Diarrheal Diseases, Part 1

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Diarrheal diseases caused by bacteria usually are classified as:
*dysentery - bloody diarrhea w/fever
*watery diarrhea
Shigella and E.coli O157:H7 are well-known for producing Shiga Toxin. This toxin binds to receptors on intestinal cells and is allowed inside. It then blocks protein synthesis and can actually kill the cell. The damages the integrity of the mucosal lining.
Shiga toxin that gets into the submucosal capillaries can damage the endothelial lining, which allows erythrocytes to escape the capillaries and enter the lumen of the intestine. This is the source of the bloody diarrhea.
If Shiga toxin reaches the kidney, it may damage the delicate kidney capillaries and result in hemolytic uremic syndrome.
Antibiotic use for such bacterial infections needs to be considered carefully; the antibiotics can actually worsen the disease in some cases by causing the Gram negative bacteria to release its endotoxin (part of its LPS lipid layer) which can cause a cytokine storm and lead to septic shock.
Shigella and Listeria bacteria are infamous for their ability to trigger endocytosis into our intestinal cells, then harness human actin protein to use to propel itself from one cell to another - spreading the infection rapidly.
White blood cells that engulf the bacteria or the toxin will then present the antigen to helper T cells to start the adaptive immune response. Activated helper T cells stimulate cytotoxic T cells (that can directly destroy the pathogen) or stimulate B cells to produce antibodies.
Antibodies may successfully lead to immunity from the disease, but sometimes comes at a steep cost. In some cases about 2-3 weeks later a "reactive" arthritis may occur if the antibodies bound to parts of our joints. Such "cross-reactions" can occur with any organ, but are best documented with joints.
Animals such as pigs, deer, and cows can be carriers for E.coli O157:H7 because they lack the intestinal receptors that allow the toxin to enter their cells. Thus, they won't get sick from it but can pass it on if their feces contaminate crops such as lettuce.
Watery diarrhea is most classically explained using Vibrio cholera as an example. Cholera toxin causes intestinal cells to insert too many K+ channels into their cell membranes. This allows too much K+ to leave the cells and enter the intestinal lumen. Water follows the K+ and so massive watery diarrhea occurs -- sometimes called "rice water diarrhea". Extreme dehydration and electrolyte imbalance can thus lead to hypovolemic shock and organ failure.

[@susan5440]

Thank you for this important topic which happened to me Christmas gone. I was 7 days in hospital and 6 days full Watery Diarrhea. I was terrible sick and at one stage I thought I was going to die, when I was released from Hospital it continued for a further 3 days. Doctors don't explain in too much detail, so thanks.

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I’m pretty sure I have a watery diarrhea infection because I’ve been having diarrhea for the past night, what do I do!!!!

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