I am concerned about the safety of our town's newly revamped kiddie pool. After three consecutive days swimming there, my daughter came down with a high fever, vomiting, diarrhea and cramping. When her condition worsened after two days, I took her to the doctor, who saw a throat infection, put her on amoxicillin, and said she probably had strep. She has been on the antibiotics for three days now and still has diarrhea, so I wonder if there is more than just strep. Could she have been exposed to cryptosporidium in the pool? The only other time we used the pool, months ago, three days in a row, she also came down with a high fever. How can I find out if she is infected with cryptosporidium, so I can take it up with local health officials?

L.J.

There are a few important points I would like to make. Can one become infected in a pool? Certainly. Many cases of waterborne illness have occurred in such a setting. Most infections that can be spread in food and water can occur in a swimming pool that is improperly maintained. The majority of these infections -- such as cryptosporidiosis and shigellosis (also called dysentery) -- are spread by fecal-oral contact, which means that a small amount of feces containing the microbe is unknowingly consumed. When swimming, there is always a risk of accidentally ingesting water contaminated by feces. This is especially true in a children's pool, where there is a greater chance of someone defecating in the water. Most foodborne and waterborne illnesses cause diarrhea, which may be difficult to detect in a pool.

Your child had fever, vomiting and diarrhea -- common manifestations of foodborne illness -- so I highly doubt that your daughter had strep throat, which more typically causes sore throat, fever and lymph node swelling. You mentioned cryptosporidiosis, but I also doubt that this is the cause of your daughter's illness. Cryptosporidium), the one-celled parasite responsible for this infection, can cause swimming-pool-related illness. Public health authorities reported a large outbreak associated with a wave pool, where there is a high risk of ingesting water. However, cryptosporidiosis has an incubation period (the time between infection and the onset of symptoms) of more than five days, making it an unlikely cause of your daughter's illness. Also, fever and vomiting are not prominent in this infection; nausea, diarrhea and malaise are the common manifestations of cryptosporidiosis.

While I cannot exclude the possibility that the swimming pool was the source of your daughter's illness, the evidence supporting this claim is rather weak. A single illness after an event such as swimming could easily be a coincidence. To convince me that there is a relationship, there would have to be multiple people with similar ailments all related to swimming. When public health workers investigate such an outbreak, they interview many people to detect cases of an illness. You could speak to the managers of the pool and ask if other people reported developing similar symptoms. You could also contact the health department directly and ask them if an investigation is warranted. To find out with certainty if your daughter's illness is cryptosporidiosis, a simple stained smear of her stool could be performed.