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

Using GIS technology to identify areas of tuberculosis transmission and incidence

Background

Currently in the U.S. it is recommended that tuberculosis screening and treatment programs be targeted at high-risk populations. While a strategy of targeted testing and treatment of persons most likely to develop tuberculosis is attractive, it is uncertain how best to accomplish this goal. In this study we seek to identify geographical areas where on-going tuberculosis transmission is occurring by linking Geographic Information Systems (GIS) technology with molecular surveillance.

Methods

This cross-sectional analysis was performed on data collected on persons newly diagnosed with culture positive tuberculosis at the Tarrant County Health Department (TCHD) between January 1, 1993 and December 31, 2000. Clinical isolates were molecularly characterized using IS6110-based RFLP analysis and spoligotyping methods to identify patients infected with the same strain. Residential addresses at the time of diagnosis of tuberculosis were geocoded and mapped according to strain characterization. Generalized estimating equations (GEE) analysis models were used to identify risk factors involved in clustering.

Results

Evaluation of the spatial distribution of cases within zip-code boundaries identified distinct areas of geographical distribution of same strain disease. We identified these geographical areas as having increased likelihood of on-going transmission. Based on this evidence we plan to perform geographically based screening and treatment programs.

Conclusion

Using GIS analysis combined with molecular epidemiological surveillance may be an effective method for identifying instances of local transmission. These methods can be used to enhance targeted screening and control efforts, with the goal of interruption of disease transmission and ultimately incidence reduction.

Infectious Disease Screening for Refugees Resettled in the United States

Refugees resettling in the United States carry a significant burden of infectious diseases as a result of exposures in their countries of origin and the circumstances of their migration. Overseas screening is required before entry, but it incompletely assesses infectious diseases in refugees. Domestic health assessment has the potential to provide more comprehensive assessment for infectious diseases. Screening protocols ideally should test for tuberculosis, hepatitis B, and intestinal and other parasites and should include mechanisms for providing or updating immunizations. Testing for other infectious diseases, including malaria, hepatitis C, human immunodeficiency virus, and sexually transmitted diseases, can be performed on the basis of clinical signs and symptoms. This article reviews the current status of overseas and domestic health screening for refugees, infectious disease burdens, and future goals for health assessment of refugees and other immigrants.

Acute care issues in internationally adopted children

Over the past decade there has been a dramatic increase in international adoptions in the United States. While most adopted children will have common illnesses, others may have unique medical issues as a result of the conditions in their birth country requiring a broadened differential diagnosis. Knowledge of these issues is essential in the management of these patients. This review will predominately focus on infectious disease issues commonly seen in international adoptees but will also discuss other medical conditions and some of the psychosocial issues which may be encountered by caregivers in the emergency department.

A no-name tuberculosis tracking system

Foreign-born persons from countries where tuberculosis (TB) is endemic make up a significant percentage of poultry industry workers in Delaware, a leading poultry-producing state. Many of these workers enter the United States without documentation and assume multiple identities, making it difficult for public health staff to investigate TB contacts who work in the poultry plants. The Sussex County Health Unit of the Delaware Division of Public Health developed a no-name TB tracking system to facilitate identification and treatment of poultry plant workers with TB infection and disease in a high-risk population whose members assume one or more aliases. Completion rates for treatment of latent TB infection in this group increased from 48% to 64% 2 years after the program's implementation.

Tuberculosis among foreign-born children in the State of Florida, 1993–1999: A re-emergence phase after a sustained decline?

STUDY OBJECTIVE

To determine the temporal trend of tuberculosis disease among foreign-born children in the State of Florida.

DESIGN AND SETTING

Descriptive population-based study on data obtained from the Tuberculosis Control and Surveillance Program in the State of Florida. We employed Poisson assumption to derive estimates for rates of tuberculosis among US-born and foreign-born children in the studied population. We also applied linear and non-linear regression equations to describe the best trajectories for observed temporal trends in incidence cases of the disease.

PATIENTS

All cases of tuberculosis disease among children notified in the State of Florida between 1993 and 1999 inclusive.

MAIN RESULTS

The incidence rate of TB over the study period was five times higher among foreign-born children (11.3 per 10(5); CI = 8.0-14.6 per 10(5)) as compared to US-born (1.7 per 10(5); CI = 0.8-4.2 per 10(5)). Whereas, new cases of TB among US-born children have continuously and significantly dropped throughout the period of study, our data indicated that the decline achieved from 1993 to 1996 among foreign-born children has ceased, and a resurgence of tuberculosis in this population was apparent.

