Comparison of tuberculosis surveillance systems in low-incidence industrialised countries.

The comparative analysis of National Tuberculosis Control Programmes (NTPs) in industrialised, low-tuberculosis-incidence countries is limited. Analysis of applied methods, function and accumulated experience contributes to improving global tuberculosis control. A questionnaire addressing NTP surveillance infrastructure and characteristics was completed in 19 industrialised countries, with populations of >3 million and annual notified tuberculosis incidence rates of <16 cases per 100,000 population (2003 data). All European countries surveyed adopted World Health Organization Collaborating Centre for the Surveillance of Tuberculosis in Europe (EuroTB) definitions. Surveillance information, which usually includes names, was transferred electronically to the national level in 17 out of the 19 countries. Surveillance systems capture process and social determinants. Case notification to the central level occurred within a median period of 7 days, independent of mandatory notification requirements. The mean completeness of tuberculosis case-reporting was estimated to be 93.5% (range 65-100%). Integration between HIV and tuberculosis registries was performed in two countries, and, in seven others, both databases were cross-matched periodically. National Tuberculosis Control Programme function in industrialised low-incidence countries utilises well-established infrastructure and relies upon centralised operations. Approaches are consistent with current World Health Organization surveillance recommendations. The present study lays collaborative groundwork for additional multinational analyses for the enhancement of global tuberculosis surveillance, which may assist policy-makers in countries moving from medium to low rates of incidence.

[How to continue in the treatment of tuberculosis in the Czech Republic?]. / Jak pokracovat v dalsím zdolávání tuberkulózy u nás?

BACKGROUND: The Czech Republic belongs to low TB burden countries in last years with incidence around 10/100,000. In such countries TB control consist in not only finding and effective treatment of new TB cases but in identification and containment of pool for new TB cases (latent or subclinical TB infection-LTBI) as well. Recently amended recommendations for TB control in other low TB burden countries, US and England and Wales, were published. The objective of the paper was to determine which of the amended recommendations could be used in our country. METHODS AND RESULTS: In England and Wales the BCG vaccination is recommended only in newborns from families with higher TB risk. In these groups it is necessary to seek out new TB cases as well. In TB diagnostic, emphasis is now placed in England and Wales and also in the US on the use of several diagnostic methods. Drug use self check is more appropriate in all health responsible patients. Liquid drug forms or fixed-dose combination tablets are recommended as well. In both above mentioned countries the LTBI diagnostic is done either by tuberculin skin tests (TST) or by in vitro immunological IGRA tests. In England and Wales positive TST is followed by IGRA test, in the U.S. either TST or IGRA test is recommended. LTBI persons are preventively treated. CONCLUSIONS: In the Czech Republic the introduction of IGRA tests for LTBI diagnostic should have, due to the BCG policy, even higher benefit. Introduction of IGRA tests seems to be inevitable. Persons with supposed LTBI should be offered either preventive treatment or intensive follow up care with the objective to detect early even incipient signs of TB. As TB develops most often soon after LTBI conception this follow up care should last several years after LTBI detection.

[Tuberculosis in the Czech Republic in 2002]. / Hodnocení situace tuberkulózy v Ceské republice v roce 2002.

BACKGROUND: The number of all notified TB cases decreased in the year 2002. 1200 (11.8/100,000) cases of new TB diseases and relapses were reported in the year 2002. 972(9.6/100,000) were pulmonary TB and from them 658 (6.4/100,000) were confirmed pulmonary cases. METHODS AND RESULTS: The decreasing trend in TB incidence, reported since 1999, has continued. The treatment of confirmed pulmonary cases notified in 2001 and evaluated in 2002 was effective. Treatment success was in 71% of cases, but failures and interrupted were only 3.3%. Results of treatment were affected by many patients who died for other reason then TB, because they were from the oldest group of population. We have no influence on these deaths. The resistance for AT drugs was less then 7% and MDR cases were less the 2%. CONCLUSION: The low level of resistance and the effectiveness of treatment allow presuming a further decrease of TB cases. Next target of TB control should be active case finding in high-risk groups and monitoring latent infection.

[Tuberculosis in the Czech Republic in the year 2000]. / Tuberkulóza v Ceské republice v roce 2000.

