Public health and environmental response to the first case of naturally acquired inhalational anthrax in the United States in 30 years: infection of a new york city resident who worked with dried animal hides.

In Pennsylvania on February 16, 2006, a New York City resident collapsed with rigors and was hospitalized. On February 21, the Centers for Disease Control and Prevention and the New York City Department of Health and Mental Hygiene were notified that Bacillus anthracis had been identified in the patient's blood. Although the patient's history of working with dried animal hides to make African drums indicated the likelihood of a natural exposure to aerosolized anthrax spores, bioterrorism had to be ruled out first. Ultimately, this case proved to be the first case of naturally occurring inhalational anthrax in 30 years. This article describes the epidemiologic and environmental investigation to identify other cases and persons at risk and to determine the source of exposure and scope of contamination. Because stricter regulation of the importation of animal hides from areas where anthrax is enzootic is difficult, public healthcare officials should consider the possibility of future naturally occurring anthrax cases caused by contaminated hides. Federal protocols are needed to assist in the local response, which should be tempered by our growing understanding of the epidemiology of naturally acquired anthrax. These protocols should include recommended methods for reliable and efficient environmental sample collection and laboratory testing, and environmental risk assessments and remediation.

Increased case-fatality rate associated with outbreaks of Neisseria meningitidis infection, compared with sporadic meningococcal disease, in the United States, 1994-2002.

BACKGROUND: Outbreaks of meningococcal disease are infrequent but important public health events. We characterize outbreak-associated cases in the United States and compare them with sporadic disease. METHODS: Outbreaks of meningococcal disease that occurred during the period of 1 July 1994 through 30 June 2002 were identified through state health departments, Centers for Disease Control and Prevention records, and a review of newspapers and the medical literature. Cases associated with outbreaks were compared with sporadic cases identified through population-based surveillance. RESULTS: We identified 69 outbreaks of Neisseria meningitidis infection (median, 9.5 outbreaks per year; range, 3-14 outbreaks per year), which involved 229 patients from 30 states. Forty-three (62%) of the outbreaks involved N. meningitidis serogroup C, 17 (25%) involved serogroup B, and 9 (13%) involved serogroup Y. Twenty-five outbreaks (36%) occurred in communities, and 44 (64%) were organization based, including 12 that occurred in colleges and universities, 19 that occurred in primary and secondary schools, and 8 that occurred in nursing homes. Vaccination campaigns (with the A/C/Y/W-135 meningococcal polysaccharide vaccine) were conducted for 31 outbreaks (28 involving serogroup C and 3 involving serogroup Y). After controlling for age, serogroup, and clinical presentation, outbreak-associated cases were associated with a higher case-fatality rate than were sporadic cases (21% vs. 11%; odds ratio, 3.3; 95% confidence interval, 2.0-5.5). CONCLUSIONS: Outbreaks remain an important but infrequent public health issue, representing <2% of all cases of meningococcal disease. However, given the increased case-fatality rate found among outbreak-related cases of N. meningitidis infection, additional investigation of factors that favor the transmission and virulence of outbreak-related strains is warranted.

Prevention and control of meningococcal disease. Recommendations of the Advisory Committee on Immunization Practices (ACIP).

