Invasive pneumococcal disease in an Alaska native population, 1980 through 1986

From 1980 through 1986, one hundred fourteen Alaska Native patients from the Yukon-Kuskokwim Delta had community-acquired invasive pneumococcal disease confirmed by isolates of Streptococcus pneumoniae from normally sterile body sites. The annual bacteremia rates per 100,000 persons were 105 cases for all ages, 1195 cases for infants under 2 years of age, and 130 cases for adults over 59 years of age. These were six to 34 times higher than rates reported for other US populations. The most common underlying conditions in infants diagnosed before 24 months of age were previously diagnosed anemia and pneumonia, while alcoholism and anemia were most common in adults. The case-fatality rate for infants under 2 years of age was 3.2%, and the case-fatality rate for adults over 59 years of age was 30%. Serotyping of more than half the isolates identified 96% of these isolates to be present in the currently available pneumococcal polysaccharide vaccine. The pneumococcal disease rates reported herein are likely to be underestimates since most diseases that occur in this region are treated at the village level without laboratory confirmation.