Tuberculosis in Poland in 2011

AIM OF THE STUDY

To evaluate the main features of TB epidemiology in 2011 in Poland and to compare with the corresponding EU data.

METHODS

Analysis of case- based clinical and demographic data on TB patients from Central TB Register, of data submitted by laboratories on anti-TB drug susceptibility testing results in cases notified in 2011, data from National Institute of Public Health- National Institute of Hygiene on cases of tuberculosis as AIDS-defining disease, from Central Statistical Office on deaths from tuberculosis based on death certificates, data from ECDC report "Tuberculosis surveillance in Europe 2011".

RESULTS

8478 TB cases were reported in Poland in 2011. The incidence rate was 22.2 cases per 100,000, with large variability between voivodeships from 12.8 to 37.0. The mean annual decrease of TB incidence in 2007 - 2011 was 0.4%. 7515 cases had no history of previous treatment i.e. 19.7 per 100,000. The number of all notified pulmonary tuberculosis cases was 7879 i.e. 20.6 per 100,000. The proportion of extrapulmonary tuberculosis was 7.1% (599 cases). TB was diagnosed in 111 children (1.3% of all cases, incidence 1.9). The incidence of tuberculosis increased with age to 41.9 among patients 65 years old and older. The mean age of TB patients was 53.3 years. The incidence among men i.e. 31.0 was more than two times higher than among women i.e. 14.0. The incidence in rural population was slightly lower than in urban, respectively 21.9 and 22.4. Bacteriologically confirmed cases (5327) constituted 67.6% of all pulmonary TB cases. The number of smear positive pulmonary TB cases was 2916 (37.0% of all pulmonary cases). There were 38 foreigners registered among all cases of tuberculosis in Poland and 204 cases registered among prisoners. There were 41 patients with MDR-TB (0.8% of 4993 cases with DST results). TB was initial AIDS indicative disease in 26 cases. There were 575 deaths due to tuberculosis in 2010 (1.5 TB deaths per 100,000). Mortality among males--2.5--was four times higher than among females--0.6.

CONCLUSIONS

In Poland the incidence of tuberculosis is higher than the average in EU countries. In 2011 the highest incidence occurred in older age groups and was higher in men. Positive characteristic also when compared with the situation in many EU countries is the low incidence of tuberculosis in children and the low percentage of patients with drug-resistant tuberculosis.

Identifying predictors of interferon-γ release assay results in pediatric latent tuberculosis: a protective role of bacillus Calmette-Guerin?: a pTB-NET collaborative study

RATIONALE

Interferon-γ (IFN-γ) release assays are widely used to diagnose latent infection with Mycobacterium tuberculosis in adults, but their performance in children remains incompletely evaluated to date.

OBJECTIVES

To investigate factors influencing results of IFN-γ release assays in children using a large European data set.

METHODS

The Pediatric Tuberculosis Network European Trials group pooled and analyzed data from five sites across Europe comprising 1,128 children who were all investigated for latent tuberculosis infection by tuberculin skin test and at least one IFN-γ release assay. Multivariate analyses examined age, bacillus Calmette-Guérin (BCG) vaccination status, and sex as predictor variables of results. Subgroup analyses included children who were household contacts.

MEASUREMENTS AND MAIN RESULTS

A total of 1,093 children had a QuantiFERON-TB Gold In-Tube assay and 382 had a T-SPOT.TB IFN-γ release assay. Age was positively correlated with a positive blood result (QuantiFERON-TB Gold In-Tube: odds ratio [OR], 1.08 per year increasing age [P < 0.0001]; T-SPOT.TB: OR, 1.14 per year increasing age [P < 0.001]). A positive QuantiFERON-TB Gold In-Tube result was shown by 5.5% of children with a tuberculin skin test result less than 5 mm, by 14.8% if less than 10 mm, and by 20.2% if less than 15 mm. Prior BCG vaccination was associated with a negative IFN-γ release assay result (QuantiFERON-TB Gold In-Tube: OR, 0.41 [P < 0.001]; T-SPOT.TB: OR, 0.41 [P < 0.001]). Young age was a predictor of indeterminate IFN-γ release assay results, but indeterminate rates were low (3.6% in children < 5 yr, 1% in children > 5 yr).