In January 2005, a tetravalent meningococcal polysaccharide-protein conjugate vaccine ([MCV4] Menactra, manufactured by Sanofi Pasteur, Inc., Swiftwater, Pennsylvania) was licensed for use among persons aged 11-55 years. CDCns Advisory Committee on Immunization Practices (ACIP) recommends routine vaccination of young adolescents (defined in this report as persons aged 11-12 years) with MCV4 at the preadolescent health-care visit (at age 11-12 years). Introducing a recommendation for MCV4 vaccination among young adolescents might strengthen the role of the preadolescent visit and have a positive effect on vaccine coverage among adolescents. For those persons who have not previously received MCV4, ACIP recommends vaccination before high-school entry (at approximately age 15 years) as an effective strategy to reduce meningococcal disease incidence among adolescents and young adults. By 2008, the goal will be routine vaccination with MCV4 of all adolescents beginning at age 11 years. Routine vaccination with meningococcal vaccine also is recommended for college freshmen living in dormitories and for other populations at increased risk (i.e., military recruits, travelers to areas in which meningococcal disease is hyperendemic or epidemic, microbiologists who are routinely exposed to isolates of Neisseria meningitidis, patients with anatomic or functional asplenia, and patients with terminal complement deficiency). Other adolescents, college students, and persons infected with human immunodeficiency virus who wish to decrease their risk for meningococcal disease may elect to receive vaccine. This report updates previous reports from ACIP concerning prevention and control of meningococcal disease. It also provides updated recommendations regarding use of the tetravalent meningococcal polysaccharide vaccine (MPSV4) and on antimicrobial chemoprophylaxis.

Epidemiology of invasive Haemophilus influenzae type A disease among Navajo and White Mountain Apache children, 1988-2003.

BACKGROUND: Before the introduction of Haemophilus influenzae type b (Hib) conjugate vaccines, rates of H. influenzae disease among Navajo and White Mountain Apache (WMA) children were among the highest reported worldwide. Routine Hib vaccination has significantly reduced rates of Hib disease in these populations. As Hib disease rates decrease to very low levels, there are concerns that non-type b strains of H. influenzae may emerge as more prevalent causes of invasive disease in children. METHODS: We reviewed population-based, active laboratory surveillance data from the period of 1988-2003 for invasive H. influenzae type a (Hia) disease among Navajo and WMA children aged <5 years. Clinical information on cases was collected by chart review. A sample of Hia isolates from Navajo children was typed by pulsed-field gel electrophoresis (PFGE). RESULTS: During 1988-2003, a total of 76 reported cases of invasive Hia disease occurred among Navajo and WMA children. The overall annual incidence was 20.2 cases per 100,000 population aged <5 years. There was no increase in Hia disease rates after Hib vaccination was introduced. The median age of patients was 12 months. Meningitis (50% of cases) was the most common presentation, followed by pneumonia (27.6%). Two children with Hia disease died. PFGE analysis revealed a limited genetic diversity of Hia strains in this population. CONCLUSIONS: Active surveillance data showed high rates of invasive Hia disease among Navajo and WMA children but no increase in the incidence after Hib vaccination was introduced. The presentation of Hia disease is similar to that of Hib disease in the prevaccine era.

Responding to detection of aerosolized Bacillus anthracis by autonomous detection systems in the workplace.

Autonomous detection systems (ADSs) are under development to detect agents of biologic and chemical terror in the environment. These systems will eventually be able to detect biologic and chemical hazards reliably and provide approximate real-time alerts that an agent is present. One type of ADS that tests specifically for Bacillus anthracis is being deployed in hundreds of postal distribution centers across the United States. Identification of aerosolized B. anthracis spores in an air sample can facilitate prompt on-site decontamination of workers and subsequent administration of postexposure prophylaxis to prevent inhalational anthrax. Every employer who deploys an ADS should develop detailed plans for responding to a positive signal. Responding to ADS detection of B. anthracis involves coordinating responses with community partners and should include drills and exercises with these partners. This report provides guidelines in the following six areas: 1) response and consequence management planning, including the minimum components of a facility response plan; 2) immediate response and evacuation; 3) decontamination of potentially exposed workers to remove spores from clothing and skin and prevent introduction of B. anthracis into the worker's home and conveyances; 4) laboratory confirmation of an ADS signal; 5) steps for evaluating potentially contaminated environments; and 6) postexposure prophylaxis and follow-up.

Serious adverse events among participants in the Centers for Disease Control and Prevention's Anthrax Vaccine and Antimicrobial Availability Program for persons at risk for bioterrorism-related inhalational anthrax.

