Zika virus resurfaces in Singapore

According to the Communicable Diseases Agency (CDA) in Singapore, 2 recent cases of Zika virus disease have been reported in Singapore (June 19, 2025). Neither were pregnant at the time of infection.

In follow up of the notifications, wastewater surveillance was undertaken by the National Environment Agency (NEA), to investigate possible locations for the disease. Urine has been found to be a reliable source of antigen if the disease is present.

Evidence of the disease was found in a northern region of Singapore. This area has also experienced a recent outbreak of dengue fever. Zika and Dengue are both transmitted by the bite of the same mosquito, Aedes aegypti or Aedes albopictus.

Mosquito reduction measures have been implemented in the area to reduce the possibility of more cases.

Wastewater surveillance may prove to be an important public health measure to reduce the risk of zika virus exposure when pregnant.

Zika virus symptoms, risks and health impacts

Unfortunately, the presence of Zika virus disease isn’t always appreciated early in a community outbreak – the disease is often mild and the rash minor. Large outbreaks can just happen as was the case in 2016 when the WHO Director- General of WHO declared the virus, and its impact on pregnant women, a public health emergency of international concern.

The virus has been found to cause severe foetal damage. A developmental disorder – congenital zika syndrome – has been described. The impact of the virus is likely to be more severe earlier in pregnancy.

More than 3,000 cases of congenital zika syndrome were reported during a large outbreak of the disease in Brazil between 2015 and 2018.

Zika has also been associated with the neurological disease – Guillain-Barre Syndrome.

Travel advice and prevention measures

Travellers who are pregnant or intending to get pregnant should reconsider their need to travel to areas of concern. Male partners should also be aware of viral persistence in semen. In one study, the virus persisted for an average of 20 days. In some cases, it remained a lot longer.

There is currently no vaccine for Zika, and prevention is mostly focused on mosquito avoidance measures.

Zika risk classification and global monitoring

The Centre for Disease Control (CDC) defines risk from high to low:

• Current outbreak being reported
• Past reports of zika virus disease
• Low level risk based on altitude (> 2000m)
• Country or location where zika has not been reported
• Country or location with no mosquitoes that transmit zika

A geographic risk assessment can be found here.

The World Health Organisation provided an update on global Zika in May 2024.