Cause
Herpes zoster (shingles) is caused by the reactivation of varicella-zoster virus (VZV), the same virus that causes varicella (chickenpox).
Primary infection with VZV causes varicella. After a person has varicella, the virus remains dormant in the dorsal root ganglia. VZV can reactivate later in a person's life and cause herpes zoster, a painful maculopapular, and then a vesicular rash.
Keep Reading:Clinical Overview of Chickenpox (Varicella)
Who is at risk
People who had chickenpox can get shingles.
Anyone infected with varicella can develop herpes zoster. About 99.5% of people born before 1980 in the United States have had the wild-type VZV. Children who receive varicella vaccine have a lower risk of herpes zoster when compared with children infected with wild-type VZV.
About 1 in 3 people in the United States will develop herpes zoster during their lifetime. Most people have only one episode, but herpes zoster can recur.
A person's risk for herpes zoster and related complications, including hospitalizations, sharply increases after 50 years of age. The reasons why VZV reactivates and causes herpes zoster are not well understood.
However, a person's risk for herpes zoster increases as their VZV-specific cell-mediated immunity declines. This decline in immunity can result from increasing age and medical conditions or medications that suppress a person's immune system.
People with the following conditions that compromise or suppress their immune system have an increased risk for herpes zoster:
- Bone marrow or solid organ (renal, cardiac, liver, and lung) transplant recipients.
- Cancer, especially leukemia and lymphoma.
- Human immunodeficiency virus (HIV).
- Taking immunosuppressive medications, including steroids.
About 30% of people hospitalized with herpes zoster have compromised or suppressed immune systems.
Other potential risk factors for herpes zoster have been identified, but the findings are inconsistent or unexplained. For example:
- More women than men develop shingles.
- Herpes zoster is less common in black people than in white people.
How it spreads
People with active herpes zoster lesions can spread VZV. VZV causes varicella in people who never had chickenpox or those who didn't receive the varicella vaccine. Once varicella resolves, these people would be at risk for herpes zoster.
Active herpes zoster lesions are infectious through direct contact with vesicular fluid; or breathing in virus particles from the blisters until they dry and scab over.
People with active herpes zoster lesions should cover their lesions; and avoid contact with susceptible people in their household and occupational settings until their lesions are dry and scabbed.
Disease rates
An estimated one million cases of herpes zoster occur annually in the United States. The incidence of herpes zoster varies by age and is approximately two to nine cases per 1,000 US population annually. The precise incidence of recurrence is not known.
Death rates
One study estimated 96 deaths occur each year where herpes zoster was the underlying cause (0.28–0.69 per 1 million population). Almost all of the deaths were in older adults or those with weakened immune systems.
Clinical features
People with herpes zoster can have pain, itching, or tingling in the area where the rash will develop.
People with herpes zoster have a rash in one or two adjacent dermatomes. The rash most commonly appears on the trunk along a thoracic dermatome or on the face. It usually does not cross the body's midline and heals in 2 to 4 weeks.
Shingles complications include postherpetic neuralgia, hearing or vision loss, encephalitis, and pneumonia.
The signs and symptoms of herpes zoster are usually distinctive enough to make an accurate clinical diagnosis once the rash appears. However, clinical diagnosis of herpes zoster might not be possible in the absence of a rash.
Keep Reading:Detailed Signs, Complications, and Clinical Diagnosis of Shingles
Photos of Shingles
View photo examples of shingles rash on the human body.
Prevention
CDC recommends two doses of recombinant zoster vaccine (RZV, Shingrix) to prevent shingles and related complications in adults 50 years and older.
Shingrix is also recommended for adults 19 years and older who have weakened immune systems because of disease or therapy. Administer two doses of RZV for the prevention of shingles and related complications in adults 19 years or older who are, or will be, immunodeficient or immunosuppressed because of disease or therapy.
Shingle Vaccine Information for Healthcare Providers
Information for healthcare providers about shingles (herpes zoster) vaccination, including vaccine r...
Shingrix Use in Immunocompromised Patients
These clinical considerations are a supplement to the MMWR policy note published in January 2022 on...
Varicella vaccines contain live attenuated VZV, which results in latent infection. Although herpes zoster has always been uncommon among children, the rate in U.S. children has declined since the routine varicella vaccination program started in 1995.
- Children (healthy and immunocompromised) vaccinated against varicella have lower rates of herpes zoster when compared to children who had natural infection with varicella.
- Vaccinated children are less likely to become infected with wild-type VZV.
- The risk of reactivation of vaccine-strain VZV in children is lower when compared with reactivation of wild-type VZV.
- Vaccinated children are less likely to become infected with wild-type VZV.
- Few older adults have received the varicella vaccine since it was licensed in 1995. There is very little information on the risk of herpes zoster in people who got varicella vaccine as adults.
The CDC continues to monitor the impacts of the U.S. varicella and herpes zoster vaccination programs among adults and children.
Preventing VZV Transmission in Healthcare Settings
Learn about preventing shingles in a healthcare setting and among healthcare personnel.
Testing
Varicella-zoster virus (VZV) laboratory testing information applies to testing and diagnosis of primary VZV infection (varicella) and reactivation (herpes zoster). Polymerase chain reaction (PCR) is the most helpful laboratory test for confirming cases of herpes zoster. PCR can detect VZV DNA rapidly.
Laboratory Testing for Varicella-Zoster Virus (VZV)
Learn about lab testing for varicella-zoster virus (VZV), the cause of chickenpox and shingles.
Treatment and recovery
Diagnose and treat early!
Treatment is most effective within 72 hours of symptom onset. Diagnose and treat early to prevent progressive corneal involvement and potential vision loss.
There are three preferred antiviral drugs available for the initial treatment of shingles:
- Acyclovir
- Valacyclovir
- Famciclovir
These antivirals accelerate the resolution of lesions; reduce the development of new lesions and viral shedding; and decrease the severity of acute pain. Discuss treatment options with your patient to provide a specific treatment plan based on their condition.
Trends
Previously, herpes zoster rates in the United States gradually increased over a long period. We don't know the reason for that increase. Recently, herpes zoster rates across age groups have recently plateaued or declined.
CDC studies have found that rates started increasing before the varicella vaccine was introduced in the United States; and did not accelerate after the routine varicella vaccination program started.
Resources
- Shingles Vaccine Information for Healthcare Professionals
- Five things you should know about shingles | Sermo
- Zoster (Shingles) | Immunize.org
- ACIP Recommendations for Use of Herpes Zoster Vaccines | MMWR
- ACIP Recommendations for Use of RZV in Immunocompromised Adults | MMWR
- Common Shingrix Reactions: Which Can Be Prevented? | Medscape