CONCLUSIONS

Our data show that BCG vaccination may be effective in protecting children against Mycobacterium tuberculosis infection. To restrict use of IFN-γ release assays to children with positive skin tests risks underestimating latent infection.

The role of interferon-gamma release assays in the diagnosis of active tuberculosis

BACKGROUND

Interferon-gamma release tests are appealing alternatives to the tuberculin skin test (TST) for latent tuberculosis infection.

OBJECTIVES

To determine the yield of the Quantiferon TB Gold test (QFT-G) in the diagnosis of active tuberculosis disease, with a focus on elderly patients, human immunodeficiency virus (HIV) co-infection, and extra-pulmonary tuberculosis (EPTB).

METHODS

The QFT-G test was performed in 98 patients suspected of having active tuberculosis. The results were evaluated for each subgroup of patients and compared to the results of the TST.

RESULTS

Active tuberculosis was diagnosed in 92 of the 98 patients. Sixteen (17.3%) were elderly patients (over age 70), 15 (16%) were co-infected with HIV, and 14 (15%) had EPTB. QFT-G was positive in 49 patients (53%) and indeterminate in 4. The results were not significantly affected by HIV coinfection (P = 0.17), old age (P = 0.4), orthe presence of EPTB (P = 0.4). There was a good correlation between the TST and the QFT-G test (P < 0.001). In EPTB and in the elderly, the QFT-G test appears to be better than the TST.

CONCLUSIONS

The QFT-G test is suboptimal in its ability to detect active tuberculosis and should not be used to exclude it.

[Tuberculosis in Poland in 2010]

AIM OF THE STUDY

To evaluate the main features of TB epidemiology in 2010 in Poland and to compare with the corresponding EU data.

METHODS

Analysis of case- based clinical and demographic data on TB patients from Central TB Register, of data submitted by laboratories on anti-TB drug susceptibility testing in cases notified in 2010, data from National Institute of Public Health- National Institute of Hygiene on cases of tuberculosis as AIDS-defining disease, from Central Statistical Office on tuberculosis as underlying cause of death based on death certificates, data from ECDC report "Tuberculosis surveillance in Europe 2010".

RESULTS

7509 TB cases were reported in Poland in 2010. The incidence rate was 19.7 cases per 100000, with large variability between voivodeships from 12,8 to 31.9. The mean annual decrease of TB incidence in 2001 - 2010 was 2.9%. 6610 cases had no history of previous treatment i.e. 17.3 per 100000. The number of all notified pulmonary tuberculosis cases was 6992 i.e. 18.3 per 100 000. The proportion ofextrapulmonary tuberculosis was 6.9% (517 cases). TB was diagnosed in 62 children (0.8% of all cases, incidence 1,1). The incidence of tuberculosis increased with age to 34.9 among patients 65 years old and older. The mean age of TB patients was 52.7 years. The incidence among men i.e. 28.0 was more than two times higher than among women i.e. 11.9. The incidence in rural population was slightly lower than in urban, respectively 19.4 and 19.8. Bacteriologically confirmed cases (4585) constituted 65.6% of all pulmonary TB cases. The number of smear positive pulmonary TB cases was 2803 (40.1%). There were 45 cases of tuberculosis registered among foreigners and 215 cases registered among prisoners. There were 30 patients with MDR-TB (0.8% of 3706 cases with DST results). TB was initial AIDS indicative disease in 24 cases. There were 743 deaths due to tuberculosis in 2009 (2.0 TB deaths per 100 000). Mortality among males--3.2--was four times higher than among females--0.8.

CONCLUSIONS

In Poland in the last decade the incidence of tuberculosis has decreased by nearly 30% but is higher than the average in EU countries. In 2010 the highest incidence occurred in older age groups and was higher in men. Positive characteristic also when compared with the situation in many EU countries is the low incidence of tuberculosis in children and the low percentage of patients with drug-resistant tuberculosis.

[Socio-economic status and duration of TB symptoms in males treated at the Mazovian Treatment Centre of Tuberculosis and Lung Diseases in Otwock]

INTRODUCTION

The incidence of tuberculosis depends on many factors, not only on health issues but also on socioeconomic factors. The aim of this study was to assess the duration of symptoms and the extent of radiological changes in men with bacteriologically confirmed pulmonary tuberculosis in relation to their socioeconomic status.

