The shell of the egg may be contaminated with Salmonella by feces or environment, or its interior (yolk) may be contaminated by penetration of the bacteria through the porous shell or from a hen whose infected ovaries contaminate the egg during egg formation.Nevertheless, such interior egg yolk contamination is theoretically unlikely. Even under natural conditions, the rate of infection was very small (0.6% in a study of naturally contaminated eggs and 3.0% among artificially and heavily infected hens). Prevention
The US Food and Drug Administration (FDA) has published guidelines to help reduce the chance of food-borne salmonellosis. Food must be cooked to 145–165 °F (63–74 °C), and liquids such as soups or gravies should be boiled when reheating. Freezing kills some Salmonella, but it is not sufficient to reliably reduce them below infectious levels. While Salmonella is usually heat-sensitive, it acquires heat-resistance in high-fat environments such as peanut butter. Vaccine
Antibodies against nontyphoidal Salmonella were first found in Malawi children in research published in 2008. The Malawian researchers identified an antibody that protects children against bacterial infections of the blood caused by nontyphoidal Salmonella. A study at Queen Elizabeth Hospital in Blantyre found that children up to two years old develop antibodies that aid in killing the bacteria. This could lead to a possible Salmonella vaccine for humans.A 2014 study tested a vaccine on chickens which offered efficient protection against salmonellosis.Vaccination of chickens against Salmonella essentially wiped out the disease in the United Kingdom.
Over 400 people had been infected with Salmonella enterica serovar Stanley (S. Stanley) that usually appears in the regions of Southeast Asia. After several DNA analyses seemed to point to a specific Belgian strain, the "Joint ECDC/E FSA Rapid Risk Assessment" report detected turkey production as the source of infection.In Germany, food poisoning infections must be reported. Between 1990 and 2005, the number of officially recorded cases decreased from about 200,000 to about 50,000. Elsewhere
In March 2007, around 150 people were diagnosed with salmonellosis after eating tainted food at a governors reception in Krasnoyarsk, Russia. Over 1,500 people attended the ball on March 1 and fell ill as a consequence of ingesting Salmonella-tainted sandwiches.About 150 people were sickened by Salmonella-tainted chocolate cake produced by a major bakery chain in Singapore in December 2007.South Africa reported contamination of its poultry carcasses by Salmonella. Egypt showed that Salmonella was predominant in poultry along with other non-typhoid strains. In  Indonesia, the isolation of Salmonella Typhi was the main focus,  while other serovars were also included from poultry. In India, Salmonella was predominant in poultry. Romania reported Salmonella serovars in poultry that affect humans. History
Both salmonellosis and the microorganism genus Salmonella derive their names from a modern Latin coining after Daniel E. Salmon (1850–1914), an American veterinary surgeon. He had help from Theobald Smith, and together they found the bacterium in pigs.Salmonella enterica was possibly the cause of the 1576 cocliztli epidemic in New Spain.