Insights into the pathogenesis of varicella viruses

Simian Varicella Virus: Molecular Virology and Mechanisms of Pathogenesis

Simian varicella virus (SVV) was first isolated in 1966 from African green monkeys (Cercopithecus aethiops) imported from Nairobi, Kenya, to the Liverpool School of Tropical Medicine in the United Kingdom (UK) (Clarkson et al., Arch Gesamte Virusforsch 22:219-234, 1967). SVV infection caused severe disease that resulted in a 56% case fatality rate (CFR) in the imported animals within 48 h of the appearance of a varicella-like rash (Clarkson et al., Arch Gesamte Virusforsch 22:219-234, 1967; Hemme et al., Am J Trop Med Hyg 94:1095-1099, 2016). The deceased animals presented with fever, widespread vesicular rash, and multiple hemorrhagic foci throughout the lungs, liver, and spleen (Clarkson et al., Arch Gesamte Virusforsch 22:219-234, 1967). This outbreak was quickly followed by a second outbreak in 47 patas monkeys (Erythrocebus patas) imported from Chad and Nigeria by Glaxo Laboratories (London, England, UK), which quickly spread within the facility (McCarthy et al., Lancet 2:856-857, 1968).

Association of asthma and herpes zoster, the role of vaccination: A literature review

Herpes Zoster (HZ) is the reactivation of a previous infection with varicella-zoster virus (VZV) which shares the same mode of transmission as HZ. It presents with painful erythematous vesicles in a dermatome which is characterized by a burning sensation before and after the rash. Any conditions with suppressed cellular immunity example diabetes mellitus, chronic obstructive pulmonary disease, asthma, cardiovascular diseases, chronic steroid uses, malignancy, etc. causes reactivation of the virus. Impaired immune responses in asthma patients either in any age group may increase their susceptibility to HZ infection owing to skewed Th1/Th2 immunity, resulting in predominant Th2 conditions and an unwarranted Th2 cell response against respiratory allergens. Similarly, many studies have delineated the association of asthma with HZ. However, the relation between steroid use in asthma and HZ is uncertain, its immunosuppressive effect might be responsible for increased susceptibility to the infection. As HZ increases the economic burden and morbidity, its prevention should use vaccines. There are two types of Food and Drug Administration (FDA)-approved vaccine available against HSV one of which is given as a single dose vaccine called Zostavax, for people 50-59 years but its efficacy falls after 3rd dose and on the subsequent 4th dose and is also contraindicated in human immunodeficiency virus/acquired immunodeficiency syndrome, pregnancy and people taking immunosuppressive drugs. Shingrix is preferred by FDA which is a two doses vaccine that is given 6 months apart for people above 50 years and to immunocompromised people. Hence, proper counseling and education about the risks of herpes should be informed to the patients with timely utilization of the vaccine.

Adjuvanted recombinant zoster vaccine in solid organ transplant and hematopoietic stem-cell transplant recipients

PURPOSE OF REVIEW

Hematopoietic stem-cell (HSCT) and solid organ transplant (SOT) recipients are particularly at risk to develop herpes zoster and its complications. A recently approved nonlive, adjuvanted recombinant zoster vaccine (aRZV) is a potential candidate to provide durable prevention of herpes zoster. This review summarizes current scientific evidence and expert recommendations for its use in these populations and offers practical clinical guidance.

RECENT FINDINGS

Recent clinical trials have shown aRZV to be well tolerated and efficacious in the prevention of herpes zoster, even in the elderly. Data are emerging that this vaccine might also be effective in immunocompromised individuals, such as SOT and HSCT recipients. Evidence is sparse regarding optimal timing of vaccination and durability of responses. However, several specialized societies have already established expert-based aRZV immunization recommendations for these vulnerable populations.

SUMMARY

Practical considerations, safety concerns, and timing of vaccine administration vary from one immunocompromised subpopulation to another. Initial studies show that aRZV has a favorable safety and immunogenicity profile in SOT and HSCT recipients. However, data are sparse, particularly in allogeneic HSCT, and practical recommendations are mostly based on expert opinion. Additional research is needed to offer better insight on aRZV administration in immunocompromised patients.

Varicella Zoster Virus Reactivation Involving the Vagus Nerve

OBJECTIVES

To characterize the presentation, clinical course and functional outcomes of patients with varicella zoster virus (VZV) reactivation involving the vagus nerve. To highlight the role of otolaryngology in acute and long-term management of laryngopharyngeal VZV and its sequelae.

METHODS

Retrospective review of 3 patients with laryngopharyngeal VZV, managed at a tertiary referral center.

RESULTS

All cases presented with vesicular lesions involving mucosa of the laryngopharynx. Each experienced vocal fold hypomobility, among other otolaryngologic sequelae. All were treated with systemic antivirals and corticosteroids. Mucosal lesions resolved within 7 days of treatment initiation; functional deficits persisted for months to years. Dysphonia improved to a plateau at 3 months, while dysphagia took longer to resolve. One patient with disseminated disease experienced bilateral vocal fold paralysis requiring temporary tracheostomy.

CONCLUSIONS

Vagal neuropathy secondary to VZV reactivation is a rare clinical entity with a variety of laryngeal manifestations. Early initiation of systemic therapy and serial endoscopic evaluations are critical components of acute management when laryngopharyngeal involvement is suspected. Otolaryngologists should plan for long-term phonatory and deglutitive therapy in these cases, as neurologic sequelae can persist for months to years following initial insult.

LEVEL OF EVIDENCE

Level 4 (Case-series).