In 1885, a research-assistant to Daniel Salmon discovered the first strain of Salmonella choleraesuis– and thereby the name Salmonella and today there are over 2500 known types. Salmonellosis is one of the most common and widely distributed foodborne diseases, in fact, it is estimated that millions of people are infected each year, some occurring in death. This constitutes a major health concern.
Salmonella is frequently found in food production animals such as poultry, pigs and to lesser extent ruminants. Feces from food animal production may contaminate vegetables, fruits and nuts. Consumption is the most common cause of salmonellosis in humans. However, salmonellosis may also be obtained from the environment and contact with animals including pets and transmission within the human population.
A major unease in the last two decades is that Salmonella bacteria are becoming increasingly resistant to antimicrobials. Some bacteria are multiple resistant, creating a difficulty in treating those sick with Salmonella. The increasing levels of multiple resistance are partly attributed to antimicrobial use both in humans and animals.
How many people are actually affected?
This is remarkably difficult to determine because so many cases are left unreported. The vast majority of people affected suffers ‘silently’ for a few days and then recover.
Europe: In 2007, approximately 152,000 human salmonellosis cases were reported in the European Union (ECDC/EFSA). Cases of salmonellosis are not always diagnostically confirmed and reported, and the true number of cases may be 10 times as high. However, the incidence of reported salmonellosis continues to decrease in the European Union with a statistically significant trend over the last four years. In the EU, among the foodborne cases of human salmonellosis, eggs and egg products are still the most frequently implicated sources (EFSA). Meat is also an important source of foodborne salmonellosis, with poultry and pork implicated more often than beef and lamb. In the EU, Salmonella Enteritidis and Typhimurium are the serotypes most frequently associated with human illness.
United States: 40,000 cases are reported annually and it is estimated that only about 3% of Salmonella cases are officially reported, and many milder cases are never diagnosed, the true incidence is undoubtedly much higher. The Centre for Disease Control in Atlanta estimates that 1.4 million cases occur annually, however some estimates are much higher, between 2 and 4 million cases (FDA).
World Health Organization
Center of Disease Control and Prevention, USA
US Food and Drug Administration, Bad Bug Book.
US Morbidity and Mortality Weekly Reports on Salmonella
European Public Health Agency-Assessment of sources for foodborne Salmonella
Salmonella infections associated with reptiles
European Center for disease prevention and control EFSA-ECDC report on trends and sources of zoonoses in the European Union in 2007