Investigation of a Salmonella Typhi cluster among a Pacific Islander labour community in a fruit industry: perspective from a regional public health unit.

Abstract

Background: Australia is largely dependent on immigrant workers to bridge the employment gap in the agricultural sector and in agriculture-related food production; this poses a potential risk of the introduction and transmission of non-endemic vaccine preventable disease. We report the response to a Salmonella Typhi (S. Typhi) outbreak amongst workers from the Pacific Australia Labour Mobility (PALM) scheme in regional Queensland.

Methods: A cluster of invasive Salmonella infections was investigated in accordance with the Communicable Diseases Network Australia guidelines. Active case finding of the at-risk group was undertaken to identify potential causal links and further transmission.

Results: Three confirmed cases of S. Typhi were reported, all male, with a median age of 31 years (range: 29-33 years). All cases were hospitalised and were managed with antibiotics and supportive care, with a median illness duration of nine days. Full recovery was reported for all cases, without complications. No recent travel history or contact with a recent typhoid case were reported. We identified 310 individuals in the exposed cohort, with a median age of 31 years (range: 22-55 years), all males. Of the exposed cohort, 305/310 individuals (98·4%) provided a faecal sample for S. Typhi testing; all returned a negative result. Genomic sequencing concluded the likely source of infection in this outbreak was chronic carriage of S. Typhi.

Conclusion: Australia has had a significant increase in the number of PALM workers in regional areas, particularly within the agricultural sector, to mitigate employment gaps. A greater emphasis on culturally appropriate and linguistically sound hand hygiene education, and consideration of pre-employment health checks and vaccinations in these workers, would be beneficial in the reduction of communicable disease outbreaks.