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0«COyyOMUM-JMTMaL» #M7©)), 2023 / MEDICAL SCIENCES
93
UDC : 616-001/-009
Melenko Svitlana Romanivna,
PhD. Associate Professor of the Department of Infectious Diseases and Epidemiology
Bukovinian State Medical University Dubova Viktoriia, student
Bukovinian State Medical University Klumchuk Nastya,
student
Bukovinian State Medical University.
Dubova Viktoriia, Klumchuk Nastya Bukovinian State Medical University.
DOI: 10.24412/2520-6990-2023-11170-93-94
HERPES ZOSTER
Abstract.
Herpes zoster, or shingles, is caused by reactivation of the varicella-zoster virus, which causes chickenpox. An estimated 1 million cases are reported annually in the United States, with an individual lifetime risk of 30%. Patients with conditions that reduce cellular immunity are 20-100 times more likely to develop herpes zoster. Two to three days before the classic maculopapular rash appears, patients may experience malaise, headache, mild fever and abnormal skin sensations. The rash is typically unilateral, confined to one dermatome, and usually progresses to clear vesicles that become cloudy and crusted after seven to 10 days. Herpes zoster can be treated with acyclovir, valacyclovir or famciclovir, ideally within 72 hours of the onset of the rash. Postherpetic neuralgia is the most common complication, occurring in about one in five patients. It is defined as pain in the area of dermatomal spread that persists for at least 90 days after acute herpes zoster. Treatment is aimed at symptom control and includes topical application of lidocaine or capsaicin and oral administration of gabapentin, pregab-alin or tricyclic antidepressants. Two varicella vaccines reduce the incidence of herpes zoster and are approved for adults aged 50 years and older. The Advisory Committee on Immunization Practices of the U.S. Centers for Disease Control and Prevention recommends two doses of adjuvanted recombinant varicella-zoster vaccine (DPT) for adults 50 years of age and older, including those who have already been vaccinated with live varicella vaccine.
Keywords: Herpes zoster, virus dermatomal
The clinical problem. Primary infection with varicella-zoster virus (VZV) results in varicella zoster, manifested by viremia with diffuse rash and involvement of multiple sensory ganglia, where the virus establishes lifelong latency. Herpes zoster occurs as a result of reactivation of latent VZV from the cranial nerve or dorsal root ganglia with spread of the virus along the sensory nerve to the dermatome. More than 1 million cases of herpes zoster are reported annually in the United States with an annual incidence of 3-4 cases per 1000 people. Studies indicate that the incidence of herpes zoster is increasing. Unvaccinated individuals who live to 85 years of age have a 50% chance of developing herpes zoster. Up to 3% of patients with herpes zoster require hospitalization.
Evaluation. Herpes zoster rashes are dermatomal and do not cross the midline, which corresponds to reactivation from the dorsal root or cranial nerve ganglia. Most often, the rash appears on the dermatomes of the chest, trigeminal, lumbar and cervical spine, although any skin area can be affected. In non-immunocompro-mised individuals, it is not unexpected to have multiple scattered lesions outside the affected dermatome. The rash is often preceded by tingling, itching and/or pain for 2-3 days, which may be constant or episodic. Depending on the location and severity, this prodromal pain can lead to misdiagnosis and costly work-up. The rash begins as macules and papules that evolve into vesicles and then pustules New rashes appear within 3-5
days, often with dermatome filling, despite antiviral treatment. The rash usually dries with crusting in 7-10 days. Some individuals experience pain in the absence of a rash, called herpes zoster, which is difficult to diagnose and can lead to numerous unnecessary tests or procedures.
Diagnosis. Most cases of herpes zoster can be diagnosed clinically, although in atypical eruptions direct immunofluorescence for VZV antigen or PCR for VZV DNA in cells from the base of the lesions after they have been opened may be required. In a study comparing PCR with other diagnostic methods, the sensitivity and specificity of PCR were 95% and 100%, respectively, and 82% and 76%, respectively, when using immunofluorescence testing for VZV antigen.6 The most common condition mistaken for herpes zoster is herpes simplex virus, which can recur with dermatomal dissemination; accordingly, when patients present with "recurrent herpes zoster", atypical lesions, or are immunocompromised with disseminated skin lesions, specific testing for both VZV and herpes simplex virus is often useful. The presence of VZV in the saliva of individuals with shingles has been demonstrated, although such testing currently has no proven role in clinical practice.