CONCLUSIONS

Our data tend to suggest a re-emergence of tuberculosis among foreign-born children in the State of Florida as from 1997 after several years of decline. There is a need for a more in-depth investigation to elucidate and address causes responsible for the resurgence if the current battle to eliminate tuberculosis from the State is to succeed.

Comparison of T-cell-based assay with tuberculin skin test for diagnosis of Mycobacterium tuberculosis infection in a school tuberculosis outbreak

BACKGROUND

The diagnosis of latent tuberculosis infection relies on the tuberculin skin test (TST), which has many drawbacks. However, to find out whether new tests are better than TST is difficult because of the lack of a gold standard test for latent infection. We developed and assessed a sensitive enzyme-linked immunospot (ELISPOT) assay to detect T cells specific for Mycobacterium tuberculosis antigens that are absent from Mycobacterium bovis BCG and most environmental mycobacteria. We postulated that if the ELISPOT is a more accurate test of latent infection than TST, it should correlate better with degree of exposure to M tuberculosis.

METHODS

A large tuberculosis outbreak in a UK school resulted from one infectious index case. We tested 535 students for M tuberculosis infection with TST and ELISPOT. We compared the correlation of these tests with degree of exposure to the index case and BCG vaccination.

FINDINGS

Although agreement between the tests was high (89% concordance, kappa=0.72, p<0.0001), ELISPOT correlated significantly more closely with M tuberculosis exposure than did TST on the basis of measures of proximity (p=0.03) and duration of exposure (p=0.007) to the index case. TST was significantly more likely to be positive in BCG-vaccinated than in non-vaccinated students (p=0.002), whereas ELISPOT results were not associated with BCG vaccination (p=0.44).

INTERPRETATION

ELISPOT offers a more accurate approach than TST for identification of individuals who have latent tuberculosis infection and could improve tuberculosis control by more precise targeting of preventive treatment.

Assessment of tuberculosis treatment completion in an ethnically diverse population using two data sources. Implications for treatment interventions

Many adolescents who are prescribed therapy for tuberculosis (TB) infection fail to complete it. This article presents the results of a demographic and epidemiological assessment of TB treatment completion in adolescent populations using (a) surveillance data from the Los Angeles Health County Department and (b) a prospective/retrospective medical chart review from targeted clinics. Patients who did not complete the 6-month recommended medical treatment for latent tuberculosis therapy (LTBI) averaged 13 weeks in care. Younger age (OR = 1.15; 95% CI 1.03-1.29), birth in the United States (OR = 1.92; 95% CI 1.14-3.22, compared to Mexico), and Asian ethnicity were associated with completion of care. In multiple logistic regression analysis, age (OR = .88; 95% CI .78-.98) and Latino ethnicity (OR = .53; 95% CI .29-.95) remained significant predictors of completion of treatment. These findings indicate the need for age-specific educational reinforcement and cultural differentials in completing care for LTBI.

Tuberculosis in association with travel

Throughout history, tuberculosis has been spread by the movement of human populations. Modern travel continues to be associated with risk of tuberculosis infection and disease. TB transmission has been documented on commercial aircraft, from personnel or passengers to other personnel and passengers, but the risk of transmission is low. As in other settings, the likelihood of transmission is proportional to duration and proximity of contact. Travellers from low incidence to high incidence countries have an appreciable risk of acquiring TB infection similar to that of the general populations in the countries they visit, but the risk is higher if they work in health care. Two-step tuberculin skin testing prior to departure, followed by single-step tuberculin testing after return, is recommended for all such travellers. For travellers from high incidence to low incidence countries the risk of acquiring new TB infection is low. Tuberculin screening is not beneficial and not recommended. Chest X-ray screening is expensive and complex but may be beneficial for long-term migrants. For short-term travellers, such as the pilgrims to Mecca in Saudi Arabia, there is no practical or feasible intervention to detect or prevent TB. Emphasis should be placed on public awareness and education campaigns to facilitate passive diagnosis of symptomatic cases. Mycobacterium tuberculosis (MTB) continues to be a common concern for the global traveller.