On 20 December 2001, the Centers for Disease Control and Prevention (CDC) initiated the Anthrax Vaccine and Antibiotic Availability Program (hereafter, the "Program") under an investigational new drug application with the US Food and Drug Administration. This Program provided options for additional preventive treatment for persons at risk for inhalation anthrax as a result of recent bioterrorism attacks who had concluded or were concluding a 60-day course of antimicrobial prophylaxis. Participants were offered an additional 40 days of antibiotic therapy (with ciprofloxacin, doxycycline, or amoxicillin) or antibiotic therapy plus 3 doses of anthrax vaccine. By 11 February 2002, a total of 5420 persons had received standardized education about the Program and 1727 persons (32%) had enrolled. Twelve participants have been identified as having serious adverse events (SAEs). One SAE, which occurred in a participant with ciprofloxacin-induced allergic interstitial nephritis, was considered to be probably associated with treatment received in the Program. No SAEs were associated with anthrax vaccine. CDC will continue to monitor Program participants during the next 2 years.

Neonatal meningococcal disease in the United States, 1990 to 1999.

BACKGROUND: Although neonatal bacterial meningitis is common, the rate of invasive meningococcal disease in the United States among children < or =30 days old has not been defined. Most relevant literature consists of case reports or case series, which note high case-fatality ratios but do not describe the overall burden of disease. METHODS: We used active, population-based surveillance data from the Active Bacterial Core Surveillance program to estimate the incidence of neonatal meningococcal disease in the United States from 1990 to 1999. A case of neonatal meningococcal disease was defined as isolation of Neisseria meningitidis from a normally sterile site in a resident of the surveillance area < or =30 days of age. RESULTS: The median annual number of neonates under surveillance was 25 900. Between 1990 and 1999, 22 cases of neonatal meningococcal disease were identified. Three (14%) patients died. The average annual incidence was 9 per 100 000. CONCLUSIONS: The rate of neonatal meningococcal disease in the United States is higher than previous estimates. Meningococcal disease is uncommon in neonates, but its rate is similar to that of meningococcal disease in 6- to 23-month-old children.

Vaccinating first-year college students living in dormitories for Meningococcal disease: an economic analysis.

BACKGROUND: Surveillance of meningococcal disease among U.S. college students found an elevated rate of this disease among first-year students living in dormitories. OBJECTIVE: This study examines the economics of routinely vaccinating a cohort of 591,587 incoming first-year students who will live in dormitories for > or =1 years. METHODS: A cost-benefit model (societal perspective) was constructed to measure the net present value (NPV) of various vaccination scenarios, as well as the cost/case and cost/death averted. Input values included hospitalization costs from $10,924 to $24,030 per hospitalization; immunization costs (vaccine plus administration costs) from $54 to $88 per vaccine; 30 nonfatal, vaccine-preventable cases over a 4-year period (includes 3 with sequelae); 3 premature deaths; value of human life from $1.2 million to $4.8 million; and long-run sequelae costs from $1298 to $14,600. Sensitivity analyses were also conducted on vaccine efficacy (80% to 90%); discount rate (0% to 5%); and coverage (60% to 100%). RESULTS: The costs of vaccination outweighed the benefits gained with NPVs ranging from -$11 million to -$49 million. The net cost per case averted ranged from $0.6 million to $1.9 million. The net cost per death averted ranged from $7 million to $20 million. The break-even costs of vaccination (when NPV=$0) at 60% coverage ranged from $23 (90% vaccine efficacy) to $5 (80% efficacy). CONCLUSIONS: The model showed that the vaccination program is not cost-saving. Key variables influencing the results were the low number of vaccine-preventable cases and the high cost of vaccination. However, from the perspective of students and parents, the cost of vaccination might be worth the real or perceived benefit of reducing the risk to an individual student of developing meningococcal disease.

Vaccines for the prevention of meningococcal disease in children.

