The benefits of evaluating close associates of child tuberculin reactors from a high prevalence group.

To determine the efficacy of evaluating persons (associates) in close contact to children with significant tuberculin reactions, we prospectively evaluated 831 associates of 297 children younger than eight years who had significant (greater than or equal to 10 mm) tuberculin reactions. Eighty-seven per cent of the index reactors were foreign-born, as were 84 per cent of the associates. All associates were evaluated by tuberculin skin testing; chest roentgenograms and sputum cultures were obtained if indicated. Four hundred sixty-one (55 per cent) of the associates had significant tuberculin reactions, and 15 had current tuberculosis. However, only three of these cases were newly discovered (total case rate: 1.81/100, new case rate: 0.36/100). Two of the three new cases were detected in the associates of children younger than three years of age. In addition, 338 candidates for isoniazid (INH) preventive therapy were found. We conclude that although the yield of new cases was low, the evaluation of associates did provide a convenient, high yield method of identifying candidates for INH preventive therapy. Moreover, it served as a useful mechanism for monitoring the adequacy of other case-finding activities.     

Epidemiology of a tuberculosis outbreak in a South Carolina junior high school

A 13-year-old, female, seventh-grade student (the index patient) was found to have smear-positive, cavitary, pulmonary tuberculosis. Epidemiologic and contact investigation, involving skin testing over 900 people, revealed a 40 per cent tuberculin reactor rate for persons in the junior high school she attended compared to a 2 per cent rate for control schools. Repeat skin testing of initial non-reactors identified an additional 3 per cent of infected school children. School teachers showed a seven-fold increase in the prevalence of positive skin-test reactions following the outbreak. Tuberculin-reactor rates for seventh graders were substantially higher than for eighth graders. The more classes shared with the index patient, the higher the probability of being a reactor. Among students who shared no classes with the index patient, the highest rates of tuberculin reactions were found for those who had entered a classroom immediately after the index patient had left it. Evidence of transmission on the school bus and in the church choir was also suggested. Six secondary cases (three pulmonary) resulted from the outbreak. Identical phage types from the index and secondary patients suggest who had left school during the term proved useful in determining when transmission began. The index case was found to be a missed contact of a previously identified case of tuberculosis. Since household contacts are at high risk for developing active disease, there is a need for meticulous and complete investigation and preventive therapy for all such persons, especially children.     

Foreign-born persons with tuberculosis in the United States.

Two recent surveys of selected states and cities suggest that foreign-born persons account for approximately 15 per cent of the new cases of tuberculosis reported annually in the areas surveyed. In both surveys the largest number of foreign-born persons came from the Western Hemisphere, the next largest from Asia. The largest number of foreign-born persons with tuberculosis are in the 15-29 year age group, presumably because most entering aliens are in this age group. Among persons with tuberculosis, a larger per cent of foreign-born patients have extrapulmonary disease than do native-born patients. About 50 per cent of the foreign-born persons with tuberculosis entered the United States within the five years prior to onset of disease. Within the United States, significant inter-area variation exists in the proportion of persons with tuberculosis who are foreign-born and in countries of origin of these persons.     

Language Discordance and Testing for Latent Tuberculosis Infection Among Recent Asian and Latino Immigrants

The foreign-born population is disproportionately affected by tuberculosis (TB). Testing to identify persons with latent TB infection is critical. The aim of this study was to assess clinic-based testing for latent tuberculosis infection among recent Asian and Latino immigrants. A randomized controlled trial of interpreting methods and their impact on medical outcomes was conducted at the primary care clinic of a New York City municipal hospital. This study is a nested cohort of recruited patients with an indication to receive tuberculin testing, based on recent migration to the US from endemic areas. Medical record data were abstracted to determine referral for, and completion of, tuberculin testing. Bivariate analyses were used to test for differences in tuberculin testing between language concordant and discordant groups. Seven hundred and eighty-two patients were enrolled. One hundred and ninety-one had migrated within 5 years of enrollment from endemic areas. None spoke English as a primary language. Seventy percentage of patient-provider encounters were language discordant. Seventeen of 191 were referred for testing. Fifteen (88%) completed testing. Six (40%) had positive results. There were no significant differences between language concordant and discordant patients. In this at-risk population, every patient in clinical care should be considered for testing if indicated by country of origin.     

