Immunopathology of Diarrhea in Animals

Enteritis is defined as an inflammation of the intestine and affects wide age groups and is characterized by dull and depressed appearance, abdominal pain, weight loss and characteristically diarrhea. Diarrhea is defined as increase in frequency of faeces output (more than 3 to 4 times a day) and a decrease in the consistency. Globally, billions of peoples are found to be affected with diarrhea, and most badly driven is people of the developing countries. Crucial management of diarrhea is necessary as excess loss of water and electrolyte may lead to death. Diarrhea is mainly seen as a manifestation of gastrointestinal infection, which may be bacterial, viral, and parasitic in origin. It spreads mainly through ingestion of the contaminated food and water, and poor hygienic condition. Worst struck are the young and immuno-compromised animals. Disease and infections affecting large intestine causes diarrhea due to disturbances in water conservation; whereas, in the small intestine, it is osmotic or secretary activity. Balance between secretion and absorption of electrolytes is a dynamic process and its imbalance results into diarrhea. There are multiple causes for diarrhea and the following classification provides a useful framework for approaching diarrhea; 1) Diarrhea secondary to altered mucosal transport or secretory dysfunction, 2) Osmotic diarrhea, 3) Diarrhea secondary to malabsorption, 4) Exudative diarrhea, and 5) Diarrhea secondary to altered bowel motility. Besides above, there are various mediators involved in diarrhea and are broadly mentioned in this book chapter.