Simultaneous infection with multiple strains of Mycobacterium tuberculosis

Drug-susceptible and drug-resistant isolates of Mycobacterium tuberculosis were recovered from 2 patients, 1 with isoniazid-resistant tuberculosis (patient 1) and another with multidrug-resistant tuberculosis (patient 2). An investigation included patient interviews, record reviews, and genotyping of isolates. Both patients worked in a medical-waste processing plant. Transmission from waste was responsible for at least the multidrug-resistant infection. We found no evidence that specimens were switched or that cross-contamination of cultures occurred. For patient 1, susceptible and isoniazid-resistant isolates, collected 15 days apart, had 21 and 19 restriction fragments containing IS6110, 18 of which were common to both. For patient 2, a single isolate contained both drug-susceptible and multidrug-resistant colonies, demonstrating 10 and 11 different restriction fragments, respectively. These observations indicate that simultaneous infections with multiple strains of M. tuberculosis occur in immunocompetent hosts and may be responsible for conflicting drug-susceptibility results, though the circumstances of infections in these cases may have been unusual.

Risk factors for positive mantoux tuberculin skin tests in children in San Diego, California: evidence for boosting and possible foodborne transmission

OBJECTIVES

Source case finding in San Diego, California, rarely detects the source for children with tuberculosis (TB) infection or disease. One third of all pediatric TB isolates in San Diego are Mycobacterium bovis, a strain associated with raw dairy products. This study was conducted to determine risk factors for TB infection in San Diego.

DESIGN

Case-control study of children </=5 years old screened for TB as part of routine health care visit. Asymptomatic children with a positive (>/=10 mm) Mantoux skin test (TST) were matched by age to 1 to 2 children with negative TST from the same clinic. We assessed risk factors for TB infection through parental interview and chart review.

RESULTS

A total of 62 cases and 97 controls were enrolled. Eleven cases and 25 controls were excluded from analysis because of previous positive skin tests. Compared with controls, cases were more likely to have received BCG vaccine (73% vs 7%, odds ratio [OR] 44), to be foreign born (35% vs 11%, OR 4.3), and to have eaten raw milk or cheese (21% vs 8%, OR 3.76). The median time between the most recent previous TST and the current test was 12 months for cases and 25 months for controls. Other factors associated with a positive TST included foreign travel, staying in a home while out of the country, and having a relative with a positive TST. There was no association between contact with a known TB case. In a multivariable model, receipt of BCG, contact with a relative with a positive TST, and having a previous TST within the past year were independently associated with TB infection.

CONCLUSIONS

We identified several new or reemerging associations with positive TST including cross border travel, staying in a foreign home, and eating raw dairy products. The strong associations with BCG receipt and more recent previous TST may represent falsely positive reactions, booster phenomena, or may be markers for a population that is truly at greater risk for TB infection. Unlike studies conducted in nonborder areas, we found no association between positive TB skin tests and contact with a TB case or a foreign visitor. Efforts to control pediatric TB in San Diego need to address local risk factors including consumption of unpasteurized dairy products and cross-border travel. The interpretation of a positive TST in a young child in San Diego who has received BCG is problematic.

Tuberculosis cases reported among migrant farm workers in the United States, 1993-97

Migrant farm workers (MFWs) are considered a high-risk group for tuberculosis. MFW tuberculosis cases reported to the Centers for Disease Control and Prevention represented 1 percent of all reported tuberculosis cases from 1993 to 1997. Most of these cases (70 percent) were reported from Florida, Texas, and California. MFW tuberculosis cases were more likely to be male, foreign-born, or Hispanic and to have a history of alcohol abuse and homelessness than were non-MFWs. Most (79 percent) foreign-born MFWs were from Mexico. HIV status was poorly reported, with results available for only 28 percent of MFW and 33 percent of non-MFW cases. Of the MFWs tested, 28 percent were HIV infected, whereas 34 percent of non-MFWs were HIV infected. Twenty percent of MFWs move or are lost to follow-up before completing therapy; these cases pose a management challenge for the nation's tuberculosis control efforts.

Use and efficacy of tuberculosis infection control practices at hospitals with previous outbreaks of multidrug-resistant tuberculosis

OBJECTIVE

To evaluate the implementation and efficacy of selected Centers for Disease Control and Prevention guidelines for preventing spread of Mycobacterium tuberculosis.

DESIGN

Analysis of prospective observational data.

SETTING

Two medical centers where outbreaks of multidrug-resistant tuberculosis (TB) had occurred.

PARTICIPANTS

All hospital inpatients who had active TB or who were placed in TB isolation and healthcare workers who were assigned to selected wards on which TB patients were treated.

METHODS

During 1995 to 1997, study personnel prospectively recorded information on patients who had TB or were in TB isolation, performed observations of TB isolation rooms, and recorded tuberculin skin-test results of healthcare workers. Genetic typing of M tuberculosis isolates was performed by restriction fragment-length polymorphism analysis.

RESULTS

We found that only 8.6% of patients placed in TB isolation proved to have TB; yet, 19% of patients with pulmonary TB were not isolated on the first day of hospital admission. Specimens were ordered for acid-fast bacillus smear and results received promptly, and most TB isolation rooms were under negative pressure. Among persons entering TB isolation rooms, 44.2% to 97.1% used an appropriate (particulate, high-efficiency particulate air or N95) respirator, depending on the hospital and year; others entering the rooms used a surgical mask or nothing. We did not find evidence of transmission of TB among healthcare workers (based on tuberculin skin-test results) or patients (based on epidemiological investigation and genetic typing).

CONCLUSIONS

We found problems in implementation of some TB infection control measures, but no evidence of healthcare-associated transmission, possibly in part because of limitations in the number of patients and workers studied. Similar evaluations should be performed at hospitals treating TB patients to find inadequacies and guide improvements in infection control.

Completeness and timeliness of tuberculosis case reporting. A multistate study

BACKGROUND

Tuberculosis (TB) control activities are contingent on the timely identification and reporting of cases to public health authorities to ensure complete assessment and appropriate treatment of contacts and identification of secondary cases. We report the results of a multistate evaluation of completeness and timeliness of reporting of TB cases in the United States during 1993 and 1994.

METHODS

To determine completeness of TB reporting, laboratory log books, death certificates, hospital discharge, Medicaid databases, and pharmacy databases were reviewed in seven states to identify possible unreported cases. Timeliness of TB reporting was calculated using the number of days between date of TB diagnosis and date of report to the local or state health department. Cases reported >7 days after diagnosis were considered to have delayed reporting.

RESULTS

Of 2711 cases identified through review of secondary data sources, 14 (0.5%) were previously unreported to public health. The largest yield of unreported cases was identified through review of laboratory records; 13 of the 14 unreported cases were identified, of which eight were found only through this method. Timeliness of reporting varied between sites from a median of 7 days to a median of 38 days. The number of cases with delayed reporting varied from 5% to 53% between sites. Factors associated with delayed reporting included infectiousness, type of provider, diagnosing provider, and reporting source.

