Detection of Mycobacterium tuberculosis infection in United States Navy recruits using the tuberculin skin test or whole-blood interferon-gamma release assays.

BACKGROUND: Military personnel are at risk for acquiring Mycobacterium tuberculosis infection because of activities in close quarters and in regions with a high prevalence of tuberculosis (TB). Accurate tests are needed to avoid unnecessary treatment because of false-positive results and to avoid TB because of false-negative results and failure to diagnose and treat M. tuberculosis infection. We sought to estimate the specificity of the tuberculin skin test (TST) and 2 whole-blood interferon-gamma release assays (QuantiFERON-TB assay [QFT] and QuantiFERON-TB Gold assay [QFT-G]) and to identify factors associated with test discordance. METHODS: A cross-sectional comparison study was performed in which 856 US Navy recruits were tested for M. tuberculosis infection using the TST, QFT, and QFT-G. RESULTS: Among the study subjects, 5.1% of TSTs resulted in an induration > or = 10 mm, and 2.9% of TSTs resulted in an induration > or = 15 mm. Eleven percent of QFT results and 0.6% of QFT-G results were positive. Assuming recruits at low risk for M. tuberculosis exposure were not infected, estimates of TST specificity were 99.1% (95% confidence interval [CI], 98.3%-99.9%) when a 15-mm cutoff value was used and 98.4% (95% CI, 97.3%-99.4%) when a 10-mm cutoff value was used. The estimated QFT specificity was 92.3% (95% CI, 90.0%-94.5%), and the estimated QFT-G specificity was 99.8% (95% CI, 99.5%-100%). Recruits who were born in countries with a high prevalence of TB were 26-40 times more likely to have discordant results involving a positive TST result and a negative QFT-G result than were recruits born in countries with a low prevalence of TB. Nineteen (50%) of 38 recruits with this type of discordant results had a TST induration > or = 15 mm. CONCLUSIONS: The QFT-G and TST are more specific than the QFT. No statistically significant difference in specificity between the QFT-G and TST was found using a 15-mm induration cutoff value. The discordant results observed among recruits with increased risk of M. tuberculosis infection may have been because of lower TST specificity or lower QFT-G sensitivity. Negative QFT-G results for recruits born in countries where TB is highly prevalent and whose TST induration was > or = 15 mm suggest that the QFT-G may be less sensitive than the TST. Additional studies are needed to determine the risk of TB when TST and QFT-G results are discordant.

Measures to control an outbreak of pertussis in a neonatal intermediate care nursery after exposure to a healthcare worker.

BACKGROUND: Hospitalized premature infants are particularly vulnerable to morbidity and mortality from pertussis. Effective prevention and investigative and control measures are not well described. OBJECTIVE: To identify the source of nosocomial pertussis in a 2-month-old premature infant in a neonatal intermediate care nursery (ICN) and to critically review the investigation and outbreak control measures. SETTING: An ICN and a neonatal intensive care unit. METHODS: We queried healthcare workers (HCWs) and family members about cough illness and contacted potentially exposed patients to determine whether they had symptoms of pertussis. Culture and polymerase chain reaction (PCR) testing for Bordetella pertussis were performed by the hospital laboratory with specimens collected from symptomatic patients and HCWs. Levels of pertussis toxin immunoglobulin G antibodies were measured in HCWs with cough of at least 14 days' duration at a public health laboratory. Extensive control measures were instituted. RESULTS: Four ICN HCWs met the clinical case definition for presence of pertussis. Serologic test results were positive for 3 of the HCWs. The primary case patient was a 36-year-old HCW with a cough illness of 3-weeks' duration that was accompanied by paroxysms, whoop, posttussive emesis, and pneumothorax. Among the 4 affected HCWs, the duration of cough illness prior to identification of the infant index patient ranged from 11 to 25 days. Outbreak control measures included isolation of the infant case patient, furlough and treatment of symptomatic HCWs, administration of chemoprophylaxis to contacts, and surveillance for additional cases. Seventy-two infant patients and 72 HCWs were exposed and were given antibiotic prophylaxis. One additional case of pertussis, confirmed by PCR and culture, occurred in a resident physician who declined prophylaxis; she had cared for the index patient but had no contact with symptomatic HCWs. CONCLUSION: HCWs or patients may serve as the source of pertussis in nosocomial outbreaks, which can result in substantial morbidity and outlay of resources for control measures. Our review suggested that a diagnosis of pertussis should be an early consideration for HCWs with cough illness. Targeted pertussis immunization of HCWs, employee health policies that provide for testing and furlough of HCWs with prolonged cough, and monitoring of HCWs for compliance with infection control measures could reduce the morbidity and costs associated with pertussis outbreaks. These measures will require evaluation of their effectiveness.

Outbreak of pertussis among healthcare workers in a hospital surgical unit.

