Excessive rectal mucus is frequently caused by ulcerative colitis, shigellosis, and proctitis. Since it is also found in your daughter, then it most likely to be shigellosis. Shigellosis is a bacterial infection of the intestinal lining that is caused by a group of bacteria called Shigella. Shigella are spread when the bacteria are released in the stool and enter the mouth through the ingestion of contaminated food or water. Symptoms of shigellosis may develop in one to seven days, but generally show up three days after infection. Symptoms of shigellosis include abdominal pain and cramps, fever, blood in the stool, rectal mucus, rectal pain, nausea, vomiting and diarrhea. Shigellosis usually goes away on its own within seven days.
Antibiotics may be given to decrease the severity of symptoms and reduce the contagiousness of the infection. It is important to drink plenty of water while symptoms persist in order to prevent dehydration.