CONCLUSIONS

Through a review of several different secondary data sources, few unreported TB cases were detected; however, timeliness of reporting was poor among the reported cases.

Transmission of Mycobacterium tuberculosis from medical waste

CONTEXT

Washington State has a relatively low incidence rate of tuberculosis (TB) infection. However, from May to September 1997, 3 cases of pulmonary TB were reported among medical waste treatment workers at 1 facility in Washington. There is no previous documentation of Mycobacterium tuberculosis transmission as a result of processing medical waste.

OBJECTIVE

To identify the source(s) of these 3 TB infections.

DESIGN, SETTING, AND PARTICIPANTS

Interviews of the 3 infected patient-workers and their contacts, review of patient-worker medical records and the state TB registry, and collection of all multidrug-resistant TB (MDR-TB) isolates identified after January 1, 1995, from the facility's catchment area; DNA fingerprinting of all isolates; polymerase chain reaction and automated DNA sequencing to determine genetic mutations associated with drug resistance; and occupational safety and environmental evaluations of the facility.

MAIN OUTCOME MEASURES

Previous exposures of patient-workers to TB; verification of patient-worker tuberculin skin test histories; identification of other cases of TB in the community and at the facility; drug susceptibility of patient-worker isolates; and potential for worker exposure to live M tuberculosis cultures.

RESULTS

All 3 patient-workers were younger than 55 years, were born in the United States, and reported no known exposures to TB. We did not identify other TB cases. The 3 patient-workers' isolates had different DNA fingerprints. One of 10 MDR-TB catchment-area isolates matched an MDR-TB patient-worker isolate by DNA fingerprint pattern. DNA sequencing demonstrated the same rare mutation in these isolates. There was no evidence of personal contact between these 2 individuals. The laboratory that initially processed the matching isolate sent contaminated waste to the treatment facility. The facility accepted contaminated medical waste where it was shredded, blown, compacted, and finally deactivated. Equipment failures, insufficient employee training, and respiratory protective equipment inadequacies were identified at the facility.

CONCLUSION

Processing contaminated medical waste resulted in transmission of M tuberculosis to at least 1 medical waste treatment facility worker. JAMA. 2000;284:1683-1688.

Using DNA fingerprinting to detect transmission of Mycobacterium tuberculosis among AIDS patients in two health-care facilities in Puerto Rico

BACKGROUND

Fourteen cases of tuberculosis (TB) in Puerto Rico, diagnosed from April 1993 to April 1995, had the same DNA fingerprint, documenting disease caused by the same strain of Mycobacterium tuberculosis. The 14 cases were retrospectively investigated for epidemiologic links.

METHODS

Records were reviewed and staffs of the TB program, hospital/clinic, and AIDS residential facilities were interviewed.

RESULTS

Half of the AIDS cases were epidemiologically related, providing evidence of TB transmission in an emergency department, an AIDS inpatient ward, and an AIDS residential facility. DNA fingerprinting allowed detection of M tuberculosis transmission, but contact investigators could have documented it sooner. Factors contributing to transmission included delayed diagnosis, prolonged infectiousness, inadequate discharge planning and infection control procedures, and poor communication between health-care facilities.

CONCLUSIONS

The numbers of AIDS residential facilities are increasing and must understand proper monitoring of TB patients and infection control measures that prevent transmissions.

Analysis of Mycobacterium tuberculosis transmission patterns in a homeless shelter outbreak

SETTING

From July 1997 through May 1998, ten tuberculosis (TB) cases were reported among men in a Syracuse New York homeless shelter for men.

OBJECTIVE AND DESIGN

Investigation to determine extent of, and prevent further, transmission of Mycobacterium tuberculosis.

RESULTS

Epidemiologic and laboratory evidence suggests that eight of the ten cases were related. Seven cases had isolates with matching six-band IS6110 DNA fingerprints; the isolate from another case had a closely related fingerprint pattern and this case was considered to be caused by a variant of the same strain. Isolates from eight cases had identical spoligotypes. The source case had extensive cavitary disease and stayed at the shelter nightly, while symptomatic, for almost 8 months before diagnosis. A contact investigation was conducted among 257 shelter users and staff, 70% of whom had a positive tuberculin skin test, including 21 with documented skin test conversions.

CONCLUSIONS

An outbreak of related TB cases in a high-risk setting was confirmed through the use of IS6110 DNA fingerprinting in conjunction with spoligotyping and epidemiologic evidence. Because of the high rate of infection in the homeless population, routine screening for TB and preventive therapy for eligible persons should be considered in shelters.

Extensive transmission of Mycobacterium tuberculosis from a child

BACKGROUND AND METHODS

Young children rarely transmit tuberculosis. In July 1998, infectious tuberculosis was identified in a nine-year-old boy in North Dakota who was screened because extrapulmonary tuberculosis had been diagnosed in his female guardian. The child, who had come from the Republic of the Marshall Islands in 1996, had bilateral cavitary tuberculosis. Because he was the only known possible source for his female guardian's tuberculosis, an investigation of the child's contacts was undertaken. We identified family, school, day-care, and other social contacts and notified these people of their exposure. We asked the contacts to complete a questionnaire and performed tuberculin skin tests.

RESULTS

Of the 276 contacts of the child whom we tested, 56 (20 percent) had a positive tuberculin skin test (induration of at least 10 mm), including 3 of the child's 4 household members, 16 of his 24 classroom contacts, 10 of 32 school-bus riders, and 9 of 61 day-care contacts. A total of 118 persons received preventive therapy, including 56 young children who were prescribed preventive therapy until skin tests performed at least 12 weeks after exposure were negative. The one additional case identified was in the twin brother of the nine-year-old patient. The twin was not considered infectious on the basis of a sputum smear that was negative on microscopical examination.

CONCLUSIONS

This investigation showed that a young child can transmit Mycobacterium tuberculosis to a large number of contacts. Children with tuberculosis, especially cavitary or laryngeal tuberculosis, should be considered potentially infectious, and screening of their contacts for infection with M. tuberculosis or active tuberculosis may be required.

Spread of strain W, a highly drug-resistant strain of Mycobacterium tuberculosis, across the United States

Strain W, a highly drug-resistant strain of Mycobacterium tuberculosis, was responsible for large nosocomial outbreaks in New York in the early 1990s. To describe the spread of strain W outside New York, we reviewed data from epidemiologic investigations, national tuberculosis surveillance, regional DNA fingerprint laboratories, and the Centers for Disease Control and Prevention Mycobacteriology Laboratory to identify potential cases of tuberculosis due to strain W. From January 1992 through February 1997, 23 cases were diagnosed in nine states and Puerto Rico; 8 were exposed to strain W in New York before their diagnosis; 4 of the 23 transmitted disease to 10 others. Eighty-six contacts of the 23 cases are presumed to be infected with strain W; 11 completed alternative preventive therapy. Strain W tuberculosis cases will occur throughout the United States as persons infected in New York move elsewhere. To help track and contain this strain, health departments should notify the Centers for Disease Control and Prevention of cases of tuberculosis resistant to isoniazid, rifampin, streptomycin, and kanamycin.

