Bangladesh has detected a cluster of Zika virus cases for the first time, in a worrying development in a country that is already struggling to contain the Aedes mosquito-borne dengue virus.

Although Zika virus infection is rarely fatal in healthy individuals, it poses a significant threat to pregnant women, as it can cause severe fetal complications such as microcephaly, leading to an increased risk of infant mortality and intellectual disability in the infant.

Not only through mosquitoes, the disease can also spread via sexual intercourse, blood transfusion, mother-to-child transmission, and non-sexual physical contact.

As many as five Zika-positive patients were identified by icddr,b scientists from 152 samples collected from the capital's Mohakhali area in 2023.

"The presence of Zika virus infection in five of these samples suggests that a larger, nationwide screening is necessary to quantify the true burden of the disease in Bangladesh," said the article by icddr,b scientists on the study's findings.

Read more

Zika virus may hide in organs protected from immune system

All five patients lived within a one-kilometre radius, and all of them were from the Mohakhali area, said Shafiul Alam, a scientist who was the principal investigator of the project.

They had no history of international travel in the past two years, indicating that the infection occurred locally, he told The Daily Star yesterday.

The patients all got tested within a month, suggesting they were part of the same chain of transmission.

One of the five cases was also infected with dengue virus, marking the first recorded instance of Zika-dengue coinfection in Bangladesh, said the article, which was published on the icddr,b website yesterday.

Both dengue and Zika are vector-borne diseases transmitted by Aedes mosquitoes. Coinfection by both diseases can cause more complexities, Alam said.

Zika virus was first detected in Bangladesh in 2016 after testing samples collected in 2014.

Read more

Is the world ready for the next pandemic?

To further understand the virus, the icddr,b scientists carried out whole genome sequencing of samples from three of the cases at the health research organisation's genome centre.

A comparative analysis found that the Bangladeshi Zika strains belong to the Asian lineage, which has been linked to microcephaly and other neurological disorders.

Experts believe that Bangladeshi migrant workers returning from Zika-affected countries in Southeast Asia could be a possible route for the virus to spread within and beyond their communities in Bangladesh.

"Zika cases are mostly overlooked," he said, adding that the Zika virus infection is likely underdiagnosed and underreported for two reasons.

Firstly, about 80 percent of infected individuals do not develop noticeable symptoms. Secondly, when symptoms such as headache, fever, and muscle pain do appear, they resemble those of dengue and chikungunya, leading to misdiagnosis.

Subsequently, icddr,b emphasised the need for routine Zika virus testing for travellers arriving from Zika-affected regions, enhanced diagnostic capacity, and systematic national surveillance to prevent future outbreaks.