Treatment and preventation
Antiviral therapy
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Antiviral therapy is recommended for herpes zoster in certain patients with normal immunity and all immunocompromised patients. Other individuals may also benefit from antiviral therapy, although their risk of complications of herpes zoster is lower. Three gua-nosine analogues - acyclovir, valacyclovir and famciclovir - have been licensed by the Food and Drug Administration (FDA) for the treatment of herpes zoster. The oral bioavailability and blood levels of antiviral activity of the drugs are higher and more reliable in those receiving three times daily valacyclovir or famciclovir than for acyclovir 5 times daily. This is important because VZV is less sensitive than herpes simplex virus to acyclovir, valacyclovir or famciclovir. These antiviral drugs accelerate the resorption of lesions, reduce the formation of new lesions, reduce the release of virus and reduce the severity of acute pain. For example, in the largest randomized, double-blind trial of acyclovir in shingles, oral acyclovir within 47 hours of disease onset reduced the mean time to the last day of new rash formation, vesicle disappearance, and complete crusting by 0.5 days, 1.8 days, and 2.2 days, respectively, compared with placebo. In another large study, acyclovir shortened the duration of virus rash by 0.8 days compared to placebo. In a meta-analysis of several randomized, controlled trials, antiviral drugs did not significantly reduce the incidence of HHV, and they are not approved by the U.S.
Acute pain associated with herpes zoster Several medications are used to treat acute pain associated with herpes zoster. Nonsteroidal anti-inflammatory drugs or acetaminophen can be tried for patients with mild pain. Opioids such as oxycodone are used for more severe pain associated with herpes zoster. In a randomized, placebo-controlled trial, opioids were more effective than gabapentin for pain in herpes zoster. Gabapentin was shown in one but not the other controlled trial to reduce pain associated with herpes zoster. Lidocaine patches reduced pain associated with herpes zoster in a placebo-controlled trial, and should be applied only to uninjured skin and not to the area of the rash.
Preventation of Herpes Zoster
The live attenuated herpes zoster vaccine is recommended by the Advisory Committee on Immunization Practices for the prevention of herpes zoster and its complications, including PHN, in persons 60 years of age and older. According to the results of a recent clinical trial, the vaccine is approved by the FDA for use in persons aged 50 years and older for the prevention of herpes zoster. The efficacy of the vaccine for the prevention of herpes zoster is 70% in persons aged 50 to 59 years, 64% in persons aged 60 to 69 years and 38%
in persons aged 70 years and older, and for the prevention of HSV - 66% in persons aged 60 to 69 years and 67% in persons aged 70 years and older.
Areas of uncertainty
Improved methods are needed to treat pain associated with herpes zoster and PGN, as well as to prevent the development of PGN after herpes zoster. Research is needed to determine which patients are at highest risk of developing PGN so that more aggressive therapy can be prescribed. There are uncertainties regarding the efficacy of the herpes zoster vaccine in persons aged >80 years, the safety and efficacy of the vaccine in persons with immunocompromising conditions that are currently considered contraindications to vaccination, the duration of vaccine-induced immunity, and whether booster doses will be required.
Guidelines
Recommendations for the treatment of herpes zoster from an expert panel and for the prevention of herpes zoster from the Advisory Committee on Immunization Practices have been published. This review is generally consistent with these recommendations.
Conclusions and recommendations
While herpes zoster is often mild in healthy young adults, older adults are at increased risk for pain and complications, including PGN, ocular disease, motor neuropathy, or CNS disease. In the vast majority of cases, the diagnosis can be made clinically. Antiviral therapy is most beneficial for individuals with complications of shingles or at increased risk of complications, such as the elderly and immunocompromised, and should be initiated as soon as possible, and usually within 72 hours of the onset of the rash. Valacyclovir or famciclovir are preferred to acyclovir because of the lower dosing frequency and higher levels of antiviral activity. The patient described above should receive oral antiviral therapy, pain medication (e.g. opioids, with gabapentin added if necessary) and immediate referral to an ophthalmologist. You should also be advised to avoid contact with persons who have not had chickenpox or have not received the varicella vaccine until the rash is completely crusted over. I would recommend vaccination against herpes zoster in the future to reduce the risk of recurrence, but I would recommend postponing it for an immunocompetent patient for approximately 3 years, given that an episode of herpes zoster is expected to enhance his cellular immune response to VZV.
References
1. Neurocutaneous herpes simplex 1.1
2. Herpes zoster-induced acute urinary retention: Two cases and literature review 1.2
3. Diagnosis and management of herpes zoster ophthalmicus 1.3
