Dysentery

Dysentery is an inflammatory disease of the intestine, especially of the colon, which always results in severe diarrhea and abdominal pains. Other symptoms may include fever and a feeling of incomplete defecation. The disease is caused by several types of infectious pathogens such as bacteria, viruses and parasites. The most common form of dysentery is bacillary dysentery, which is typically a mild sickness, causing symptoms normally consisting of mild gut pains and frequent passage of stool or diarrhea. Symptoms normally present themselves after 1-3 days, and are usually no longer present after a week. The frequency of urges to defecate, the large volume of liquid feces ejected, and the presence of blood, mucus or pus depends on the pathogen causing the disease. Temporary lactose intolerance can occur, as well. In some caustic occasions severe abdominal cramps, fever, shock and delirium can all be symptoms. In extreme cases, dysentery patients may pass more than one liter of fluid per hour. More often, individuals will complain of intense abdominal pains and severe diarrhea with blood or mucus, accompanied by rectal pain and low-grade fever. Rapid weight loss and generalized muscle aches sometimes also accompany dysentery, while nausea and vomiting are rare. On rare occasions, the amoebic parasite will invade the body through the bloodstream and spread beyond the intestines. In such cases, it may more seriously infect other organs such as the brain, lungs, and most commonly the liver. Dysentery results from viral, bacterial, or parasitic infections. These pathogens typically reach the large intestine after entering orally, through ingestion of contaminated food or water, oral contact with contaminated objects or hands, and so on. Each specific pathogen has its own mechanism or pathogenesis, but in general, the result is damage to the intestinal linings, leading to the inflammatory immune responses. This can cause elevated physical temperature, painful spasms of the intestinal muscles (cramping), swelling due to fluid leaking from capillaries of the intestine (edema) and further tissue damage by the body's immune cells and the chemicals, called cytokines, which are released to fight the infection. The result can be impaired nutrient absorption, excessive water and mineral loss through the stools due to breakdown of the control mechanisms in the intestinal tissue that normally remove water from the stools, and in severe cases, the entry of pathogenic organisms into the bloodstream. Anemia may also arise due to the blood loss through diarrhea. Bacterial infections that cause bloody diarrhea are typically classified as being either invasive or toxogenic. Invasive species cause damage directly by invading into the mucosa. The toxogenic species do not invade, but cause cellular damage by secreting toxins, resulting in bloody diarrhea. This is also in contrast to toxins that cause watery diarrhea, which usually do not cause cellular damage, but rather they take over cellular machinery for a portion of life of the cell. Some microorganisms – for example, bacteria of the genus Shigella – secrete substances known as cytotoxins, which kill and damage intestinal tissue on contact. Shigella is thought to cause bleeding due to invasion rather than toxin, because even non-toxogenic strains can cause dysentery, but E. coli with shiga-like toxins do not invade the intestinal mucosa, and are therefore toxin dependent. Viruses directly attack the intestinal cells, taking over their metabolic machinery to make copies of themselves, which leads to cell death. Definitions of dysentery can vary by region and by medical specialty. The U. S. Centers for Disease Control and Prevention (CDC) limits its definition to 'diarrhea with visible blood'. Others define the term more broadly. These differences in definition must be taken into account when defining mechanisms. For example, using the CDC definition requires that intestinal tissue be so severely damaged that blood vessels have ruptured, allowing visible quantities of blood to be lost with defecation. Other definitions require less specific damage.