Immigration and tuberculosis among children on the United States-Mexico border, County of San Diego, California

OBJECTIVE

To identify factors contributing to a 400% increase in tuberculosis among children in San Diego County, California, from 1985 to 1993.

DESIGN

Review of medical records of reported cases in 1989, 1991, and 1993 and their source case.

RESULTS

Of 192 children with tuberculosis, the largest increase was observed in children younger than 5 years old, of whom 77.4% were born in the United States, 67.8% had a foreign-born parent, 73.1% came from a non-English-speaking household, and 46.2% were known to visit Mexico. Of 28 source cases, 82.1% were born outside the United States, primarily in Mexico (67.9%). Resistance to at least one first-line antituberculous drug was identified in 27.5% of isolates from children and in 33.3% of isolates from source cases.

CONCLUSIONS

The increase in tuberculosis and high level of drug-resistance among children born in the United States may be attributed to transmission outside of the United States or within the United States from household contacts born in countries in which tuberculosis is highly endemic.

Tuberculosis screening in private physicians' offices, Pennsylvania, 1996

OBJECTIVE

To assess tuberculin skin testing practices of physicians after community-wide screening of 1400 children exposed to a pediatrician with active tuberculosis (TB).

DESIGN

A self-administered questionnaire.

SETTING

Medium-sized city in eastern Pennsylvania.

PARTICIPANTS

Pediatricians and family practitioners seeing pediatric patients.

MAIN OUTCOME MEASURES

Percentages of physicians who followed published recommendations for placement and reading of TB skin tests published by the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC).

RESULTS

Questionnaires were completed by 60/80 (75%) physicians. The 60 physicians had practiced a mean of 17 years (range 3-38 years), and only one did not do TB skin testing for pediatric patients. The 59 physicians doing TB skin testing reported routinely tuberculin testing more than 900 children per month. Only 8/59 (14%) physicians followed published guidelines for placement and reading of tuberculin tests. Those physicians screened 158 (17%) of the pediatric patients undergoing TB skin testing in a typical month.

CONCLUSION

In this community where a highly publicized TB case prompted massive pediatric screening, most physicians seeing children in private practice do not follow standard TB skin testing guidelines. Increased understanding of how private-practice physicians learn about and decide to use recommended standards are needed if tuberculin tests are to be correctly performed and TB appropriately diagnosed.

A train passenger with pulmonary tuberculosis: evidence of limited transmission during travel

In January 1996, smear- and culture-positive tuberculosis (TB) was diagnosed for a 22-year-old black man after he had traveled on two U.S. passenger trains (29.1 hours) and a bus (5.5 hours) over 2 days. To determine if transmission had occurred, passengers and crew were notified of the potential exposure and instructed to undergo a tuberculin skin test (TST). Of the 240 persons who completed screening, 4 (2%) had a documented TST conversion (increase in induration of > or = 10 mm between successive TSTs), 11 (5%) had a single positive TST (> or = 10 mm), and 225 (94%) had a negative TST (< 10 mm). For two persons who underwent conversion, no other risk factors for a conversion were identified other than exposure to the ill passenger during train and/or bus travel. These findings support limited transmission of Mycobacterium tuberculosis from a potentially highly infectious passenger to other persons during extended train and bus travel.

Cross-matching TB and AIDS registries: TB patients with HIV co-infection, United States, 1993-1994

OBJECTIVES

Because of limited reporting of HIV status in case reports to the national tuberculosis (TB) surveillance system, the authors conducted this study to estimate the proportion of US TB cases with HIV co-infection and to describe demographic and clinical characteristics of co-infected patients.

METHODS

The 50 states, New York City, and Puerto Rico submitted the results of cross-matches of TB registries and HIV-AIDS registries. The authors determined the number of TB cases reported for 1993-1994 that were listed in HIV-AIDS registries and analyzed data on demographic and clinical characteristics by match status.

RESULTS

Of 49,938 TB cases reported for 1993-1994, 6863 (14%) were listed in AIDS or HIV registries. The proportions of TB-AIDS cases among TB cases varied by reporting area, from 0% to 31%. Anti-TB drug resistance was higher among TB-AIDS cases, particularly resistance to isoniazid and rifampin (multidrug resistance) and rifampin alone, In some areas with low proportions of multidrug-resistant TB cases, however, the difference in multidrug resistance between TB-AIDS patients and non-AIDS TB patients was not found.

CONCLUSIONS

The proportion of TB cases with HIV co-infection, particularly in some areas, underscores the importance of the HIV-AIDS epidemic for the epidemiology of TB. Efforts to improve HIV testing as well as reporting of HIV status for TB patients should continue to ensure optimum management of coinfected patients, enhance surveillance activities, and promote judicious resource allocation and targeted prevention and control activities.

Tuberculin skin test screening practices among US colleges and universities

CONTEXT

Concern about transmission of Mycobacterium tuberculosis on college campuses has prompted some schools to institute tuberculin skin test screening of students, but this screening has never been evaluated.

OBJECTIVE

To describe tuberculin skin test screening practices and results of screening in colleges and universities in the United States.

DESIGN AND SETTING

Self-administered mail and telephone questionnaire in November and December 1995 to a stratified random sample of US 2-year and 4-year colleges and universities.

MAIN OUTCOME MEASURES

Type of tuberculin screening required; types of schools requiring screening; number and rate of students with positive skin test results and/or diagnosed as having tuberculosis.

RESULTS

Of the 3148 US colleges and universities, 624 (78%) of 796 schools surveyed responded. Overall, 378 schools (61%) required tuberculin screening; it was required for all new students (US residents and international students) in 161 (26%) of 624 schools, all new international students but not new US residents in 53 (8%), and students in specific academic programs in 294 (47%). Required screening was more likely in 4-year vs 2-year schools, schools that belonged to the American College Health Association vs nonmember schools, schools with immunization requirements vs schools without, and schools with a student health clinic vs those without (P<.001 for all). Public and private schools were equally likely to require screening (64% vs 62%; P=.21). In the 378 schools with screening requirements, tine or multiple puncture tests were accepted in 95 (25%); test results were recorded in millimeters of induration in 95 (25%); and 100 (27%) reported collecting results in a centralized registry or database. Of the 168 (27%) of 624 schools accepting only Mantoux skin tests and reporting results for school years 1992-1993 through 1995-1996, 3.1% of the 348 368 students screened had positive skin test results (median percentage positive, 0.8%). International students had a significantly higher case rate for active tuberculosis than US residents (35.2 vs 1.1 per 100000 students screened).

CONCLUSIONS

Widespread tuberculin screening of students yielded a low prevalence of skin test reactors and few tuberculosis cases. To optimize the use of limited public health resources, tuberculin screening should target students at high risk for infection.

The fall after the rise: Tuberculosis in the United States, 1991 through 1994

OBJECTIVES

Factors associated with decreases in tuberculosis cases observed in the United States in 1993 and 1994 were analyzed.

