Understanding Varicella Virus: Types, Symptoms, and Management
The Varicella virus is known for its distinct skin manifestations and can be categorized into three different types: herpes simplex Type 1 (oral or cold sores), herpes simplex Type 2 (genital herpes), and herpes zoster (varicella-zoster or shingles).
Herpes Simplex Virus (HSV)
The herpes simplex virus (HSV) remains present in an individual for a lifetime due to the presence of a latent virus pool in terminally differentiated neurons, typically in the peripheral ganglion. HSV is a DNA virus that invades the cell nucleus, resulting in partial thickness wounds on the mouth and lips. The activation of herpes simplex Type 1 is commonly referred to as "cold sores" that occur on the lips and mouth, while herpes simplex Type 2 is recognized as a sexually transmitted disease that leads to lesions on the genital skin. Both types can be reactivated and, in immune-compromised individuals, can cause local infections, chronic herpetic ulcers, mucous membrane damage, as well as systemic infections in the central and peripheral nervous systems, gastrointestinal tract, and ocular system.
Chickenpox (Varicella zoster virus): A Childhood Disorder
Chickenpox is a childhood disorder caused by the varicella-zoster virus (VZV). The virus enters through the respiratory system and infects the tonsillar T cells. From there, the infected T cells carry the virus to the reticuloendothelial system, where major replication occurs, and to the skin, where the rash appears.
Reactivation as Shingles
The VZV can remain latent in the nerve ganglion and reactivate later in life, usually during periods of stress or immunosuppression, resulting in herpes varicella-zoster or "shingles." Vesicles can appear on the corium and dermis, characterized by ballooning, multinucleated giant cells, and eosinophilic intra-nuclear inclusions. Infection may also involve localized dermal blood vessels, leading to necrosis and epidermal hemorrhage. Individuals who are immunosuppressed may experience more severe cases of herpes, with the incidence of herpes zoster being more than 14 times higher in adults with HIV.
Herpes simplex typically begins in childhood and progresses through different stages, including prodrome, erythema, papule, vesicle, ulcer, hard crust, and residual dry flaking and swelling. Lesions can become secondarily infected by staphylococcus or streptococcus. Individuals tend to experience recurrent eruptions, with non-ulcerative lesions lasting about 3 days and full-blown ulcerative lesions lasting 7-10 days.
Chickenpox presents with prominent fever, malaise, and a pruritic rash that starts on the face, scalp, and trunk, gradually spreading to the extremities. The rash initially appears maculopapular and rapidly progresses to vesicles, then pustules that rupture, and finally crusts.
Herpes Varicella-Zoster (Shingles)
Herpes varicella-zoster manifests as an eruption of grouped vesicles on an erythematous base, usually limited to a single dermatome. Initial symptoms include tingling or pain in the affected dermatome 48-72 hours before the onset of lesions. The lesions develop quickly into vesicles, then rupture, ulcerate, and dry out. Usually, they resolve within 10-15 days, but post-herpetic neuralgia may cause persistent pain. In patients with advanced HIV, the herpetic infection may develop into chronic ulcers and fissures with a significant degree of edema. It's crucial to detect and diagnose herpes varicella-zoster early to initiate prompt treatment.
In most cases, the history and clinical presentation are sufficient to establish a diagnosis of herpes, making confirmatory tests such as Tzanck smear preparation, biopsy, or viral culture rarely necessary. However, other conditions with similar symptoms should be considered, including smallpox, disseminated HSV, meningococcemia, atopic dermatitis, atypical measles, poison ivy, and spinal nerve compression (pain). Careful evaluation of the symptoms and clinical presentation can help differentiate varicella from these conditions.
Chickenpox usually resolves within two weeks without medical intervention. Uncomplicated herpes varicella-zoster can be treated for 7-10 days with oral antiviral medications such as acyclovir (Zovirax), famciclovir (Famvir), or valacyclovir (Valtrex). These medications reduce the duration and severity of adult symptoms. Oral prednisone may be prescribed to decrease the risk of post-herpetic neuralgia. VariZIG, a varicella-zoster immune globulin, can prevent complications in immunocompromised and pregnant patients and decrease the severity of symptoms. Additionally, a new vaccine called Shingrix has been recommended since October 2017. It is administered twice, 2-6 months apart, and has been shown to be 90% effective in preventing shingles and post-herpetic pain. Antihistamines can help reduce itching, and Zostix may assist in relieving severe neuralgia. If the lesions have not healed within 3-4 weeks, the patient may have a drug-resistant virus, which may require treatment with IV foscarnet.
For herpes simplex, topical acyclovir and mild corticosteroid ointments can be used for treatment. Alternatively, a thin hydrocolloid dressing can be applied. Moisture retentive dressings like hydrogels, hydrocolloids, transparent films, or alginates may facilitate autolytic debridement of necrotic tissue and promote the healing of herpes-varicella wounds. They also protect the lesions from friction caused by clothing, reducing pain. The varicella virus, whether it manifests as herpes simplex or herpes zoster, causes skin disorders that require early detection, diagnosis, and treatment to achieve optimal resolution and prevent long-term complications. Understanding the different types, symptoms, and management options is crucial in providing effective care for individuals affected by the varicella virus.