BACKGROUND: In September 1999, a pertussis outbreak was detected among surgical staff of a 138-bed community hospital. Patients were exposed to Bordetella pertussis during the 3-month outbreak period. OBJECTIVE: To describe the outbreak among surgical staff, to evaluate implemented control measures, and to determine whether nosocomial transmission occurred. METHODS: Clinical pertussis was defined as acute cough illness with a duration of 14 days or more without another apparent cause; persons with positive culture, PCR, or serologic test results were defined as having laboratory-confirmed pertussis. Surgical healthcare workers (HCWs) were interviewed regarding pertussis symptoms, and specimens were obtained for laboratory analysis. Patients exposed to B. pertussis during an ill staff member's 3-week infectious period were interviewed by phone to determine the extent of nosocomial spread. PARTICIPANTS: A total of 53 HCWs assigned to the surgical unit and 146 exposed patients. HCWs with pertussis were defined as case subjects; HCWs without pertussis were defined as non-case subjects. RESULTS: Twelve (23%) of 53 HCWs had clinical pertussis; 6 cases were laboratory confirmed. The median cough duration in the 12 case subjects was 27 days (range, 20-120 days); 10 (83%) had paroxysms. Eleven (92%) of 12 case subjects and 28 (86%) of 41 non-case subjects received antibiotic treatment or prophylaxis. Seven case subjects (58%) reported they always wore a mask when near patients. Of 146 patients potentially exposed to pertussis from the 12 case subjects, 120 (82%) were interviewed; none reported a pertussis-like illness. CONCLUSIONS: Surgical staff transmitted B. pertussis among themselves; self-reported data suggests that these HCWs did not transmit B. pertussis to their patients, likely because of mask use, cough etiquette, and limited face-to-face contact. Control measures might have helped limit the outbreak once pertussis was recognized.

Infant pertussis: who was the source?

BACKGROUND: In the United States in the 1990s, the incidence of reported pertussis in adults, adolescents and infants increased; infants younger than 1 year of age had the highest reported incidence. METHODS: In 4 states with Enhanced Pertussis Surveillance, we examined the epidemiology of reported pertussis cases to determine the source of pertussis among infants. A source was defined as a person with an acute cough illness who had contact with the case-infant 7-20 days before the infant's onset of cough. RESULTS: The average annual pertussis incidence per 100,000 infants younger than 1 year of age varied by state: 22.9 in Georgia; 42.1 in Illinois; 93.0 in Minnesota; and 35.8 in Massachusetts. Family members of 616 (80%) of 774 reported case-infants were interviewed; a source was identified for 264 (43%) of the 616 case-infants. Among the 264 case-infants, mothers were the source for 84 (32%) and another family member was the source for 113 (43%). Of the 219 source-persons with known age, 38 (17%) were age 0-4 years, 16 (7%) were age 5-9 years, 43 (20%) were age 10-19 years, 45 (21%) were age 20-29 years and 77 (35%) were age > or =30 years. CONCLUSIONS: The variation in reported pertussis incidence in the 4 states might have resulted from differences in awareness of pertussis among health care providers, diagnostic capacity and case classification. Among case-infants with an identifiable source, family members (at any age) were the main source of pertussis. Understanding the source of pertussis transmission to infants may provide new approaches to prevent pertussis in the most vulnerable infants.

Population immunity to polioviruses among preschool children from four urban underserved low income communities, United States, 1997-2001.

BACKGROUND: In 1997, the Advisory Committee for Immunization Practices (ACIP) recommended a change in polio vaccination policy, the first in 30 years, from the oral poliovirus vaccine (OPV) to a combined OPV/inactivated poliovirus vaccine (IPV) sequential schedule for routine childhood vaccination. To evaluate the impact of the change in polio vaccination schedule on population immunity, we conducted a seroprevalence survey among low income preschool children from selected urban areas. METHODS: A repeat cross-sectional serosurvey was conducted during 1997-2001. Children 19-35 months of age receiving well-child care were recruited from outpatient clinics of academic medical centers. Serum samples were obtained and tested for neutralizing antibodies to polioviruses types 1, 2 and 3. A standardized questionnaire was administered to the parents or guardians of enrolled children. RESULTS: Seroprevalence remained high and stable during the study period. Among children sampled in the last study year (initiating their vaccinations from August 1997 through September 2000), seroprevalence was >/=95% to poliovirus serotypes 1 and 2 and >/=94% to serotype 3. Overall coverage with >/=3 doses of polio vaccine was 82-95% across sites during this period. The proportion initiating their vaccination schedule with IPV increased from 2.6% in study year 1 (children born October 1994-January 1997) to 80% in study year 4 (children born October 1997-January 2000). CONCLUSIONS: Children in these underserved low income communities are well-protected against the spread of polioviruses; the introduction of IPV did not adversely impact coverage or seroprevalence. Continued monitoring is needed to evaluate population immunity in the absence of OPV circulation.

Trends in pertussis among infants in the United States, 1980-1999.