METHODS

Changes in case counts reported to the national surveillance system were evaluated by dividing the number of incident cases of TB reported in 1993 and 1994 by the number of cases reported in 1991 and 1992 and stratifying these ratios by demographic factors, AIDS incidence, and changes in program performance.

RESULTS

Case counts decreased from 52,956 in 1991 and 1992 to 49,605 in 1993 and 1994 (case count ratio = 0.94, 95% confidence interval [CI] = 0.93, 0.95). The decrease, confined to US-born patients, was generally associated with AIDS incidence and improvements in completion of therapy, conversion of sputum, and increases in the number of contacts identified per case.

CONCLUSIONS

Recent TB epidemiology patterns suggest that improvements in treatment and control activities have contributed to the reversal in the resurgence of this disease in US-born persons. Continued success in preventing the occurrence of active TB will require sustained efforts to ensure appropriate treatment of cases.

Evaluation of transmission of Mycobacterium tuberculosis in a pediatric setting

OBJECTIVE

To determine the extent of transmission of Mycobacterium tuberculosis to pediatric patients exposed to a pediatrician with smear- and culture-positive pulmonary tuberculosis (TB).

METHODS

Clinic billing and hospital admission records were used to identify patients seen during the pediatrician's infectious period. Patients were notified of the potential exposure and were offered screening.

RESULTS

A total of 1416 pediatric patients were identified as exposed. Of the 606 who completed screening, 12 (2%) had a skin test result > or = 10 mm, 2 (0.3 had a result 5 to 9 mm, and 592 (98%) had a negative test result (0 to 4 mm). No active TB cases were identified. Of the 14 children with a skin test result > or = 5 mm, 7 were U.S.-born and had no other risk for a positive skin test. The remaining seven had either been exposed to another person with infections TB or were from countries with a high prevalence of TB.

CONCLUSION

We found evidence of limited transmission of Mycobacterium tuberculosis in the outpatient pediatric setting. Despite extensive resources dedication, only 43% of exposed children completed screening. In similar situations decision should balance the responsibility to protect children exposed to Mycobacterium tuberculosis with other public health priorities and available resources.

Risk factors for rifampin mono-resistant tuberculosis

Use of rifampin is required for short-course treatment regimens for tuberculosis. Tuberculosis caused by isolates of M. tuberculosis with resistance to rifampin and susceptibility to isoniazid is unusual, but it has been recognized through surveillance. Patients with tuberculosis (cases) with rifampin mono-resistance were compared with HIV-matched controls with tuberculosis caused by a drug-susceptible isolate. A total of 77 cases of rifampin mono-resistant tuberculosis were identified in this multicenter study. Three were determined to be laboratory contaminants, and 10 cases had an epidemiologic link to a case with rifampin mono-resistant tuberculosis, suggesting primary acquisition of rifampin-resistant isolates. Of the remaining 64 cases and 126 controls, there was no difference between cases and controls with regard to age, sex, race, foreign birth, homelessness, or history of incarceration. Cases were more likely to have a history of prior tuberculosis than were controls. Of the 38 cases and 74 controls with HIV infection, there was no difference between cases and controls with regard to age, sex, race, foreign birth, homelessness, history of incarceration, or prior tuberculosis. Cases were more likely to have histories of diarrhea, rifabutin use, or antifungal therapy. Laboratory analysis of available isolates showed that there was no evidence of spread of a single clone of M. tuberculosis. Further studies are needed to identify the causes of the development of rifampin resistance in HIV-infected persons with tuberculosis and to develop strategies to prevent its emergence.

Tuberculosis and race/ethnicity in the United States: impact of socioeconomic status

Despite the long-standing observation that tuberculosis (TB) case rates are higher among racial and ethnic minorities than whites in the United States (U.S.), the proportion of this increased risk attributable to socioeconomic status (SES) has not been determined. Values for six SES indicators (crowding, income, poverty, public assistance, unemployment, and education) were assigned to U.S. TB cases reported from 1987-1993 by ZIP code- and demographic-specific matching to 1990 U.S. Census data. TB risk between racial/ethnic groups was then evaluated by quartile for each SES indicator utilizing univariate and Poisson multivariate analyses. Relative risk (RR) of TB increased with lower SES quartile for all six SES indicators on univariate analysis (RRs 2.6-5.6 in the lowest versus highest quartiles). The same trend was observed in multivariate models containing individual SES indicators (RRs 1.8-2.5) and for three SES indicators (crowding, poverty, and education) in the model containing all six indicators. Tuberculosis risk increased uniformly between SES quartile for each indicator except crowding, where risk was concentrated in the lowest quartile. Adjusting for SES accounted for approximately half of the increased risk of TB associated with race/ethnicity among U.S.-born blacks, Hispanics, and Native Americans. Even more of this increased risk was accounted for in the final model, which also adjusted for interaction between crowding and race/ethnicity. SES impacts TB incidence via both a strong direct effect of crowding, manifested predominantly in overcrowded settings, and a TB-SES health gradient, manifested at all SES levels. SES accounts for much of the increased risk of TB previously associated with race/ethnicity.

An outbreak involving extensive transmission of a virulent strain of Mycobacterium tuberculosis

BACKGROUND AND METHODS

From 1994 to 1996, there was a large outbreak of tuberculosis in a small, rural community with a population at low risk for tuberculosis. Twenty-one patients with tuberculosis (15 with positive cultures) were identified; the DNA fingerprints of the 13 isolates available for testing were identical. To determine the extent of transmission, we investigated both the close and casual contacts of the patients. Using a mouse model, we also studied the virulence of the strain of Mycobacterium tuberculosis that caused the outbreak.

RESULTS

The index patient, in whom tuberculosis was diagnosed in 1995; the source patient, in whom the disease was diagnosed in 1994; and a patient in whom the disease was diagnosed in 1996 infected the other 18 persons. In five, active disease developed after only brief, casual exposure. There was extensive transmission from the three patients to both close and casual contacts. Of the 429 contacts, 311 (72 percent) had positive skin tests, including 81 [corrected] with documented skin-test conversions. Mice infected with the virulent Erdman strain of M. tuberculosis had approximately 1000 bacilli per lung after 10 days and about 10,000 bacilli per lung after 20 days. In contrast, mice infected with the strain involved in the outbreak had about 10,000 bacilli per lung after 10 days and about 10 million bacilli per lung after 20 days.

CONCLUSIONS

In this outbreak of tuberculosis, the growth characteristics of the strain involved greatly exceeded those of other clinical isolates of M. tuberculosis. The extensive transmission of tuberculosis may have been due to the increased virulence of the strain rather than to environmental factors or patient characteristics.

Trends in drug-resistant tuberculosis in the United States, 1993-1996

CONTEXT

With the resurgence of tuberculosis (TB) disease in the late 1980s and early 1990s in the United States, multidrug-resistant (MDR) TB emerged as a serious challenge to TB control. In response, the Centers for Disease Control and Prevention in 1993 added drug susceptibility test results to the information collected for the national surveillance system to monitor trends in drug resistance.

OBJECTIVE

To determine the extent of drug-resistant tuberculosis (TB) in the United States.