MATERIAL AND METHODS

This was a retrospective study based on the analysis of 300 hospital records of patients hospitalised in 2004-2006 in the male ward of the Mazovian Treatment Centre of Lung Diseases and Tuberculosis in Otwock. In all patients, the diagnosis of tuberculosis was bacteriologically confirmed. We evaluated the duration of symptoms prior to hospitalisation, the extent of radiological changes and socioeconomic status. We also took into account the place of residence, professional activity, age and marital status.

RESULTS

Among patients with TB hospitalised in the Mazovia Region, 74% were professionally inactive persons and 57% were unemployed. Patients population in cities and villages were similar, but as much as 10% of the patients hospitalised who were actively spreading bacilli in Mazovia Region were homeless. In the study group, 60% of the men were unmarried. In 63% of the patients symptoms of tuberculosis were present for more than two months. Chronic symptoms were reported more often in the unemployed (60%) and in single patients. As much as 81% of the patients at the initiation of treatment, had extensive radiological changes in 3 or more lung fields. Quite often sweeping pulmonary changes were observed in the homeless, unemployed and pensioners. Sputum smear-positive tuberculosis, was demonstrated in 87% of the examined patients.

CONCLUSIONS

The incidence of tuberculosis observed in the Mazovia Region was especially observed in the unemployed, disabled and pensioners. Among these patients, many were homeless. The majority of patients in Mazovia Region at the start of treatment already had very extensive radiological changes and the symptoms were present with them for several weeks.

Immunosurveillance for Mycobacterium tuberculosis of health care personnel in a third level care hospital

BACKGROUND

Health care workers are at risk for Mycobacterium tuberculosis (MTB) infection.

OBJECTIVES

To perform an occupational health survey among 621 employees of a 800-bed third level care hospital covered by MTB surveillance.

METHODS

Statistical analysis was applied to results from tuberculin skin test (TST), QuantiFERON - TB Gold in tube assay (QFT), PPD-ELISA for serum antibodies, and occupational or vaccine data.

RESULTS

29.1% of subjects were TST positive, 18.5% were QFT positive. In 23% of subjects no correlation between these tests was found, presumably linked to BCG-vaccination, since TST positivity was 4 times higher among vaccinated subjects, whereas both tests correlated well in unvaccinated subjects. QFT values above 2 IU/ml were significantly associated with positive TST and age over 40 years. Working in MTB risk level 4 was significantly associated with QFT, TST and PPD-antibody levels, suggesting booster effects by repeated exposure. No clear correlation was observed with medical specializations but significantly higher QFTpositivity was found in subjects not assigned to the classical medical professions and originating from MTB high risk areas.

CONCLUSIONS

These results shift the focus on maintenance personnel, who mostly worked in MTB risk level 2 areas. The less positive QFT results in vaccinated subjects highlight QFT's advantage as a screening tool and argue for a protective effect of the BCG-vaccine, although percentages of vaccinated persons varied largely between different medical professions. Interestingly, the percentage of QFT positive persons was lower among subjects reporting MTB exposure than those who were not aware of exposure events.

High annual risk of tuberculosis infection among nursing students in South India: a cohort study

Background

Nurses in developing countries are frequently exposed to infectious tuberculosis (TB) patients, and have a high prevalence of TB infection. To estimate the incidence of new TB infection, we recruited a cohort of young nursing trainees at the Christian Medical College in Southern India. Annual tuberculin skin testing (TST) was conducted to assess the annual risk of TB infection (ARTI) in this cohort.

Methodology/Principal Findings

436 nursing students completed baseline two-step TST testing in 2007 and 217 were TST-negative and therefore eligible for repeat testing in 2008. 181 subjects completed a detailed questionnaire on exposure to tuberculosis from workplace and social contacts. A physician verified the questionnaire and clinical log book and screened the subjects for symptoms of active TB. The majority of nursing students (96.7%) were females, almost 84% were under 22 years of age, and 80% had BCG scars. Among those students who underwent repeat testing in 2008, 14 had TST conversions using the ATS/CDC/IDSA conversion definition of 10 mm or greater increase over baseline. The ARTI was therefore estimated as 7.8% (95%CI: 4.3–12.8%). This was significantly higher than the national average ARTI of 1.5%. Sputum collection and caring for pulmonary TB patients were both high risk activities that were associated with TST conversions in this young nursing cohort.

