Download Viruses, Bacteria, and Parasites in the Digestive Tract

Viruses, Bacteria, and Parasites in the Digestive Tract
What are viruses, bacteria, and parasites?
Viruses, bacteria, and parasites are living organisms that are found all around us. They exist in
water and soil, on the surfaces of foods that we eat and on surfaces that we touch, such as
countertops in the bathroom or kitchen. Some bacteria live in and on our bodies and do not cause
problems. Other kinds of bacteria (as well as parasites and viruses) can make us quite ill if they
invade our bodies. Bacteria and viruses can live outside of the human body (for instance, on a
countertop) sometimes for many hours or days. Parasites, however, require a living host in order
to survive.
Bacteria and parasites can usually be destroyed with antibiotics. On the other hand, antibiotics
cannot kill viruses. Children with viral illnesses can be given medications to make them
comfortable, but antibiotics are ineffective against treating these infections.
Bacteria, viruses, and parasites can cause a wide variety of illnesses, and can infect any of the
organs of the body. Viruses are often responsible for respiratory illnesses (such as the common
cold) and digestive illnesses (such as diarrhea). Bacteria can infect any part of the body, but often
cause diarrhea when they invade the digestive tract.
What is diarrhea?
Diarrhea can be caused by a variety of bacteria, viruses, and parasites. Children can also have
diarrhea without having an infection, such as when diarrhea is caused by food allergies or as a
result of taking medications (such as antibiotics). A child is considered to have diarrhea when the
child's bowel movements are both more frequent than usual and looser and more watery than
usual.
Children with diarrhea may have additional symptoms including nausea, vomiting, stomach
aches, headache, or fever.
How does a child usually come in contact with bacteria, viruses, or parasites that cause
diarrhea?

When touching the stool of an infected person (such as when touching soiled diapers)

When touching an object contaminated with the stool of an infected person, and then
ingesting the germs--this usually occurs by touching the mouth with a contaminated hand
(can occur at day care centers or at home in areas where diapered babies play)

By ingesting contaminated food or water
Why is infection with these organisms a concern?
Viruses, bacteria, and parasites that invade the digestive tract usually cause diarrhea. Large
amounts of water are lost with the diarrhea, leading to dehydration in children. Children become
dehydrated much quicker than adults, and this can lead to serious problems if fluids are not
replaced. Infections caused by parasites and a few types of infections caused by bacteria may
also need treatment with medications.
Also, children with a severely weakened immune system are at risk for more serious disease.
Symptoms may be more severe and could lead to serious illness. Examples of persons with
weakened immune systems include those with HIV/AIDS, cancer and transplant patients who are
taking certain immunosuppressive drugs, and those with inherited diseases that affect the
immune system.
Common bacteria, viruses, and parasites that cause diarrhea
Bacteria
E. coli
Description
Escherichia coli O157:H7 is just one of the hundreds of strains of the
bacterium Escherichia coli (E. coli). Most strains of E. coli are harmless and
live in the intestines of healthy humans and animals. E. coli, however,
produces a powerful toxin that can cause a severe infection. (The
combination of letters and numbers in the name of the bacterium refers to
the specific markers found on its surface and distinguishes it from other
types of E. coli.)
The CDC recognizes E. coli as a foodborne illness. Infection often leads to
bloody diarrhea, stomach cramps, vomiting, and fever.
Most E. coli illness has been associated with eating undercooked,
contaminated ground beef. E. colibacteria live in the intestines of healthy
cattle and, although the number of organisms required to cause disease is
not known, it is suspected to be very small. Meat becomes contaminated
during slaughter, and organisms can be thoroughly mixed into beef when it
is ground. Contaminated beef looks and smells normal. Other ways to
transmit E. coli include:
Transmission

Person-to-person contact in families and in child-care and other
institutional-care centers can also be places where the transmission
of the bacteria can occur.

Bacteria present on a cow's udders, or on equipment, may get into
raw milk causing the infection.

Infection may also occur after swimming in or drinking sewagecontaminated water.

It has been confirmed that unpasteurized juices, such as apple cider,
may also cause the infection.
Bacteria in diarrhea stools of infected people can be passed from one person
to another if hygiene or handwashing habits are inadequate. This is
particularly likely among toddlers who are not toilet trained. Family
members and playmates of these children are at high risk of becoming
infected.
Young children typically shed the organism in their feces for a week or two
after their illness resolves.
CDC recommendations for prevention of the infection include:
Prevention

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.

Using a digital instant-read meat thermometer, the temperature of
the meat should reach a minimum of 160 degrees F.

