First cluster of Zika virus cases reported in Bangladesh: Icddr,b

Scientists at the International Centre for Diarrhoeal Disease Research, Bangladesh (Icddr,b) have identified the country’s first cluster of Zika virus cases.

Five confirmed infections were detected among patient samples collected in 2023.

The findings, published on the Icddr,b website on Monday, highlight a significant public health concern.

The Zika virus, an emerging pathogen, was first recorded in humans in Nigeria in 1954 and remained undetected in Asia and Africa for more than fifty years.

Bangladesh’s first confirmed Zika case was identified through a retrospective surveillance study conducted by the Institute of Epidemiology, Disease Control & Research (IEDCR) in 2016. The positive sample, collected in 2014 from a patient without a history of international travel, indicated that the virus had been circulating in the country before the large-scale outbreak in Brazil in 2015.

In the latest study, researchers screened 152 patients with fever and at least one other Zika-related symptom at Icddr,b’s diagnostic facility in Mohakhali, Dhaka. PCR-based testing confirmed Zika infection in five individuals, suggesting the need for a broader nationwide investigation to assess the actual prevalence of the virus.

The infected individuals lived within a one-kilometer radius of each other and had not traveled outside Bangladesh in the past two years. They were tested within the span of a month, indicating a potential localized transmission chain. Additionally, one of the patients was co-infected with dengue virus, marking the first documented case of Zika and dengue co-infection in Bangladesh.

Zika virus infections are often underdiagnosed and underreported due to mild or asymptomatic cases. Only around 20% of infected individuals develop noticeable symptoms, which commonly include fever, headache, and muscle pain—symptoms similar to dengue and chikungunya.

While Zika infection is rarely fatal in healthy individuals, it poses severe risks to pregnant women. The virus can cause microcephaly in newborns, leading to an increased risk of infant mortality and intellectual disabilities. Given these serious complications, surveillance and control efforts are crucial to preventing widespread transmission.

Zika virus can spread through mosquito bites, sexual contact, blood transfusions, mother-to-child transmission, and potentially through non-sexual physical contact. The movement of Bangladeshi migrant workers in Zika-affected regions of Southeast Asia may facilitate the spread of the virus within and beyond their communities.

Implementing routine Zika screening for travelers returning from affected areas, increasing diagnostic capacity, and establishing systematic nationwide surveillance will be essential in mitigating future outbreaks.

Bangladesh’s tropical climate, characterized by high temperatures and prolonged monsoon seasons, provides ideal conditions for Aedes mosquitoes, which transmit multiple viruses, including dengue, chikungunya, and Zika. In recent years, dengue has emerged as a major public health crisis, with the country experiencing its largest outbreak in 2023, recording 321,179 infections and 1,705 deaths.

Given past global epidemics of chikungunya and Zika, proactive measures, including enhanced vector control and public health awareness, are vital in preventing another widespread outbreak in Bangladesh.