Giardiasis is a parasitic disease caused by Giardia duodenalis (also known as G. lamblia and G. intestinalis). Infected individuals who experience symptoms (about 10% have no symptoms) may have diarrhea, abdominal pain, and weight loss. Less common symptoms include vomiting and blood in the stool. Symptoms usually begin 1 to 3 weeks after exposure and, without treatment, may last two to six weeks or longer.Giardiasis usually spreads when Giardia duodenalis cysts within feces contaminate food or water that is later consumed orally. The disease can also spread between people and through other animals. Cysts may survive for nearly three months in cold water. Giardiasis is diagnosed via stool tests.Prevention may be improved through proper hygiene practices. Asymptomatic cases often do not need treatment. When symptoms are present, treatment is typically provided with either tinidazole or metronidazole. Infection may cause a person to become lactose intolerant, so it is recommended to temporarily avoid lactose following an infection. Resistance to treatment may occur in some patients.Giardiasis occurs worldwide. It is one of the most common parasitic human diseases. Infection rates are as high as 7% in the developed world and 30% in the developing world. In 2013, there were approximately 280 million people worldwide with symptomatic cases of giardiasis. The World Health Organization classifies giardiasis as a neglected disease. It is popularly known as beaver fever in North America. Signs and symptoms
Symptoms vary from none to severe diarrhea with poor absorption of nutrients.
Gallstone ileus is a rare form of small bowel obstruction caused by an impaction of a gallstone within the lumen of the small intestine. Such a gallstone enters the bowel via a cholecysto-enteric fistula. The presence of large stones, >2.5 cm in diameter, within the gallbladder are thought to predispose to fistula formation by gradual erosion through the gallbladder fundus. Once a fistula has formed, a stone may travel from the gallbladder into the bowel and become lodged almost anywhere along the gastrointestinal tract. Obstruction occurs most commonly at the near the distal ileum, within 60 cm proximally to the ileocecal valve. Rarely, gallstone ileus may recur if the underlying fistula is not treated.First described by Thomas Bartholin in 1654, the name "gallstone ileus" is a misnomer because an ileus is, by definition, a non-mechanical bowel motility failure  (as opposed to a mechanical obstruction by a stone). Diagnosis
Diagnosis of gallstone ileus requires radiographic studies. Classic radiographic findings are known as Riglers triad:
pneumobilia (air within the biliary tree)
evidence of small bowel obstruction
radiopaque gallstone on abdominal radiograph

Treatment
Initial management involves fluid resuscitation and potentially nasogastric suctioning. Since gallstone ileus constitutes a form of mechanical small bowel obstruction, it can be a surgical emergency and requires open or laparoscopic surgery to remove an impacted stone. The different strategies for surgical management are either enterolithotomy alone, allowing a delayed cholecystectomy after an inflammation-free period of 4–6 weeks (and therefore two-stage surgery) or enterolithotomy in combination with a cholecystectomy and fistula division (one-stage surgery).