Conclusions

Our study showed a high ARTI among young nursing trainees, substantially higher than that seen in the general Indian population. Indian healthcare providers and the Indian Revised National TB Control Programme will need to implement internationally recommended TB infection control interventions to protect its health care workforce.

An evaluation of factors associated with taking and responding positive to the tuberculin skin test in individuals with HIV/AIDS

BACKGROUND

The tuberculin skin test (TST) is still the standard test for detecting latent infection by M tuberculosis (LTBI). Given that the Brazilian Health Ministry recommends that the treatment of latent tuberculosis (LTBI) should be guided by the TST results, the present study sets out to describe the coverage of administering the TST in people living with HIV at two referral health centers in the city of Recife, where TST is offered to all patients. In addition, factors associated with the non-application of the test and with positive TST results were also analyzed.

METHODS

A cross-sectional study was carried out with HIV patients, aged 18 years or over, attending outpatient clinics at the Correia Picanço Hospital/SES/PE and the Oswaldo Cruz/UPE University Hospital, who had been recommended to take the TST, in the period between November 2007 and February 2010. Univariate and multivariate logistic regression analyses were carried out to establish associations between the dependent variable - taking the TST (yes/no), at a first stage analysis, and the independent variables, followed by a second stage analysis considering a positive TST as the dependent variable. The odds ratio was calculated as the measure of association and the confidence interval (CI) at 95% as the measure of accuracy of the estimate.

RESULTS

Of the 2,290 patients recruited, 1087 (47.5%) took the TST. Of the 1,087 patients who took the tuberculin skin test, the prevalence of TST ≥ 5 mm was 21.6% among patients with CD4 ≥ 200 and 9.49% among those with CD4 < 200 (p = 0.002). The patients most likely not to take the test were: men, people aged under 39 years, people with low educational levels and crack users. The risk for not taking the TST was statiscally different for health service. Patients who presented better immunity (CD4 ≥ 200) were more than two and a half times more likely to test positive that those with higher levels of immunodeficiency (CD4 < 200).

CONCLUSIONS

Considering that the TST is recommended by the Brazilian health authorities, coverage for taking the test was very low. The most serious implication of this is that LTBI treatment was not carried out for the unidentified TST-positive patients, who may consequently go on to develop TB and eventually die.

Tuberculosis transmission in Kenya: results of the third National Tuberculin Survey

SETTING

Kenya, a country with a high burden of tuberculosis (TB) and human immunodeficiency virus (HIV) infection.

OBJECTIVES

To assess the prevalence of TB infection, bacille Calmette-Guérin (BCG) coverage and the annual risk of tuberculosis infection (ARTI), and to compare estimates with previous findings.

METHODS

A sample of primary school children aged 6-14 years from the same study districts sampled in previous surveys were tuberculin skin tested using the Mantoux method from September 2004 to July 2007. The prevalence of TB infection was estimated by the mirror method, with the mode at 17 mm.

RESULTS

Of the 94 771 registered children, 76 676 (80.9%) completed the survey investigations, 12 107 (15.8%) of whom had no BCG scar. The prevalence of TB infection was estimated at 10.2%, with a corresponding ARTI of 1.1%. The ARTI obtained from the current survey is comparable to that of the 1994-1996 survey and higher than that of the 1986-1990 survey. The BCG coverage was comparable with the 1994-1996 survey and higher than in the 1986-1990 survey.

CONCLUSION

TB transmission in Kenya has remained the same over the last decade, which suggests that activities undertaken by the TB control programme have been sufficient to hold TB transmission steady, but insufficient to reduce it.

Use of the QuantiFERON-TB Gold test to confirm latent tuberculosis infection in a Canadian tuberculosis clinic

SETTING

Capital Health Tuberculosis (TB) Clinic, Edmonton, Alberta, Canada.

OBJECTIVE

To analyze the QuantiFERON-TB Gold In-Tube test (QFT) results after implementation as a routine test for tuberculin skin test (TST) positive patients.

DESIGN

From November 2004 until January 2007, patients who were TST-positive and were eligible for preventive treatment based on Canadian guidelines, were offered a QFT.