Childhood tuberculosis in North Carolina: a study of the opportunities for intervention in the transmission of tuberculosis to children.

New cases of tuberculosis in children continue to appear. A retrospective review of the medical records of a representative sample of such cases occurring from 1977 through 1981 was conducted to gain an understanding of why this preventable disease continues to occur in North Carolina children. Three per cent of cases were detected by routine screening; 17 per cent were diagnosed after the child's symptomatic presentation; and 80 per cent after contact screening. However, 14 per cent of cases detected by contact screening developed disease while receiving isoniazid prophylaxis for a positive tuberculin test; and 19 per cent of cases detected by contact screening developed disease while under surveillance, but not receiving isoniazid prophylaxis, as tuberculin negative contacts of known infectious cases. Adherence to accepted recommendations for prophylaxis should reduce the childhood tuberculosis case rate.     

Tuberculosis in employees at a Vermont furniture plant.

In a case-contact investigation of a patient (A) with smear- and culture-positive pulmonary tuberculosis, we found that co-workers in one room of a furniture factory had a higher prevalence of significant reactions to 5 Tu PPD tuberculin than other furniture factory workers. One co-worker also had active pulmonary tuberculosis. It was concluded that Patient A probably transmitted mycobacteria in a well-ventilated, spacious work setting; and that Patient A's disease and the subsequent outbreak could have been prevented.     

BCG scar and positive tuberculin reaction associated with reduced child mortality in West Africa. A non-specific beneficial effect of BCG?

Previous studies have suggested that the bacille Calmette-Guérin (BCG) vaccine may have a non-specific beneficial effect on childhood survival in areas with high mortality. We examined whether BCG-vaccinated children with a BCG scar or a positive tuberculin reaction had better survival than children without such reactions. As part of an ongoing two-dose measles vaccine trial for which children were recruited at 6 months of age, we examined 1813 children for BCG scar at 6 months of age and 813 BCG-vaccinated children were skin-tested for delayed hypersensitivity to tuberculin, tetanus and diphtheria. We found that BCG-vaccinated children with a BCG scar had significantly lower mortality compared with BCG scar-negative children, the mortality ratio in the first 12 months of follow-up being 0.41 (0.25-0.67). BCG-vaccinated children with a positive tuberculin test had a mortality ratio of 0.45 (0.24-0.85) compared with tuberculin negative children. These results were unchanged by control for potential confounders or using different cut-off points for a tuberculin-positive response. Exclusion of dead children who had HIV antibodies did not modify the estimate (mortality rate (MR)=0.46 (0.23-0.94)). After censoring for tuberculosis (TB) exposure at home, the mortality ratios for having a scar and being tuberculin-positive were 0.46 (0.27-0.79) or 0.42 (0.21-0.84), respectively. Children positive to tetanus or diphtheria in the skin test had the same mortality as children not responding to these vaccine-related antigens. Thus, BCG scar and a positive tuberculin reaction were associated with better survival in early childhood in an area with high mortality. Since nothing similar was found for responders to diphtheria-tetanus-pertussis (DTP) vaccine, and the effect could not be explained by protection against tuberculosis, the effect of BCG vaccination could be due to non-specific immune-stimulation protecting against other infections.     

