Uncovering the Causes of Herpes Zoster (Shingles)

Herpes zoster, often referred to as shingles, is an unbearably painful viral infection that can significantly impact a person's quality of life ^1#. This debilitating condition can disrupt sleep, work, and personal relationships, leading to physical discomfort and emotional distress¹. 

While many are familiar with the characteristic painful, red rash, the underlying causes and risk factors associated with this condition are often misunderstood.

Let's explore the complexities of herpes zoster disease to understand its causes, symptoms, and prevention better.

Understanding Herpes Zoster (Shingles) As a Disease

Herpes zoster (shingles) is a painful viral disease caused by the reactivation of the varicella-zoster virus, which is the same virus that causes chickenpox ^2#. After a person has chickenpox, the virus remains dormant or inactive in the nervous system. It can reactivate years later, leading to a painful red rash^2#. 

The herpes zoster rash typically appears as a single, blistering stripe on either the left or right side of the torso or on other areas of the body. This rash usually resolves within 2 to 4 weeks³.

Approximately 1 in 3 individuals may experience herpes zoster at some point in their lives⁴. 

What are the Risks & Causes of Herpes Zoster?

The varicella-zoster virus is responsible for herpes zoster disease and is the same virus that causes chickenpox (varicella)². Chickenpox typically occurs in childhood as the primary varicella-zoster virus infection⁵. It appears as an itchy rash that begins with small bumps and blisters, eventually forming dried crusts within 7 to 10 days. If you have had chickenpox, the virus can reactivate in your body, causing shingles².

The exact cause of the varicella-zoster virus's reactivation is not fully understood, but it is believed to be linked to a decline in cell-mediated immunity specific to the virus⁶. This decline can occur naturally with ageing or due to certain medical conditions that weaken the immune system.

Possible herpes zoster cause factors include: 

• Previous Chickenpox Infection: Anyone who has had chickenpox is at risk of developing shingles later in life².
• Age: The risk of herpes zoster disease rises significantly with age. People aged 50 and older are most likely to develop the condition⁴, with 90% of adults over 50 carrying the virus⁷. As the immune function weakens with age⁸, the virus can reactivate and cause herpes zoster.
• Family History: Having a parent or sibling with a history of herpes zoster can increase your risk by 2.4 times⁹.
• Certain Medical Conditions: Individuals with specific health conditions have a higher chance of developing herpes zoster and experiencing more severe symptoms. These conditions include:
  • Cancer⁹
  • Diabetes¹⁰
  • Autoimmune diseases (such as rheumatoid arthritis, lupus, and inflammatory bowel disease)⁹
  • Chronic lung conditions (chronic obstructive pulmonary disease, asthma, etc.)¹¹
  • Cardiovascular disease⁹
• Stress⁹
• Medical Treatments¹²

Signs & Symptoms of Herpes Zoster (Shingles)

The first symptoms of herpes zoster include unbearable pain and a burning sensation, usually on one side of the body ^14#. This pain can feel like electric shocks ^15# or nail piercing sensations¹⁵, lasting for weeks or months ^16#. Many individuals describe it as being more painful than chickenpox^17# and even labour pain during pregnancy^18#.

The unbearable pain of herpes zoster disease affects nearly every aspect of life^1#: 

• Sleep

• Work productivity

• Quality time with family

• Enjoyment of daily activities 

Following the pain, a red rash develops, appearing as a band of small, fluid-filled blisters around one side of the body, either the left or right¹⁴. The rash may also occur around one eye or on one side of the face¹⁴.

In rare cases, the rash can spread across the body and resemble a chickenpox rash¹⁴. This typically happens in individuals with weakened immune systems¹⁴.

In addition to the common rash, other herpes zoster symptoms may include¹⁴:

• Fever
• Chills
• Fatigue
• Headache
• Upset stomach

Beyond these symptoms, herpes zoster can lead to many complications, including:

• Postherpetic Neuralgia (PHN) - If herpes zoster persists, it can lead to postherpetic neuralgia, a type of persistent nerve pain that continues even after the rash has resolved^19#. PHN occurs when damaged nerves send mixed signals to the brain, resulting in intense and prolonged pain that may last for months or even years^19#. This complication affects around 1 in 4 individuals with the infection¹⁹ and is more prevalent among older adults¹⁹. 
• Herpes Zoster Ophthalmicus (HZO) - Herpes zoster ophthalmicus is shingles that affects the eye or its surrounding area. It can occur in 1 in 4 shingles patients²⁰, and up to half of those with HZO may face ophthalmic complications²⁰, such as painful eye infections and permanent vision damage.
• Encephalitis - Around 1% of individuals infected with herpes zoster disease may develop brain inflammation (encephalitis)²¹, which is a neurological complication characterised by symptoms such as headache, fever, confusion, and seizures.
• Herpes Zoster Oticus - The varicella-zoster virus can reactivate in the auditory system, resulting in herpes zoster oticus²². Symptoms may include hearing loss, vertigo, tinnitus, and severe facial pain²².
• Ramsay Hunt Syndrome - Herpes zoster disease can impact the facial nerves, leading to facial paralysis known as Ramsay Hunt Syndrome ²².

Preventive Measures of Herpes Zoster