Shingles is an infection with the varicella-zoster virus; it's best known for the painful rash it causes. Unlike other viruses, the shingles virus can remain dormant for decades with no symptoms. One of the first signs is a burning, itching, or tingling sensation where the rash will form.
Many factors can cause the dormant shingles virus to reemerge, usually in older adults.
Anyone who has had chickenpox carries the virus that causes shingles. The virus remains dormant in the nerve tissue until something causes it to reactivate. The virus is considered opportunistic: this means it strikes when the immune system is weakened for some other reason.
If a person has never had chicken pox and they contract the varicella-zoster virus, they will get chicken pox, not shingles, whatever their age.
A person with active shingles can pass the varicella-zoster virus to another person who is not immune to chickenpox, either from a previous infection or vaccination. Some people who are exposed to the shingles virus don't show symptoms at that time, while others develop chickenpox initially and shingles later.
The virus is transmitted through the oozing and open sores of the rash. A person with shingles remains contagious until all the sores have crusted over.
Although younger people can contract shingles, the most common demographic is people 50 and older. Researchers don't fully understand why risk increases with age, though the virus' opportunistic reaction to a weakened immune system is a primary theory; the immune system tends to weaken as we age.
People with cancer being treated with chemotherapy or radiation are at increased risk of developing shingles. These life-saving treatments kill cancer cells, but they also kill healthy cells and suppress the immune system, which lowers resistance to bacterial or viral infections. Anyone undergoing this type of treatment should stay away from people with chickenpox or shingles.
As with aging, autoimmune disorders and other chronic conditions weaken the immune system. People with HIV, AIDS, or cancer have a much greater risk of developing shingles. Unfortunately, avoiding people with the active virus isn't always enough to prevent developing shingles if a person already has the dormant virus in them. Varicella-zoster is likely to take advantage of a time when the immune system is lowered.
Autoimmune disorders cause the immune system to over-react, so some people with these conditions are prescribed medication that suppresses their immune system to reduce symptoms. However, this suppression puts the patient at greater risk of the dormant shingles virus resurfacing.
Likewise, drugs that prevent the rejection of a transplanted organ can increase the chance of developing shingles.
A study by the Mayo Clinic concluded over 70 percent of those with asthma will develop shingles.
Researchers believe that over time, asthma weakens the immune system, making it easier for the shingles virus to reactivate. People with asthma are encouraged to get the shingles vaccine to reduce the likelihood of the virus reactivating.
People with family members who've had shingles are at increased risk for developing this painful infection. This 2016 review of multiple study concluded that family history is a significant risk factor for developing shingles.
More and more studies are showing the negative impact stress can have on health. One of the known effects is the weakening of the immune system. In addition to the direct causes, stress often leads to a person taking less good care of themselves day to day. The longer stress remains, the more likely the shingles virus will note the weak system and take advantage.
Chronic medical conditions, such as diabetes or heart disease, can increase the chances of having a shingles outbreak. As with other illness examples, a chronic disorder will keep the immune system in an overworked state, which weakens it.
Even a strong, healthy person can contract shingles, so it is even more important for people with chronic medical conditions to be extra vigilant in avoiding all other risk factors for shingles.
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