The long-term trend in prevalence of tuberculosis infection in Cyprus

Two tuberculin testing surveys have been carried out in schools in Cyprus by WHO teams, one in 1955 and one in 1963. It happens that three schools in Nicosia were included in both surveys, thus permitting a direct study of the time-trend in prevalence of tuberculosis infection; there are good reasons to believe that the techniques of the two surveys were sufficiently comparable for this purpose. In the 1955 survey, 42 children were found to be infected out of the 1532 who were tested and had their reactions read, while, in the 1963 survey, 24 children were found to be infected among 1680. The difference between the two rates is statistically significant at the 1% level, and it is concluded that tuberculosis infection is on the decline in Cyprus.     

Pediatric tuberculosis in Alberta: epidemiology and case characteristics (1990-2004)

BACKGROUND: Pediatric tuberculosis (TB) is important medically and indicative of a public health problem. An understanding of the epidemiology and case characteristics of pediatric TB, in a province that accepts large numbers of immigrants, can inform TB elimination strategy. METHODS: All cases of pediatric TB notified in Alberta between 1990 and 2004 were identified in the TB Registry. Individual diagnostic criteria were reviewed and case patients were related to a population grid derived from Statistics Canada censuses and population estimates of Status Indians from the Department of Indian and Northern Affairs, Canada. Incidence rates were determined by ethnic group and gender. Clinical/mycobacteriologic case characteristics were compared by ethnic group and birth country. RESULTS: Among 124 notified cases, 95 (96 episodes) met strict diagnostic criteria: 45 Status Indians, 30 Canadian-born 'other' and 21 foreign-born. Incidence rates were much higher in Status Indians and the foreign-born compared to the Canadian-born 'other'; 10.7, 5.4, and 0.4 per 100,000 person-years, respectively. Among Canadian-born 'other' cases, 12 were Métis and 11 were Canadian-born children of foreign-born parents. Compared to foreign-born cases, Canadian-born cases were more likely to have a source case in Alberta, to be detected through contact tracing, to have primary pulmonary TB, and to have a rural address. CONCLUSION: Pediatric TB in Alberta is mainly the result of ongoing transmission in Aboriginal peoples and immigration to Canada of persons with latent TB infection. The elimination of pediatric TB will require interruption of transmission in Aboriginal peoples and prevention of disease in immigrants.     

Tuberculosis infection in urban adolescents: results of a school-based testing program.

In 1986-87 a pilot tuberculosis (TB) skin testing program was introduced for seventh and tenth grade students in the Boston (Massachusetts) public schools. The 8.9 percent tuberculin positivity rate in tenth grade students was significantly higher than the 5.1 percent rate found in seventh graders. A majority of those who were skin test positive were born outside the United States. These results suggest that tuberculin testing in an urban school setting may identify a significant number of candidates for TB preventive therapy, particularly among tenth grade students and those who are foreign-born.     

Dental health of recent immigrant children in the Newcomer schools, San Francisco.

Dental screenings of 1,012 recent immigrant elementary school children in San Francisco showed 77 per cent of children needed dental treatment on first screening, compared to 25 per cent in the 1979-80 National Institute of Dental Research (NIDR) survey for the western United States. The prevalence of dental caries in primary teeth of the immigrant six and seven year-olds was twice that of their US counterparts. Non-refugee immigrants had more serious dental needs but used dental services less often than children with refugee status.     

Risk factors for positive tuberculin skin test in Guinea-Bissau

BACKGROUND: The tuberculin skin test is used for tracing of tuberculosis transmission and identifying individuals in need of prophylactic treatment. METHODS: Using a case-control study design, we recruited 220 smear-positive tuberculosis cases and 223 randomly selected healthy community controls in Bissau, Guinea-Bissau, during 1999-2000. Tuberculin skin tests were performed on family members of cases and controls (n = 1059 and n = 921, respectively). Induration of 10 mm or greater was considered positive. Risk factors were calculated for children (<15 years) and adults separately in multivariate logistic regression analysis. RESULTS: The prevalence of positive tuberculin skin test was 41% in case-contacts compared with 22% in control-contacts, resulting in a prevalence ratio of 1.48 (95% confidence interval = 1.37-1.60). Positive skin tests among case-contacts increased with age for children, as well as with proximity to a case during the night, for both children and adults. A Bacille Calmette Guerin scar increased the likelihood of having a positive tuberculin skin test for adults in case households, but not in other categories of contacts. Among control-contacts the prevalence of positive skin test was associated with older age in children, history of tuberculosis in the family, and a positive tuberculin skin test of the control person. CONCLUSIONS: Risk factors for a positive tuberculin skin test among case- and control-contacts are closely related to tuberculosis exposure. Having a BCG scar did not increase the risk of positive skin test in unexposed individuals. Tuberculin skin testing remains a useful tool for diagnosing tuberculosis infection.     

