Herpes zoster is caused by the varicella zoster virus (VZR) – the same virus that causes chickenpox. After a person recovers from chickenpox, the virus can enter the nervous system and lie dormant for years in the dorsal root ganglia without exhibiting any obvious symptoms. However, the virus can reactivate as herpes zoster whenever the body’s immunity to infections is lowered, such as in older adults, those who do not get enough sleep or rest, patients infected with the HIV virus, patients with SLE autoimmune disease, patients taking immunosuppressive drugs, or those with chronic diseases like diabetes, heart disease, kidney disease, and so on.
 

The first symptoms of herpes zoster are usually pain and burning sensations. In some patients, even the slightest touch or having clothing touch or rub against the skin can cause pain. After about 2 or 3 days, a rash will begin to appear, developing into clusters of chickenpox-like blisters. Unlike chickenpox, however, the herpes zoster rash does not cover the entire body, but rather occurs as a band, strip, or small area of blisters over the infected nerve fibers. The blisters fill with fluid and then finally crust over into scabs. Some patients also experience fever or flu-like symptoms.

The most common complication of herpes zoster is known as post-herpetic neuralgia (PHN), and is found most frequently in patients who are 60 years of age or older. The duration of the pain from PHN is dependent on the individual; for some it lasts months, for others it lasts years, and for a few it can last for the rest of their lives. Other complications include bacterial infections causing skin inflammation or eye infections.

Herpes zoster treatment may involve antiviral medicine, which can help to reduce pain, inflammation, and the amount of blisters developing on the skin. Doctors may also prescribe other medications according to the symptoms and/or complications found, such as pain relief medicine, antihistamines, antibiotics, etc.

At present, Thailand has a vaccine for the prevention of herpes zoster in older adults, and a one-injection vaccination is recommended for adults aged 60 and over. This vaccine can help to reduce both the occurrence of herpes zoster and the severity of symptoms associated with herpes zoster once contracted. However, for patients with chronic conditions or other diseases that could cause weakened immune systems, it may be necessary to receive the vaccination before reaching the age of 60 and/or as per the recommendations of a doctor.