By: Kellie Vinal, Ph.D.
After extensive, collaborative investigations by the Maryland Department of Health (MDH), the Centers for Disease Control and Prevention (CDC), and the U.S. Food & Drug Administration (FDA), an official recall has been announced for Caribeña brand Maradol papayas due to the linked ongoing Salmonella outbreak. Although Grande Produce released a limited recall of these papayas, specifically targeting Maradol papayas distributed between July 10 and July 19, health officials are urging consumers to avoid these fruits altogether while the investigation continues.
The salmonellosis outbreak, which has sickened 46 and killed 1 across 12 U.S. states, is likely not over – federal officials say that other brands and/or distributors are likely involved.
Two strains – Salmonella Kiambu and Salmonella Thompson – have been identified, linking all of these cases together.
What you need to know about Salmonella – the basics
Salmonella are bacteria that can grow in or on virtually all animals, including rodents, birds, reptiles, livestock, birds, domestic animals, poultry, and, of course, humans. In addition to foodborne outbreaks, Salmonella infections are continually propagated from the use of Salmonella-contaminated animal feeds, and can be spread animal-to-animal.
Some strains of the bacteria are unable to cause disease in nonhuman hosts, such as S. typhi and S. paratyphi, as they are specifically adapted to humans. Other strains are adapted specifically to animals, but can cause severe disease if transferred to humans, such as S. choleraesuis. However, most strains of Salmonella do not have host specificity, meaning they can cause disease in both human and nonhuman hosts.
Most Salmonella infections result from either ingesting contaminated food products or, in the case of children, from ingesting contaminated fecal particles (also known as direct fecal-oral spread). As is typical with many bacterial infections, disease is more common for those older than the age of 60 or younger than the age of 5. People with weakened immune systems are likelier to develop more severe infections.
Salmonella infections are more common during the summer and autumn seasons, especially due to consumption of contaminated foods at outdoor social gatherings. Most commonly, human infections stem from contaminated dairy products, eggs, poultry, and/or foods prepared on contaminated cutting boards or other food preparation surfaces.
The CDC estimates that Salmonella is to blame for over one million foodborne illnesses in the United States each year, approximately 19,000 of which lead to hospitalizations, and 380 of which result in death.
For the most part, infections of Salmonella are mild and do not require treatment. Between 12 and 72 hours after becoming infected, most individuals experience abdominal cramps, diarrhea, and fever. Typically, an infection lasts 4 to 7 days. Less commonly, some individuals experience diarrhea so severe that hospitalization is required. In patients with extreme cases, the Salmonella infection might have spread from the point of origin, the intestinal tract, to the blood stream or other body sites. It’s crucial that individuals with extreme cases get treated with antibiotics immediately, as the infection can ultimately lead to death.
Clinical diseases caused by Salmonella
There are several clinical diseases that are caused by Salmonella infections.
Gastroenteritis is the most common form of disease, in which the stomach and intestines become inflamed. Initially, a case of gastroenteritis presents as nausea, vomiting, and non-bloody diarrhea within 6 to 48 hours. Sometimes, these symptoms are accompanied by headache, fever, abdominal cramps, and muscle weakness. These symptoms persist anywhere from 2 days to 1 week before the infection spontaneously resolves.
Septicemia, or blood poisoning, can occur in rare cases. The risk is higher for septicemia in immunodeficient, pediatric, and geriatric patients. Antibiotics are required to resolve these infections.
Enteric Fever, sometimes known as thyphoid fever, is caused by a particular strain of Salmonella – S. typhi. Typhoid fever infections are usually acquired by either ingesting contaminated drinking water or poor sanitation. Symptoms are similar to that of other foodborne illnesses – fever, headache, nausea, diarrhea – however, infections of this bacteria can cause severe disease
Diagnosis of Salmonella infection
Diagnosis of Salmonella infection typically requires isolating and identifying the bacteria from stool specimens. Laboratory scientists first grow – or “culture” – a patient’s sample in the lab. If they’re able to grow Salmonella bacteria from a patient’s sample, the scientists confirm the diagnosis of Salmonella infection.
Once the diagnosis is initially confirmed, lab scientists submit samples to state public health laboratories to conduct DNA analysis of the bacterial strain. Scientists compare the Salmonella DNA from a patient’s stool sample to other strains of Salmonella to identify which particular serotype the patient is infected with. Using this type of technology and analysis, scientists are able to track which strains have affected which patients in each location, and from there, they can piece together which cases are part of the same outbreak.
Treatment, Prevention, and Control
Antibiotic therapy can shorten the length of disease in some infectious cases, and is absolutely required in more severe cases, especially when the Salmonella have spread to the bloodstream.
In order to protect yourself from Salmonella infection, avoid consuming raw eggs or raw milk. The CDC recommends cooking eggs, meat, and poultry thoroughly, and immediately washing all surfaces that came in contact with raw meat or poultry. Be sure to wash your hands with soap and warm water after handling pet feces, baby animals, reptiles, or birds. Infants and immunocompromised individuals should be particularly careful to avoid contact with reptiles. Because there is no vaccine to prevent salmonellosis, it is crucial to focus on prevention and mindful food practices.
In the case of Caribeña brand Maradol papayas, it’s best to err on the side of safety. Toss any papayas you might have in your kitchen, and stay tuned to the FDA’s website for updates.
Medical Microbiology, Fifth Edition, Murray, P.R., et al