Low birthweight among US Hispanic/Latino subgroups: the effect of maternal foreign-born status and education

We investigated whether maternal foreign-born status confers a protective effect against low birthweight (LBW) across US Hispanic/Latino subgroups (i.e., Mexicans, Puerto Ricans, Cubans and Central/South Americans) in the USA, and whether the association between maternal education and LBW varies by Hispanic/Latino subgroup and by foreign-born status. We conducted logistic regression analyses of the 2002 US Natality Detail Data (n=634,797). Overall, foreign-born Latino women are less likely to have LBW infants than US-born Latino women. The protective effect of foreign-born status is stronger among Latino women with less than high school education. The maternal education gradient is significantly flatter among foreign-born Latino women than among their US-born counterparts (p<0.001). Patterns among Mexican-origin women account for the overall trends among all Latinos.Foreign-born status (main effect) reduces the risk of LBW among Mexicans by about 21% but does not protect against LBW among other Latino subgroups (i.e., Puerto Ricans, Cubans and Central/South Americans). Among Mexicans and Central South Americans, the protective effect of foreign-born status is stronger among women with low education (i.e., 0-11 and 12 years) than among women with more education (i.e., 13-15 and 16+ years). The educational gradient in LBW is less pronounced among foreign-born Mexicans and Central/South Americans than among their US-born counterparts. As such, maternal foreign-born status and education are associated with LBW, though the direction and strength of these associations vary across Latino subgroups. A "health paradox" is apparent for foreign-born Mexican and Central/South American women among whom there is a weak maternal educational gradient in LBW. Future research may test hypotheses regarding the mechanisms underlying these variations in LBW among Latino subgroups, i.e., different gradients in sending countries, health selection of immigrants, cultural factors, and social support.     

Low birthweight among US Hispanic/Latino subgroups: The effect of maternal foreign-born status and education

We investigated whether maternal foreign-born status confers a protective effect against low birthweight (LBW) across US Hispanic/Latino subgroups (i.e., Mexicans, Puerto Ricans, Cubans and Central/South Americans) in the USA, and whether the association between maternal education and LBW varies by Hispanic/Latino subgroup and by foreign-born status. We conducted logistic regression analyses of the 2002 US Natality Detail Data (n=634,797). Overall, foreign-born Latino women are less likely to have LBW infants than US-born Latino women.The protective effect of foreign-born status is stronger among Latino women with less than high school education. The maternal education gradient is significantly flatter among foreign-born Latino women than among their US-born counterparts (p<0.001). Patterns among Mexican-origin women account for the overall trends among all Latinos.Foreign-born status (main effect) reduces the risk of LBW among Mexicans by about 21% but does not protect against LBW among other Latino subgroups (i.e., Puerto Ricans, Cubans and Central/South Americans). Among Mexicans and Central South Americans, the protective effect of foreign-born status is stronger among women with low education (i.e., 0–11 and 12 years) than among women with more education (i.e., 13–15 and 16+ years). The educational gradient in LBW is less pronounced among foreign-born Mexicans and Central/South Americans than among their US-born counterparts.As such, maternal foreign-born status and education are associated with LBW, though the direction and strength of these associations vary across Latino subgroups. A “health paradox” is apparent for foreign-born Mexican and Central/South American women among whom there is a weak maternal educational gradient in LBW. Future research may test hypotheses regarding the mechanisms underlying these variations in LBW among Latino subgroups, i.e., different gradients in sending countries, health selection of immigrants, cultural factors, and social support.     

