Symptoms vary from none to severe diarrhea with poor absorption of nutrients. The cause of this wide range in severity of symptoms is not fully known but the intestinal flora of the infected host may play a role. Diarrhea is less likely to occur in people from developing countries. Symptoms typically develop 9–15 days after exposure, but may occur as early as one day. The most common and prominent symptom is chronic diarrhea which can occur for weeks or months if untreated. Diarrhea is often greasy and foul-smelling, with a tendency to float. This characteristic diarrhea is often accompanied by a number of other symptoms, including gas, abdominal cramps, and nausea or vomiting. Some people also experience symptoms outside of the gastrointestinal tract, such as itchy skin, hives, and swelling of the eyes and joints, although these are less common. Fever occurs in only about 15% of people, in spite of the nickname "beaver fever". Prolonged disease is often characterized by diarrhea, along with malabsorption of nutrients in the intestine. This malabsorption results in fatty stools, substantial weight loss, and fatigue. Additionally, those suffering from<unk>  often have difficulty absorbing lactose, vitamin A, folate, and vitamin B12. In children, prolonged<unk>  can cause failure to thrive and may impair mental development. Symptomatic infections are well recognized as causing lactose intolerance, which, while usually temporary, may become permanent.
Giardiasis
Irritable bowel syndrome
Cryptosporidiosis
Cyclosporiasis
Eosinophilic gastroenteritis
Dientamoebiasis
Opisthorchiasis
Amoebiasis