Salmonella infection, or salmonellosis, is one of the most common foodborne illnesses worldwide.
It impacts millions of people annually, causing illness that ranges from mild gastrointestinal discomfort to severe, life-threatening conditions.
What is Salmonella?
Salmonella is a genus of bacteria divided into many serotypes. These bacteria reside in the intestines of humans and animals, and can be transmitted through contaminated food or water, or through contact with infected animals or environments.
Causes and sources of Salmonella
The primary sources include:
- Raw or undercooked poultry, eggs, beef, and sometimes seafood
- Contaminated fruits and vegetables that are not properly washed
- Cross-contamination from raw foods to cooked foods
- Infected animals, especially reptiles like turtles and lizards, and pet birds
- Unsanitary food handling and preparation practices
The bacteria are ingested through contaminated food and water. Once ingested, Salmonella bacteria invade the intestinal lining, leading to inflammation and symptoms.
Symptoms and Risk factors
Most infected individuals develop symptoms within 6 hours to 6 days after exposure.
Common symptoms include:
- Diarrhea (sometimes bloody)
- Fever
- Abdominal cramps
- Nausea and vomiting
Typically, symptoms last for 4 to 7 days, and recovery occurs without antibiotics.
However, in vulnerable populations, the infection can cause serious complications such as dehydration, bacteremia, or spread to other organs, requiring hospitalization and antimicrobial therapy.
Risk factors include:
- Young children
- Elderly individuals
- Immunocompromised persons
- Pregnant women
Differences between Salmonella Typhi and non-Typhi
| Feature | Salmonella Typhi | Non-Typhoidal Salmonella |
|---|---|---|
| Disease Caused | Typhoid fever | Gastroenteritis (food poisoning) |
| Where It Comes From | Humans only | Animals (poultry, eggs, reptiles, livestock) |
| How It Spreads | Contaminated water/food from human waste | Contaminated food, undercooked meat, contact with animals |
| Severity | Severe, systemic, potentially life-threatening | Mild to moderate, usually self-limiting |
| Symptoms | High fever, abdominal pain, rash, systemic illness | Diarrhea, vomiting, stomach cramps, moderate fever |
| Need for Antibiotics? | Yes | Usually no (except in high-risk patients) |
| Vaccine Available? | Yes | No |
Diagnosis
Culture (e.g., stool, urine, blood) is the gold standard for diagnosis.
Resulting isolates can provide additional information used for patient care (such as virulence and antimicrobial resistance) and public health practice (such as outbreak identification).
- If Salmonella is identified by a PCR multiplex panel or other culture-independent diagnostic test (CIDT), follow-up culture is recommended to obtain an isolate for antimicrobial susceptibility testing.
- Serologic testing is unreliable and not advised.
Treatment
In most cases, treatment involves supportive care, including hydration, antidiarrheals (Tiorfan for example), antiemetics (Vogalene for example), probiotics, painkillers (Paracetamol, Spasfon) and mild foods (bananas, rice, soup, yogurt).
Antibiotics are reserved for severe cases or vulnerable groups, as unnecessary use can prolong carrier state and resistance. We check with the antibiogram if the bacteria is resistant (R), Intermediate (I) or sensible (S) to choose the good antibiotic.
Prevention Strategies
Preventive measures are essential for reducing infection risk:
- Cook meats, eggs, and seafood thoroughly
- Use a food thermometer to ensure proper internal temperatures
- Avoid cross-contamination by using separate cutting boards
- Keep raw foods separate from cooked or ready-to-eat foods
- Ensure food is properly cooked and still hot when served.
- Avoid raw milk and products made from raw milk. Drink only pasteurized or boiled milk.
- Avoid ice unless it is made from safe water.
- When the safety of drinking water is questionable, boil it or if this is not possible, disinfect it with a reliable, slow-release disinfectant agent (usually available at pharmacies).
- Wash hands thoroughly and frequently using soap, in particular after contact with pets or farm animals, or after having been to the toilet.
- Wash fruits and vegetables carefully, particularly if they are eaten raw. If possible, vegetables and fruits should be peeled.
A vaccine is available against the Typhoid fever (Salmonella typhi). Don’t forget to be vaccinated if you travel in an endemic area.
Outbreaks and Public Health Impact
According to the World Health Organization (WHO), Salmonella causes approximately 93.8 million cases of illness worldwide annually, resulting in over 155,000 deaths (WHO, 2018).
Outbreaks often occur linked to contaminated food products, especially poultry, eggs, and produce. The globalized food supply chain has increased the potential for nationwide outbreaks.
Conclusion
Salmonella remains a significant public health challenge but is largely preventable through proper food safety measures.
While Salmonella Typhi and non-typhoidal Salmonella belong to the same bacterial family, their impact on human health differs significantly. Typhoid fever is a systemic and dangerous infection requiring prompt antibiotic treatment, while non-typhoidal Salmonella mainly causes food poisoning and often resolves on its own.
Awareness and adherence to hygiene protocols are key to minimizing outbreaks and protecting vulnerable populations.
