A salmonella outbreak in the US has hit Oklahoma with 51 confirmed cases. Here's what we know.

A nationwide outbreak of salmonella has brought 51 confirmed cases to Oklahoma, with health officials working across several states to figure out the source.

As of Monday, Oklahoma was the second-highest state with confirmed cases of the outbreak strain Salmonella Oranienburg, according to the Oklahoma State Department of Health. Texas was the top state, at 81.

CDC first identified salmonella outbreak in early September

On Sept. 2, the Centers for Disease Control and Prevention first identified an outbreak of 20 Salmonella Oranienburg infections. By Sept. 15, the CDC reported 127 people in 25 states had contracted the same strain, resulting in 18 hospitalizations. Before that week's end, the CDC announced the number of reported illnesses had more than doubled: 279 people had fallen ill.

Infected cases have ranged from less than a year old to 82 years old, and more than half of them are female. 

Eddie Withers, lead epidemiologist for the Oklahoma City-County Health Department, said there were nine confirmed cases associated with the outbreak strain in Oklahoma County. 

But Withers said the actual number of outbreak infections is likely higher, since some people recover from illness without medical care and don't seek testing for salmonella.

"I suspect that number will grow a little bit," Withers said. "I'm just not sure at what speed. Hopefully, this slows down because this is moving fairly quickly."

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How is salmonella infection confirmed?

Salmonella infection is confirmed when laboratory testing detects the bacteria in a person’s bowel movement, body tissue, or fluids. But the CDC has estimated that for every confirmed case of salmonella, 30 more cases go unreported. Plus, it can take a few weeks to determine if someone has fallen sick with the outbreak strain. 

"I'll tell you, we have quite a few salmonella cases out there," Withers said. "The number of cases has definitely jumped, I'd say, in the last week or so. Obviously, our biggest concern at this point is COVID, but we went from where we typically see maybe five or six salmonella cases a week to where, just today, I think they reported another six to us. But it's a hit-or-miss if they'll be this particular strain."

Salmonella symptoms include stomach cramps, fever, vomiting, diarrhea and dehydration, which can begin within 12 to 72 hours after being exposed to the bacteria, according to the U.S. Food and Drug Administration. Most people improve without treatment within four to seven days. 

Children under the age of 5, people 65 years and older and those with underlying health conditions are at risk of severe illness from salmonella. In some people, dehydration from salmonella can become severe enough to need hospitalization.

Infection may spread from the intestines to the bloodstream, and then to other parts of the body. In less than 1% of cases, salmonella infection can lead to death, unless the person is treated with appropriate antibiotics.

As of Monday, no one has reportedly died from the outbreak strain. 

Origin of salmonella outbreak still unclear

Salmonella is typically a food-borne illness, so state and local officials backtracked many of these sick people to restaurants where they ate. The outbreak strain of Salmonella Oranienburg was found in a sample of cilantro and lime from a takeout condiment cup, according to the CDC. One sick person said the condiment container had also carried onions, but none were left in the cup by the time it was tested.

"Because multiple food items were present in the container and in the sample that was tested, it is not possible to know which food item was contaminated," the CDC said in a statement. "We are using this information in conjunction with other available information to help narrow the list of possible foods linked to illness."

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Kendra Dougherty, a division administrative program manager for the Oklahoma State Department of Health's Acute Disease Service, is director of the Oklahoma investigation into the outbreak. She said a specific food item has not been identified as the source of the outbreak, but the investigation is ongoing across several agencies.

The health department "is working closely with the FDA, CDC, and other states in a coordinated response to identify the source," Dougherty said. "Information will be released to the public as soon as a food item is definitively identified."

Health officials recommend people talk with their healthcare provider if they start showing salmonella symptoms, and then report their illness and what they've recently eaten to their local health department.

How to help prevent salmonella infection

The CDC and the FDA also recommend following a four-step food safety guide to prevent salmonella infection:

• Clean: Wash your hands, utensils and surfaces regularly. Rinse fruits and vegetables under running water before eating, cutting and peeling them.
• Separate: Avoid cross-contamination by keeping raw meat, poultry and seafood away from other food items that won't be cooked.
• Cook: Use a food thermometer to ensure you've cooked your food to a temperature high enough to kill germs before you eat it. 
• Chill: Refrigerate perishable foods within 2 hours. Thaw food safely in your refrigerator, not on the counter.