Pseudo-outbreak of tuberculosis in poultry plant workers, Sussex County, Delaware

Delaware is a leading US poultry-producing state, and foreign-born workers make up a significant percentage of those employed by Delaware's poultry plants. In Sussex County, Delaware, a high percentage of the poultry workers are from two countries with a high incidence of tuberculosis (TB), Mexico and Guatemala, and thus are at risk for TB infection and disease. Furthermore, their risk of TB may be increased because many of these workers live in crowded conditions and lack access to medical care.

Screening of international immigrants, refugees, and adoptees

Frequently clinicians are faced with screening and providing preventive care to immigrants, refugees, and international adoptees. Evidence-based medicine on which to base screening protocols for these populations is lacking. It is important to review all health and vaccination records of the patient. In addition to acute symptoms, one should inquire about the symptoms of diseases prevalent in the country of origin or transit (e.g., hematuria). Many unexpected pathologic conditions may be detected by a thorough physical examination. If a reliable immunization record is presented, one need not repeat the vaccines or check titers. Remaining vaccines should be administered according to ACIP guidelines, except for certain populations (e.g., adoptees). Routine laboratory screening tests should include CBC with differential, stool for ova and parasites, urinalysis, general chemistry profile, serology for hepatitis B, and tests for HIV and syphilis. A tuberculin skin test should be performed on all immigrants, and a chest radiograph should be obtained for any patient with symptoms or a positive PPD. Lead level, hepatitis C, and TSH should be obtained for all children and most adoptees. In addition, special screening tests (e.g., for malaria, hepatitis C, and STIs) may be indicated in high-risk populations. A more organized screening system that emphasizes evidence-based and population-specific screening protocols and better communication between international, federal, state, and local levels is needed in the United States.

Prevalence of tuberculosis, hepatitis B virus, and intestinal parasitic infections among refugees to Minnesota

OBJECTIVE

The purpose of this study was to define the prevalence of infection with Mycobacterium tuberculosis, hepatitis B virus, and various intestinal parasites among different groups of primary refugees immigrating to Minnesota.

METHODS

2,545 refugees arriving in Minnesota during 1999 received a domestic health examination that included tuberculin skin testing, hepatitis B virus serologic testing, and stool ova and parasite examinations. The Refugee Health Assessment form asked specifically about screening results for amebiasis, ascariasis, clonorchiasis, giardiasis, hookworm, schistosomiasis, strongyloidiasis, and trichuriasis.

RESULTS

Forty-nine percent of refugees had a reactive tuberculin test of >or=10 mm induration, with a higher prevalence in males (54%) and refugees >or=18 years of age (63%) (p<0.001). Seven percent had a positive hepatitis B surface antigen, with the highest prevalence in those people from sub-Saharan Africa (8%) (p=0.002) and those refugees >or=18 years of age (9%) (p=0.006). Twenty-two percent had one or more intestinal parasites asked about, including 30% of those refugees <18 years of age (p<0.001). The most commonly reported parasitic infections were trichuriasis (8%) and giardiasis (7%).

CONCLUSIONS

Evidence of infection with M. tuberculosis, hepatitis B virus, or one of eight intestinal parasites was present in a substantial proportion of refugees receiving the domestic health assessment. Screening for such infections gives new immigrants the opportunity to receive important medical evaluation and treatment, provides valuable surveillance data, and allows appropriate public health measures to be taken.

Tuberculosis screening in the federal prison system: an opportunity to treat and prevent tuberculosis in foreign-born populations

OBJECTIVES

Despite recent success in tuberculosis (TB) control efforts in the United States, marked declines in TB case rates have not been observed in foreign-born populations. Because foreign-born populations are becoming more important for targeted national TB control efforts, the Federal Bureau of Prisons (BOP) reviewed inmate medical data to evaluate risk factors associated with Mycobacterium tuberculosis infection and active TB disease. To improve screening strategies, BOP implemented chest radiograph screening for all inmates entering a federal detention center in San Diego, California.

METHODS

Tuberculin skin test (TST) data from an approximated intake cohort of inmates entering the system from February 1 to June 30, 1999, were analyzed to assess risk factors for M. tuberculosis infection among inmates entering federal prisons. The most recent case reports of inmates diagnosed with TB disease were reviewed. All inmates entering a San Diego detention facility from July 1 to December 31, 1998, were screened for TB by symptom review, TST, and chest radiographs.