RESULTS

Of 1446 TST-positive patients, only 566 (39.6%) were QFT-positive. Categorized by reason for TST testing, 43.1% of 304 contacts, 32.8% of 348 employment screens and 24.2% of 298 post secondary school screens were QFT-positive. In contrast, 59.7% of 290 immigration screens were QFT-positive. A multivariate analysis found that QFT positivity was associated with older age, larger TST size, high-incidence TB region of birth, history of TB and chest X-ray findings suggestive of previous TB.

CONCLUSION

Implementation of the QFT as a secondary test for latent TB infection (LTBI) can significantly reduce the number of patients given LTBI treatment in a low-incidence country such as Canada.

Interpretation of a serial Mantoux test taking into account the annual risk of tuberculous infection

BACKGROUND

Interpretation of tuberculin tests (TSTs) can be difficult. However, it is even more difficult to classify an individual as infected or non-infected if he or she has undergone a prior TST, as the difference between the booster effect and true conversion is not always clear.

OBJECTIVE

To determine the size of the induration that is indicative of true infection after a second Mantoux test, based on the fact that the annual risk of tuberculous infection (ARTI) is equivalent, regardless of whether it is calculated directly or indirectly.

METHOD

We performed two TSTs in the same population (aged 6 years at the first examination) with a 1-year interval. We calculated the prevalence of infection the first year (1.16%, 95%CI 0.67-1.65) and the ARTI using the indirect method (0.18%, 95%CI 0.00-0.37). For the second year, we considered different induration sizes and finally accepted a diameter of >10 mm as the criterion according to which the ARTI, calculated directly, corresponded to the value of the previous year (0.18%).

CONCLUSION

Although they served as an aid in the interpretation of the TST, calculations of this type will probably be unnecessary in the future, when in vitro diagnostic tests for tuberculosis are made available in every health centre, thus enabling the classification of those individuals with indurations of intermediate size in the TST.

Prevalence of tuberculous infection among school children in Kerala

BACKGROUND

There is paucity of information on epidemiological situation of Tuberculosis (TB) in the State of Kerala. The DOTS strategy under the Revised National Tuberculosis Control Programme (RNTCP) was introduced in the year 1998 to cover the entire State by 2002.

OBJECTIVE

To estimate the prevalence of tuberculous infection among children attending 1-4th standard in a sample of selected schools in Kerala.

METHODS

A cluster-sample school-based tuberculin survey was carried out in 70 schools selected by a two-stage sampling procedure. A total of 4821 children (including those with and without BCG scar) in the age group of 5-9 years were tuberculin tested using 1 TU PPD RT23 with Tween 80 and the maximum transverse diameter of induration was measured about 72 hours later. About 81% of the children were found to have BCG scars. Analysis was also undertaken by mixture model.

RESULTS

While 67% of children without BCG scar and 62% with scar did not elicit any induration at the test site, the mode or anti-mode of reactions due to infection with tubercle bacilli could not be identified from the distribution graphs. Analysis by mixture model also did not provide the best fit thus precluding estimation of prevalence of infection. About 5% of children had reactions > or =10 mm, 3% had reactions > or =12 mm and 2% had reactions > or =14 mm.

CONCLUSION

Low proportion of reactors indicated a low level of transmission of infection in Kerala. Considering the problems in interpretation of tuberculin survey data, it may not be feasible to use ARTI as an epidemiological parameter to monitor future trends of TB situation in the state.

Annual risk of tuberculosis infection in Chennai city

AIM

To study the proportion of children infected with Mycobacterium Tuberculosis in Chennai city.

METHODOLOGY

A cluster sampling methodology was adopted to select an estimated sample size of 7000 children from five corporation zones selected systematically from ten zones of the city. A total of 7098 children aged 1-9 years were subjected to Mantoux and test read; 1897 (27%) from slum area and 5201 (73%) from non-slum area.

RESULTS

The prevalence of infection among children without BCG scar was estimated to be 10.5 % (ARTI of 2.0%) and was similar to that among children irrespective of scar status. The prevalence of infection was higher among children in slum areas (11.1%; ARTI 2.1%) compared to non-slum areas (8.9%; ARTI 1.7%); but the difference was not statistically different.

CONCLUSION

The tuberculosis situation in Chennai as measured by risk of infection was higher in urban city area than rural areas and comparable to that found in other cities as reported from earlier studies. This information can be used as baseline information for monitoring the epidemiological trends in Chennai city in future.