If you are served an undercooked hamburger in a restaurant, send it
back.

Consume only pasteurized milk and milk products. Avoid raw milk.

Consume only pasteurized juices and ciders.

Make sure that infected people, especially children, wash their hands
carefully and frequently 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.

Avoid swallowing lake or pool water while swimming.

Wash hands thoroughly after using the toilet.

People with diarrhea should not:
o
Swim in public pools or lakes
o
Bathe with others
o
Prepare food for others
Salmonella
Salmonella is a bacteria that infects the intestines and causes diarrhea, fever,
and abdominal cramps 12 to 72 hours after infection. Over 1 million cases
of salmonella infection are reported in the United States each year. The
illness usually lasts four to seven days and most people recover without
treatment.
Description
However, in some people the diarrhea may be so severe that the patient
needs to be hospitalized. In those patients, the salmonella infection may
spread from the intestines to the blood stream and then to other body sites
and can cause death unless the person is treated promptly with antibiotics.
Infants and those with impaired immune systems are more likely to have a
severe illness.
Salmonella may be spread by:

Eating raw foods contaminated with animal feces.
Contaminated foods usually look and smell normal. Contaminated
foods are often of animal origin, such as beef, poultry, milk, or eggs,
but all foods, including some unwashed fruits and vegetables, and
peanut butter, may become contaminated. Many raw foods of animal
origin are frequently contaminated, but fortunately, thorough
cooking kills salmonella.

Handling reptiles. Reptiles (such as iguanas and turtles) are
particularly likely to harbor Salmonella and people should always
wash their hands immediately after handling a reptile, even if the
reptile is healthy. Adults should also be careful that children wash
their hands after handling a reptile.
Transmission
Since foods of animal origin pose the greatest threat of salmonella
contamination, do not eat raw or undercooked eggs, poultry, or meats.
Remember that some sauces and desserts use raw eggs in their preparation,
so be cautious of these, particularly in foreign countries. Also, follow these
recommendations by the CDC:
Prevention

Make sure poultry and meat, including hamburgers, are well-cooked,
not pink in the middle.

Do not consume raw or unpasteurized milk or other dairy products.

Thoroughly wash produce before eating it.

Avoid cross-contamination of foods. Uncooked meats should be
kept separate from produce, cooked foods, and ready-to-eat foods.

All utensils, including cutting boards, knives, counters, etc., should
be thoroughly washed after handling uncooked foods.

Thoroughly wash hands before handling foods and between
handling different food items.

Thoroughly wash hands after contact with feces.

Thoroughly wash hands after handling any reptiles, since reptiles are
particularly likely to have Salmonella.
Viruses
Rotavirus
Rotavirus is the most common cause of severe diarrhea among children,
resulting in the death of over 500,000 children annually worldwide.
Description
In the United States, the disease occurs most often in the winter, with annual
epidemics occurring from December to June. The highest rates of illness
occur among infants and young children, and most children in the United
States are infected by 5 years of age. Adults can also be infected, though
disease tends to be mild.
The incubation period for rotavirus disease is approximately two days. The
disease is characterized by vomiting and watery diarrhea for three to eight
days, and fever and abdominal pain occur frequently. Immunity after
infection is incomplete, but repeat infections tend to be less severe than the
original infection.
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.
Transmission
Prevention
A rotavirus vaccine that was approved by the FDA in 1998 was pulled from
the market in 1999 because of an association between the vaccine and an
increased risk for intussusception (form of bowel blockage) in infants aged
one year or younger. However, no direct link was established to the vaccine
as a cause of intussusception.
A new rotavirus vaccine was approved by the FDA in 2006. The risk for
intussusception with the new vaccine was evaluated in a large clinical trial
of over 30,000 children, and no increased risk was found. The manufacturer
of the vaccine will continue to closely monitor the vaccine's safety in
additional clinical studies. Some, but not all, studies indicate there may be a
very small risk of intussusception, but the benefits outweigh the
possible risks and the CDC continues to recommend routine rotovirus
vaccination of infants.
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.

Children should 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
frequently, especially if a sick child has been in the home.

Use diapers with waterproof outer covers that can contain liquid
stool or urine, or use plastic pants.

Make sure that children wear clothes over diapers.
Parasites
Giardia
Description
During the past 15 years, Giardia lamblia has become recognized as one of
the most common waterborne diseases in humans in the United States.
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 region of the United States and throughout the
world.
Diaper-aged children who attend day care centers, international travelers,
hikers, campers, and others who drink untreated water from contaminated
sources, are most at risk for developing infection with Giardia. Several
community-wide outbreaks of infection have been linked to drinking
municipal water contaminated with Giardia.
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 become infected with Giardia include:
Transmission

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, diaper pails.
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.

