There’s no need to send a sympathy card to Salmonella. Yes, this proud bug dropped into second place on CDC’s list of organisms responsible for foodborne illness in the U.S. in 2016, with 8,172 cases reported on CDC’s Foodborne Diseases Active Surveillance Network (FoodNet), compared to 8,547 cases for Campylobacter. But Salmonella took the lead among all foodborne bacterial pathogens for causing most hospitalizations, 2,255, and deaths, 40, as reported in FoodNet’s April 21, 2017 issue of the Morbidity and Mortality Weekly Report.
CDC estimates this relentless gram negative rod causes about 1.2 million illnesses in the U.S. annually, not to mention 23,000 hospitalizations and 450 deaths. Food is the source for about one million of these illnesses.
Salmonellosis in humans is generally contracted through the consumption of contaminated food
of animal origin, mainly eggs, meat, poultry, and milk, although other foods, including fruits and vegetables, have been implicated in its transmission.
Specifically, foods that are most likely to contain Salmonella include raw or undercooked eggs, raw milk, contaminated water, and raw or undercooked meats. Eating unwashed vegetables or fruits, including seeded vegetables and sprouts, increases the risk of Salmonella infection. In recent years, contamination with Salmonella has been found in a variety of tree nuts, including almonds, cashews, pistachios, pine nuts, Brazil nuts, macadamia nuts, and walnuts.
According to the December 2017 report by the Interagency Food Safety Analytics Collaboration (IFSAC) that addresses foodborne illness source attribution estimates for 2013, 75.4 percent of Salmonella illnesses were attributed to seven food categories: seeded vegetables (16 percent), eggs (11.5 percent), chicken (10.4 percent), other produce, such as nuts (9.8 percent), pork (9.3 percent), beef (9.1 percent), and fruits (8.9 percent).
The IFSAC is a tri-agency group created by the CDC, FDA, and the USDA’s Food Safety and Inspection Service.
Salmonella challenges abound, but fortunately, much tireless work is in progress to minimize the negative effects of this organism throughout the food chain.
(In the plus column for Salmonella, the organism is demonstrating remarkable capabilities for treating brain cancer, but that’s another story. Bugs as drugs definitely hold promise, research shows.)
Faster Salmonella Test
A new diagnostic procedure has been developed that provides accurate, rapid testing for Salmonella, including serotype Dublin, an emerging food animal and food safety concern.
Salmonella Dublin can be difficult or slow to grow in culture, typically making detection challenging, according to Laura Goodman, PhD, an assistant research professor in the Department of Population Medicine and Diagnostic Sciences (PMDS) at Cornell University, Ithaca, N.Y., and lead author of the study that resulted in this new rapid test.
“Tests for Salmonella environmental screening used to take days, now they take 24 hours,” Dr. Goodman points out. “The new method can also detect one hundredfold fewer Salmonella Dublin bacteria.”
Salmonella Dublin is host adapted in cattle, meaning infected animals can become permanent or long-term carriers, putting herd mates, especially susceptible calves, at risk, explains Belinda Thompson, DVM, a PMDS assistant clinical professor and senior author on the study. “This serotype can infect people who may be exposed by contact with infected animals, by drinking raw milk, or by consuming other contaminated food products,” she relates. “In humans, Salmonella Dublin has higher hospitalization and fatality rates than other Salmonella types; it causes systemic infection of body tissues, similar to typhoid.”
Similarly, in cattle, serotype Dublin is associated with invasive disease, multi-drug resistance, and opportunities for infection following survival in the environment, Dr. Thompson mentions.
“Salmonella enterica subspecies enterica serotype Dublin (S. enterica Dublin) emerged for the first time in New York, Pennsylvania, and Ohio in 1988,” she notes. “Since that time this serotype has spread throughout the veal and dairy beef raising operations in the region.”