Neisseria meningitidis is one of the most feared infections in pediatrics as the result of its rapid progression, high fatality rate, and frequent occurrence of sequelae. The 5 major meningococcal serogroups associated with disease are A, B, C, Y, and W-135. Currently available polysaccharide vaccines are effective in preventing disease caused by serogroups A, C, Y, and W-135 in older children and adults but do not elicit good long-term protection in young children. Vaccines that protect against serogroup B disease are still in development. As with the Haemophilus influenzae type b and pneumococcal polysaccharide vaccines, conjugation of the polysaccharide vaccine to a protein carrier dramatically changes vaccine characteristics, with resulting efficacy in infants. New meningococcal conjugate vaccines against serogroups A, C, Y, and W-135 are being developed. A serogroup C conjugate vaccine has been introduced successfully into the routine childhood schedule in the United Kingdom. New meningococcal conjugate vaccines are likely to have a dramatic effect on the burden of meningococcal disease within the next decade.

Evaluation of serogroup A meningococcal vaccines in Africa: a demonstration project.

Endemic and epidemic meningococcal disease constitutes a major public-health problem in African countries of the 'meningitis belt' where incidence rates of the disease are many-fold higher (up to 25 cases per 100,000 population) than those in industrialized countries, and epidemics of meningococcal disease occur with rates as high as 1,000 cases per 100,000 people. Using the precedent established during the licensing of conjugate vaccines against Haemophilus influenzae type b and serogroup C meningococci and components of currently-licensed meningococcal polysaccharide vaccines, new meningococcal conjugate vaccines will likely be licensed using immunological endpoints as surrogates for clinical protection. Post-licensure evaluation of vaccine effectiveness will, therefore, be of increased importance. One vaccine being developed is the serogroup A meningococcal (Men A) conjugate vaccine produced by the Meningitis Vaccine Project (MVP), a partnership between the World Health Organization and the Program for Applied Technology in Health. This vaccine will likely be the first meningococcal conjugate vaccine introduced on a large scale in Africa. This paper summarizes the general steps required for vaccine development, reviews the use of immunogenicity criteria as a licensing strategy for new meningococcal vaccines, and discusses plans for evaluating the impact of a meningococcal A conjugate vaccine in Africa. Impact of this vaccine will be measured during a vaccine-demonstration project that will primarily measure the effectiveness of vaccine. Other studies will include evaluations of safety, vaccine coverage, impact on carriage and herd immunity, and prevention-effectiveness studies.

One-year health assessment of adult survivors of Bacillus anthracis infection.

CONTEXT: Little is known about potential long-term health effects of bioterrorism-related Bacillus anthracis infection. OBJECTIVE: To describe the relationship between anthrax infection and persistent somatic symptoms among adults surviving bioterrorism-related anthrax disease approximately 1 year after illness onset in 2001. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 15 of 16 adult survivors from September through December 2002 using a clinical interview, a medical review-of-system questionnaire, 2 standardized self-administered questionnaires, and a review of available medical records. MAIN OUTCOME MEASURES: Health complaints summarized by the body system affected and by symptom categories; psychological distress measured by the Revised 90-Item Symptom Checklist; and health-related quality-of-life indices by the Medical Outcomes Study 36-Item Short-Form Health Survey (version 2). RESULTS: The anthrax survivors reported symptoms affecting multiple body systems, significantly greater overall psychological distress (P<.001), and significantly reduced health-related quality-of-life indices compared with US referent populations. Eight survivors (53%) had not returned to work since their infection. Comparing disease manifestations, inhalational survivors reported significantly lower overall physical health than cutaneous survivors (mean scores, 30 vs 41; P =.02). Available medical records could not explain the persisting health complaints. CONCLUSION: The anthrax survivors continued to report significant health problems and poor life adjustment 1 year after onset of bioterrorism-related anthrax disease.

Effectiveness of a trivalent serogroup A/C/W135 meningococcal polysaccharide vaccine in Burkina Faso, 2003.

