Introduction to diarrhea:

Normal baby stool can look a lot like an adult's diarrhea stool. Healthy baby poop is often soft and runny, and (especially in the first month) quite frequent. One 2-week-old with 10 runny stools a day may be perfectly healthy, while another 4-month-old with 3 stools a day, all firmer than the other baby's, may have diarrhea. So how can a parent tell?

What is diarrhea?

When children lose more fluid and electrolytes in the stool than is healthy, they have diarrhea. Diarrhea can be caused by a change in diet (including a change in mother's diet if the baby is breastfed), by infection, by antibiotic use, or by a number of rare diseases. Each year there are about one billion cases of diarrhea in children worldwide. In most cases (more than 990 million of them), the diarrhea will resolve by itself within a week or so. Still, more than 3 million young children die each year from diarrhea (about 400-500 in the United States).

Who gets diarrhea?

Most children will have diarrhea several times throughout childhood. Most children with diarrhea have a viral infection in the gastrointestinal tract. Rotavirus, adenovirus, and the Norwalk virus are common causes. Bacteria, such as campylobacter or salmonella, and parasites, such as Giardia, can also cause diarrhea.

Diarrhea hits hardest in children 3 to 24 months old, although it can happen at any age.

Viral diarrhea is most common between November and May in the temperate climates of the Northern hemisphere.

What are the symptoms of diarrhea?

Look for a sudden increase in the frequency of the stools. Each child has her own stool frequency pattern that changes slowly over time. If it changes noticeably within only a few days, she may have diarrhea.

Any baby who has more than one stool per feeding should also be suspected of having diarrhea, even if this isn't a sudden change.

Also, look for a sudden increase in the water content of the stool. Other signs of illness in your baby, such as poor feeding, a newly congested nose, or a new fever, make the diagnosis of diarrhea more likely.

Is diarrhea contagious?

Most infections that cause diarrhea are quite contagious, spread by the fecal-oral route and by fomites.

How long does diarrhea last?

The duration of diarrhea will depend on the underlying cause. Diarrhea caused by antibiotic use may last as long as the child is taking the antibiotics.

An average diarrhea virus lasts for 5 to 7 days.

How is diarrhea diagnosed?

Diarrhea is diagnosed by history, physical exam, and by examining the stool. If there is blood or pus in the diarrhea, or if the diarrhea is not improving as expected, stool studies may be performed to determine the specific cause.