Viruses, Ba​cteria & 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 kit​chen. Some bacteria live in 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 illnesse​s 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 (su​ch as diarrhea). Bacteria can infect any part of the body, but often cause diarrhea when they invade the digestive tract. 


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 ha​ve additional sympto​ms including nausea, vomiting, stomach aches, headache or fever. 

Coming in ​Contact

Children can come in contact with bacteria, viruses and parasites in numerous ways, including the following:

  • ​When touching the stool of an infected person
  • When touching a contaminated object
  • By ingesting contaminated food or water 


Viruses, bacteria and parasites that invade the digestive tract usually cause diarrhea. Large amounts of water are lost with the diarrhe​a, leading to dehydration in children. Children become dehydrated much quicker than adults, and this can lead to serious problems if fluids are not replaced and the infection treated. 

Also, children with a severely weakened immune system are at risk for more serious disease. Symptoms may be more severe and could lea​d 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. 

Germs from Fo​od

Almost everyone has experienced a food-borne illnes​s at some point in time. Contrary to popular belief, food-borne 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 Centers for Disease Control and Prevention, each year food-borne illnesses kill up to 9,000 people of all ages. They also cause fever, stomach cramps, vomiting and diarrhea in almost 80 million Americans, or about one in three people. 

Tips to Prevent Contaminatin​g Food  

Use caution when buying f​o​od 

  • ​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.
  • Take food home right away so that it does not spoil in a hot car. 
  • Avoid raw or unpasteurized milk. 
  • Because eggs, meat, seafood and poultry are most likely to contain bacteria, do not allow their juices to drip on other food. 

Store Food Pr​operly

  • ​Store eggs, raw meat, poultry and seafood in the refrigerator
  • A refrigerator should be set at 40° F 
  • A freezer should be set at 0° F
  • Regularly clean and disinfect the refrigerator and freezer
  • Use containers to prevent contaminating other foods or kitchen surfaces
  • Do not store food uncovered in the refrigerator or freezer

Preparing & Cooking Food Carefully

  • ​Wash your hands and clean and disinfect kitchen surfaces before, during, and after handling, cooking and serving food. 
  • Defrost frozen food on a plate either in the refrigerator or in a microwave, but not on the counter. 
  • Cook food immediately after defrosting. 
  • Use different dishes and utensils for raw foods than you use for cooked foods.
  • Wash raw fruits and vegetables before eating them. 
  • Cool and promptly store leftovers after food has been served. 
  • Because harmful bacteria grow at room temperature, keep hot food hot at 140° F or higher, and keep cold food cold at 40° F or cooler. This is especially important during picnics and buffets.
  • Do not leave perishable foods out for more than two hours.
  • Promptly refrigerate or freeze leftovers in shallow containers or wrapped tightly in bags.