Review supports temperature-infection increase link

An analysis has provided evidence of higher temperatures leading to more Salmonella and Campylobacter infections.

A search was conducted for peer-reviewed epidemiological studies published between January 1990 and March 2024.

Out of 3,472 results, 44 studies were included in the systematic review, covering more than 1 million cases each of Salmonella and Campylobacter infections. Overall, 22 studies examined Salmonella infection, 15 investigated Campylobacter, and seven assessed both infections. Studies covered 27 countries across five continents, but most were from high-income nations.

For each 1-degree C (33.8 degrees F) rise in temperature, the risk of Salmonella and Campylobacter infections increased by 5 percent.

Findings published in The Lancet journal biomedicine emphasize the relationship between temperature and the incidence of Salmonella and Campylobacter infections.

Elevated temperatures directly influence pathogen growth and replication while also indirectly impacting food storage, dietary habits such as consuming raw or undercooked foods, and food handling practices during warmer weather.

Scientists said results demonstrate the importance of implementing focused interventions and measures, such as the establishment of localized early warning systems and preventive strategies that account for climatic fluctuations.

National notifiable disease surveillance systems and regional health databases were the primary data sources in most studies, and hospital records were used twice. Exposure data were collected from national meteorological agencies in 40 studies, and remotely sensed and validated temperature data were used in the remaining four.

Salmonella and Campylobacter findings

For Salmonella infection studies, researchers observed a positive association between the annual mean temperature of the study locations and the effect estimates obtained from the Oceania continent, compared to estimates from Asia. However, they did not find any association between latitude, longitude, and countries’ GDP per capita.

Temperature plays a pivotal role in pathogen proliferation. Salmonella exhibits optimal multiplication within a temperature range of 35 to 37 degrees C (95 to 98.6 degrees F). However, when temperatures drop below 15 degrees C (59 degrees F), the spread is significantly reduced.

Campylobacter species thrive best at 30 to 42 degrees C (86 to 107.6 degrees F). There was a significant positive association between countries’ GDP per capita and effect estimates for Campylobacter infection studies.

Effect estimates derived from the Mediterranean warm summer climate zone exhibited a positive association with the warm summer continental climate zone. However, scientists found no associations between effect estimates for infection studies and continent, latitude, longitude, or annual mean temperature of the study locations.

Studies have identified major risk factors for infection, including chicken consumption, contact with raw meat, and having unpasteurized milk or barbecued beef, all of which are influenced by changes in ambient temperature.

“The existing body of evidence from epidemiological studies suggests that high temperatures increase the risk of enteric infections. The association between temperature and enteric infections varies across different climate zones, continents, and income levels. These findings could aid in health service planning and inform the development of tailored preventive measures and optimizing resource allocation,” said researchers.

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Source: https://www.foodsafetynews.com/2024/10/review-supports-temperature-infection-increase-link/