Changing epidemiology of invasive pneumococcal disease among White Mountain Apache persons in the era of the pneumococcal conjugate vaccine.
ABSTRACT Prior to the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7), the rate of invasive pneumococcal disease (IPD) was 8-fold higher among White Mountain Apache persons of all ages than it was among the general US population, . We aimed to assess the impact of PCV7 and 23-valent pneumococcal polysaccharide vaccine on the rate of IPD among White Mountain Apache persons.
From 1991 through 2006, we conducted active laboratory- and population-based surveillance among Native American residents of the White Mountain Apache reservation. Charts were reviewed and pneumococcal isolates were collected for serotype testing. Three time periods were defined: the pre-PCV7 baseline period (1991-1997), the PCV7 efficacy trial period (1998-2000), and the PCV7 routine-use period (2001-2006).
We identified 246 cases of IPD; the mean annual IPD rate fell from 126 cases per 100,000 person-years in the period 1991-1997 to 87 cases per 100,000 person-years in the period 2001-2006 (p = .01). The rate of IPD attributable to PCV7 serotypes of Streptococcus pneumoniae decreased by 252 cases per 100,000 person-years (92%) among children aged <5 years, and that attributable to non-PCV7 serotypes of S. pneumoniae decreased by 87 cases per 100,000 person-years (44%) among children aged <5 years. Among adults, the rate of IPD remained unchanged; PCV7 serotypes of S. pneumoniae accounted for only 25% of adult cases during the period 1991-1997.
Since the introduction of PCV7, the rate of IPD among White Mountain Apache children aged <5 years has decreased to the lowest rate ever (122 cases per 100,000 person-years), but it remains 5.7-fold greater than the rate of IPD among children in the general US population. In contrast to some other high-risk populations, there is no evidence of non-vaccine-type replacement disease in this age group. Among White Mountain Apache adults, the rate of IPD remains substantially higher than that observed in the general US population. Vaccines with broader serotype coverage are needed to further reduce the disparity in the rate of IPD between the White Mountain Apache and general US populations.
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ABSTRACT: 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. 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. The Whiteriver Indian Health Service Hospital is located on the 1.7-million-acre White Mountain Apache Reservation in eastern Arizona. 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. The average annual incidence rates of invasive pneumococcal disease were calculated and clinical characteristics were reviewed. 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. The incidence rate was highest in children between 1 and 2 years--2396 per 100,000. 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.Archives of Internal Medicine 12/1992; 152(11):2277-82. · 11.46 Impact Factor
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ABSTRACT: In early 2000, a protein-polysaccharide conjugate vaccine targeting seven pneumococcal serotypes was licensed in the United States for use in young children. We examined population-based data from the Active Bacterial Core Surveillance of the Centers for Disease Control and Prevention to evaluate changes in the burden of invasive disease, defined by isolation of Streptococcus pneumoniae from a normally sterile site. Serotyping and susceptibility testing of isolates were performed. We assessed trends using data from seven geographic areas with continuous participation from 1998 through 2001 (population, 16 million). The rate of invasive disease dropped from an average of 24.3 cases per 100,000 persons in 1998 and 1999 to 17.3 per 100,000 in 2001. The largest decline was in children under two years of age. In this group, the rate of disease was 69 percent lower in 2001 than the base-line rate (59.0 cases per 100,000 vs. 188.0 per 100,000, P<0.001); the rate of disease caused by vaccine and vaccine-related serotypes declined by 78 percent (P<0.001) and 50 percent (P<0.001), respectively. Disease rates also fell for adults; as compared with base line, the rate of disease in 2001 was 32 percent lower for adults 20 to 39 years of age (7.6 cases per 100,000 vs. 11.2 per 100,000, P<0.001), 8 percent lower for those 40 to 64 years of age (19.7 per 100,000 vs. 21.5 per 100,000, P=0.03), and 18 percent lower for those 65 years of age or more (49.5 per 100,000 vs. 60.1 per 100,000, P<0.001). The rate of disease caused by strains that were not susceptible to penicillin was 35 percent lower in 2001 than in 1999 (4.1 cases per 100,000 vs. 6.3 per 100,000, P<0.001). The use of the pneumococcal conjugate vaccine is preventing disease in young children, for whom the vaccine is indicated, and may be reducing the rate of disease in adults. The vaccine provides an effective new tool for reducing disease caused by drug-resistant strains.New England Journal of Medicine 06/2003; 348(18):1737-46. · 51.66 Impact Factor
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ABSTRACT: Five of seven serotypes in the pneumococcal conjugate vaccine, introduced for infants in the United States in 2000, are responsible for most penicillin-resistant infections. We examined the effect of this vaccine on invasive disease caused by resistant strains. We used laboratory-based data from Active Bacterial Core surveillance to measure disease caused by antibiotic-nonsusceptible pneumococci from 1996 through 2004. Cases of invasive disease, defined as disease caused by pneumococci isolated from a normally sterile site, were identified in eight surveillance areas. Isolates underwent serotyping and susceptibility testing. Rates of invasive disease caused by penicillin-nonsusceptible strains and strains not susceptible to multiple antibiotics peaked in 1999 and decreased by 2004, from 6.3 to 2.7 cases per 100,000 (a decline of 57 percent; 95 percent confidence interval, 55 to 58 percent) and from 4.1 to 1.7 cases per 100,000 (a decline of 59 percent; 95 percent confidence interval, 58 to 60 percent), respectively. Among children under two years of age, disease caused by penicillin-nonsusceptible strains decreased from 70.3 to 13.1 cases per 100,000 (a decline of 81 percent; 95 percent confidence interval, 80 to 82 percent). Among persons 65 years of age or older, disease caused by penicillin-nonsusceptible strains decreased from 16.4 to 8.4 cases per 100,000 (a decline of 49 percent). Rates of resistant disease caused by vaccine serotypes fell 87 percent. An increase was seen in disease caused by serotype 19A, a serotype not included in the vaccine (from 2.0 to 8.3 per 100,000 among children under two years of age). The rate of antibiotic-resistant invasive pneumococcal infections decreased in young children and older persons after the introduction of the conjugate vaccine. There was an increase in infections caused by serotypes not included in the vaccine.New England Journal of Medicine 05/2006; 354(14):1455-63. · 51.66 Impact Factor