Clinico-radiological profile of new smear positive pulmonary tuberculosis cases among young adult and elderly people in a tertiary care hospital at Deheradun (Uttarakhand)

SETTING

Patients of pulmonary tuberculosis (TB) attending the out and in patient department of pulmonary medicine, Himalayan Institute of Medical Sciences (HIMS), a post graduate institute and a large tertiary care center in Dehradun.

OBJECTIVE

To compare the clinico-radiological pattern of pulmonary tuberculosis in the young adult (18-59 years) and elderly (> or = 60 years) patients.

DESIGN

Prospective observational study of pulmonary and associated extra pulmonary tuberculosis cases, diagnosed between October 2005 to September 2006 in pulmonary medicine department of HIMS.

RESULT

Mean age of young adult and elderly patients was 35.71 +/- 5.7 years and 68.57 +/- 3.03 years respectively. Elderly patients had a higher number of co-morbidities like diabetes mellitus, hypertension, and malignancy. Tuberculin positivity was less among elderly patients (36.0%) as compared to young adults (65.9%). Hemoptysis (29.5% vs. 6%), fever (95.4% vs. 76%) and night sweats (54.5% vs. 18.0%) were significantly higher in the young adult patients than the elderly. As for roentgenographic abnormalities, a higher involvement of lower zone (24.0% vs. 7.9%) and far advanced lesions (32.0% vs. 14.7%) were seen in the elderly patients as compared to young adults. The elderly showed a higher frequency of TB related mortality (8% vs. 1.1%) and associated extra pulmonary involvement (40% vs. 7%).

CONCLUSION

Young adults are more likely to have hemoptysis, night sweats and positive PPD response while lower lung field involvement is more common in elderly.

Prevalence of positive tuberculin skin tests in foreign-born children

AIMS

To evaluate the prevalence of positive tuberculin skin tests (TST) in internationally adopted and immigrant children. To identify risk factors for positive TST in these populations.

METHODS

The study was a retrospective medical record review in a tertiary care pediatric hospital. All children evaluated at the International Adoption and Immigrant Health Clinic of CHU Sainte-Justine in Montreal, Canada, between 01-01-1998 and 31-12-2001 were included. Demographic and anthropometrical data, BCG vaccination, TST, chest X-ray results and treatment were extracted from the medical records of the patients and analyzed. Positive TST was defined as induration = 10 mm, 48 to 72 hours after injection of five tuberculin units of purified protein derivate.

RESULTS

Our population included 670 children: 112 immigrants and 558 adoptees. Median age was 6.9 years for immigrants and 1.1 years for adopted children. Overall incidence of positive TST was 12.2% in our cohort: 31% in the immigrant and 8% in the adopted children groups. There was one case of active tuberculosis. Older age on arrival in Canada and BCG vaccination were identified as risk factors for positive TST in our multivariate model. For each one-year increase in age on arrival in Canada, there was a 1.2 times greater risk for positive TST.

CONCLUSIONS

Latent tuberculosis is a frequent problem in foreign-born children. The higher incidence in immigrant children can be explained by older age on arrival.

Reliability of control skin tests with common antigens in children undergoing tuberculin skin test

The aim of this study was to determine the reliability of skin tests with common antigens as a measure of delayed-type hypersensitivity response in children undergoing tuberculin skin test (TST). Children from developing countries underwent TST as well as skin tests with diphtheria-tetanus vaccine (DT) and candida antigens prior to heart surgery. We included 52 children (mean age: 7.16 years). Forty-two (81%) and 20 of the 52 patients (38%) reacted to the DT and candida skin tests, respectively (P < 0.001 for the difference in response to these antigens). There was no difference in response to candida and DT antigens between patients with positive or negative TST. There was no difference between patients aged 6 years or older compared to younger patients in the response to DT or candida antigen. Skin tests with common antigens are associated with a high false-negative rate and may not predict reliably a state of anergy.

The effect of open heart surgery on tuberculin skin test reactivity

To examine whether treatment with cardiopulmonary bypass (CPB), which causes transient cellular immunity depression, influences tuberculin skin testing (TST) interpretation. The study was also aimed to assess the degree of cellular immunity depression following open heart surgery. Fifteen children from developing countries with latent tuberculosis (TST >or=10 mm), undergoing open heart surgery had their TST repeated within 48-72 h following surgery. We compared the size of skin test induration before and after surgery and the relation of postsurgery skin induration to time on CPB (pump time). There was no significant difference in the size of induration before and after surgery (mean: 14.7 mm versus 13 mm, respectively). Pump time ranged from 38 to 204 min (mean: 110 min). Two of the children had pump time over 3 h. The TST of both of them turned negative after surgery, as opposed to all other children (P = 0.01). Most patients retained skin test reactivity. Only patients with pump time longer than 3 h had a negative TST.

