# Public health surveillance of Vibrio cholerae in travellers returning to the United Kingdom

## TL;DR

This study analyzed Vibrio cholerae cases in UK travelers to understand its spread and risk factors, highlighting the need for better surveillance and global cooperation.

## Contribution

The study provides a detailed UK-based analysis of V. cholerae isolates from travelers, identifying key trends and recommending improved surveillance strategies.

## Key findings

- Cholera toxin-producing ST69 was the most common sequence type among isolates.
- Travel restrictions during the pandemic led to a significant drop in reported cases in 2020 and 2021.
- India, Pakistan, and Kenya were the most frequently reported travel destinations for V. cholerae cases.

## Abstract

Introduction.
Vibrio cholerae is a diverse species of bacteria that causes watery diarrhoea, vomiting and stomach cramps and is the aetiological agent of cholera.

Gap statement. Despite the global upsurge in notifications of cholera and concerns over the impact of climate change, systematic analysis of national and international surveillance data describing the microbiology and epidemiology of V. cholerae is sparse.

Aim. We reviewed the microbiology and epidemiology of V. cholerae isolated from travellers returning to the UK.

Methodology. All human isolates of V. cholerae detected from 2004 to 2024 were extracted from UK Health Security Agency reference laboratory surveillance systems. Microbiological data were analysed and linked to available epidemiological data and genome sequences for all isolates from 2016 to 2024.

Results. There were 984 notifications of V. cholerae from 2004 to 2024 (an average of 51 each year), of which 266 (27.0%) belonged to serogroup O1. There were over 180 different sequence types (STs), of which cholera toxin producing ST69 was the predominant type (n=99, 28.2%). The highest number of isolates was in 2010 (n=74), while the lowest was in 2020 (n=8) and 2021 (n=4) due to travel restrictions imposed during the COVID-19 pandemic. Children under the age of 10 and the middle-aged and elderly population were most susceptible to infection, and 51.6% of the cases were male. There was a seasonal peak in August and September. Travel was reported by 92.9% of cases, and the most frequently reported travel destinations were India, Pakistan and Kenya.

Conclusion. From the UK perspective, to assess the risk to food safety and to more accurately determine the clinical burden of V. cholerae, we recommend (i) widespread molecular testing of shellfish to monitor the emergence of V. cholerae in UK waters due to climate change and (ii) comprehensive testing of faecal specimens from non-travellers with gastrointestinal symptoms. Public health surveillance and information sharing at the global level is essential to assess the impact of investment in water, sanitation and hygiene initiatives for the prevention of cholera.