Following a large Neisseria meningitidis W135 (NmW135) epidemic in Burkina Faso (BF) during 2002, a newly licensed trivalent A/C/W135 meningococcal polysaccharide vaccine was introduced in 2003. We conducted a case-control study to assess the vaccine effectiveness (VE) against meningococcal disease. Thirty-two N. meningitidis A (NmA) and 3 NmW135 meningitis cases were enrolled and matched by age-neighborhood to 103 controls. After adjusting for confounding risk factors, VE against NmA or NmW135 was 83.6% (95% CI 31.8-97.0, p=0.01) for persons with verified vaccination. VE against probable/definite NmA alone was 94.0% (95% CI 58.7-99.0, p=0.0003). Low number of NmW135 cases did not allow estimation of VE against NmW135 alone. The vaccine was highly effective against the epidemic. Since 2003, the trivalent vaccine continues to be effectively used in Africa for the control of meningococcal disease epidemics.

Predictors of immunity after a major serogroup W-135 meningococcal disease epidemic, Burkina Faso, 2002.

BACKGROUND: The African meningitis belt undergoes recurrent epidemics caused by Neisseria meningitidis serogroup A. During 2002, Burkina Faso documented the first large serogroup W-135 (NmW-135) meningococcal disease epidemic. To understand the emergence of NmW-135, we investigated meningococcal carriage and immunity. METHODS: Immediately after Burkina Faso's epidemic, we conducted a cross-sectional survey of meningococcal carriage and seroprevalence in an epidemic and a nonepidemic district. We identified predictors of elevated NmW-135 serum bactericidal activity (SBA), a functional correlate of protection, using multivariate logistic regression. RESULTS: The NmW-135 carriage rate was 25.2% in the epidemic district and 3.4% in the nonepidemic district (P<.0001). Compared with residents of the nonepidemic district, those of the epidemic district had higher geometric mean titers of NmW-135 SBA (P<.0001). NmW-135 SBA titers>or=1:8, an estimated protective threshold, were observed in 60.4% and 34.0% of residents of the epidemic and nonepidemic district, respectively (P=.0002). In a multivariate model, current NmW-135 carriage, age, and residence in the epidemic district were independent predictors of having an NmW-135 SBA titer>or=1:8. CONCLUSIONS: Extensive NmW-135 carriage and transmission in the epidemic area caused residents to acquire natural immunity. Serial carriage and seroprevalence surveys could establish the duration of immunity in the population. The persistent circulation of NmW-135 underscores the potential for periodic NmW-135 epidemics in Africa.

Cost-effectiveness of conjugate meningococcal vaccination strategies in the United States.

CONTEXT: The US Food and Drug Administration approved a meningococcal conjugate A/C/Y/W-135 vaccine (MCV-4) for use in persons aged 11 to 55 years in January, 2005; licensure for use in younger age groups is expected in 2 to 4 years. OBJECTIVE: To evaluate and compare the projected health and economic impact of MCV-4 vaccination of US adolescents, toddlers, and infants. DESIGN: Cost-effectiveness analysis from a societal perspective based on data from Active Bacterial Core Surveillance (ABCs) and other published and unpublished sources. Sensitivity analyses in which key input measures were varied over plausible ranges were performed. SETTING AND PATIENTS: A hypothetical 2003 US population cohort of children 11 years of age and a 2003 US birth cohort. INTERVENTIONS: Hypothetical routine vaccination of adolescents (1 dose at 11 years of age), toddlers (1 dose at 1 year of age), and infants (3 doses at 2, 4, and 6 months of age). Each vaccination scenario was compared with a "no-vaccination" scenario. MAIN OUTCOME MEASURES: Meningococcal cases and deaths prevented, cost per case prevented, cost per life-year saved, and cost per quality-adjusted life-year saved. RESULTS: Routine MCV-4 vaccination of US adolescents (11 years of age) would prevent 270 meningococcal cases and 36 deaths in the vaccinated cohort over 22 years, a decrease of 46% in the expected burden of disease. Before program costs are counted, adolescent vaccination would reduce direct disease costs by $18 million and decrease productivity losses by $50 million. At a cost per vaccination (average public-private price per dose plus administration fees) of $82.50, adolescent vaccination would cost society $633000 per meningococcal case prevented and $121000 per life-year saved. Key variables influencing results were disease incidence, case-fatality ratio, and cost per vaccination. The cost-effectiveness of toddler vaccination is essentially equivalent to adolescent vaccination, whereas infant vaccination would be much less cost-effective. CONCLUSIONS: Routine MCV-4 vaccination of US children would reduce the burden of disease in vaccinated cohorts but at a relatively high net societal cost. The projected cost-effectiveness of adolescent vaccination approaches that of recently adopted childhood vaccines under conditions of above-average meningococcal disease incidence or at a lower cost per vaccination.

