New research conducted by the University of Adelaide in Australia shows there is no greater risk of salmonella contamination in the production of free range eggs in Australia due to hot summer weather, compared with other seasons.

Despite a higher number of cases of salmonella poisoning from eggs and egg products during the hot summer months, researchers at the university's School of Animal & Veterinary Sciences said the egg production process itself is not to blame for the increase in cases.

The researchers said the findings are further evidence that the hygiene around egg handling in the supply chain and in household and restaurant kitchens is critical to reducing food poisoning from eggs.

Researchers conducted a study of four Australian commercial free range egg farms, with the results now published online ahead of print in the journal Applied & Environmental Microbiology.

"Eggs and egg products have been associated with an increased risk of salmonella contamination. Because the use of free range eggs by consumers is on the rise, we felt it was important to better understand the risk factors at the production stage," said lead author Kapil Chousalkar, an associate professor from the School of Animal & Veterinary Sciences at the university's Roseworthy campus.

"Birds raised in the free range production system could potentially be exposed to weather extremes, and the free range environment is not as easily controlled as in cage egg production. Therefore, it has been assumed that hot weather has a role to play in the potential contamination of eggs at the site of free range egg production," Chousalkar said.

"Our results show that the types and levels of salmonella found in and around free range egg farms, and on the eggs themselves, is highly variable, often dependent on the specific husbandry and management practices employed by each farm. However, we found that there was no direct association between hot weather and increased prevalence of salmonella at the production stage, even when data was collected in the hottest month of February," Chousalkar said.

"This helps to reinforce a simple health safety message: that it's important for people to wash their hands before and after handling eggs, whether at home, in a restaurant, or while working in the supply chain."