Viruses, Bacteria, and Parasites in the Digestive Tract

E. coli

Description

There are hundreds of different types, or strains, of the bacteria E. coli (Escherichia coli). Most of these are harmless and live in the intestines of healthy people and animals. But some strains of E. coli make a strong toxin that can cause a severe infection.

The CDC recognizes E. colias a foodborne illness. This means it is spread by consuming contaminated food or drink. Infection often leads to bloody diarrhea, stomach cramps, vomiting, and fever.

Transmission

Most E. coliillness has been linked to eating undercooked, contaminated ground beef. E. coli bacteria live in the intestines of healthy cattle. The number of organisms required to cause disease is not known. But it is thought to be very small. Meat becomes contaminated during slaughter. Organisms can be mixed into beef when it is ground. Contaminated beef looks and smells normal. Other ways to transmit E. coli are:

• Person-to-person contact in families and in child-care and other institutional-care centers

• Bacteria present on a cow's udders, or on equipment, getting into raw milk

• Infection after swimming in or drinking sewage-contaminated water

• Drinking unpasteurized juices, such as apple cider

Bacteria in diarrhea stools of infected people can be passed from one person to another if hygiene or handwashing habits are not good. This is very likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of getting infected. Young children often pass the organism in their stool for a week or 2 after their illness goes away.

Prevention

CDC recommends these steps to prevent the infection:

• Cook all ground beef or hamburger thoroughly. Make sure that the cooked meat is gray or brown throughout (not pink), any juices run clear, and the inside is hot.

• Use a digital instant-read meat thermometer. The temperature of the meat should reach a minimum of 160°F.

• If you are served an undercooked hamburger in a restaurant, send it back.

• Drink only pasteurized milk and milk products. Don't drink raw milk.

• Drink only pasteurized juices and ciders.

• Check that infected people, especially children, wash their hands well and often with soap to reduce the risk of spreading the infection.

• Drink municipal water that has been treated with adequate levels of chlorine, or other effective disinfectants.

• Try not to swallow lake or pool water while swimming.

• Wash hands well after using the toilet.

• People with diarrhea should not:

  • Swim in public pools or lakes

  • Bathe with others

  • Prepare food for others

Salmonella

Description

Salmonella is a bacteria that infects the intestines. It causes diarrhea, fever, and stomach cramps 12 to 72 hours after infection. Over 1 million cases of salmonella infection occur in the U.S. each year. The illness often lasts 4 to 7 days. Most people get better without treatment.

But in some people, the diarrhea may be so severe that they need to stay in the hospital. In these people, the salmonella infection may spread from the intestines to the bloodstream and then to other body sites. It can cause death unless the person is treated right away with antibiotics. Babies and those with a weakened immune system are more likely to have a severe illness.

Transmission

Salmonella may be spread by:

• Eating raw foods contaminated with animal feces. Contaminated foods often look and smell normal. They are often of animal origin, such as beef, poultry, milk, or eggs. But all foods, such as some unwashed fruits and vegetables and peanut butter, may become contaminated. Many raw foods of animal origin are often tainted. But thorough cooking kills salmonella.

• Handling reptiles. Reptiles such as iguanas and turtles are very likely to have Salmonella. People should always wash their hands right away after handling a reptile, even if the reptile is healthy. Adults should also be careful that children wash their hands after handling a reptile.

Prevention

Don't eat raw or undercooked eggs, poultry, or meats. Remember that some sauces and desserts use raw eggs to make them. So be cautious of these, particularly in foreign countries. Also, follow these tips by the CDC:

• Check that poultry and meat, including hamburgers, are well-cooked. They should not be pink in the middle.

• Don't drink or eat raw or unpasteurized milk or other dairy products.

• Thoroughly wash produce before eating it.

• Don't cross-contaminate foods. Uncooked meats should be kept separate from produce, cooked foods, and ready-to-eat foods.

• All utensils, cutting boards, and counters should be thoroughly washed after handling uncooked foods.

• Wash hands well before handling foods and between handling different food items.

• Wash hands well after contact with feces.

• Wash hands well after handling any reptiles. Reptiles are very likely to have Salmonella.

Rotavirus

Description

Rotavirus is the most common cause of severe diarrhea among children. It results in the death of over 500,000 children each year worldwide.

In the U.S., the disease occurs most often in the winter. Yearly epidemics occur from December to June. The highest rates of illness occur among infants and young children. Most children in the U.S. are infected by 5 years of age. Adults can also be infected. But the disease tends to be mild.

The incubation period for rotavirus disease is about 2 days. The disease causes vomiting and watery diarrhea for 3 to 8 days. Fever and stomach pain occur often. Immunity after infection is incomplete. But repeat infections tend to be less severe than the original infection.