An overview of adverse events reported by participants in CDC's anthrax vaccine and antimicrobial availability program.

PURPOSE: The CDC's Anthrax Vaccine and Antibiotic Availability Program was implemented under an Investigational New Drug (IND) application to provide additional post-exposure prophylaxis for individuals potentially exposed to Bacillus anthracis in the fall of 2001. Participants were provided with two options: (1) 40 additional days of antimicrobial prophylaxis (i.e., ciprofloxacin, doxycycline, or amoxicillin); or (2) 40 additional days of antimicrobial prophylaxis plus three doses of anthrax vaccine adsorbed (AVA). METHODS: Participants were monitored for adverse events (AEs). Participants were asked to complete 2-week AE diaries for 6 weeks post-enrollment, and approximately 2 months after enrollment, active surveillance was conducted through telephone interviews with 1113 (64%) participants. RESULTS: A total of 1727 of approximately 10 000 previously prophylaxed persons enrolled to receive 40 additional days of antibiotics. Of these, 199 opted at enrollment to receive three doses of AVA in addition to the additional 40 days of antibiotic. Overall, 28% of participants reported at least one AE on their diaries. Results varied by surveillance mechanism, the diary data indicated differences in the proportion reporting AEs between participants receiving antibiotic only and participants receiving antibiotic and AVA. However, during the active 2-month telephone follow-up, the rates of AEs reported for both the antibiotic only and antibiotic plus AVA treatment regimens were similar. Additionally, ciprofloxacin and doxycycline had similar AE profiles, with only rigors reported significantly more often among ciprofloxacin recipients. CONCLUSIONS: Overall, the rates of AEs experienced by all participants were acceptable given the seriousness of potential B. anthracis exposure.

Assessing the risk of laboratory-acquired meningococcal disease.

Neisseria meningitidis is infrequently reported as a laboratory-acquired infection. Prompted by two cases in the United States in 2000, we assessed this risk among laboratorians. We identified cases of meningococcal disease that were possibly acquired or suspected of being acquired in a laboratory by placing an information request on e-mail discussion groups of infectious disease, microbiology, and infection control professional organizations. A probable case of laboratory-acquired meningococcal disease was defined as illness meeting the case definition for meningococcal disease in a laboratorian who had occupational exposure to an N. meningitidis isolate of the same serogroup within 14 days of illness onset. Sixteen cases of probable laboratory-acquired meningococcal disease occurring worldwide between 1985 and 2001 were identified, including six U.S. cases between 1996 and 2000. Nine cases (56%) were serogroup B; seven (44%) were serogroup C. Eight cases (50%) were fatal. All cases occurred among clinical microbiologists. In 15 cases (94%), isolate manipulation was performed without respiratory protection. We estimated that an average of three microbiologists are exposed to the 3,000 meningococcal isolates seen in U.S. laboratories yearly and calculated an attack rate of 13/100,000 microbiologists between 1996 and 2001, compared to 0.2/100,000 among U.S. adults in general. The rate and case/fatality ratio of meningococcal disease among microbiologists are higher than those in the general U.S. population. Specific risk factors for laboratory-acquired infection are likely associated with exposure to droplets or aerosols containing N. meningitidis. Prevention should focus on the implementation of class II biological safety cabinets or additional respiratory protection during manipulation of suspected meningococcal isolates.