Tuberculin skin test size and risk of tuberculosis development: a large population-based study in contacts

SETTING

Contacts of tuberculosis (TB) cases identified from eight Provincial databases in British Columbia, Canada, between 1990 and 2000.

OBJECTIVE

To assess the risk of developing TB based on tuberculin skin test (TST) sizes in contacts of TB cases who did not receive treatment for latent TB infection.

DESIGN

Retrospective, population-based cohort study with a 12-year follow-up.

RESULTS

Among 26,542 contacts, 180 individuals developed TB (TB rate 678/100,000). Household contacts with a TST size 0-4 mm had a TB rate of 1014/100,000, those with 5-9 mm a TB rate of 2162/100,000 and those with 10-14 mm a rate of 4478/100,000. Children aged 0-10 years with 0-4 mm had a TB rate of 806/100,000, those with 5-9 mm a TB rate of 5556/100,000 and those with 10-14 mm a rate of 42,424/100,000. Immunosuppressed contacts with TST sizes 0-4 mm had a TB rate of 630/100,000, those with 5-9 mm a TB rate of 1923/100,000, and those with 10-14 mm a rate of 1770/100,000.

CONCLUSIONS

TB rates were high for all TST sizes in household contacts, 0-10 year old contacts and immunosuppressed contacts. These contacts may benefit from treatment for latent TB infection, regardless of the size of their TST.

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.

Tuberculin testing to detect latent tuberculosis in developing countries

Despite the multiple studies done over several decades that have established the utility of the tuberculin skin test (TST) for the diagnosis of latent tuberculosis, the test is rarely used in developing countries experiencing a resurgence of tuberculosis. Nevertheless, several clinical trials have found that treatment of HIV-positive or HIV-negative persons with latent tuberculosis is effective in the prevention of the clinical activation of tuberculosis. Clinicians commonly justify their failure to diagnose and treat latent tuberculosis with the belief that BCG vaccine, even when it is used in infancy, will cause false positive reactivity in the TST. The important study by Gustafson and colleagues from Guinea-Bissau in this issue of the journal refutes this belief. In this study only persons with a history of BCG who also had household contact with an active case of tuberculosis had increased rates of TST positivity. Although the current emphasis is on directly observed therapy, short course (DOTS) to control tuberculosis is necessary and critically important, it is not always sufficient to control the tuberculosis epidemic in some countries with major epidemics of HIV. In many of these countries, early diagnosis of active tuberculosis and prevention of activation of latent tuberculosis will also be needed. The evidence from the Guinea-Bissau study suggests that a history of BCG vaccination should not be an obstacle to the diagnosis and treatment of latent tuberculosis.

Educational outreach to promote screening for tuberculosis in primary care: a cluster randomised controlled trial

BACKGROUND

Tuberculosis is re-emerging as an important health problem in industrialised countries. Uncertainty surrounds the effect of public-health control options. We therefore aimed to assess a programme to promote screening for tuberculosis in a UK primary health care district.

METHODS

In a cluster randomised controlled trial, we randomised 50 of 52 (96%) eligible general practices in Hackney, London, UK, to receive an outreach programme that promoted screening for tuberculosis in people registering in primary care, or to continue with usual care. Screening was verbal, and proceeded to tuberculin skin testing, if appropriate. The primary outcome was the proportion of new cases of active tuberculosis identified in primary care. Analyses were done on an intention-to-treat basis. This study was registered at clinicaltrials.gov, number NCT00214708.

FINDINGS

Between June 1, 2002, and Oct 1, 2004, 44,986 and 48,984 patients registered with intervention and control practices, respectively. In intervention practices 57% (13,478 of 23,573) of people attending a registration health check were screened for tuberculosis compared with 0.4% (84 of 23 051) in control practices. Intervention practices showed increases in the diagnosis of active tuberculosis cases in primary care compared with control practices (66/141 [47%] vs 54/157 [34%], odds ratio (OR) 1.68, 95% CI 1.05-2.68, p=0.03). Intervention practices also had increases in diagnosis of latent tuberculosis (11/59 [19%] vs 5/68 [9%], OR 3.00, 0.98-9.20, p=0.055) and BCG coverage (mean BCG rate 26.8/1000 vs 3.8/1000, intervention rate ratio 9.52, 4.0-22.7, p<0.001).

