Shingles & Post-herpetic Neualgia

by D. Kishore Yellumahanthi, MD, MPH

Herpes Zoster or Shingles is caused by the same virus that causes chicken pox – Varicella Zoster Virus. After a person gets chicken pox, the rash resolves after few weeks but the virus remains inside the body for the rest of the life. At a later point, this virus, could get activated and manifest as shingles.

It is not clearly known what actually causes this activation. It could be spontaneous or associated with factors like stress, immunosuppression or radiation therapy and so on. Although Shingles can occur at any age, the risk increases sharply after 50 years of age. The incidence for herpes zoster is approximately 4 cases per 1,000 U.S. population annually, age-adjusted to the 2000 U.S. population. The incidence among people 60 years of age and older is about 10 cases per 1,000 U.S. population annually.

HOW DOES THE RASH OF SHINGLES LOOKS LIKE?

• Rash looks like groups of blisters arranged in a ribbon like shape.

• Burning pain usually precedes the rash by few days.

• The rash can occur anywhere – Lower extremity or Upper extremity or Trunk or Belly or Face.

• The rash characteristically occurs on only one side of the body.

• Never crosses the midline.

WHO ARE SUSCEPTIBLE TO SHINGLES? All those who had chicken pox disease and also chicken pox vaccine are susceptible to shingles. It is to be noted that, people who had chicken pox vaccine are also prone to shingles just as people who had chicken pox disease, although the chances are less.

For most part, shingles occurs only one time in lifetime. Second and subsequent attacks are rare.

WHAT IS POST-HERPETIC NEURALGIA? The dreaded complication of shingles is ‘Post - herpetic Neuralgia’ or PHN. Unfortunately, it is the most common complication of shingles. Generally, if pain in the area of shingles persists beyond 3 months, it is categorized as PHN. This complication, which occurs in approximately 20% of patients who had shingles, can severely affect the quality of life of that individual, as it can cause severe pain and can last for several years. It would not be an exaggeration to state that, PHN can diminish quality of life to the same extent as that of congestive heart failure, heart attack, type II diabetes and major depression.

It is worthy to note that 80% of PHN cases occur in patients 50 years or older.

TREATMENT OF SHINGLES: Anti viral drugs like Acyclovir or Famciclovir or Valacyclovir, if taken within 72hrs of onset of shingles, can help in faster healing. It is not exactly clear if these drugs have any role in reducing the chances of PHN or not.

ARE ANY VACCINES AVAILABLE TO PREVENT SHINGLES? Currently there are two vaccines available that can prevent shingles. They are Zostavax and Shingrix. Both vaccines can be administered after 50 years old. Zostavax has been in the market since 2006. It is administered as a single shot (Intramuscular injection). No second dose is required. It reduces the risk of developing shingles by about 51% and PHN by about 67%.

On the other hand, Shingrix which has been introduced in October 2017, is administered as two doses, 2 to 6 months apart. Two doses of Shingrix is supposed to be about more than 90% effective at preventing Shingles. The efficacy of two doses of Shingrix for prevention of PHN was about 91% for adults 50years and older and 88.8% in adults age 70 years and older.

WHAT DOES FUTURE HOLD FOR SHINGLES AND PHN? Given that vaccine is the only way to prevent shingles and the subsequent PHN, it is certainly very exciting to know that there is a vaccine available in the market, that is more than 90% effective in preventing shingles. Since shingles is more common in people above 50 years, effective vaccination is going to significantly reduce the number of new cases of shingles, which in turn is going to reduce the number of PHN cases. Also, the severe long lasting PHN is more common in patients who are affected with shingles after 50 years. Keeping this in view, I believe that with effective vaccination, we can not only drastically reduce the incidence of shingles and PHN but also make the severe debilitating type of PHN, a rare case scenario. In the words of a patient of mine who is suffering with severe PHN, the pain of PHN is a very agonizing pain that she does not want to wish even her deadliest foes to suffer with. Would it not be a great accomplishment, if we can make such an entity a rare one?

Therefore, if you are 50 years and above, please contact your healthcare provider to discuss about shingles vaccine.

SUMMARY Please keep your eyes open for shingles in any painful rash and seek medical advice as soon as possible - Remember, antivirals, if taken within 72hrs after the onset of the rash, can help in faster healing. Given shingles can cause PHN, a dreaded complication that can cause significant long lasting pain, every effort needs to be made to prevent shingles occurring in the first place through vaccination.

Vaccine, Zostavax, reduces the risk of developing shingles by about 51% and PHN by about 67%.

Another vaccine, Shingrix, introduced in October 2017, is supposed to be about more than 90% effective in preventing Shingles. It prevents PHN by about 91% for adults 50years and older and 88.8% in adults age 70 years and older.

Both vaccines can be administered for all adults 50 years and above unless contraindicated.

If you are 50 years and above, please contact your healthcare provider to discuss about shingles vaccine.

Reference: CDC.gov Saquil A, Kane S, Mercado M, Lauters R Herpes Zoster and Postherpetic-Neuralgia: Prevention and Management. Am Fam Physician. 2017 Nov 15;96(10):656-663. www.nfid.org/publications/factsheets/varicellaadult.pdf