Neisseria meningitidis serogroup W-135 carriage among US travelers to the 2001 Hajj.

In 2000, a large international outbreak of meningococcal disease caused by Neisseria meningitidis serogroup W-135 was identified among pilgrims returning from the Hajj in Saudi Arabia. To assess ongoing risk, we evaluated N. meningitidis carriage among US travelers to the 2001 Hajj. Of 25 N. meningitidis isolates obtained, 15 (60%) were nongroupable and 8 (32%) were serogroup W-135 when tested by standard slide-agglutination techniques. Two additional nongroupable isolates were characterized as serogroup W-135 when tested by polymerase chain reaction. Nine of 10 serogroup W-135 isolates were indistinguishable from the Hajj-2000 clone. None of the departing, but 9 (1.3%) of the returning, pilgrims carried serogroup W-135 (P=.01); all carriers reported previous vaccination. Carriage of N. meningitidis serogroup W-135 increased significantly in pilgrims returning from the Hajj. Although the risk of disease to pilgrims appears to be low, the risk of spread to others of this pathogenic strain remains a concern.

Opportunities for control of meningococcal disease in the United States.

The United States currently has relatively low rates of meningococcal disease caused by Neisseria meningitidis. Serogroups Y, C, and B are most common. Although most cases are sporadic, a minority are associated with outbreaks. Pediatric populations have disproportionately higher rates of disease, but nearly two thirds of all cases occur in persons aged 15 years and older. The major challenge to control of domestic meningococcal disease is the absence of a vaccine to prevent sporadic cases spanning many age groups. The quadrivalent A/C/Y/W-135 meningococcal polysaccharide vaccine is licensed in the United States, but because of its limited efficacy in children under two years of age, it is recommended for high-risk groups and outbreak response rather than routine childhood immunization. New conjugate meningococcal vaccines have successfully reduced endemic disease in the United Kingdom, and similar vaccines promise to have a dramatic impact on the burden of meningococcal disease in the United States.

Reemergence, in southwestern Alaska, of invasive Haemophilus influenzae type b disease due to strains indistinguishable from those isolated from vaccinated children.

Haemophilus influenzae type b (Hib) invasive disease and oropharyngeal carriage continue in rural Alaska despite widespread vaccination. This study investigated whether invasive-disease reemergence during 1996-1997 could be attributed to strains distinguishable from strains carried by vaccinated children. Twenty-four invasive and 42 carriage Hib isolates, collected during 1992-1997, were characterized by pulsed-field gel electrophoresis (PFGE), multilocus enzyme electrophoresis, and biotyping. This Hib population was highly clonal, since only 2 strains, electrophoretic type (ET) 55/PFGE 1 and ET 56/PFGE 3, accounted for 62% of all isolates. The ET 55/PFGE 1 and ET 56/PFGE 3 strains were found in 74% of the carriers and caused 80% of the invasive Hib disease that occurred during April 1996-March 1997. Strains causing invasive disease could not be distinguished from strains carried by vaccinated children. Continued monitoring of Hib carriage may provide insights into the epidemiology of continued transmission in an era of widespread vaccination.

Antimicrobial postexposure prophylaxis for anthrax: adverse events and adherence.

We collected data during postexposure antimicrobial prophylaxis campaigns and from a prophylaxis program evaluation 60 days after start of antimicrobial prophylaxis involving persons from six U.S. sites where Bacillus anthracis exposures occurred. Adverse events associated with antimicrobial prophylaxis to prevent anthrax were commonly reported, but hospitalizations and serious adverse events as defined by Food and Drug Administration criteria were rare. Overall adherence during 60 days of antimicrobial prophylaxis was poor (44%), ranging from 21% of persons exposed in the Morgan postal facility in New York City to 64% of persons exposed at the Brentwood postal facility in Washington, D.C. Adherence was highest among participants in an investigational new drug protocol to receive additional antibiotics with or without anthrax vaccine--a likely surrogate for anthrax risk perception. Adherence of <60 days was not consistently associated with adverse events.