High Incidence Rates of Invasive Pneumococcal Disease in the White Mountain Apache Population

Objective.—In this article we determine the incidence and clinical spectrum of invasive pneumococcal disease in the White Mountain Apache population, a group known to have a high incidence of invasive disease due to Haemophilus influenzae type b. Design.—Patients from whom cultures of normally sterile body sites yielded Streptococcus pneumoniae were identified retrospectively through review of hospital laboratory records from a 6.8-year period. Clinical data were reviewed and incidence rates were computed. Setting.—The Whiteriver Indian Health Service Hospital is located on the 1.7-million-acre White Mountain Apache Reservation in eastern Arizona. Patients.—Approximately 10 000 members of the White Mountain Apache Tribe reside on or near the reservation and receive health care through the Whiteriver Indian Health Service Hospital. Outcome Measures.—The average annual incidence rates of invasive pneumococcal disease were calculated and clinical characteristics were reviewed. Results.—One hundred thirty-eight cases of invasive pneumococcal disease were identified. The average annual incidence rate was 207 per 100 000 population, and 156 per 100 000 population when adjusted for age by direct standardization to the 1988 US population. Conclusions.—The incidence rate was highest in children between 1 and 2 years—2396 per 100000. The overall case-fatality rate was 5%. Pneumococcal pneumonia was the diagnosis in 79% of the patients 5 years of age or older. Alcohol abuse, identified in 66% of the cases in adults, was the most common underlying medical condition. The incidence rates in White Mountain Apaches are the highest reported for any population. A vaccine effective in children would greatly benefit this population.