BACKGROUND: Incidence of tuberculosis (TB) in the Czech Republic (CR) during the year 2000 was evaluated on the basis of newly detected cases as well the restriction of known TB sources by antituberculosis treatment. Data from compulsory reported TB cases in the TB register for the year 2000 were used as well as data from the analysis of treatment in cohorts of patients reported quarterly in 1999 and evaluated 12 months later. METHODS AND RESULTS: 1442 cases of new diseases and TB relapses were reported in 2000 (14.1/100,00). 1244 cases (12.1/100,000) were TB of the respiratory system, 198 cases (2.0/100,000) belonged to the extra-respiratory TB. 61.9% of cases were bacteriologically verified TB of the respiratory system. In comparison with the year 1999, the number of TB cases was lower by 11.7%, respectively by 9.3% in TB of the respiratory system. The positive trend in TB incidence recorded in CR since 1998 has continued. From 1442 cases of the TB, 916 were males (63.5%) and 526 females (36.5%). Majority of patients was older than 65 years. 143 (9.9%) of TB cases were patients born extra CR ("foreigners"), namely coming from Ukraine (41), Vietnam (16), and Romania (14). 74 patients died of tuberculosis, mostly those older than 65 years. The youngest was the 24-year-old Ukrainian and a 38 year old homeless person, the citizen of CR. The highest incidence of TB was in West Bohemia, in Prague and in North Moravia; the lowest incidence was in South Moravia and in South Bohemia. TB was identified because of patient's troubles (68.0%), in the risk groups (13.3%), and by examination of contact persons (4.7%). Other mycobacteriosis than TB was identified in 92 patients. The treatment was evaluated in 606 persons with the pulmonary TB, which was bacteriologically verified; analysis was done in cohorts of patients reported quarterly in 1999. 70.1 to 77.5% of patients in individual cohorts were successfully treated, in 3 patients the treatment failed and 9 patients interrupted the treatment. Remaining 25% of patients either died before or during the treatment. The high mortality rate resulted from the high age and other diseases in some of the patients. CONCLUSIONS: WHO includes CR between countries with low TB incidence. Within the stabile population of CR the continuous decrease of TB incidence should continue, unless some unfavourable effects occur.

Implementation of the DOTS strategy for tuberculosis in the Leningrad Region, Russian Federation (1998-1999).

SETTING: The DOTS pilot project for tuberculosis control in the Leningrad Region of the Russian Federation, supported by the Finnish Lung Health Association and the World Health Organization (WHO). OBJECTIVE: To assess the efficacy of WHO-recommended standard short-course chemotherapy in newly detected pulmonary tuberculosis cases positive by smear or with extensive lung lesions suggestive of culture positivity, under project conditions. METHODS: Analysis of data on case detection, sputum smear conversion and treatment outcome based on standardised (WHO) registers from districts and a central computerised database. RESULTS: Of 859 adult pulmonary tuberculosis cases (292 smear-positive) notified in the Leningrad Region in the study period, 312 new cases were included in the project. The sputum conversion rate at the end of the second month was 82.8% and 91.1% at the end of the third month. Of bacteriologically confirmed cases, 71.3% were successfully treated, 4.9% died, 11.7% defaulted and 8.1% failed. CONCLUSION: In the first year of the pilot project in the Leningrad Region, the DOTS strategy revealed feasibility and moderate efficacy among new pulmonary tuberculosis cases who were either smear-positive or showed extensive lung lesions on chest X-ray, and who were therefore of high epidemiological and medical priority.

[Multiresistant tuberculosis in the Czech Republic in 1998 and causes of its occurrence]. / Multirezistentní tuberkulóza v Ceské republice v roce 1998 a príciny jejího vzniku.

Multidrug resistant tuberculosis (MDR-TB) belongs to the most serious forms of TB. The number of MDR-TB patients represents an indicator of the effectiveness of TB regimentation. The aim of the study was to determine the number of registered MDR-TB patients in CR in 1998 and to identify causes of the resistance. Analysis of clinical documentation of 27 patients with MDR-TB positive sputum was done in 1998. According to the documentation, this form of tuberculosis was not confirmed in 5 persons. Out of 22 patients with confirmed MDR-TB, 21 were males and one female. In 3 of them we could not reveal whether they had been cured with antituberculotics before MDR-TB developed. Such resistance was then classified as an initial form. In 19 patients we found that resistance developed during treatment. Those cases were classified as secondary forms. In 16 patients the secondary resistance was related to the interruption of treatment, which was done wantonly by the patients in 14 cases. The consistent treatment of the sensitive TB is therefore the best prevention for MDR-TB development. Incidence of MDR-TB cases has not been influenced by immigration from countries with high rate of occurrence of MDR-TB.

Is quarterly cohort analysis useful for assessing treatment outcomes in a low incidence country?