Avoiding drinking water from lakes, rivers, springs, ponds, or
streams unless it has been filtered and chemically treated.

Boiling drinking water for one minute to kill the Giardia parasite.
This will ensure safe drinking water during community-wide
outbreaks caused by contaminated drinking water.

When camping or traveling in countries where the water supply may
be unsafe, avoid drinking unboiled tap water and avoid uncooked
foods washed with unboiled tap water. Bottled or canned carbonated
beverages, seltzers, pasteurized fruit drinks, and steaming hot coffee
and tea, are safe to drink.
Prevention
If your child has Giardia, avoid swimming in pools for two weeks after the
diarrhea or loose stools have cleared. Giardia is fairly chlorine resistant and
is passed in the stools of infected people for several weeks after they no
longer have symptoms.
Cryptosporidium
Description
Cryptosporidium, often referred to as "crypto," is a tiny parasite that can
live in the intestines of humans and animals. The parasite is protected by an
outer shell that allows it to survive outside the body for long periods of time
and makes it very resistant to chlorine disinfection.
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 cryptosporidium up from surfaces contaminated with stool
from an infected person (such as toys, bathroom fixtures, changing
tables, and diaper pails).
Transmission
The CDC recommends:

Your child should wash their hands with soap and water after using
the toilet, changing diapers, and before eating or helping prepare
food.

Avoid water or food that may be contaminated.

Washing and/or peeling all raw vegetables and fruits before giving
them to your child to eat.

Avoiding drinking water from lakes, rivers, springs, ponds, or
streams unless it has been filtered and chemically treated.

Boiling drinking water for one minute to kill the cryptosporidium
parasite. This will ensure safe drinking water during communitywide outbreaks caused by contaminated drinking water.

When camping or traveling in countries where the water supply may
be unsafe, avoid drinking unboiled tap water and avoid uncooked
foods washed with unboiled tap water.

Avoiding swimming in pools if your child has had cryptosporidium
and for at least two 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
Prevention
cryptosporidium among pool users. Crypto can survive in
chlorinated pools for several days.
Can my child get germs from food?
Almost everyone has experienced a foodborne illness at some point in time. Contrary to popular
belief, foodborne illnesses can occur when food is prepared at a restaurant or at home. If food is
handled and prepared safely, most illnesses can be avoided.
All food may contain some natural bacteria, and improper storage or handling gives the bacteria
a chance to grow. Also, food can be contaminated with bacteria from other sources that can make
you ill. Contaminated or unclean food can be very dangerous, especially to children. According
to the CDC, each year foodborne illnesses kill 3,000 people of all ages. They also cause fever,
stomach cramps, vomiting, and diarrhea in an estimated 48 million Americans.
Four major tips recommended by the CDC to prevent contaminating food



Use caution when buying food:
o
When at the grocery store, pick up perishable food such as meat, eggs, and milk at
the very end of your shopping, so they will stay cool.
o
Take food home right away so that it does not spoil in a hot car.
o
Avoid raw or unpasteurized milk.
o
Because eggs, meat, seafood, and poultry are most likely to contain bacteria, do
not allow their juices to drip on other food.
Store food properly:
o
Store eggs, raw meat, poultry, and seafood in the refrigerator.
o
A refrigerator should be set between 32 degrees F and 40 degrees F.
o
A freezer should be set at or below 0 degrees F.
o
Regularly clean and disinfect the refrigerator and freezer.
o
Use containers to prevent contaminating other foods or kitchen surfaces. Do not
store food uncovered in the refrigerator or freezer.
Use special precautions when preparing and cooking food:
o
Wash your hands and clean and disinfect kitchen surfaces before, during, and
after handling, cooking, and serving food.
o
Defrost frozen food on a plate either in the refrigerator or in a microwave, but not
on the counter.
o
Cook food immediately after defrosting.

o
Use different dishes and utensils for raw foods than you use for cooked foods.
o
Wash raw fruits and vegetables before eating them.
Cool and promptly store leftovers after food has been served:
o
Because harmful bacteria grow at room temperature, keep hot food hot and keep
cold food cold. This is especially important during picnics and buffets.
o
Do not leave perishable foods out for more than two hours.
o
Promptly refrigerate or freeze leftovers in shallow containers or wrapped tightly
in bags.
Medical Reviewers:

Dozier, Tennille, RN, BSN, RDMS

MMI board-certified, academically-affiliated clinician