Severe Zika Infection Causes 13-fold Greater Mortality Risk in Children

Last year, the Region of the Americas reported over 42,127 Zika virus (ZIKV) cases, many including children. Some of these young Zika patients died from severe infections in their mother's wombs or immediately after birth. 

The findings of a new Original Investigation conducted in May 2024 should empower insights that develop protocols to prevent early mortality and improve child survival during Zika outbreaks.

Published in JAMA Network Open on January 23, 2025, this population-based study of mortality rates among 11.4 million children born with a severe Zika virus infection had a strikingly higher risk of overall and cause-specific mortality.

Young children with congenital Zika syndrome (CZS) had a 13-fold higher risk of death compared with those without CZS.

This study found the cause-specific mortality hazard ratio was 30.28.

Of 3,080 children notified as CZS cases, 444 (14.4%) died, including 154 (34.7%) from respiratory diseases, 152 (34.2%) from infectious and parasitic diseases, and 82 (18.5%) from nervous system diseases. 

These researchers wrote, 'In children with CZS, dysphagia may favor the premature escape of the bolus into the pharynx, increasing the risk of death due to airway obstruction and the acquisition of respiratory infections caused by bronchoaspiration.'

'This could potentially explain the high respiratory system mortality risk. Furthermore, other factors in children with CZS, such as phrenic nerve palsy with diaphragmatic paralysis22 and seizures, can increase the risk of pulmonary aspiration, leading to respiratory failure.'

A separate study published in Pediatrics in January 2025 concluded children exposed to ZIKV in utero, even without CZS, demonstrate a greater risk for neurodevelopmental delay in early childhood, with the timing of maternal infection being a significant predictive risk factor.

Additionally, the International Journal of Infectious Diseases published a study in 2025 showing that children with CZS will have more frequent hospitalizations in early childhood. Scientists have reported that ZIKV RNA is detectable in the semen of infected men for months and is found in newborn children.

Previous research focused on the 2015–2016 ZIKV outbreak in the Region of the Americas revealed the ability of ZIKV from the Asian lineage to cause birth defects of the brain and eyes, including severe microcephaly.

In the United States, the U.S. CDC reported 19 non-congenital Zika cases in the U.S. (1 imported case in Texas) last year. In 2023, the CDC reported five non-congenital cases in U.S. residents and 27 in U.S. territories.

The CDC says Zika-spreading mosquitoes are found throughout Puerto Rico.

Currently, the best way to avoid contracting ZIKV is to avoid being bitten by a virus-carrying mosquito.

As of January 24, 2025, no approved Zika vaccines exist, but vaccine candidates are currently conducting clinical research.