The first case of imported Zika infection in Singapore was announced on the mainstream media yesterday – a Singaporean permanent resident who had traveled to Sao Paulo, Brazil between 27th March and 7th May and who had developed symptoms on 10th May. According to the news report, he is recovering (Zika causes mild disease in adults) but will be quarantined at the Communicable Disease Centre to minimise the risk of transmission of the virus to local mosquitoes. The importation of Zika into Singapore is in many ways inevitable given that there are on average more than 5,000 tourist arrivals from South America each month (this figure excludes returning travelers who had gone to South America on business or holidays).

Screenshot from the online version of the Business Times (14th May 2016).

Depending on the continued spread of Zika in the Americas and Pacific islands, we should expect more cases over time, and perhaps some degree local transmission in the future as well. The map below (from the CDC site) shows the countries where active Zika transmission is occurring, as of 12th May.

Map of countries with active Zika transmission (from the US CDC Zika page).

What else is new about Zika?

• The virus’ effect on foetuses during pregnancy is beyond doubt, with both epidemiological evidence as well as mouse models demonstrating the direct effect of the virus (from two papers published in Cell and its sister journal Cell Stem Cell).
• Although the virus is cleared from the blood within a few days, it continues to be shed in urine for more than 5 days (potentially up to 15 days), and therefore urinary testing may be complementary to serum testing.
• In a rather troubling study that should be further confirmed, researchers showed that the presence of antibodies to dengue may enhance Zika infection.