DESIGN

Descriptive analysis of TB surveillance data.

STUDY POPULATION

Patients reported to the national TB surveillance system as confirmed TB cases with culture-positive disease from 1993 through 1996 by the 50 states, New York City, and the District of Columbia (DC).

MAIN OUTCOME MEASURE

Percentage of case patients with culture-positive disease whose isolates are resistant to specific anti-TB drugs.

RESULTS

Overall resistance to at least isoniazid was 8.4%; rifampin, 3.0%; both isoniazid and rifampin (ie, MDR TB), 2.2%; pyrazinamide, 3.0%; streptomycin, 6.2%; and ethambutol hydrochloride, 2.2%. Rates of resistance were significantly higher for case patients with a prior TB episode. Among those without prior TB, isoniazid resistance of 4% or more was found in 41 states, New York City, and DC. A total of 1457 MDR TB cases were reported from 42 states, New York City, and DC; however, 38% were reported from New York City. Rates of isoniazid and streptomycin resistance were higher for cases among foreign-born compared with US-born patients [corrected] but rates of rifampin resistance and MDR TB were similar. Among US-born patients, resistance to first-line drugs, particularly rifampin monoresistance, was significantly higher among those with human immunodeficiency virus (HIV) infection.

CONCLUSIONS

Compared with recent US surveys in 1991 and 1992, isoniazid resistance has remained relatively stable. In addition, the percentage of MDR TB has decreased, although the national trend was significantly influenced by the marked decrease in New York City. Foreign-born and HIV-positive patients and those with prior TB have higher rates of resistance. The widespread extent of isoniazid resistance confirms the need for drug susceptibility testing to guide optimal treatment of patients with culture-positive disease.

Tuberculosis transmission among five school bus drivers and students in two New York counties

OBJECTIVE

Between November 1994 and April 1995, more than 3300 students in 49 schools in two counties in New York were potentially exposed to five school bus drivers with tuberculosis. This investigation was carried out to determine the extent of transmission of Mycobacterium tuberculosis among students.

METHODS

Components of the epidemiologic investigation included tuberculin skin-test screening and collection of demographic information for students exposed to a driver with tuberculosis, chest radiography and medical evaluation of individuals with positive skin tests, and DNA fingerprinting of M tuberculosis isolates. A positive skin test was defined as >/=10 mm induration, and a converter was an individual with an increase in reaction size of >/=10 mm in the past 2 years.

RESULTS

The rates of positive skin tests were 0.8%, 0.3%, 9.9%, 1.1%, and 0.7% among US-born students exposed to drivers 1 through 5, respectively. The relative risk for a positive tuberculin skin test was significant only for students exposed to driver 3, and the only secondary case identified among students was exposed to driver 3. The DNA fingerprint patterns of isolates from drivers 3 and 4 matched.

CONCLUSION

There was no clear evidence of transmission of M tuberculosis to students from drivers 1, 2, 4, or 5. However, evidence suggests that driver 3 transmitted M tuberculosis to students and another driver. Routine annual tuberculin skin-test screening of drivers would not have prevented these tuberculosis exposures.

Comparison of sensitivities to two commercially available tuberculin skin test reagents in persons with recent tuberculosis

Discrepancies have been reported between results obtained with tuberculin skin tests (TSTs) performed with use of different reagents. We compared TST results and determined the sensitivities of the two commercially available TSTs in 51 human immunodeficiency virus-negative persons with culture-confirmed active tuberculosis. Simultaneous TSTs were done with use of the Mantoux method and 5-tuberculin unit purified protein derivative (PPD) tuberculin preparations from single lots of Aplisol and Tubersol. Aplisol skin test reactions ranged from 5 mm to 26 mm (median, 16.0 mm), and Tubersol reactions ranged from 7 mm to 23 mm (median, 15.0 mm). The mean difference in paired reaction sizes for the two reagents was 0.58 mm and was not statistically different from zero (P value, 0.26). The difference in reaction sizes was < or =2 mm in 55% and > or =5 mm in 18% of patients. With a cutoff of either 5 mm or 10 mm to define a positive reaction, all results were concordant, with sensitivity of 100% and 96%, respectively. We found indistinguishable reaction size distributions and median TST results for the two commercially available PPD TST reagents, Aplisol and Tubersol, in a population with recent culture-proven tuberculosis.

Behaviors of heterosexual sexually, transmitted disease clinic patients with sex partners at increased risk for human immunodeficiency virus infection

BACKGROUND AND OBJECTIVES

From March 1989 through December 1992, the Centers for Disease Control and Prevention conducted annual, voluntary surveys of human immunodeficiency virus (HIV) risk behavior in sentinel sexually transmitted disease (STD) clinics in 25 cities in the United States.

GOAL

Describe behaviors of heterosexual participants who reported as their only risk for HIV infection sexual contact with persons at increased risk for HIV.

STUDY DESIGN

Participants responded to a standard questionnaire that collected demographic data and medical, drug use, and sexual histories.

RESULTS

Sex with an injection drug user was the most common risk behavior. Fewer than 5% of participants always used condoms in the preceding year; 38% never used condoms. Multivariate analyses identified three independent predictors of HIV infection in men: living in the Northeast (odds ratio [OR] = 3.6; P < 0.001), sex with an HIV-infected woman (OR = 3.6; P < 0.01), and black race (OR = 2.7; P < 0.01). For women, sex with an HIV-infected man was the strongest predictor (OR = 12.0; P < 0.001) followed by Northeast residence (OR = 5.4; P < 0.001) and black race (OR = 3.4; P < 0.01).

CONCLUSION

Sexually transmitted disease clinic patients throughout the United States knowingly engaged in sexual activities with partners at increased risk for HIV infection. HIV prevention activities need to be targeted to all sexually active persons, particularly in areas where injection drug use and HIV are prevalent.

Long-term risk of tuberculosis among foreign-born persons in the United States

CONTEXT

Cases of tuberculosis (TB) in the United States have declined for 4 consecutive years, but cases among foreign-born persons account for an increasing percentage.

OBJECTIVE

To describe the risk of tuberculosis among foreign-born persons with respect to their length of residence in the United States.

DESIGN

Cross-sectional analysis of national surveillance data.

SETTING

The United States.

PATIENTS

All verified TB cases reported to the Centers for Disease Control and Prevention between 1986 and 1994.

MAIN OUTCOME MEASURE

Stratum-specific incidence rates of TB by age, place of birth, length of residence, age at arrival in the United States, or combinations of these variables.

RESULTS

Several groups of persons from countries with a high prevalence of TB had incidence rates higher than 20 per 100,000 person-years more than 20 years after arrival. Among long-term residents, those who arrived in the United States after their fifth birthday had incidence rates of TB 2 to 6 times higher than those of similar age who arrived before their fifth birthday. A total of 45% of the TB cases were among persons younger than 35 years and an additional 18% were among persons who arrived in the United States before their 35th birthday.

