Salmonella is one of the most common and well-known germs that can make you sick through food around the world. It causes about 94 million cases of gastroenteritis and more than 155,000 deaths around the world every year, making it a major public health issue on every continent. This group of bacteria is very small, but it has a huge effect on human health, food safety systems, and trade between countries.

Salmonella is not a single organism. It is a large genus of gram-negative, rod-shaped bacteria in the family Enterobacteriaceae. Salmonella comes in more than 2,500 different subtypes, or serotypes. Each one has a few small differences. Salmonella enterica and Salmonella bongori are the two species that are most important to human health. Most infections in humans are caused by Salmonella enterica. There are some very well-known serotypes of Salmonella enterica. Non-typhoidal salmonellosis, the type of infection that makes you sick from food, is most often caused by Salmonella Typhimurium and Salmonella Enteritidis. Typhoid fever and paratyphoid fever are both caused by Salmonella Typhi and Salmonella Paratyphi. These are more serious systemic diseases that are mostly spread through dirty water in places with bad sanitation.

In 1885, American veterinary scientist Daniel Elmer Salmon found Salmonella for the first time. He named the bacteria after himself, but his colleague Theobald Smith actually made the discovery. They got the organism from pigs while they were studying hog cholera. Over the next 100 years, scientists slowly made a map of the genus’s huge diversity and got a better idea of how it spreads, how it causes disease, and how it can be controlled. During the 20th century, the industrialization of food production opened up new ways for Salmonella to spread to a lot of people at once. Once limited to a single village, outbreaks can now spread to thousands of people in many countries through shared supply chains.

In what place does Salmonella live?

Salmonella is found in a huge number of places in nature. The bacteria lives in the guts of many animals, like chickens, cows, pigs, reptiles, amphibians, rodents, and wild birds, and these animals usually don’t show any obvious signs of illness. This means that animals can carry the bacteria in their feces and pass it on without getting sick, which makes it hard to find.

The bacteria can live for a long time without a host. It stays in soil, water, and on surfaces, and it does especially well in dry, low-moisture places. Salmonella has been found in sewage, river water, animal feed, and farm tools. Even though it can live in cold places, it doesn’t grow below about 7 degrees Celsius. Heat is what hurts it. Food that is cooked to a temperature of 74 degrees Celsius (165 degrees Fahrenheit) will kill it.

How does it get to people?

Salmonella infections in people usually happen when they eat or drink something that is contaminated. In the past, poultry and eggs were the main sources. This is because Salmonella Enteritidis can infect hens’ ovaries and taint eggs before the shell is even formed. Because the bacteria are inside the egg, even a clean egg that isn’t cracked can hold them.

Some other common food carriers are meat that is raw or undercooked, dairy products that have not been pasteurized, fresh fruits and vegetables like tomatoes, peppers, sprouts, and leafy greens, and processed foods like peanut butter, chocolate, and spice mixes. Cross-contamination in the kitchen is a big problem. Bacteria from raw chicken that gets on a cutting board can easily get to a salad or fruit that was made on the same surface.

Another important way to spread disease is through direct contact with animals. Snakes, turtles, lizards, and other reptiles are known to carry Salmonella and can easily give it to people by touching them. Infections can also come from chickens in your backyard, farm animals, and even some pets.

Person-to-person transmission is less common, but it can happen, especially in places where cleanliness is very important, like schools, care homes, or hospitals. One big thing that makes this route possible is not washing your hands after using the bathroom or handling raw food.

In low-income areas, contaminated drinking water is still a major cause of salmonellosis, even though it is less of a problem in high-income areas with treated water supplies.

Signs and sickness

Salmonella bacteria get into the small intestine when they are eaten. There, they infect the cells that line the gut wall and cause inflammation. It’s called salmonellosis, and the illness usually starts between six and seventy-two hours after exposure.

The most common signs are diarrhea, stomach cramps, fever, feeling sick, and throwing up. For most healthy adults, the illness is unpleasant but short-lived; it goes away on its own in four to seven days without medical help. During this time, the most important thing to do is to stay hydrated.

