Shingles (Herpes Zoster): Painful Rash Caused by Chickenpox Virus

What is Shingles (Herpes Zoster)? 

Shingle is a disease caused by a virus called varicella-zoster virus (VZV) or human herpesvirus 3 (HHV-3), which is the same virus that causes Chickenpox. If you contracted and recovered from Chickenpox early in life, you have lifelong immunity against Chickenpox. However, such immunity to Chickenpox does not mean that the varicella-zoster virus is eliminated from the body. The virus remains inactive and lies dormant in the nervous system for years, or indeed for life, after chickenpox recovery. Years later, the varicella-zoster virus can reactivate and cause Shingles. 

Shingles develops along the nerves on one side of the face or body, such as the torso or the neck. It is not usually life-threatening, but it can be extremely painful and unpleasant. Most cases of Shingles resolve in several weeks; however in some cases, particularly in older people, the pain from Shingles can take months or years to resolve. This is called Post-Herpetic Neuralgia (PHN).

Cause and risk factors for Shingles

The cause of Shingles is the reactivation of varicella-zoster virus (VZV) in the setting of weakened immunity. 

Shingles is caused by the varicella-zoster virus (VZV) which is the same virus that causes Chickenpox. After you have recovered from Chickenpox, the virus remains dormant in your nervous system and reactivates to cause Shingles years later.

Although Shingles is caused by the same virus as Chickenpox, not everyone who once suffered from Chickenpox develops Shingles. The reactivation of the VZV virus occurs mainly when the immune system is weakened by factors such as:

• Age: The incidence of Shingles increases with age, rising dramatically after the age of 50. Rarely, Shingles can occur in young children whose immunity is weak. 
• Medications: Oral steroids (e.g. prednisolone) and drugs that are given after organ transplantation (e.g. cyclosporin, tacrolimus) can suppress the immune system Medical conditions: Conditions such as HIV/AIDs, autoimmune diseases and certain cancers (e.g. leukemia, lymphoma) can cause immunodeficiency, thus increasing the risk of Shingles. 
• Other conditions: Patients who are undergoing chemotherapy or radiotherapy, usually have a weaker immune system. Therefore, the VZV virus reactivates more readily to cause Shingles. 

Signs and symptoms of Shingles

Signs and symptoms of shingles mainly occur in a single stripe on one side of the body along the nerves, especially the torso or the face. Typical signs and symptoms of shingles include:

• Pain, burning, itching or tingling of the skin
• Rash develops several days after the onset of tingling or pain
• Fluid-filled blisters that break open and crust over
• Headache
• Fever
• Chills
• Fatigue
• Sensitivity to bright light (Photophobia)

Pain is usually the first symptom of Shingles and may occur before the  development of the characteristic rash, but in the same area. Occasionally, people may experience pain only without developing the rash. Shingles may also occur in other parts of the body, such as the face, back and buttocks. It is important to be aware that if Shingles occur near the eyes, you should seek medical help immediately because it may result in herpes zoster ophthalmicus and lead to serious complications including vision loss.

Are Shingles contagious?

Interestingly, you cannot catch Shingles from someone with Shingles, but you may catch Chickenpox instead. Direct contact with the oozing blister of a Shingles patient can spread the virus to someone who has never had Chickenpox or has never taken the Chickenpox vaccine. In Hong Kong, Chickenpox was the third most common infectious disease in 2020, following COVID-19 and tuberculosis. 

The varicella-zoster virus (VZV) cannot be spread before the Shingles blisters appear or after the rash crusts over. In any case, the risk of spreading the virus is relatively low if the affected areas are well covered.

Diagnosis of Shingles

In general, the diagnosis of Shingles can be made on clinical grounds,  by assessing medical history (e.g. history of Chickenpox or Chickenpox vaccination) and signs and symptoms of Shingles (e.g. localised pain and characteristic rash). 

The diagnosis can be more difficult if a Shingles rash does not appear at the time of diagnosis, or in cases of Shingles without rash. Therefore, other laboratory tests might be needed such as taking a sample of scabs from crusted lesions for analysis by polymerase chain reaction (PCR).

Complications of Shingles

Although shingles itself is not life-threatening, if its signs and symptoms are not well diagnosed and treated properly, it may lead to the following serious complications:

• Postherpetic neuralgia (PHN): This is a common complication of shingles, in which the sensation of pain lasts for long terms even after the Shingles rash goes away. The risk of postherpetic neuralgia increases with age. 
• Ramsay Hunt syndrome: When Shingles develops around your ear, it can lead to a rare condition called Ramsay Hunt syndrome. Ramsay Hunt syndrome may lead to facial paralysis and hearing loss if left untreated. 
• Vision loss: When Shingles develop near your eyes,  it can result in severe eye pain and vision loss if left untreated. 
• Brain inflammation: In rare cases, brain inflammation (encephalitis) can be caused. Such brain inflammation is serious and life-threatening. 
• Bacterial skin infection: Bacterial skin infection may sometimes happen when blisters are not treated properly. 

Treatments of Shingles

Although Shingles is incurable, it is self-limiting. Early treatment can shorten the duration of infection and prevent complications. Shingles treatment aims to reduce the activity of VZV, decrease the severity of the Shingles rash, and manage and relieve the pain. Medications for shingles treatments mainly include:

• Antivirals: Antiviral medications, such as acyclovir, valacyclovir and famciclovir, can speed up your recovery. They are most effective when taken within 72 hours of the first appearance of the rash. 
• Pain relievers: For mild Shingles, paracetamol and non-steroidal anti-inflammatory drugs (e.g ibuprofen, naproxen) are sufficient to relieve pain and inflammation. For severe pain, a stronger pain killer may be needed, such as opioids (e.g. morphine, fentanyl) or a medication for nerve pain (e.g. pregabalin)
• Antipruritics: If itching is bothersome, antipruritics (e.g. calamine) and certain antihistamines (e.g. diphenhydramine) can be used to alleviate it. 
• Other medications: In more severe pain and inflammation, corticosteroids might be needed for Shingles treatment.

Shingles vaccine in Hong Kong: Types & costs

To prevent Shingles, the Shingles vaccine (zoster vaccine) is recommended for healthy adults aged 50 or above. Two shingles vaccines are currently registered in Hong Kong: Zostavax® and Shingrix®.

Zostavax® is a live-attenuated vaccine, while Shingrix® is a recombinant vaccine made by DNA technology. Shingrix® is the preferred agent because it is significantly more effective and lasts longer than Zostavax®. For this reason Zostavax is rarely used these days.  Be reminded that Shingles vaccines are indicated to prevent Shingles (herpes zoster) but not Chickenpox (herpes varicella), even though they are caused by the same VZV virus.

According to our research, the cost for 1 dose of Zostavax® ranges from HKD$800  – $1,500, while that for 2 doses of Shingrix® ranges from HKD$5,000 – $6,000.