CONCLUSIONS

Imported Mycobacterium tuberculosis infection (active or latent) is responsible for most TB cases among foreign-born persons in the United States. Detection of active cases among recent arrivals is the main priority in these populations, but many cases were in persons who arrived in the United States before the age of 35 years that could potentially have been avoided with preventive therapy. Elimination of TB in the United States may not be feasible using available diagnostic and treatment modalities without increased efforts to address the global burden of this disease.

A nosocomial outbreak of multidrug-resistant tuberculosis

BACKGROUND

An outbreak of seven cases (in six patients and one health care worker, all of whom had AIDS) of multidrug-resistant tuberculosis occurred in a hospital in Chicago. The hospital had a respirator-fit testing program but no acid-fast bacilli isolation rooms.

OBJECTIVE

To identify risk factors for transmission of Mycobacterium tuberculosis.

DESIGN

Retrospective cohort study.

SETTING

Private hospital.

PARTICIPANTS

Patients and health care workers exposed to M. tuberculosis.

MEASUREMENTS

Analysis of M. tuberculosis isolates, tuberculin skin testing, assessment of exposure, and assessment of participant characteristics.

RESULTS

All seven M. tuberculosis isolates had matching DNA fingerprints. Of patients exposed to M. tuberculosis, those who developed tuberculosis had lower CD4+ T-lymphocyte counts (P = 0.02) and were more likely to be ambulatory (P = 0.03) than those who did not. Of 74 exposed health care workers, the 11 (15%) who had conversion on tuberculin skin testing were no more likely than those who did not have conversion to report that they always wore a respirator with a high-efficiency particulate air filter.

CONCLUSIONS

Transmission of M. tuberculosis occurred in a hospital that did not have recommended isolation rooms. A respirator-fit testing program did not protect health care workers in this setting.

Interpretation of restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates from a state with a large rural population

Epidemiologic relatedness of Mycobacterium tuberculosis isolates from Arkansas residents diagnosed with tuberculosis in 1992-1993 was assessed using IS6110- and pTBN12-based restriction fragment length polymorphism (RFLP) and epidemiologic investigation. Patients with isolates having similar IS6110 patterns had medical records reviewed and were interviewed to identify epidemiologic links. Complete RFLP analyses were obtained for isolates of 235 patients; 78 (33%) matched the pattern of > or = 1 other isolate, forming 24 clusters. Epidemiologic connections were found for 33 (42%) of 78 patients in 11 clusters. Transmission of M. tuberculosis likely occurred many years in the past for 5 patients in 2 clusters. Of clusters based only on IS6110 analyses, those with > or = 6 IS6110 copies had both a significantly greater proportion of isolates that matched by pTBN12 analysis and patients with epidemiologic connections, indicating IS6110 patterns with few bands lack strain specificity. Secondary RFLP analysis increased specificity, but most clustered patients still did not appear to be epidemiologically related. RFLP clustering in rural areas may not represent recent transmission.

Nosocomial transmission of human immunodeficiency virus and subsequent transmission of multidrug-resistant tuberculosis in a healthcare worker

A phlebotomist with nosocomially acquired human immunodeficiency virus infection developed tuberculosis 10 months after exposure to multidrug-resistant Mycobacterium tuberculosis during a nosocomial outbreak. Healthcare workers with immunosuppression are at increased risk of tuberculosis if infected and, if exposed, should be considered for preventive therapy regardless of tuberculin skin-test status.

The epidemiology of tuberculosis in the United States

After a dramatic increase in the incidence of TB in the United States from 1985 to 1992, the epidemiology of TB changed, with both the number of cases and the incidence of TB decreasing since 1992. The decreases have been focal, however, affecting only certain geographic areas (e.g., New York, California, and New Jersey) and certain populations (e.g., 25-44 year age group and people born in the United States). The factors responsible for the decrease in those areas and populations are multiple but the most important are thought to be improvements in TB control and treatment programs in communities serving populations at greatest risk for TB. Despite the overall decline in TB cases, the numbers of foreign-born people with TB continue to increase. Factors contributing to the increase in TB among foreign-born people include the prevalence of TB in the country of origin, duration of residence in the United States after immigration, inadequate screening for or treatment of TB before entering the United States, and inadequate follow-up of those who have entered the United States with noninfectious TB (i.e., abnormal chest radiograph with negative sputum smears). Control of TB among the foreign-born population is essential if the current downward trend in reported TB cases in the United States is to be maintained. The HIV epidemic had a significant impact on the increase in TB incidence in the United States in the late 1980s but improvements in measures to control transmission of TB appear to have been effective in reversing that trend. The current national decrease trend in TB morbidity can be sustained through organized efforts by federal and private agencies and state and local health departments to ensure that all people with TB are identified and treated promptly. Such efforts must be aimed at areas and populations identified as high risk for TB, especially foreign-born people and people who are infected with HIV.

Tuberculosis risk after exposure on airplanes

SETTING

Domestic and international air-flights.

OBJECTIVE

To estimate the risk of tuberculosis (TB) transmission aboard aircraft.

DESIGN

A contact investigation of passengers and crew from two flights was conducted following identification of a fellow passenger with pulmonary TB. Immediate post-exposure and follow-up tuberculin skin tests (TSTs) were obtained.

RESULTS

Of 120 contacts, 86 (72%) had a negative TST (< 5 mm); 29 (24%) a positive TST (> or = 5 mm), and 5 (4%) a TST conversion. Of the 29 persons with a positive TST, 27 had other identified risk factors for TB. Risk factors for positive TST included non-US birth (Relative Risk (RR) 9.7 P < 0.01) or history of Bacille Calmette-Guérin (BCG) vaccination (RR undefined; P < 0.01). Risk was not associated with specific aircraft or seat relative to the index case for US-born contacts. All five TST converters were born in countries where BCG vaccine is routinely given.

CONCLUSION

The positive TST reactions and conversions suggest boosting from BCG vaccination or prior exposure in TB-endemic countries. Since two positive contacts had no other identified risk factor, TB transmission on board the aircraft could not be excluded. Contact investigation of exposed aircraft passengers should be considered on a case-by-case basis, with consideration of the infectiousness of the ill passenger and the flight circumstances.

The association between occupation and tuberculosis. A population-based survey

There has been increasing interest in the potential association between occupation and the risk of tuberculosis. Therefore, we analyzed occupational information collected on all patients with clinically active tuberculosis in 29 states from 1984 to 1985. Census data were used to estimate the number of persons in each of the occupations. Information on employment and occupation was ascertained for 9,534 (99%) of the working age (16 through 64 yr) tuberculosis patients. The overall case rate of tuberculosis in this age group in the study areas was 8.4 per 100,000 persons, which was slightly lower than the national rate of 9.3 per 100,000 persons. As a group, health care workers had rates of tuberculosis similar to the general population (standardized morbidity ratio [SMR]: 1.0; 95% CI: 0.9 to 1.1). However, elevated rates were observed for inhalation therapists (SMR: 2.9; 95% CI: 1.2 to 6.0), and lower-paid health care workers (SMR: 1.3; 95% CI: 1.1 to 1.5). Elevated rates were also noted for funeral directors (SMR: 3.9; 95% CI: 2.2 to 6.1) and farm workers (SMR: 3.7; 95% CI: 3.4 to 4.1). These data suggest that even in communities with relatively low rates of tuberculosis certain occupations may be associated with an elevated risk.