SETTING: In the Czech Republic, a country regarded as having a low incidence of tuberculosis (TB), short-course chemotherapy (SCC) of TB has been implemented in routine practice country-wide. OBJECTIVE: To assess the outcome of SCC by quarterly cohort analysis of patients using the methodology recommended by the World Health Organization (WHO). DESIGN: Patients with newly detected bacteriologically confirmed pulmonary TB notified in 1998 were treated according to local recommendations (SCC) or with the WHO-recommended DOTS strategy. The type of chemotherapy and its outcome were evaluated 12 months later by quarterly cohort analysis. RESULTS: A total of 731 patients with bacteriologically confirmed pulmonary TB, 403 of them smear-positive, were assessed. The proportion of those treated under the DOTS strategy increased from 56.2% to 75.1%. Favourable treatment outcomes (cure or treatment completed) were achieved in 69.0% of patients in the first quarter and 74.0% in the fourth quarter. Only four treatment failures and 21 defaulters were recorded. A total of 129 patients (15-21% in different cohorts) died before or during treatment, mostly from causes not connected with TB. If this proportion were not taken into account, treatment efficacy would have attained 85%. CONCLUSIONS: Analysis of SCC based on quarterly cohorts proved feasible in routine conditions in a country with a low incidence of TB and ongoing TB control, and provided more information than once yearly analysis.

Screening of TB contacts by tuberculin skin tests in a low-incidence community by BCG vaccination.

A 36-year-old man, an unemployed waiter, a regular patron of two bars living in a Czech city suffered for about a year from disorders caused probably by tuberculosis (TB). When hospitalised, diabetes mellitus and extensive lung TB were diagnosed. TB was found also at the post mortem examination when the patient died one week later. Screening of his contacts by tuberculin skin tests (2TU RT23 W. Tw.80) provided data for analyzing the usefulness of tuberculin tests for monitoring of propagation of TB infection among BCG vaccinated population with high TB prevalence in the A statistically significant difference was found in tuberculin reactivity between 543 contacts and 232 individuals who had not reported contact with, the patient. A skin reaction of 12 mm and more was found in 55.6% contacts while only in 2.6% of those included in the second group. The high tuberculin reactivity was proved in the individuals exposed to massive TB infection. Neither BCG vaccination, nor possible previous contact with TB in the past seemed to influence the actual tuberculin reactivity in the group of non-contacts. Furthermore, it is indicative of the fact that unknown TB sources are rare among the Czech population. The high tuberculin reactivity is suggestive of a fresh infection and justifies the tuberculin testing and the application of chemoprophylaxis.

[Tuberculosis in the Czech Republic in 1998]. / Situace tuberkulózy v Ceské Republice v roce 1998.

In Czech Republic (CR) the epidemiological situation in tuberculosis (TB) was evaluated in 1998 using the notification TB into the TB register. 1805 new TB cases and relapses were notified (17.5/100,000 citizens). Majority TB cases, 1535 (14.9/100,000 citizens) were of the respiratory system and 270 TB cases were in other localized Two thirds (988 cases = 9.6/100,000 citizens) of the respiratory system TB, were bacteriologically verified thereout 564 direct smear positive. Patients with lung TB only were 10% less frequent than those with respiratory system TB. 69 TB cases were identified in foreigners. Relapse of TB was found in 66 patients. Among the notified TB cases were 62.9% of males and 37.1% females. In both sexes patients over 70 predominated. In the medium age category males also prevailed. Due to subjective troubles of patients TB was passively identified in 72.2%, actively by the physician 12.9% were identified. Late TB diagnosis during section occurred at 5.4% of patients. During the last 9 years annual number of notified patients has not changed. Only the number of bacteriologically verified cases of the respiratory system TB decreased and number of not verified cases increased. Decease due to TB was notified in 73 (0.7/100,000 citizens) usually old patients. In 67 patients TB was diagnosed premortally or at section. Differences in TB prevalence were found in different regions. Higher numbers of the TB patients than in average for the whole state were found in Prague, northern and western Bohemia and in northern Moravia. 112 new cases and relapses of MOTT were reported in 1998. Notification of TB in CR was on a good level. State of TB morbidity was stabilised and under control. However, the decrease of numbers of bacteriologically verified cases and increase of not verified ones, causes of occurrence of microscopically positive diseases will be necessary to analyse and groups which will require higher dispensary care have to be recognised.

[Tuberculosis in the Czech Republic in 1999]. / Tuberkulóza v Ceské republice v roce 1999.