Prevalence of tuberculosis infection among primary school-entry children in Sydney

Abstract: A cross-sectional survey of 2044 Year 1 children enrolled in 24 primary schools was performed to determine the prevalence of tuberculosis (TB) infection. Of the 2044 children, 1458 (71 per cent) were Mantoux-tested and 1452 Mantoux reactions were read. Of the total, 6.5 per cent were Mantoux-positive; 17.8 per cent of overseas-born children and 2.8 per cent of Australian-born children were Mantoux-positive (relative risk for overseas-born 6.9, 95 per cent confidence interval 4.2 to 9.6). In the areas of Sydney where the study was conducted, there is a high prevalence of TB infection (noncontagious) among overseas-born children in the five- to seven-year age group. This indicates that there may be a large pool of infected children, a proportion of whom are at risk of developing active (contagious) adult-type TB in the future. These data, with other published data on TB infection rates in other age groups, can contribute to the estimation of the size of the infected pool in Australia to allow rational decisions regarding control of TB in Australia, including the possibility of introducing Mantoux screening and preventive therapy programs for high-risk groups.     

Comparison of various tuberculosis screening strategies based on tuberculin testing in schoolchildren in Paris

BackgroundFollowing the discontinuation in 2004 of routine tuberculin testing in children in France, we have performed a study aiming at assessing the relevancy and identifying the best modalities of continuation of tuberculosis screening activities in schoolchildren in Paris.MethodThe study was conducted in children attending the last grade of primary school. A preliminary case control study was carried out in order to identify risk factors for abnormal tuberculin test results. Data on tuberculin testing activities conducted in 2004 were analyzed in order to compare the impact and the efficiency of five different target populations for screening. The impact of each of the screening strategies was assessed as the number of tuberculosis infections for which a specific treatment has been proposed and their efficiency as the average number of tuberculin tests needed to identify such an infection.ResultsBeside multiple BCG vaccinations, the main risk factor for an abnormal tuberculin test result was the fact that at least one of the child's parents was born in a country of high tuberculosis prevalence. Within the five strategies tested, two can be selected on the basis of their impact and efficiency: the testing of all children and the targeting of the testing to children with characteristics putting them at high risk of tuberculosis.DiscussionFor Paris or other large cities in France, decision-makers will have to consider the local tuberculosis epidemiology, the resources that can be devoted to tuberculosis screening of schoolchildren and the regional specificities of the new BCG vaccination policy.     

Effectiveness of tuberculin skin test screening in a rural family practice

Tuberculin skin tests were performed on 1,146 patients out of an active patient population of 3,112 patients over a ten-year period in a rural western New York State family practice. There were 19 new positive tuberculin reactions and six cases of active tuberculosis discovered in the population. All but two of the patients with new positive tuberculin reactions and all of the patients with new cases of active tuberculosis were members of at least one of the following high-risk groups: (1) contract with an individual with active tuberculosis, or a positive family history of the disease; (2) immigrants to the United States; (3) a history of alcohol abuse; (4) having lived in an institutional setting; (5) health care personnel; and (6) having signs and symptoms of tuberculosis (cough, anorexia, weight loss, positive chest roentgenogram). All new cases of active tuberculosis were diagnosed because of symptoms. No asymptomatic person with a positive tuberculin test developed active disease during the study period. The positive predictive value of using risk factors to prescreen for the tuberculin skin test was 16 percent. The negative predictive value of not screening people without risk factors (because they will have a negative tuberculin test) was 99.8 percent.     