Transmission of Mycobacterium tuberculosis from tuberculosis patients with HIV infection or AIDS

Contacts exposed to tuberculosis patients with acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus (HIV) infection were compared with contacts of HIV-negative patients for evidence of Mycobacterium tuberculosis transmission, based on a review of records of tuberculin skin tests administered during routine health department follow-up investigations in Miami/Dade County, Florida, from 1985 through 1989. After an adjusted analysis designed to balance background prevalence, tuberculin positivity was 42.0% in 2,158 contacts of HIV-negative patients compared with 28.6% and 31.3% in 363 contacts of HIV-infected patients and 732 contacts of AIDS patients, respectively. Similar results were observed in a subset of 5- to 14-year-old contacts of United States-born black or white tuberculosis patients chosen to minimize the possibility of false-negative tuberculin tests in contacts due to undiagnosed HIV infection. Analysis of contacts as sets showed a more than expected number of sets with none or all contacts infected, but this did not differ by HIV/AIDS group. In this study, tuberculosis patients with AIDS or HIV infection were less infectious to their contacts and, in this community, exposed fewer contacts than HIV-negative tuberculosis patients.

Tuberculin skin test screening in schoolchildren in the United States

OBJECTIVE

To determine the current practices and results of tuberculin skin test (TST) screening of schoolchildren in the United States.

METHODS

Tuberculosis program staff in all states and the District of Columbia were asked about current requirements, practices, and results of school-based TST screening.

RESULTS

Thirty-four states and the District of Columbia (69%) reported no current statewide statutes or policies for tuberculin screening of schoolchildren, and 10 (19%) reported having statewide requirements. In 6 states (12%), requirements were instituted at the local level, and 24 localities in these states were known to require screening. Of the 34 areas requiring screening, 18 (53%) screened all new entrants, 7 (21%) screened children in specific grades, and 9 (26%) used other criteria for screening. TST results were collected for 26 (76%) of 34 areas, and 6 areas collected results of follow-up evaluation of tuberculin-positive children. Additionally, 8 localities in 7 states with no screening requirements conducted tuberculin surveys. Sixteen areas provided results. In 7 of the 8 areas that collected information about birthplace, less than 2% of US-born children were tuberculin positive; foreign-born children had rates 6 to 24 times higher than US-born children. TST screening identified new cases of tuberculosis, less than 0.02% of the children screened.

CONCLUSIONS

School-based tuberculin screening identified low rates of positive TST results in US-born children. Resources should be directed toward screening children at high risk for tuberculous infection, as recommended by the American Academy of Pediatrics and the Advisory Committee for Elimination of Tuberculosis.

Tuberculosis surveillance in the United States: case definitions used by state health departments

Health departments in all 53 reporting areas in the United States were asked to submit the case definition they used for tuberculosis surveillance. Sixteen areas used the 1990 case definition; two areas sent 1977 guidelines; and 34 areas sent other definitions. Case reports sent to the Centers for Disease Control and Prevention (CDC) in 1992 were analyzed; 4% of cases did not meet the 1990 definition. Tuberculosis case reporting criteria are not uniformly applied in the United States. CDC, in collaboration with state and local health officials, is evaluating the current definition and will implement uniform national criteria for tuberculosis surveillance.

Transmission of multidrug-resistant Mycobacterium tuberculosis during a long airplane flight

BACKGROUND

In April 1994, a passenger with infectious multi-drug resistant tuberculosis traveled on commercial-airline flights from Honolulu to Chicago and from Chicago to Baltimore and returned one month later. We sought to determine whether she had infected any of her contacts on this extensive trip.

METHODS

Passengers and crew were identified from airline records and were notified of their exposure, asked to complete a questionnaire, and screened by tuberculin skin tests.

RESULTS

Of the 925 people on the airplanes, 802 (86.7 percent) responded. All 11 contacts with positive tuberculin skin tests who were on the April flights and 2 of 3 contacts with positive tests who were on the Baltimore-to-Chicago flight in May had other risk factors for tuberculosis. More contacts on the final, 8.75-hour flight from Chicago to Honolulu had positive skin tests than those on the other three flights (6 percent, as compared with 2.3, 3.8, and 2.8 percent). Of 15 contacts with positive tests on the May flight from Chicago to Honolulu, 6 (4 with skin-test conversion) had no other risk factors; all 6 had sat in the same section of the plane as the index patient (P=0.001). Passengers seated within two rows of the index patient were more likely to have positive tuberculin skin tests than those in the rest of the section (4 of 13, or 30.8 percent, vs. 2 of 55, or 3.6 percent; rate ratio, 8.5; 95 percent confidence interval, 1.7 to 41.3; P=0.01).

CONCLUSIONS

The transmission of Mycobacterium tuberculosis that we describe aboard a commercial aircraft involved a highly infectious passenger, a long flight, and close proximity of contacts to the index patient.

The need for epidemic intelligence

The past decade has witnessed an unprecedented upturn in tuberculosis morbidity and outbreaks of difficult- to-treat and highly lethal multidrug-resistant tuberculosis. In the early 1990s, a national consensus developed among public health officials to define more comprehensively the problem, and in January 1993, expanded tuberculosis surveillance was implemented nationwide. Carefully selected epidemiologic and case management variables were added to the Report of Verified Case of Tuberculosis form. Information is collected on the health status and treatment of patients, including human immunodeficiency virus status, drug susceptibility test results, and the initial drug regimen. Completion of therapy and use of directly observed therapy are also monitored. The new surveillance system allows a comparison of the quality of care of patients in the public and private sectors. Additional epidemiologic variables include membership in high-risk groups (the homeless, residents of correctional or long-term care facilities, migrant workers, health care workers, and correctional employees) and substance abuse (injecting drug use, non-injecting drug use, and excess alcohol use). The additional information derived from expanded tuberculosis surveillance is crucial to optimal patient management, policy development, resource allocation, as well as program planning, implementation, and evaluation at Federal, State, and local levels.

Tuberculosis screening among homeless persons with AIDS living in single-room-occupancy hotels

Congregate facilities for homeless persons with the acquired immunodeficiency syndrome (AIDS) are often endemic for tuberculosis. We evaluated tuberculosis screening methods at single-room-occupancy hotels housing persons with AIDS. Residents were screened by cross matching the New York City Tuberculosis Registry, interviewing for tuberculosis history, skin testing, and chest radiography. Cases were classified as either previously or newly diagnosed. Among the 106 participants, 16 (15%) previously diagnosed tuberculosis cases were identified. Participants' tuberculosis histories were identified by the questionnaire (100%) or by registry match (69%). Eight participants (50%) were noncompliant with therapy. These findings prompted the establishment of a directly observed therapy program on site.

