Careful and hygienic handling of eggs through the supply chain, and in the kitchen, is vital for reducing Australia's outbreaks of salmonella poisoning, according to University of Adelaide research.
In a year-long sampling survey of poultry farms with caged chickens, the researchers did not find any instances of the most common cause of salmonella poisoning in Australia, the bacteria Salmonella Typhimurium, within the internal egg contents - even where there is known Salmonella Typhimurium-infected chickens.
"This is good news for the egg industry," says Dr Kapil Chousalkar, Senior Lecturer in the School of Animal and Veterinary Sciences. "But now it puts focus on the external environment and handling of eggs because the salmonella can be transmitted on the eggs, and may even penetrate through the shell if they're not stored properly."
In Australia, egg and food products containing egg that's uncooked or lightly cooked are the most common source of salmonella outbreaks in people. The most common type, Salmonella Typhimurium, is the "biggest concern for food poisoning from egg", says Dr Chousalkar.
A team of researchers at the University's Roseworthy Campus, led by Dr Chousalkar, is investigating the journey of salmonella "from farm to fork". The team will examine the extent of salmonella in chickens and contamination of eggs, and the transmission of salmonella from the environment to the bird and then onto the egg.
On an egg farm or in backyard hen houses, there are many potential sources of salmonella infection including the people who are handling the eggs, rodents, poultry feed or dust.
"Anyone handling eggs in restaurants or food production facilities - even in our own kitchens - should be extremely thorough with washing hands after touching eggs," says Dr Chousalkar.
"Even though buying eggs from the supermarket should be safe, I would still advise people to wash their hands carefully after handling them. If eggs are cooked and handled properly, people are much less likely to get food poisoning."
It's also very important to refrigerate egg products as poor storage can enhance the multiplication of bacteria.
The researchers are following up with a study of the different potential sources of contamination on egg farms and in the supply chain to see what influences the level of salmonella found on egg shells.