INTERPRETATION

Our educational intervention for promotion of screening for tuberculosis in primary care improved identification of active and latent tuberculosis, and increased BCG coverage. Yield from screening was low, but was augmented by improved case-finding. Screening programmes in primary care should be considered as part of tuberculosis control initiatives in industrialised countries.

Nursing and Community Rates of Mycobacterium tuberculosis Infection among Students in Harare, Zimbabwe

BACKGROUND

African hospitals have experienced major increases in admissions for tuberculosis, but they are ill-equipped to prevent institutional transmission. We compared institutional rates and community rates of tuberculin skin test (TST) conversion in Harare, Zimbabwe.

METHODS

We conducted a cohort study of TST conversion 6, 12, and 18 months into training among 159 nursing and 195 polytechnic school students in Harare. Students had negative TST results (induration diameter, < or =9 mm) with 2-step testing at the start of training.

RESULTS

Nursing students experienced 19.3 TST conversions (increase in induration diameter, > or =10 mm) per 100 person-years (95% confidence interval [CI], 14.2-26.2 conversions per 100 person-years), and polytechnic school students experienced 6.0 (95% CI, 3.5-10.4) conversions per 100 person-years. The rate of difference was 13.2 conversions (95% CI, 6.5-20.0) per 100 person-years. With a more stringent definition of conversion (increase in the induration diameter of > or =10 mm to at least 15 mm), which is likely to increase specificity but decrease sensitivity, conversion rates were 12.5 and 2.8 conversions per 100 person-years in nursing and polytechnic school students, respectively (rate difference, 9.7 conversions per 100 person-years; 95% CI, 4.5-14.8 conversions per 100 person-years). Nursing students reportedly nursed 20,868 inpatients with tuberculosis during 315 person-years of training.

CONCLUSIONS

Both groups had high TST conversion rates, but the extremely high rates among nursing students imply high occupational exposure to Mycobacterium tuberculosis. Intense exposure to inpatients with tuberculosis was reported during training. Better prevention, surveillance, and management of institutional M. tuberculosis transmission need to be supported as part of the international response to the severe human immunodeficiency virus infection epidemic and health care worker crisis in Africa.

Surprisingly high specificity of the PPD skin test for M. tuberculosis infection from recent exposure in The Gambia

Background

Options for intervention against Mycobacterium tuberculosis infection are limited by the diagnostic tools available. The Purified Protein Derivative (PPD) skin test is thought to be non-specific, especially in tropical settings. We compared the PPD skin test with an ELISPOT test in The Gambia.

Methodology/Principal Findings

Household contacts over six months of age of sputum smear positive TB cases and community controls were recruited. They underwent a PPD skin test and an ELISPOT test for the T cell response to PPD and ESAT-6/CFP10 antigens. Responsiveness to M. tuberculosis exposure was analysed according to sleeping proximity to an index case using logistic regression. 615 household contacts and 105 community controls were recruited. All three tests assessed increased significantly in positivity with increasing M. tuberculosis exposure, the PPD skin test most dramatically (OR 15.7; 95% CI 6.6–35.3). While the PPD skin test positivity continued to trend downwards in the community with increasing distance from a known case (61.9% to 14.3%), the PPD and ESAT-6/CFP-10 ELISPOT positivity did not. The PPD skin test was more in agreement with ESAT-6/CFP-10 ELISPOT (75%, p = 0.01) than the PPD ELISPOT (53%, p<0.0001). With increasing M. tuberculosis exposure, the proportion of ESAT-6/CFP-10 positive contacts who were PPD skin test positive increased (p<0.0001), and the proportion of ESAT-6/CFP-10 negative contacts that were PPD skin test negative decreased (p<0.0001); the converse did not occur.

Conclusions/Significance

The PPD skin test has surprisingly high specificity for M. tuberculosis infection from recent exposure in The Gambia. In this setting, anti-tuberculous prophylaxis in PPD skin test positive individuals should be revisited.