Causes of HUS

Related Information: Causes of hus, HUS causes, signs

Research has not yet found the causes for the Hemolytic Uremic Syndrome occurrence in most of the patients. Some of the known things about HUS are

1. The disease is non-contagious.

2. It is not a genetic disease except in some families.

3. It can affect people irrespective of age.

4. It affects women more than men.

5. Patients affected become overweight.

6. Sometimes, HUS occurs during or soon after pregnancy. Since the symptoms are similar to toxemia of pregnancy or preeclampsia (high BP resolved after pregnancy), it is difficult to be diagnosed correctly.

7. Some allergic reactions due to medicine can also cause HUS. Quinine (remedy for leg cramps) is found to cause HUS mostly.

8. HUS is mainly caused by bacterial infection. E. coli 0157:H7 in undercooked or partially cooked beef or hamburger can cause HUS. In this type, bloody diarrhea is seen initially and it mostly occurs in children.

9. And some cases of HUS may be due to autoimmunity. Here, antibodies block the function of one’s own enzymes called ADAMTS13. The enzymes are helpful in the digestion of foods. Commonly they are found in mouth, intestines and stomach.

ADAMTS13 is one such enzyme in blood which digests proteins thus making platelets to agglutinate. This is known as VWF or von Willebrand factor. This is made big in the cell lining the blood vessel and ADAMTS13 cuts the VWF smaller to its regular size. If there is deficiency of the enzyme, VWF is very large and sticky for the platelets. As a result, platelets clump together blocking blood vessels and causing TTP. Thus ADAMTS13 is essential for the prevention of platelet thrombi. Immunity refers to the natural development of antibodies in response to foreign bodies entering the body. Such diseases are referred as autoimmune since antibodies are developed against one’s own tissues. The symptoms in some patients may resemble autoimmune illnesses like lupus.

Most HUS cases in children begin after the infection through the strain E. coli O157:H7.
E. coli are bacteria found naturally in intestines of healthy animals and humans. There are hundreds of types in E. coli, of which only very few are harmful and can cause severe food-borne infections, along with those that lead to HUS as well. E. coli occurs in

• Unclean produce or partially cooked meat.

• Pools or lakes with feces contamination.

All the strains of harmful E. coli are not formed equally. For instance, the E. coli strain which causes traveler’s diarrhea frequently runs its course within a few days. There are some people who have recovered completely in just 5-10 days after being affected by the most virulent E. coli strain, O157:H7. Progression to HUS is not common.

There are chances for HUS in children to be followed by other bacterial infection. Bacteria like shigella, yersinia, salmonella, campylobacter, etc can affect. In adults, HUS can be mostly caused by autoimmunity or an infection in blood or due to some medications. But in most of the instances, the cause in adults is unclear or unknown.