The Centers for Disease Control and Prevention (CDC) estimates that each year 48 million people get sick from a foodborne illness, 128,000 are hospitalized, and 3,000 die.

CDC listed the top five germs that cause illnesses from food eaten in the United States last month:



Noroviruses are environmentally hardy organisms that not only can be transmitted by food and water, but also can be easily transmitted through person-to-person contact and contact with environmental surfaces. In the U.S., norovirus is the leading cause of illness from contaminated food or water.

About 50% of all outbreaks of food-related illness are caused by norovirus. Food can get contaminated with norovirus at any point when it is being grown, shipped, handled, or prepared.

Foods that are commonly involved in outbreaks of norovirus illness are—

  • leafy greens (such as lettuce),
  • fresh fruits, and
  • shellfish (such as oysters).

But, any food that is served raw or handled after being cooked can get contaminated.


Salmonella is a motile, non-sporeforming, Gram negative, rod-shaped bacterium that causes two kinds of illness: Gastrointestinal illness, which causes nausea, vomiting, diarrhea, cramps, and fever, with symptoms generally lasting a couple of days and tapering off within a week. In otherwise healthy people, the symptoms usually go away by themselves, but long‐term arthritis may develop and typhoidal illness.

Every year, Salmonella is estimated to cause one million foodborne illnesses in the United States, with 19,000 hospitalizations and 380 deaths.

Clostridium perfringens

Once this bacterium is eaten in contaminated food, it makes a toxin in the intestines and it’s this toxin that causes foodborne illness.

The CDC estimates that 965,958 domestically acquired cases occur annually in the U.S., second only to Salmonella when considering bacterial causes of foodborne illness.


Campylobacter Image/CDC

Campylobacter causes an estimated 1.3 million illnesses each year in the United States.

Most illnesses likely occur due to eating raw or undercooked poultry, or to eating something that touched it. Some are due to contaminated water, contact with animals, or drinking raw (unpasteurized) milk.

Although people with Campylobacter infection usually recover on their own, some need medical treatment.

LISTEN: Foodborne parasites in the US

Staphylococcus aureus

This bacterium, often called “Staph” for short, can cause food poisoning. Staphylococcus aureus is found in foods and can make toxins (enterotoxins) that might not be destroyed by cooking, although the bacterium itself can be destroyed by heat. These toxins can cause nausea, stomach cramps, vomiting, and diarrhea.

The Centers for Disease Control and Prevention (CDC) estimates that, in the United States, staphylococcal food poisoning causes approximately 241,188 illnesses, 1,064 hospitalizations, and 6 deaths each year, although the true incidence is unknown.


2012 Bad Bug Book