Prevalence of Shigellosis among household contacts of index cases in the EFGH catchment area, Dhaka, Bangladesh

TL;DR

This study found that many household members of children with shigellosis in Bangladesh are infected, often without symptoms, highlighting the need for better prevention strategies.

Contribution

The study identifies asymptomatic Shigella infections and key risk factors like improper food handling in urban slums of Bangladesh.

Findings

9% of household contacts tested positive for Shigella via culture, and 21% via qPCR.

75% of infected household contacts were adults, with most infections being asymptomatic.

Failure to reheat meals and use of non-flush toilets were significant risk factors for Shigella infection.

Abstract

This study aimed to estimate the prevalence of shigellosis among household contacts (HHCs) using data from the ‘Enterics for Global Health (EFGH)’ study, conducted at seven Asian and African countries.

In Bangladesh, the EFGH study was conducted in Maniknagar, Dhaka, to determine the burden of shigellosis among children aged 6–35 months. HHCs of Shigella-positive patients (index cases) were enrolled in this study. Stool specimens form contacts were collected within 7 days of enrollment of index cases and culture and qPCR were performed. Sociodemographic and behavioral information were obtained to identify risk factors.

A total of 400 HHCs of 118 index cases were enrolled, of which 36 (9%) were positive for Shigella spp. by culture, while qPCR revealed 21% (42/200) of contacts had Shigella infections. Individuals who failed to reheat meals before consumption had a two-fold higher risk of shigellosis compared to those who reheated meals, although other sociodemographic and behavioral factors did not show any significant association.

The study revealed a high burden of asymptomatic Shigella-infected individuals, emphasizing the need for systematic surveillance to assess the burden and develop effective preventive strategies to prevent the spread of the disease.

Asymptomatic individuals can play a key role in transmitting Shigella within communities in endemic settings. We assessed the prevalence and risk factors of Shigella infection among household contacts of culture-confirmed index cases in an urban slum of Dhaka, Bangladesh. Our study revealed a high proportion of household contacts were infected, with 97% of them excreting the organism asymptomatically. Index cases were children aged 6–35 months, and household members represented a range of age groups, with 75% being adults. Failure to reheat meals before consumption and the use of non-flush toilets were significant risk factors. These findings highlight the urgent need for interventions that extend beyond symptomatic case management, emphasizing safe food handling practices and improved sanitation to interrupt transmission chains effectively.

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