Herpes zoster is both painful and dreaded. Initial infection in childhood by the varicella-zoster virus (VZV) causes chicken pox. The virus may then lie dormant for years and reactivate in adults as herpes zoster (also called shingles), an ailment that can be extremely painful. The recurrence of this virus-induced disease may be due to many factors including aging, immunosuppression, and exposure to VZV at a very young age. Now, it has been linked to asthma.
Unlike chicken pox, which affects all areas of the skin, herpes zoster (HZ) tends to affect one or several isolated dermatomes – topical areas of the skin that receives their sensations from a single nerve via a single nerve root of the spinal cord. Prodromal symptoms include headache, malaise, acute sensitivity to light and, sometimes, pain. The acute phase sees a rash that tends not to cross the midline of the body and is accompanied by pain which can vary from being uncomfortable to being severe. The pain can be allodynia (pain at the site that results from harmless stimuli) or be a combination of itching, burning and allodynia. The vesicles last about 10 days and usually heal within 2 to 4 weeks.1
HZ affects the quality of life. It interferes with work, sleep, daily activities, and social interactions. The result is withdrawal from society and possibly also depression.
As with all diseases, complications occasionally arise. Organs and eyes may also be affected, with severe consequences. Where HZ occurs in the eyes, long-term consequences such as vision loss and keratitis (inflammation of the cornea) may result. If the pain persists for three months or more after the vesicles have healed, the pain is defined as postherpetic neuralgia (PHN). This may last a year or more with the pain being constant or intermittent or triggered by innocuous factors such as the touch of clothing. The area affected may show cutaneous scarring and either hypersensitivity or reduced sensation. In a few cases the result can include muscle weakness and tremor. If the nerves involved control muscle movement, there may even be paralysis. About 40% of individuals over the age of 60 are likely to suffer postherpetic neuralgia.
The incidence, severity and risk of complications from varicella increases with age. This is partly due to the gradual impairment of the immune system that develops with aging. Aside from PHN, HZ may cause neurologic complications that include
- chronic loss of sensation at the site of the rash
- weakness in limb
- bacterial superinfections
Complications may also arise in those who are immunosuppressed. Children who get chicken pox and who are on steroids must be seen immediately by their health care provider to avoid complications.
Asthma and HZ
A population–based case-controlled study of 277 children with HZ, under the age of 18, compared the frequency of asthma with corresponding controls in Minnesota, between 1996 and 2001. 2 The researchers found that children with asthma had a higher risk for HZ than those without. In another study, the same researchers assessed the connection between asthma and the risk of HZ in 459 subjects, and found that children and adolescents with asthma had an increased risk (OR 2.56) of HZ without consideration for the severity of the asthma. 3 Children vaccinated with varicella vaccine are rarely diagnosed with HZ. 4 Having shown a link between asthma and HZ in children, researchers looked at the risk for adults. A recent article in the Journal of Allergy and Clinical Immunology5, that compared the risk of shingles in three separate groups of adults, showed the risk to be:
- 8 % in a control group
- 12 % in individuals with atopic dermatitis
- 70 % in individuals with asthma
The researchers noted that asthma affects immunity and that atopic dermatitis is due to impaired immune function of the skin. Thus both these atopic conditions increase the risk of reactivation of the varicella zoster virus.
In a review of the 8 different types of herpes viruses, Dreyfus 6 noted that primary infection with herpes viruses may have an atypical presentation in atopic individuals and that infection in childhood may alter the atopic phenotype. Thus health care providers of allergic and atopic individuals need to be aware of this differentiation in presentation of herpes–induced disease in order to provide a correct diagnoses and appropriate treatment.
Asthma is known to have an adverse effect on adaptive immunity. HZ occurs in one in three individuals over the age of 80. While it is not known which individuals will develop zoster, prevention becomes the key particularly for persons with asthma who are at high risk of HZ. Hence, the recommendation that the herpes vaccine be given to adults 50 to 59 years of age. For cultural and religious reasons, it should be noted that the HZ vaccine contains hydolyzed porcine gelatine, monsodium L-glutamate, and bovine calf serum among its ingredients. It does not contain preservatives.
- Weaver, B A (2009). Herpes zoster overview: natural history and incidence. J Am Osteopath Assoc 109 (6 (Suppl 2)): S2–6. PMID 19553632. Retrieved 16 January 2016
- Kim BS, Mehra S, et al. Increased risk of herpes zoster in children with asthma: a population-based case-control study. J Pediatr. 2013 Sep;163(3):816-21. doi: 10.1016/j.jpeds.2013.03.010.
- Wi CI, Kim BS, et al. Risk of herpes zoster in children with asthma. Allergy Asthma Proc. 2015 Sep-Oct;36(5):372-8. doi: 10.2500/aap.2015.36.3864.
- Tseng HF, Smith N, et al. Incidence of herpes zoster among children vaccinated with varicella vaccine in a prepaid health care plan in the United States, 2002-2008. Pediatr Infect Dis J. 2009 Dec;28(12):1069-72. doi: 10.1097/INF.0b013e3181acf84f.
- Kwon HJ, Bang DW et al. Asthma as a risk factor for zoster in adults: a population-based cast-control study. J Allergy Clin Immunol. 2015;doi:10.1016/j.jaci.2015.10.032.
- Dreyfus DH. Herpesviruses and the microbiome. J Allergy Clin Immunol. 2013 Dec;132(6):1278-86. doi: 10.1016/j.jaci.2013.02.039.