RESULTS

System-wide, foreign-born inmates were 5.9 times more likely to have a positive TST than US-born inmates, and accounted for 60% of recently diagnosed TB cases. Chest radiograph screening of all inmates entering the San Diego facility reduced exposure time to active TB cases by 75%, but TB incidence remained unchanged.

CONCLUSIONS

The high prevalence of M. tuberculosis infection and TB disease among foreign-born inmates entering the federal prison system presents a strategic opportunity to provide preventive therapy to a high-risk population and to identify contagious cases that might elude traditional public health efforts. Universal chest radiograph screening was no more sensitive than TST for detecting active TB cases among newly incarcerated foreign-born inmates with a high prevalence of TB infection, but the screening reduced potential TB exposures through rapid identification of contagious cases.

Behavioral interventions for the control of tuberculosis among adolescents

OBJECTIVES

Activation of latent tuberculosis infection into tuberculosis disease (TB), the primary killer among infectious diseases worldwide, can be prevented with six months of anti-TB medication. A large percentage of adolescents started on medication, however, fail to complete their treatment. The authors developed and tested the effects of innovative educational strategies on infected adolescents at two health centers serving ethnically diverse populations.

METHODS

The authors used a randomized experimental four-group design to assess the independent and combined effects of peer counseling and a participant-parent contingency contract intervention.

RESULTS

A total of 794 adolescents were recruited into the study, for a 79% participation rate. The overall rate of treatment completion was 79.8%. Self-efficacy for medication-taking behavior at post-test correlated strongly with completion of care (R = 0.367, p = 0.002). Participants randomized to the peer counseling groups demonstrated significantly greater improvements in self-efficacy and mastery than the usual care control group. Based on the study results, continuing education seminars and workshops were implemented for TB control staff at the two health clinics and for all TB Control Division staff at the Los Angeles County Health Department. Educational materials and a training manual for enhancing completion of treatment of latent TB infection through tailored educational approaches were developed and disseminated to the clinics.

CONCLUSIONS

Health education and incentives are helpful adjuncts to the completion of treatment for latent tuberculosis infection in adolescents.

Persistent high incidence of tuberculosis in immigrants in a low-incidence country

Immigration from areas of high incidence is thought to have fueled the resurgence of tuberculosis (TB) in areas of low incidence. To reduce the risk of disease in low-incidence areas, the main countermeasure has been the screening of immigrants on arrival. This measure is based on the assumption of a prompt decline in the incidence of TB in immigrants during their first few years of residence in a country with low overall incidence. We have documented that this assumption is not true for 619 Somali immigrants reported in Denmark as having TB. The annual incidence of TB declined only gradually during the first 7 years of residence, from an initial 2,000 per 100,000 to 700 per 100,000. The decline was described by an exponential function with a half-time of 5.7 (95% confidence interval 4.0 to 9.7) years. This finding seriously challenges the adequacy of the customary practice of screening solely on arrival.

Effectiveness of the Immigration Medical Surveillance Program for tuberculosis in Ontario

BACKGROUND

Citizenship and Immigration Canada (CIC) screens immigrants for TB and permits those with inactive pulmonary TB to enter Canada conditionally, subject to medical surveillance; we studied this program in Ontario.

METHOD

This was an administrative database study with linkage of national and provincial data.

RESULTS

In 1994-95, 1,341 cases of foreign-born active TB were diagnosed and a CIC record was found for 1,095. 149 (14%) were classified for surveillance and 142 were included in the analysis. A significant proportion (39/142: 27%) were diagnosed either before or as a result of immigration screening in Canada. These persons had arrived as visitors or refugees and were excluded from further analysis. Only 21 of the remaining 103 persons (20%) with immigration screening before the diagnosis of TB adhered to surveillance. Only 1 of 16 (6%) eligible persons was given therapy to prevent future episodes of active TB. Most presented with symptoms (82/103:82%) suggesting potential for TB transmission in Ontario.

INTERPRETATION

The current TB surveillance system for high-risk immigrants to Ontario is not effective in identifying and treating latent infection, and thus not effective in preventing future cases.

Tuberculosis screening among foreign-born persons applying for permanent US residence

OBJECTIVES

This study sought to determine adherence of physicians to tuberculosis (TB) screening guidelines among foreign-born persons living in the United States who were applying for permanent residency.

