of the four microcephaly cases were actually caused by Zika, but the officials did not reveal details about where they occurred or how the mothers became infected.
So far 25 women in Thailand have contracted the virus, with nearly 350 Zika infections in the country reported in the past nine months.
On Thursday, the World Health Organization said that if the Thai microcephaly cases were linked to Zika, the next step would be to investigate what strain of the virus was involved. Despite the continued reports of new Zika infections in Southeast Asia, however, the UN's health agency said the global risk had not increased.
"Countries across the region must continue to strengthen measures aimed at preventing, detecting, and responding to Zika virus transmission," WHO said in its Sept. 29 situation report.
The U.S. Centers for Disease Control and Prevention also issued updated guidance this week for travel to Southeast Asia. The health agency recommended that pregnant women "consider postponing" any nonessential travel to 11 countries in the region, including Thailand, Indonesia, Malaysia, and Vietnam.
Zika is not new to the region, and it's endemic in certain areas, but according the CDC the heightened concern comes from variations in the number of cases being reported. While many people living in these countries are likely to have immunity, those traveling from countries like the U.S., where the virus is a relatively new threat, could still be vulnerable.
Since Brazil's first cases of microcephaly came to light in May of last year, more than 2,000 cases have been linked to Zika worldwide.