PCL 2- Predisposing factors and Epidemiology by Teh

Predisposing factors of shingles:

-people who have previously had chicken pox
-age: more common for people above 60 yrs old (because of their weakened immunity)
-weakened immune system by diseases or medications: stress, AIDS, diabetes, Hodgkin's disease, leukemia, and some kinds of drugs such as steroids, will increase one's risk for shingles.

*how steroids lowers immunity:steroid is an anti-inflammatory, makes the immune system less active

Epidemiology of shingles:

-The incidence rate of herpes zoster ranges from 1.2 to 3.4 per 1,000 person-years among healthy individuals, increasing to 3.9–11.8 per 1,000 person‐years among those older than 65 years (Dworkin RH, Johnson RW, Breuer J et al. (2007). )

- Studies have shown that Caucasians are more likely to get shingles than people of African descent, Asians or Hispanics (stoppain.org)

-In general, herpes zoster has no seasonal incidence and does not occur in epidemics
no seasonal pattern because disease results from the reactivation of latent virus and is related to host factors, not to exposure.

- The most striking feature of the epidemiology of shingles is the increase in incidence found with increasing age. Decreasing cellmediated immunity (CMI) associated with aging is thought to be responsible for these increased
rates.

-Similarly, the loss of CMI among persons with malignancies and HIV infection is thought to be responsible for higher rates of shingles among those populations.

-Approximately 20 percent of the general population will experience shingles during their lifetime and an estimated 500,000 episodes of shingles occur annually in the U.S.

-Approximately 4 percent of individuals will experience a second episode of shingles.

- the US there are 600,000 to 1 million cases of shingles per year. 10-20% of the US population will develop one or more case of shingles in their lifetime, and 50% of people living beyond the age of 80. (CDC online)

-With the introduction of the varicella vaccine in 1995 to prevent clinical infection and transmission of VZV, the epidemiology of this disease will change. A huge decrease in varicella circulation will also change how individualsí immune responses respond and interact with the latent virus.

-A recent study by Patel et al. concluded that since the introduction of the chickenpox vaccine, hospitalization costs for complications of shingles have increased by more than $700 million annually for those over 60 years.[Patel MS, Gebremariam A, Davis MM (2008).

-Another study by Yih et al. reported that as varicella vaccine coverage in children increased, the incidence of varicella decreased and the occurrence of shinges among adults increased 90%.(Yih WK, Brooks DR, Lett SM, Jumaan AO, Zhang Z. Clements KM, Seward JF (2005). "The incidence of varicella and herpes zoster in Massachusetts as measured by the Behavioral Risk Factor Surveillance System (BRFSS) during a period of increasing varicella vaccine coverage, 1998–2003"

-The results of a further study by Yawn et al. showed a 28% increase in shingles incidence from 1996 to 2001

-Additionally, there was a statistically significant increase in adult shingles cases reported to the Antelope Valley Varicella Active Surviellance Project (VASP) from 2000 to 2003.

• The 56.1% increase from 237 cases in 2000 to 370 cases in 2002 yields a rate ratio of 1.4 (95% C.I. 1.2–1.7). Increases in cases of shingles reported to VASP occurred in every age category (except 70+) from 2000 to 2001.
• VASP also reported verified cases of shingles among adults aged 50 years and older increased 27.5% from 2006 to 2007. (Annual Summary, 2001, 2002, 2003, 2006, 2007 Antelope Valley Varicella Active Surveillance Project, Los Angeles County Department of Health Services; Centers for Disease Control and Prevention (CDC) Cooperative Agreement No. U66/CCU911165-10; Mascola L, et al.)

-A 2008 study revealed that people with close relatives who have had shingles are twice as likely to develop it themselves. The study speculates that there are genetic factors in who is more susceptible to VZV (Hicks LD, Cook-Norris RH, Mendoza N, Madkan V, Arora A, Tyring SK (May 2008). "Family history as a risk factor for herpes zoster: a case-control study". Arch Dermatol 144 (5): 603–8. doi:10.1001/archderm.144.5.603. PMID 18490586.)