Shingles (Herpes Zoster) is caused by the reactivation of the varicella-zoster virus (VZV), the same virus that causes chickenpox. After recovery from chickenpox, VZV remains dormant within the nervous system. While shingles is commonly known for a painful, blistering rash on one side of the body, the virus’s internal location means its manifestations can extend far beyond the skin, confirming that shingles can affect the body internally.
The Virus’s Internal Residence
The VZV establishes a latent infection within specialized clusters of nerve cells called sensory ganglia, specifically the dorsal root ganglia (DRG), located near the spinal cord. The virus remains here for decades, held in check by the immune system, until it reactivates due to a weakened immune system (e.g., age, stress, or illness).
Upon reactivation, the virus multiplies within the neuronal cell bodies and travels along the nerve fibers toward the body’s surface. This internal journey causes the intense, localized pain that often precedes the visible rash. The characteristic rash appears only when the virus reaches the nerve endings in the skin, affecting the specific area supplied by that nerve, known as a dermatome.
Shingles Without a Rash
Viral reactivation does not always result in a rash on the skin. This form of the disease, where the virus causes internal symptoms but no rash develops, is medically termed Zoster Sine Herpete (ZSH). In ZSH cases, the virus replicates and causes inflammation within the nerve pathway but fails to cause blistering on the skin.
Patients with ZSH experience severe neuropathic pain, tingling, or numbness limited to the affected nerve’s distribution. This deep, localized pain is often misleading, leading to misdiagnosis as a heart attack, appendicitis, or other internal condition. ZSH can also cause nerve-specific disorders, such as Bell’s palsy (facial paralysis) or Ramsay Hunt syndrome (hearing loss and vertigo). Since the external symptom is absent, diagnosis relies on detecting VZV DNA or antibodies in the cerebrospinal fluid or blood.
When Visceral Organs are Affected
The most severe internal involvement occurs when VZV spreads beyond the nerve pathway and enters the bloodstream, leading to disseminated VZV infection (VD-VZV). This rare, life-threatening condition involves the virus spreading systemically to major internal organs. This systemic spread is predominantly seen in immunocompromised individuals (e.g., those with HIV, cancer, or taking immunosuppressive medications), but it has also been reported in otherwise healthy people.
The virus frequently attacks the lungs, causing VZV pneumonia, which was the most frequently affected organ in one review (56% of VD-VZV cases). It can also spread to the liver, resulting in hepatitis, and to the central nervous system, leading to VZV encephalitis or meningitis (inflammation of the brain or surrounding membranes). Visceral involvement is concerning because the typical skin rash may be absent in about 5% of cases, or internal symptoms may appear before the rash, delaying diagnosis and increasing the risk of multi-organ failure.
Other Affected Organs
Other organs that can be involved include:
- The heart
- Kidneys
- Pancreas
- Gastrointestinal tract
Recognizing Severe Symptoms and Treatment
Recognizing signs of severe or disseminated infection requires prompt medical attention, especially when a rash is absent or widespread. Warning signs indicating potential visceral involvement include:
- A persistent high fever
- Shortness of breath
- Severe and unrelenting headache or stiff neck
- Altered mental status, such as confusion or difficulty walking
- Gastrointestinal issues, including severe abdominal pain or unexpected elevated liver enzymes
Treatment for disseminated VZV infection requires the immediate administration of antiviral medications like acyclovir, valacyclovir, or famciclovir. For severe internal infections, the preferred treatment is intravenous acyclovir, given at a dosage of 10 mg/kg every eight hours for seven to ten days. Starting antiviral therapy as soon as possible is essential, as it significantly reduces the duration of the illness and prevents severe complications.