Prevalence, incidence, and risks for HIV-1 infection in female sex workers in Miami, Florida

Annual cross-sectional prevalence, incidence of new infection, and risks for human immunodeficiency virus type 1 (HIV-1) infection were studied in 607 women convicted of prostitution between October 1987 and December 1990 and tested for HIV under court order. Cross-sectional prevalence was stable for 4 years (23-24% positivity in 1987-1991, p = 0.6). However, the incidence of new infections (rate of seroconversion) in 264 women tested more than once increased significantly each year from 12 per 100 person-years in 1987-1988 to 19 per 100 person-years in 1991 (p < 0.03). Seroconverters were more likely to be young black women with a prior history of syphilis or gonorrhea. A new episode of syphilis or rectal gonorrhea during the follow-up period predicted HIV seroconversion in a survival analysis model. Female sex workers are at great risk of acquiring HIV infection. Although HIV prevalence in cross-sectional samples was stable, incidence was increasing. Interpretation of prevalence trends from convenience samples, such as screening programs, may be difficult because changes in incidence may not be detected.

Tuberculosis in a day-care center, Kentucky, 1993

In November, 1993, a 33-month-old child in a day-care center was diagnosed with tuberculosis (TB). To identify her source of infection, close contacts, other day-care children and staff were screened by tuberculin skin test (TST). TB registry and medical/laboratory records were reviewed. The only 2 community TB cases reported in the past 3 years were investigated. Of 164 children 2 were diagnosed with TB; their TSTs were > or = 10 mm but no specimens were obtained. Six children had TSTs > or = 5 mm. Of these 4 had TST conversions between December, 1993, and March, 1994. There were no additional positive TST children in June, 1994. No TB case was identified among staff or parents. A possible epidemiologic link with the index case was found for 1 community case. No source of infection was found for the other children. Possible explanations for not finding a source are: an as yet unidentified case in the day-care center or community; or false positive TST results in children related to low community prevalence of TB infection.

National trends in the concurrence of tuberculosis and acquired immunodeficiency syndrome

BACKGROUND

Elucidation of the relationship between tuberculosis (TB) and the acquired immunodeficiency syndrome (AIDS) is needed to help predict the future course of these two epidemics. We examined nationwide trends in TB and AIDS occurring in the same individual.

METHODS

Health departments in the 50 states, District of Columbia, Puerto Rico, and Guam matched their TB and AIDS case registries to determine the number of persons diagnosed with both TB and AIDS. The number of AIDS cases, TB cases, AIDS cases that matched with a TB case on the TB registry, and TB cases that matched with an AIDS case on the AIDS registry were reported to the Centers for Disease Control and Prevention, Atlanta, Ga. Data were analyzed for the period from 1981 through 1991. The number of matched TB-AIDS cases was compared with a modeled estimate of excess TB cases during the period from 1985 through 1990.

RESULTS

From 1981 through 1991 there were 11,299 AIDS cases that matched with a TB case on the TB registry, representing 5.1% (geographic variation, 0% to 9.3%) of AIDS cases. The TB cases that matched with an AIDS case on the AIDS registry represent 4.3% (geographic variation, 0% to 15.1%) of TB cases from 1981 through 1991. Since 1981, matched TB and AIDS cases increased yearly through 1990. When examined by year of AIDS report, the percentage of AIDS cases that matched with a TB case increased from 1981 to 1982 (1.9% to 5.1%), remained fairly constant from 1983 through 1987 (range, 4.0% to 4.7%), increased in 1988 (5.4%) after extrapulmonary TB was added to the AIDS case definition, and increased slightly through 1990 (5.8%). When examined by year of TB report, the percentage of TB cases that matched with an AIDS case increased steadily from 1981 through 1990 (0.1% to 9.5%). The calculated fraction of excess TB cases during the period from 1985 through 1990 that could be accounted for by identified TB-AIDS cases was 30%.

CONCLUSION

The risk of TB or AIDS among persons already diagnosed with one disease is much higher than among the general population. The percentage of persons with TB who are also diagnosed with AIDS has been increasing rapidly. Human immunodeficiency virus-induced immunosuppression is an important contributor to the TB epidemic and probably accounts for a minimum of 30% of excess TB cases during the period from 1985 through 1990.

Teenagers at risk of human immunodeficiency virus type 1 infection. Results from seroprevalence surveys in the United States

OBJECTIVE

To describe the seroprevalence of human immunodeficiency virus type 1 (HIV-1) and risk factors for HIV-1 infection among teenagers attending selected clinics.

DESIGN

Anonymous, cross-sectional serosurveys conducted in 130 clinics in 24 cities.

SETTINGS

Adolescent medicine clinics, sexually transmitted disease clinics, clinics in juvenile detention and correctional facilities, and homeless and runaway youth centers.

PATIENTS

Teenagers in whom serum samples were drawn as part of routine medical services.

MAIN OUTCOME MEASURES

Prevalence of HIV-1 infection and reported HIV risk behaviors.

RESULTS

From January 1, 1990 through December 31, 1992, serum specimens were collected from 79,802 teenagers; 591 of these specimens were positive for HIV-1 antibody. Seropositive test results were found in all 24 cities surveyed, and in 95 (73%) of the 130 clinics surveyed. The median clinic-specific prevalence was 0.2% (range, 0% to 1.4%) in 22 adolescent medicine clinics, 0.3% (range, 0% to 6.8%) in 33 correctional facilities, 0.5% (range, 0% to 3.5%) in 70 sexually transmitted disease clinics, and 1.1% (range, 0% to 4.1%) in five homeless youth centers. Rates exceeded 1% in 37 sites (28%). Excluding sites with many men reporting sex with men, rates in women were similar or somewhat higher than rates in men. Rates were highest among young men reporting sex with men, with clinic rates ranging from 16% to 17% in two homeless youth sites and 13% to 17% in two sexually transmitted disease clinics. Most teenagers with risk information reported heterosexual activity as their only potential risk exposure to HIV-1.

CONCLUSIONS

Seroprevalence of HIV was generally low but varied by type of clinic and geographic area. The highest rates were observed among young women and gay men in some settings, suggesting that targeted prevention messages are needed.

Tuberculosis in children younger than five years old: New York City

We examined medical and health department records for children < 5 years of age with suspected or confirmed tuberculosis reported to the New York City Health Department from January, 1992, through June, 1992, in order to describe the epidemiology of tuberculosis in young children and identify prevention strategies. Forty-seven children were treated for suspected or confirmed tuberculosis. Sixty-two percent (21 of 34) were foreign-born (n = 11) or had foreign-born caretakers (n = 10). A source case was found for 10 of 47 (21%) children; for 8 the adult source was diagnosed before the child. One child was human immunodeficiency virus-seropositive, however, 83% of children and 70% of adult source cases did not have human immunodeficiency virus test results available. Health care providers should test children at high risk for tuberculosis infection as recommended by the American Academy of Pediatrics and improve contact tracing to identify children exposed to adults with tuberculosis. Because most cases of tuberculosis in children are diagnosed clinically rather than by isolating Mycobacterium tuberculosis, identification of the source case is important for selecting appropriate treatment.