METHODS

Medical forms of applicants from 5 geographic areas were reviewed, along with information from a national physician database on attending physicians. Applicant and corresponding physician characteristics were compared among those who were and were not correctly screened.

RESULTS

Of 5739 applicants eligible for screening via tuberculin skin test, 75% were appropriately screened. Except in San Diego, where 11% of the applicants received no screening, most of the inappropriate screening resulted from the use of chest x-rays as the initial screening tool.

CONCLUSIONS

Focused physician education and periodic monitoring of adherence to screening guidelines are warranted.

Tuberculosis skin testing among HIV-infected pregnant women in Miami, 1995 to 1996

OBJECTIVE

Approximately 6000 women deliver annually at Jackson Memorial Hospital in Miami, where 2.4% of women has human immunodeficiency virus (HIV) and 60% is foreign-born. We conducted a retrospective review of prenatal records among HIV-infected women to evaluate tuberculin skin testing (TST).

STUDY DESIGN

We determined how many women had TSTs placed and read, and the TST results.

RESULTS

We identified 207 HIV-infected women, 87% of such women delivering in 1995 to 1996. Most did not know their HIV status before seeking prenatal care (109, 54%) and most (176, 85%) had TSTs done. Of the women, 45 had positive TSTs, 96 had negative TSTs, and 35 were anergic. Most results were not recorded using millimeters of induration. Two women (1%) had active tuberculosis (TB) disease.

CONCLUSION

Overall, 21% of all HIV-infected women had positive TSTs and 1% had active TB disease. Focused TB skin testing should be part of routine prenatal care in clinics serving populations at high-risk for TB, such as those with HIV infection and the foreign-born.

Effectiveness of postmigration screening in controlling tuberculosis among refugees: a historical cohort study, 1984-1998

OBJECTIVES

This study assessed the effectiveness of postmigration screening for the control of tuberculosis (TB) among refugee migrants.

METHODS

We conducted a historical cohort study among 24 610 predominantly Southeast Asian refugees who had arrived in Sydney, Australia, between 1984 and 1994. All had been screened for TB before arrival and had radiologic follow-up for 18 months after arrival. Incident cases of TB were identified by record linkage analysis with confirmatory review of case notes.

RESULTS

The crude annual incidence rate over 10-year follow-up was 74.9 per 100 000 person-years. Only 29.6% of the cases were diagnosed as a result of routine follow-up procedures.

CONCLUSIONS

Enhanced passive case finding is likely to be more effective than active case finding for the control of TB among refugees.

Neighborhood poverty and the resurgence of tuberculosis in New York City, 1984-1992

OBJECTIVES

The resurgence of tuberculosis (TB) in NewYork City has been attributed to AIDS and immigration; however, the role of poverty in the epidemic is unclear. We assessed the relation between neighborhood poverty and TB at the height of the epidemic and longitudinally from 1984 through 1992.

METHODS

Census block groups were used as proxies for neighborhoods. For each neighborhood, we calculated TB and AIDS incidence in 1984 and 1992 with data from the Bureaus of Tuberculosis Control and AIDS Surveillance and obtained poverty rates from the census.

RESULTS

For 1992, 3,343 TB cases were mapped to 5,482 neighborhoods, yielding a mean incidence of 46.5 per 100,000. Neighborhood poverty was associated with TB (relative risk = 1.33; 95% confidence interval = 1.30, 1.36 per 10% increase in poverty). This association persisted after adjustment for AIDS, proportion foreign born, and race/ethnicity. Neighborhoods with declining income from 1980 to 1990 had larger increases in TB incidence than did neighborhoods with increasing income.

CONCLUSIONS

Leading up to and at the height of the TB epidemic in New York City, neighborhood poverty was strongly associated with TB incidence. Public health interventions should target impoverished areas.

Mycobacterium tuberculosis disease in Somali immigrants in Minnesota

STUDY OBJECTIVE

To characterize pulmonary and extrapulmonary Mycobacterium tuberculosis cases in the Somali community in Minnesota.

DESIGN

Retrospective chart review of active tuberculosis cases in Somalis reported to the Minnesota Department of Health between January 1993 and June 1998.

PATIENTS

Ethnic Somalis in the state of Minnesota with M tuberculosis diagnosed by positive culture or radiographic findings consistent with tuberculosis and clinical improvement when treated with antituberculous drugs.

