The impact of ambient temperature on Salmonella and Campylobacter infections in the context of climate change: A Systematic review and meta-analysis

Introduction: Various epidemiological studies have investigated the incidence of Salmonella and Campylobacter infections in response to climate variations. In this study, we have conducted a comprehensive review and analysis of the existing global epidemiological evidence in order to assess the association between temperature exposure and the risk of Salmonella and Campylobacter infections in diverse climatic zones.
Methods: A systematic literature search was conducted in PubMed, Scopus, Embase, and Web of Science from January 1990 to January 09, 2024. We included peer reviewed original observational studies reporting the association of increasing ambient temperatures with Salmonella and Campylobacter infection. A random effects meta-analysis was performed to pool the relative risks (RRs) per 1 ◦C increase in temperature. Additionally, we conducted subgroup analyses based on the Koppen Geiger climate zones. Finally, we evaluated the quality and strength of evidence using the Navigation Guide systematic review methodology framework.
Findings: The search process yielded 1367 studies, of which 50 studies met the inclusion criteria for the review. Out of the included studies, 36 were deemed suitable for meta-analysis; 21 studies (with 40 estimates) on Salmonellosis and 15 studies (with 22 estimates) on Campylobacteriosis. The meta-analysis showed that the risk of enteric infection incidence increased per 1°C rise in temperature by 6.0% (95% CI 5.0–7.0%) for Salmonellosis and by 4.0% (95% CI 3.0–6.0%) for Campylobacteriosis. Subgroup analyses by climate zones suggested greater effects of temperature in humid subtropical climate zone (RR = 1.12, 95% CI: 1.06–1.18) and warm humid continental climate zone (RR = 1.03, 95% CI: 1.02–1.04) for Salmonellosis and Campylobacteriosis respectively. The overall strength of evidence was found to be “sufficient” for Salmonellosis but “limited” for Campylobacteriosis. Our results showed that the risk of both enteric infections increased with temperatures, with varying risks across climate zones.