But Salmonella can be much worse for people who are already weak. People who are young, old, pregnant, or who don’t have strong immune systems are much more likely to get really sick. Salmonella can sometimes get into the bloodstream and cause invasive non-typhoidal salmonellosis or bacteraemia, which can be very dangerous. This is especially true in sub-Saharan Africa, where malnutrition, malaria, and HIV are common. This needs antibiotics right away, and if it doesn’t, it can be fatal.

Typhoid fever, which is caused by Salmonella Typhi, is a different and more dangerous illness. It comes on more slowly and lasts longer. Some people get a rash, headaches, and a high fever that won’t go away. If you don’t treat it, it can lead to intestinal perforation and death. More than six million people got typhoid in 2023, and it killed over seven thousand people, according to the Global Burden of Disease Study.

Treatment

Most of the time, treating salmonellosis means making sure the person doesn’t get dehydrated by making sure they get enough fluids and electrolytes. Antibiotics aren’t usually suggested for mild to moderate illnesses because they can make the person shed bacteria in their stool for longer, which could spread the infection to others, and the illness usually goes away on its own.

In severe cases, when the infection has spread outside of the gut, or when the patient’s immune system is weak, antibiotics are used. Fluoroquinolones, cephalosporins, and azithromycin are the classes that are used most often. But antimicrobial resistance is a big problem that is getting worse. For example, strains of Salmonella that are not killed by many types of antibiotics have appeared and are spreading around the world, making some infections harder to treat.

Resistance to Antibiotics

Salmonella that is resistant to drugs is becoming more common. This is one of the most important problems in food safety and infectious diseases. Antibiotics are commonly used on farms to treat sick animals and to help animals grow, but they have also made it easier for bacteria that are resistant to antibiotics to grow and spread. Through the food chain, these resistant strains can get from animals to people.

In dozens of countries, strains like Salmonella Typhimurium DT104 have been found to be resistant to five different antibiotics. Recently, strains that produce extended-spectrum beta-lactamases have come into being. These make them resistant to a wider range of drugs. The World Health Organization says that new medicines are needed right away to treat Salmonella and other pathogens.

A Look at the World

Not everyone in the world has to deal with Salmonella the same way. Sub-Saharan Africa has the most cases, especially of the invasive form of the disease. Children who already have other health problems, like malnutrition or sickle cell disease, are more likely to be affected. South and Southeast Asia also have a lot of typhoid fever and salmonellosis that isn’t caused by typhus.

Salmonella is still the most common bacteria that make people sick when they eat in high-income countries. The CDC says that each year there are about 1.35 million infections, 26,500 hospitalizations, and 420 deaths in the United States alone. In 2026, England had the highest rate of Salmonella infections in ten years. Hundreds of people got sick because of outbreaks linked to imported eggs.

Major outbreaks are still happening all the time. Millions of egg cartons were recalled in the US in 2026 because of an outbreak that spread to multiple states. This was the FDA’s highest level of recall, known as Class I. A different outbreak connected to Mexican jalapeños spread through grocery stores and restaurant chains in many states. These events show how the global food supply has linked people together and how quickly contamination in one place can spread to other places.

Safety First

Individual behavior and systemic food safety measures work together to keep people from getting Salmonella.

As an individual, the best things you can do are cook meat, poultry, and eggs all the way through; wash your hands carefully with soap after touching animals or going to the bathroom; keep raw meat away from other foods in the kitchen; and promptly put food in the fridge. It is especially important for pregnant women, kids, and people with weak immune systems to stay away from eggs that are raw or runny.

Vaccinating laying hens against Salmonella Enteritidis and Typhimurium has been very successful in places where it has been used. The Lion Code scheme in the UK requires that hens that lay eggs with the red lion stamp get vaccinated. This has greatly reduced the amount of Salmonella in British eggs. Pasteurizing milk and juice, treating water, and having strict hygiene rules in places that process food are all important ways to keep people safe.

Typhoid vaccines are available and should be used for mass vaccination campaigns in areas where the disease is common and for travelers going to high-risk areas. Two vaccines are used around the world right now, and newer conjugate vaccines have shown to be very effective in kids.