RESULTS

Eighty-two Somali patients were diagnosed with tuberculosis during the study period. Extrapulmonary disease (typically lymphadenopathy) was present in 46% (n = 38). The 1997 incidence of tuberculosis in Minnesota's Somali population was estimated at 170 cases per 100,000 population compared with a national incidence of 20.5 per 100,000 among African Americans and 2.5 per 100,000 among whites. Ninety percent of Somali patients were < 40 years of age; 63% were diagnosed within 1 year of immigration, and > 90% had positive results with the purified protein derivative skin test. M tuberculosis was confirmed in 24 of 25 isolates from extrapulmonary cases. Multidrug resistance was present in 3.4%, and only two patients had AIDS.

CONCLUSIONS

Somalis have a high incidence of active disease, with frequent extrapulmonary involvement in the absence of AIDS, clinical presentation shortly after immigration, and infrequent infection with resistant organisms. Health-care providers should maintain an increased awareness for tuberculosis when evaluating Somali immigrants.

Tuberculosis in North Carolina: trends across two decades, 1980-1999

In North Carolina, we analyzed cumulative data for tuberculosis (TB) from 1980 through 1999 to determine trends in incidence, population subgroups at risk, and implications for health policy- makers. The overall incidence rates declined significantly over the study period (p = 0.0001). This decline correlates strongly with an increase in TB patients receiving directly observed therapy. Males have approximately twice the risk for disease, and persons >65 years of age are at the highest risk. For every Caucasian with TB, six blacks, six Hispanics, and eight Asians have the disease. TB incidence rates are declining in all other population subgroups but increasing in foreign-born and Hispanic persons.

Supervised preventive therapy for latent tuberculosis infection in illegal immigrants in Italy

In a multicenter, prospective, randomized, open-label study of isoniazid-preventive therapy (IPT) for latent tuberculosis infection, illegal immigrants from countries where tuberculosis is highly endemic were enrolled at two clinical sites in Northern Italy. Of 208 eligible subjects, 82 received supervised IPT at a dose of 900 mg twice weekly for 6 mo (Regimen A), 73 received unsupervised IPT 900 mg twice weekly for 6 mo (Regimen B), and 53 received unsupervised IPT 300 mg daily for 6 mo (Regimen C). Supervised IPT was delivered at either one tuberculosis clinic or one migrant clinic. The probability of completing a 26-wk regimen was 7, 26, and 41% in Regimens A, B, and C, respectively (p < 0.005, Log- rank test calculated using Kaplan-Meier plots). The mean time to dropout was 3. 8, 6, and 6.2 wk in Regimens A, B, and C, respectively (p = 0.003 for regimen A versus either Regimens B or C). Treatment was stopped in five subjects (2.4%) because of adverse events. The rate of completion of preventive therapy for latent tuberculosis infection among illegal immigrants was low. Supervised, clinic-based administration of IPT significantly reduced adherence. Alternative strategies to implement preventive therapy in illegal immigrants are clearly required.

Tuberculosis in long-term-care facilities

The geriatric population represents the largest reservoir of Mycobacterium tuberculosis infection in developed nations, including the United States. Tuberculosis (TB) case rates in the United States are highest for this age group compared with other age categories. The subtle clinical manifestations of TB in the elderly often can pose potential diagnostic dilemmas and therapeutic challenges, resulting in increased morbidity and mortality in this age group; this treatable infection unfortunately often is detected only at autopsy. Compared with their community-dwelling counterparts, the institutionalized elderly are at a greater risk both for reactivation of latent TB and for the acquisition of new TB infection. Prevention and control of TB in facilities providing long-term care to the elderly thus cannot be overemphasized.

Population mobility and infectious diseases: the diminishing impact of classical infectious diseases and new approaches for the 21st century

In an increasingly globalized world, rapid population mobility and migration is reducing the differences in infectious disease epidemiology between regions of the world. The movement and relocation of populations between locations where the prevalence and incidence of infections are markedly different poses current and future challenges to those involved in clinical infectious diseases and public health program management. Historically, international attention has focused on the screening and treatment of acute infections of epidemic potential, but, as immigration significantly changes the demography of many nations, chronic infections will require increased attention. In countries with large mobile populations, the population-based burden of infections with long latency periods or significant noninfectious sequelae will make up an increasing amount of the infectious disease caseload and will require more-modern approaches than the traditional screening of arrivals. The globalization of chronic infectious disease epidemiology will require corresponding development of integrated programs to anticipate and manage these diseases in response to an increasingly mobile patient population.

