Cause
Diarrhea—frequent and watery bowel movements—can be caused by bacteria, viruses, or parasites that infect the stomach or intestines. The specific germs involved depend on the geographic area and the level of sanitation and hygiene.
Some Infections That Cause Diarrhea Amebiasis
Especially common in the tropics, this is an infection of the large intestine caused by the parasite Entamoeba histolytica, which is transmitted by contaminated food or drink or by direct fecal-oral contact.
Campylobacter. The Campylobacter bacterium can cause diarrhea and is spread by drinking contaminated water, eating undercooked poultry or meat, or coming in contact with contaminated animals.
Cryptosporidium. This parasite is a common cause of diarrhea outbreaks in child-care centers, and it can be spread by contact with infected animals—especially cows—or infected people or by drinking contaminated water.
E. coli. Five classes of E. coli bacteria can cause diarrhea in children either by directly attacking the intestine wall or by producing a toxin that irritates the intestines. E. coli infections are usually spread through contaminated food or water. Undercooked beef in hamburgers can also be a source of E. coli infections.
Giardiasis. Caused by the parasite Giardia, this is a common cause of diarrhea among diaperwearing children, especially in child-care settings. It is spread through contaminated water supplies—especially at water parks, aquarium “touch tanks,” and pools (it is resistant to chlorine)—and through human contact.
Rotavirus. This virus is the most common cause of diarrhea in young children in the United States. It is spread through contact with infected feces, and outbreaks often occur in child-care centers and children’s hospitals.
Salmonella. These bacteria are responsible for 50 percent of food poisoning in the United States. Almost any food of animal origin, especially raw or undercooked meat, poultry, and eggs, can cause salmonella.
Shigella. These bacteria are among the major causes of dysentery (bloody diarrhea) in the world and are spread by contact with contaminated feces.
Yersinia. Contaminated water and meat products, especially chitterlings and other pork products, are a common source of infection with this organism.
Symptoms Symptoms usually include crampy abdominal pain followed by diarrhea. Some bacterial infections, including campylobacter, salmonella, E. coli, shigella, and yersinia also may cause blood in the stools. With salmonella, shigella, and yersinia, the stool may also contain mucus. Some bacteria may also cause fever, loss of appetite, nausea, or vomiting. All can potentially lead to dehydration and weight loss.
Incubation Period
Times vary depending on the germ causing the infection. The incubation period for shigella is usually 16 to 72 hours. For a virus, incubation periods range from 4 to 48 hours. Parasitic infections usually have longer incubation periods; for example, giardia has an incubation period of one to three weeks.
How Long Symptoms Last
In cases of mild diarrhea caused by a virus, the diarrhea resolves within a few days. With bacterial diarrhea, symptoms may last days to weeks. Parasitic infections may cause diarrhea lasting weeks or even months.
When to Call Your Child’s Doctor
Call your child’s doctor if your child has a severe or prolonged bout of diarrhea with fever, vomiting, or severe abdominal pain, or if the stools contain blood or mucus. Call immediately if your child shows the following signs of dehydration: dry lips and tongue; pale, dry skin; sunken eyes; listless behavior; and decreased urination.
How the Diagnosis Is Made
A stool sample may be tested in a lab to identify the specific cause of the infection.
Treatment
First ensure your child receives enough fluids and minerals to replace those lost due to diarrhea. Viral and some of the bacterial infections are not treated with antibiotics because children usually recover on their own. Those infections caused by parasites are treated with antiparasitic medicines.
Home Treatment
Plain water should not be used to treat diarrhea in infants and small children. Your child’s doctor may advise using a special drink called an oral rehydration solution (such as Pedialyte) that replaces salts and other nutrients lost with diarrhea and is available at drugstores or grocery stores. The Centers for Disease Control and Prevention recommends that these be kept in the home for treatment of bouts of diarrhea in young children.
Prevention
Hand washing is the best way to prevent infections that are spread from person to person. Child-care personnel and parents should wash hands carefully after changing children’s diapers. Bathroom surfaces should be kept clean. Wash fruits and vegetables thoroughly before eating. Wash kitchen counters and utensils that have been in contact with raw meat, especially poultry. Refrigerate meats immediately after bringing them home, and cook them until they are no longer pink.
Refrigerate left-overs as soon as possible. Never drink from streams, lakes, or springs unless health authorities have said the water is safe for drinking. In developing countries it may be safer not to drink from the tap. Be careful when buying food prepared by street vendors, especially if no health agency oversees their safety practices.
Keep pets’ feeding areas separate from family eating areas. Never wash pet cages or bowls in the same sink where meals are prepared. Reptiles and amphibians such as iguanas and turtles may carry Salmonella bacteria and are not good pets for young children, who may fail to wash their hands adequately after handling them.
Complications
Diarrhea accounts for 9 percent of hospitalizations in children younger than five years. It kills 300 to 500 children in the United States each year, most of them infants younger than one year. Worldwide, it accounts for the deaths of four million children each year.