A PRELIMINARY assessment of BCG vacination in India

A NEW ASSESSMENT ACTIVITY IN RELATION TO THE WHO/UNICEF BCG VACCINATION PROGRAMME IS DESCRIBED IN THIS REPORT: according to a detailed plan special field teams collect data on tuberculin sensitivity to determine how efficiently children are being selected for vaccination and to appraise the allergy produced by the mass vaccinations. Results of nine months' work in India have important implications for the practical BCG work.Testing of unvaccinated groups of schoolchildren shows that the pattern of tuberculin sensitivity differs in different parts of India. Specific tuberculin sensitivity is found in all areas, as evidenced by strong reactions to the 5 TU test. Many children had a low-grade non-specific sensitivity, evidenced by small reactions to 5 TU and large reactions to 100 TU. This non-specific tuberculin sensitivity was less frequent at high altitudes, and most common in low-lying humid areas: in all areas it was more prevalent than specific sensitivity.In some areas non-specific tuberculin sensitivity is so strong that it cannot be effectively distinguished from specific sensitivity: consequently, many children not infected with tuberculosis are undoubtedly being excluded from vaccination.Sample retesting of children vaccinated in the mass campaign revealed variable levels of allergy, in many instances much lower than had been expected. These results cannot be explained by a native incapacity of the Indian children to develop strong allergy-nor presumably by the vaccine used. Impairment of the vaccine by exposure to light could be no more than a contributory factor. The marked variability of the campaign results suggests that some factor connected with the handling or application of the vaccine (or possibly of the tuberculin) is involved.     

TUBERCULIN reaction size in human populations as a possible index of the prevalence of bovine infection; a preliminary report

In order to check a possible explanation of variations found in Denmark in the average size of positive tuberculin reactions in different parts of the country, a small-scale special study was made in connexion with the recent Danish mass antituberculosis campaign. The study was carried out in two selected districts; one where cattle tuberculosis has been highly prevalent in the past and one where cattle tuberculosis has been rare.The results showed a substantially larger average reaction size in the former district, and this experience was useful in analysis of some of the routine mass campaign material. Quite large and consistent variations were found in the average size of the tuberculin reactions in different parts of the country. The variations could not be explained by such obvious factors as differences in the tuberculin used, in the testing technique, or between the observers reading the reactions; nor could they be consistently related to differences in the proportions of positives. The results of the study suggested that the average size of the reactions is related to the prevalence in the past of tuberculosis in cattle, and this was again the case in the analysis of the campaign material: smaller reactions were found in counties long free of cattle tuberculosis, larger reactions in counties where bovine infection has only recently been eradicated.The present report, while regarded as preliminary, has possible implications for tuberculosis control studies in countries where very little is known about the prevalence of bovine tuberculosis.     

Tuberculosis risk among migrant farm workers on the Delmarva peninsula.

A survey was conducted to ascertain the risk of tuberculosis (TB) among migrant farm workers on the Delmarva peninsula. Relevant histories were obtained from 842 migrants; a total of 709 skin tests were completed, and 239 sputum specimens were examined for acid-fast bacilli (AFB) and culture. No cases of infectious tuberculosis were ascertained by history or AFB examination. One sputum culture was positive for M. tuberculosis and 13 were positive for various species of nontuberculous mycobacteria. Thirty-seven per cent of migrants tested had significant skin test reactions of 10 mm or more. Reaction rates for men were 41 per cent and for women 25 per cent. Age specific rates ranged from 14 per cent in children aged 5-14 to 54 per cent for ages 45-54. Rates for the principal national/ethnic groups were Haitians 55 per cent, Mexicans 36 per cent, US Blacks 29 per cent and US-born Latinos 20 per cent. Based on these results and other information currently available, it is recommended that current Centers for Disease Control (CDC) recommendations for TB prophylaxis continue to be applied for migrant workers, but that mass screening by skin testing in camp populations not be emphasized. Other recommendations focus on: case finding of active disease, improving continuity and follow-up, increasing coordination among involved agencies, and actively supporting improved economic and living conditions for migrant farm workers.