Phthisiology at the dawn of the new century

Tuberculosis (TB) has been and continues to be one of the most significant pathogens in terms of human morbidity and mortality. Although the resurgence of TB has been held in check in most developed countries, the epidemic rages on in most developing countries of the world. The specter of drug resistance is becoming a more credible challenge in many parts of the world, dimming the prospects of eventual elimination. However, great opportunities are arising as well, with an unprecedented focus on the global aspects of TB control. This article will review the status of TB today and put into perspective the prospects for its elimination in the coming century.

Tuberculosis in the inner city: impact of a continuing epidemic in the 1990s

Tuberculosis cases have recently declined in the United States, renewing interest in disease elimination. We examined the epidemiology of tuberculosis from 1991 through 1997 at an inner-city public hospital and assessed population-based tuberculosis rates by ZIP code in the 8 metropolitan Atlanta counties. During the 7 years, 1378 new patients had tuberculosis diagnosed at our hospital (mean, 197 patients/year), accounting for 25% of tuberculosis cases in Georgia. Coinfection with human immunodeficiency virus (HIV) was common, but a significant decrease in the proportion of HIV-infected patients with tuberculosis was noted over time. Most patients were members of a minority group (93%) and were born in the United States (96%). Two inner-city ZIP code areas had annual tuberculosis rates >120 cases per 100,000 persons, and 8 ZIP code areas had annual rates of 47-88 cases per 100,000 persons between 1993 and 1997, compared with the annual national average of 8.7 cases per 100,000 persons. Our hospital continues to care for large numbers of tuberculosis patients, and rates of tuberculosis remain high in the inner city. These data mandate a concentration of efforts and resources in urban locations if tuberculosis control and elimination is to be achieved in the United States.

Recent Developments in Epidemiology, Treatment, and Diagnosis of Tuberculosis

The resurgence in cases of active tuberculosis in North America in the past decade has prompted increases in funding for tuberculosis treatment, research, and education. As a result, the number of new cases of tuberculosis has declined and cases occur in smaller pockets of well-characterized populations, such as communities of foreign-born persons and socioeconomically disadvantaged groups. New strategies for the treatment of both active and latent tuberculosis may soon include the newly licensed, long-acting rifamycin, rifapentine, but further studies are needed to determine optimal dosing regimens for this agent. Experts in tuberculosis and HIV infection have made headway in defining the optimal therapy for each current therapeutic option, and recently published guidelines are a useful document for clinicians. Rifabutin-based regimens are one approach toward achieving the optimal treatment of both diseases simultaneously. Finally, newly licensed molecular diagnostic tests for direct use on clinical specimens are intriguing, but their clinical utility remains to be defined.

Preventing tuberculosis among HIV-infected persons: a survey of physicians' knowledge and practices

BACKGROUND

Guidelines exist for screening, diagnosing, and preventing tuberculosis (TB) among HIV-infected persons, but their application and utility are unknown.

METHODS

We conducted a survey of knowledge and practices among 1,300 physicians in the San Francisco Bay area to assess their practices towards TB among HIV-infected persons.

RESULTS

Of 630 respondents, 350 (56%) provided care for HIV-infected persons. Thirty-four percent of the respondents had seen the most recent guidelines for preventing tuberculosis among HIV-infected persons; 65% routinely provide information to HIV-infected patients about the risks of exposure to Mycobacterium tuberculosis; 39% provide annual tuberculin skin testing (TST) to HIV-infected patients without a history of a positive test; 86% knew that >/=5-mm induration is considered a positive TST result in HIV-infected persons; and 47% provide a 12-month regimen of chemoprophylaxis for HIV-infected persons who have a positive TST but not active tuberculosis. Physician specialty and experience with HIV-infected persons were not strongly correlated; experience was a better predictor of correct knowledge and practices.

CONCLUSIONS

Many physicians were not aware of the standards of care for preventing tuberculosis among HIV-infected patients, even in a geographic area with a high prevalence of M. tuberculosis and HIV.

