Chronic diarrhea
When diarrhea lasts for more than four weeks a number of further tests may be recommended including:
Complete blood count and a ferritin if anemia is present
Thyroid stimulating hormone
Tissue transglutaminase for celiac disease
Fecal calprotectin to exclude inflammatory bowel disease
Stool tests for ova and parasites as well as for Clostridioides difficile
A colonoscopy or fecal immunochemical testing for cancer, including biopsies to detect microscopic colitis
Testing for bile acid diarrhea with SeHCAT, 7α-hydroxy-4-cholesten-3-one or fecal bile acids depending on availability
Hydrogen breath test looking for lactose intolerance
Further tests if immunodeficiency, pelvic radiation disease or small intestinal bacterial overgrowth suspected.A 2019 guideline recommended that testing for ova and parasites was only needed in people who are at high risk though they recommend routine testing for giardia. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were not recommended. Prevention
Sanitation
Numerous studies have shown that improvements in drinking water and sanitation (WASH) lead to decreased risks of diarrhoea. Such improvements might include for example use of water filters, provision of high-quality piped water and sewer connections.In institutions, communities, and households, interventions that promote hand washing with soap lead to significant reductions in the incidence of diarrhea. The same applies to preventing open defecation at a community-wide level and providing access to improved sanitation. This includes use of toilets and implementation of the entire sanitation chain connected to the toilets (collection, transport, disposal or reuse of human excreta). There is limited evidence that safe disposal of child or adult feces can prevent diarrheal disease.
The absence of certain resources compromises the ability of the poor to defend themselves against infectious diarrhea. "Poverty is associated with poor housing, crowding, dirt floors, lack of access to clean water or to sanitary disposal of fecal waste (sanitation), cohabitation with domestic animals that may carry human pathogens, and a lack of refrigerated storage for food, all of which increase the frequency of diarrhea ... Poverty also restricts the ability to provide age-appropriate, nutritionally balanced diets or to modify diets when diarrhea develops so as to mitigate and repair nutrient losses. The impact is exacerbated by the lack of adequate, available, and affordable medical care. "One of the most common causes of infectious diarrhea is a lack of clean water. Often, improper fecal disposal leads to contamination of groundwater. This can lead to widespread infection among a population, especially in the absence of water filtration or purification. Human feces contains a variety of potentially harmful human pathogens. Nutrition
Proper nutrition is important for health and functioning, including the prevention of infectious diarrhea. It is especially important to young children who do not have a fully developed immune system. Zinc deficiency, a condition often found in children in developing countries can, even in mild cases, have a significant impact on the development and proper functioning of the human immune system. Indeed, this relationship between zinc deficiency and reduced immune functioning corresponds with an increased severity of infectious diarrhea.