Transmission

Rotavirus may be spread:

• Through accidentally swallowing the virus picked up from surfaces contaminated with stool from an infected person, such as toys, bathroom fixtures, changing tables, and diaper pails.

• Through ingestion of contaminated food, or contaminated water, such as the type of water found in a public swimming pool.

Prevention

Two rotavirus vaccines are currently used in babies in the U.S. Both vaccines are given by mouth, not by a shot. Talk with your child’s healthcare provider about which shot is best for your baby.

Handwashing is a very important means of preventing the spread of rotavirus. Careful and frequent handwashing can prevent the spread of infection to other people.

The CDC recommends:

• Adults should wash their hands after using the toilet, after helping a child use the toilet, after diapering a child, and before preparing, serving, or eating food.

• Have children wash their hands after using the toilet, after having their diapers changed (an adult should wash infant's or small child's hands), and before eating snacks or meals.

• Toys, bathrooms, and food preparation surfaces are disinfected often, especially if a sick child has been in the home.

• Use diapers with waterproof outer covers that can hold liquid stool or urine, or use plastic pants.

• Have children wear clothes over diapers.

Giardia

Description

During the past 15 years, Giardia lambliahas become one of the most common waterborne diseases in humans in the U.S. Giardia is a tiny parasite that lives in the intestines of people and animals. The parasite is passed in the bowel movement of an infected person or animal. It is found in every part of the U.S. and throughout the world.

Diaper-aged children who go to daycare centers, international travelers, hikers, campers, and others who drink untreated water from contaminated sources, are most at risk for getting infected with Giardia. Several community-wide outbreaks of infection have been linked to drinking municipal water tainted with Giardia.

Transmission

People become infected after accidentally swallowing the parasite. Giardia may be found in soil, food, water, or on surfaces.

Some of the ways people can get Giardia are:

• Eating uncooked food contaminated with Giardia

• Swallowing water from swimming pools, lakes, rivers, springs, ponds, or streams contaminated with sewage or feces from humans or animals

• Accidentally swallowing the parasite picked up from surfaces contaminated with stool from an infected person, such as toys, bathroom fixtures, changing tables, and diaper pails

Prevention

The CDC recommends:

• Washing hands with soap and water after using the toilet, changing diapers, and before handling food

• Washing and peeling all raw vegetables and fruits before eating

• Not drinking water from lakes, rivers, springs, ponds, or streams unless it has been filtered and chemically treated

• Boiling drinking water for 1 minute to kill the Giardia parasite. This will ensure safe drinking water during community-wide outbreaks caused by contaminated drinking water

• Not drinking unboiled tap water and not eating uncooked foods washed with unboiled tap water when camping or traveling in countries where the water supply may be unsafe. Bottled or canned carbonated drinks, seltzers, pasteurized fruit drinks, and steaming hot coffee and tea are safe to drink.

If your child has Giardia, don't swim in pools for 2 weeks after the diarrhea or loose stools have cleared. Giardia is fairly chlorine resistant. It is passed in the stools of infected people for several weeks after they no longer have symptoms.

Cryptosporidium

Description

Cryptosporidium, or "crypto," is a tiny parasite that can live in the intestines of humans and animals. The parasite is protected by an outer shell that lets it survive outside the body for long periods of time. It is very resistant to chlorine disinfection.

Transmission

Cryptosporidium may be spread by:

• Accidentally swallowing anything that has come in contact with the stool of a person or animal

• Swallowing contaminated water from swimming pools, hot tubs, lakes, rivers, springs, ponds, or streams contaminated with sewage or feces from humans or animals

• Eating uncooked contaminated food

• Picking crypto up from surfaces contaminated with stool from an infected person such as toys, bathroom fixtures, changing tables, and diaper pails

Prevention

The CDC recommends:

• Washing hands with soap and water after using the toilet, changing diapers, and before eating or helping prepare food

• Staying away from water or food that may be contaminated

• Washing and/or peeling all raw vegetables and fruits before giving them to your child to eat

• Not drinking water from lakes, rivers, springs, ponds, or streams unless it has been filtered and chemically treated

• Boiling drinking water for 1 minute to kill the parasite. This will ensure safe drinking water during community-wide outbreaks caused by contaminated drinking water.

• Not drinking unboiled tap water and not eating uncooked foods washed with unboiled tap water when camping or traveling in countries where the water supply may be unsafe

• Not swimming in pools if your child has had crypto and for at least 2 weeks after diarrhea stops. Crypto can be passed in the stool and contaminate water for several weeks after your child no longer has symptoms. This has resulted in several outbreaks of crypto among pool users. Crypto can survive in chlorinated pools for several days.