CONTEXT: Reported cases of pertussis among adolescents and adults have increased since the 1980s, despite increasingly high rates of vaccination among infants and children. However, severe pertussis morbidity and mortality occur primarily among infants. OBJECTIVE: To describe the trends and characteristics of reported cases of pertussis among infants younger than 12 months in the United States from 1980 to 1999. DESIGN, SETTING, AND PARTICIPANTS: Cases of pertussis in infants younger than 12 months in the United States reported to the National Notifiable Disease Surveillance System of the Centers for Disease Control and Prevention between 1980 and 1999, and detailed case data from the Supplementary Pertussis Surveillance System. MAIN OUTCOME MEASURES: Incidence and demographic and clinical characteristics of cases. RESULTS: The incidence of reported cases of pertussis among infants increased 49% in the 1990s compared with the incidence in the 1980s (19 798 vs 12 550 cases reported; 51.1 cases vs 34.2 cases per 100 000 infant population, respectively). Increases in the incidence of cases and the number of deaths among infants during the 1990s primarily were among those aged 4 months or younger, contrasting with a stable incidence of cases among infants aged 5 months or older. The proportion of cases confirmed by bacterial culture was higher in the 1990s than in the 1980s (50% and 33%, respectively); the proportion of hospitalized cases was unchanged (67% vs 68%, respectively). Receipt of fewer doses of vaccine was associated with hospitalization, when cases were stratified by age in months. CONCLUSIONS: The incidence of reported cases of pertussis among infants increased in the 1990s compared with the 1980s. The limited age group affected, the increased rate of bacteriologic confirmation, and the unchanged severity of illness suggest that an increase in infant pertussis has occurred apart from any change in reporting. Strategies are needed to prevent the morbidity and mortality from pertussis among infants too young to be fully vaccinated, according to the current recommended schedules of vaccination in the United States.

Increase in deaths from pertussis among young infants in the United States in the 1990s.

BACKGROUND: Severe pertussis primarily occurs among infants (<12 months of age). Despite high levels of immunization, reported pertussis cases increased in the United States in the 1990s among all age groups, including infants. METHODS: To characterize fatal pertussis cases, we analyzed pertussis deaths reported to CDC in the 1990s and compared these with data on pertussis deaths reported in the 1980s. Data from national surveillance systems and from available medical records were used, including data from analyses of deaths reported in 1992 through 1995. RESULTS: In 1980 through 1989, 77 pertussis deaths were reported; 61 deaths were among infants (1.67 deaths per million), including 49 among infants <4 months of age. In the 1990s 103 pertussis deaths were reported; 93 deaths were among infants (2.40 deaths per million), including 84 among infants <4 months of age. Of 89 infants with ethnicity data, 31 (36%) were Hispanic; the mortality rate among Hispanic infants (4.77 per million) was higher than among non-Hispanic infants (1.80 per million). Of 76 infants with reported gestational age, 40 (53%) were born at <37 weeks, including 22 (29%) who were born at <35 weeks. Severe pulmonary hypertension was a common lethal complication among infants. CONCLUSIONS: Pertussis deaths increased among infants too young to be protected by immunization. A disproportionate share of deaths were complicated by pulmonary hypertension and occurred among Hispanic infants and infants born at <37 weeks gestation. New approaches to prevent infection among infants <4 months of age and improved therapies for pertussis complications are needed.

Tetanus surveillance--United States, 1998--2000.

PROBLEM/CONDITION: Tetanus is a severe and often fatal infection. The incidence of reported cases in the United States has declined steadily since introduction of tetanus toxoid vaccines in the 1940s. REPORTING PERIOD: This report covers surveillance data for 1998--2000. DESCRIPTION OF SYSTEM: Physician-diagnosed cases of tetanus were reported to CDC's National Notifiable Disease Surveillance System. Supplemental clinical and epidemiologic information were provided by states. RESULTS AND INTERPRETATION: During 1998--2000, an average of 43 cases of tetanus was reported annually; the average annual incidence was 0.16 cases/million population. The highest average annual incidence of reported tetanus was among persons aged >60 years (0.35 cases/million population), persons of Hispanic ethnicity (0.37 cases/million population), and older adults known to have diabetes (0.70 cases/million population). Fifteen percent of the cases were among injection-drug users. The case-fatality ratio was 18% among 113 patients with known outcome; 75% of the deaths were among patients aged >60 years. No deaths occurred among those who were up-to-date with tetanus toxoid vaccination. Seventy-three percent of 129 cases with known injury information available reported an acute injury; of these, only 37% sought medical care for the acute injury, and only 63% of those eligible received tetanus toxoid for wound prophylaxis. INTERPRETATION: The majority of tetanus cases occurred among persons inadequately vaccinated or with unknown vaccination history who sustained an acute injury. Adults aged >60 years were at highest risk for tetanus and tetanus-related death. PUBLIC HEALTH ACTIONS: Tetanus is preventable through routine vaccination (i.e., primary series and decennial boosters) and appropriate management. A shortage of tetanus and diphtheria toxoids vaccine that began during 2000 ended in 2002. Efforts by health-care providers are warranted to vaccinate persons with delayed or incomplete vaccination, with emphasis on older persons and persons with high-risk conditions.