BACKGROUND:
Latent varicella zoster virus (VZV) in nerve tissue after primary varicella infection reactivates causing Herpes zoster (HZ) in approximately 15%-20% of infected persons. Some scientists have suggested the reduction in circulating VZV due to the varicella vaccination program may increase the incidence of HZ. However, the triggers for reactivation of VZV are poorly understood, and protection may involve external boosting, internal boosting, or other mechanisms.

OBJECTIVE:
To examine annual rates of HZ diagnoses among persons who seek health care at inner city district health centers (DHCs).

METHOD:
Individual-level data including date of birth, gender, race/ethnicity, visit date, and ICD code(s) for visit were extracted from the PDPH Ambulatory Health billing system for DHC patients seen from January 1, 1994 through December 31, 2003 with a HZ diagnosis code. A denominator file containing aggregate annual counts of DHC patients, who visited that year also was generated. PDPH will conduct chart reviews to validate the HZ ICD codes for a random sample of 50 patients. Overall, age-specific, and race-specific HZ diagnosis rates will be calculated for each year.

RESULT:
A total of 771 patients were diagnosed with HZ at 8 DHCs during the study period. Median age of the patients was 45 years (Range: 4 months-89 years). The majority (73.5%) of HZ cases were African Americans. HZ was the primary visit diagnosis for most HZ patients (71.0%). Preliminary analysis indicates that annual rates of HZ diagnoses remained constant over the study period from 1.1 initial HZ diagnoses per 1,000 patients seen in 1994 to 1.2 initial HZ diagnoses per 1,000 patients seen in 2003.

CONCLUSION:
The annual rates of HZ diagnoses among persons who sought care at inner city DHCs were constant from 1994 to 2003.

LEARNING OBJECTIVES:
To understand rates of HZ diagnoses among persons seeking health care at inner city DHCs.