Differences in contributing factors to tuberculosis incidence in U.S. -born and foreign-born persons

To determine the factors contributing to tuberculosis incidence in the U.S.-born and foreign-born populations in San Francisco, California, and to assess the effectiveness of tuberculosis control efforts in these populations, we performed a population-based molecular epidemiologic study using 367 patients with strains of Mycobacterium tuberculosis recently introduced into the city. IS6110-based and PGRS-based restriction fragment length polymorphism (RFLP) analyses were performed on M. tuberculosis isolates. Patients whose isolates had identical RFLP patterns were considered a cluster. Review of public health and medical records, plus patient interviews, were used to determine the likelihood of transmission between clustered patients. None of the 252 foreign-born cases was recently infected (within 2 yr) in the city. Nineteen (17%) of 115 U. S.-born cases occurred after recent infection in the city; only two were infected by a foreign-born patient. Disease from recent infection in the city involved either a source or a secondary case with human immunodeficiency virus (HIV) infection, homelessness, or drug abuse. Failure to identify contacts accounted for the majority of secondary cases. In San Francisco, disease from recent transmission of M. tuberculosis has been virtually eliminated from the foreign-born but not from the U.S.-born population. An intensification of contact tracing and screening activities among HIV-infected, homeless, and drug-abusing persons is needed to further control tuberculosis in the U.S.-born population. Elimination of tuberculosis in both the foreign-born and the U.S. -born populations will require widespread use of preventive therapy.

Tuberculosis in South-East Asian refugees after resettlement--can prevention be improved by better policy and practice?

OBJECTIVE

This study aimed to determine whether incident cases of tuberculosis (TB) in a cohort of South-East Asian refugees followed for 5 years after resettlement were potentially preventable and whether prevention of TB was optimal in a state refugee TB screening program in Victoria, Australia.

DESIGN

A retrospective cohort study of 1,101 refugees from Laos, Cambodia, and Vietnam screened for TB in the 6-month period from July 1989 to January 1990 was conducted. Incident cases of TB were identified by matching each refugee with the TB notification database for 5 years from the date of initial screening. Preventability was assessed for incident cases by reviewing medical records. Screening guidelines and practice were reviewed.

RESULTS

The main outcome was the preventability of cases of active tuberculosis that developed in the study population in the first 5 years after resettlement. The incidence of active TB was 363/100,000 during the first year and 109/100,000/year during the first 5 years. Five of six incident cases were assessed as potentially preventable, which if prevented would have resulted in an annual incidence of 18/100,000 over the first 5 years. Use of a more sensitive skin test definition of infection would have made an additional 245 refugees eligible for prevention and potentially prevented an additional 25 cases of TB over a lifetime.

CONCLUSIONS

There is a high incidence of tuberculosis among SE Asian refugees, particularly in the first year after resettlement. A large proportion of TB may be preventable. Improvement in case prevention may be possible with updated guidelines and better implementation of screening policy.

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.

Epidemiology and clinical consequences of drug-resistant tuberculosis in a Guatemalan hospital

STUDY OBJECTIVE

To determine the epidemiology and clinical consequences of drug-resistant TB in Guatemala.

DESIGN

A prospective study conducted for 12 months.

SETTING

A thoracic referral hospital in western Guatemala.

PATIENTS

Three hundred and seventy-six patients with confirmed TB.

RESULTS

Of 376 confirmed cases, 335 (89%) were culture-positive. Tests of drug sensitivities to four first-line antituberculous drugs were performed in 172 (51%) of the culture-positive cases. Fifty-one patients (30%) were resistant to at least one antimicrobial agent, and 26 (15%) were resistant to at least two drugs. In a multivariate model of clinically available patient characteristics, only cavitary disease (odds ratio=2.1; 95% confidence interval, 1.1-6.6) and a history of taking anti-TB medication for >2 weeks (OR=3.0; 95% CI, 1.5-10.3) were independent predictors of resistance to two or more anti-TB agents. Resistance to two or more anti-TB drugs was the single independent predictor of treatment failure (OR=6.4; 95% CI, 2.3-17.8). Twenty-four of 172 patients (14%) who denied having received prior anti-TB therapy were infected with resistant organisms, suggesting ongoing transmission of drug-resistant strains. Although 84% (69 of 82 cases) of patients with fully susceptible organisms and 89% (17 of 19 cases) with singly resistant organisms were cured, only 45% of patients (10 of 22 cases) infected with organisms resistant to two or more agents were successfully treated.

CONCLUSIONS

At this sentinel site for complicated TB, a substantial subset of cases who are infected with drug-resistant bacteria cannot be easily identified or treated.