# Investigation of an outbreak of typhoid fever in a rural district of East Malaysia, 2019

## TL;DR

A 2019 typhoid fever outbreak in a rural area of East Malaysia was traced to a restaurant worker, with 35 cases identified and control measures implemented.

## Contribution

This study identifies the source and transmission dynamics of a typhoid fever outbreak in a rural Malaysian district and proposes prevention strategies.

## Key findings

- 35 cases of typhoid fever were identified, with 80% among indigenous ethnic groups and 34.3% in children aged 7–17 years.
- The outbreak was traced to a restaurant worker who likely transmitted the infection through contaminated food or surfaces.
- Three clonal clusters of S. Typhi isolates were identified, with a dominant cluster linked to the index case and a food handler.

## Abstract

Following the notification of two cases of typhoid fever to the Kudat District Health Office in February 2019, an investigation was conducted in a rural district in Sabah, East Malaysia, to determine the extent, characteristics and source of the outbreak.

This epidemiological study used both active and passive case detection. Environmental samples were taken from water sources, food-handling areas and waste sites, and were analysed for the presence of Salmonella enterica serotype Typhi as part of the standard protocol during an announced typhoid fever outbreak. Clinical specimens underwent culture and sensitivity testing, with samples that were positive for S. Typhi analysed using pulsed-field gel electrophoresis to determine clonal relationships.

A total of 35 cases of typhoid fever were identified during 3 months. Twenty-eight cases (80.0%) occurred among Sabah’s indigenous ethnic groups, and 12 of these (34.3%) occurred in people aged 7–17 years. The index case, along with six other cases, had a history of consuming smashed fried chicken from a local restaurant. Analysis revealed three clonal clusters of S. Typhi isolates, with a dominant pattern found in 18 cases, which included the index case and a food handler from the implicated restaurant. Two paediatric patients experienced a relapse after initial treatment with intravenous antibiotics.

The source of the outbreak was most likely the infected restaurant worker who prepared chicken without wearing gloves; transmission most likely occurred through contaminated food or surfaces. Immediate steps to control the outbreak included chlorinating water wells, disinfecting waste disposal areas and promptly vaccinating all food handlers, including those working in street food settings. Recommendations for preventing future outbreaks include strengthening surveillance systems for acute gastroenteritis, conducting education campaigns to promote safe food-handling practices and implementing measures to improve vaccination coverage against typhoid fever among food handlers.