Report is given on the tuberculosis (TB) prevalence and the new diseases monitoring in Czech Republic (CR) in 1999 using the register of notifiable TB diseases. 1631 new TB cases and relapse were notified (15.9/100,000 citizens). Majority TB cases, 1369 (13.3/100,000 citizens) were of the respiratory system and 262 TB cases were in other locations. 63% of the respiratory system diseases were bacteriologically verified. In comparison with the year 1998, the number of newly notified TB patients was 9.6% lower, number of TB cases of the respiratory system which were bacteriologically verified was 12.3% lower, cases of microscopically positive TB were 17.4% less frequent. Among the notified TB patients there were 91 foreigners. TB relapse was identified in 61 patients. Among the notified TB cases, 987 (60.5%) were males and 644 (39.5%) were females. In both sexes patients over 65 predominated. Prevalence of TB cases higher than the average for the whole state was found in Prague, northern and western Bohemia. Groups with TB prevalence higher than 50/100,000 citizens were identified (the risk groups). They include homeless people, drug addicts, asylum applicants, and prisoners. Due to subjective troubles of patients TB was diagnosed in 70.2% cases, by active investigation in 13.9% patients. Late TB diagnosis at autopsy came in 6.8% cases. Decease due to TB was notified in 79 patients. In 77 of them TB had not been diagnosed premortally. 106 new cases and relapses of non-TB mycobacterial disease were notified in 1999. The case of tuberculosis in CR was in 1999 restrainable. In comparison with 1998 significant decrease of TB prevalence in individual subgroups of TB disease was described (10 to 17%). Also the decrease of the long-term trend (10 years) of newly notified TB patients and TB of the respiratory system was depicted. It is necessary to maintain the quality and extend of the TB control program in order to prevent the new outbreak of TB disease.

[Tuberculosis in the Czech Republic in 1997]. / Tuberkulóza v Ceské Republice v roce 1997.

In the Czech Republic in 1997 1834 new cases of TB and relapses were notified, i.e. 17.8 patients per 100,000 population. This number comprised 1557 cases of TB of respiratory tract (15.1 patients per 100,000 population). By bacteriological examination 952 new cases of respiratory TB were confirmed (9.2 per 100,000 population) whereby in 524 patients the sputum was direct smear positive. There were 277 (2.7/100,000) extrapulmonary forms. TB was were in 1997 the cause of death of 62 patients (0.6/100,000). These numbers did not differ significantly from data recorded in 1990-1996 and we may conclude from them that the stagnating character of TB persists. Newly detected cases of pulmonary TB (affection of the pulmonary parenchyma only) were recorded in 1328 patients. The notifications made it possible to create a set of direct and indirect epidemiological indicators (age distribution, TB mortality) which made it possible to provide evidence that in this country the validity-notification did not change substantially in recent years.

Tuberculosis control and surveillance in changing health reform in the Czech Republic.

In the Czech Republic a centralized, governmentally budgeted and vertically structured health system has been reformed to a liberalized health system with fragmentation of organisation, responsibilities and funding after 1989. Tuberculosis (TB) control and TB surveillance followed the general health system reform and implementation of liberalized health insurance system. In the liberalized health system the feasibility and accessibility of methods of TB control rather improved. In contrary to that TB surveillance in the liberalized system suffered bu absence of vertical mechanisms ensuring the completeness and validity of data collected in a centralised notification system (recording and reporting system). The rate of control notification dropped up to 50%. TB surveillance was therefore supplemented in 1996 by vertically oriented mechanisms of the hygienic (public health) service. TB consultants were appointed at regional and mostly also on district level as part-time jobs of the hygienic service and entitled to supervise all notifications from the given region (district), particularly what regards completeness of bacteriological data. As a consequence complete and reliable reports on epidemiological situation are issued and an assessment of antituberculous chemotherapy of new TB cases is made by a regional cohort analysis starting 1st quarter 1998. TB situation in the Czech republic is regarded as stable, being under control, with a decreasing trend of bacteriologically confirmed TB cases and increasing trend of bacteriologically not confirmed pulmonary TB. The TB is slowly shifting to high risk groups of population.

A cost-benefit analysis of BCG revaccination in the Czech Republic.

We assessed the direct and indirect economic costs and benefits of the current policy of revaccinating tuberculin-negative schoolchildren in the Czech Republic. The analysis is conducted from the perspective of the payer for health care. In considering whether revaccination should be discontinued, we consistently made assumptions which tend to favor revaccination. The direct costs of revaccination are estimated at Czech Koruna (KCR) 15.0 million (US$0.46 million) annually. The direct benefits are the treatment costs saved for future cases averted by revaccination. These range from KCR 0.5 million (US$0.015 million, ambulatory care, excluding transmission benefits) to KCR 13.7 million (US$0.4 million, hospitalization, including transmission benefits). Costs exceed benefits even if children are revaccinated without prior tuberculin testing. The major indirect cost is the loss of work output attributable to tuberculosis morbidity. Counting the averted loss in output as a benefit does not change the results qualitatively, although there is a 50% chance that the benefits will be greater than costs if treatment continues to be hospital-based. Thus, the costs of revaccination in the Czech Republic are found to exceed benefits over most, plausible variations in parameter values. The cost-benefit ratio is especially large if patients are given ambulatory treatment, as recommended by the World Health Organization.

Survey of BCG vaccination policy in Europe: 1994-96.

A retrospective survey, based on a standardized questionnaire sent to qualified public health experts in tuberculosis in 50 European countries, was carried out to evaluate the following: concordance between national vaccination programmes and WHO recommendations on BCG vaccination for prevention of tuberculosis; relation between BCG vaccination and revaccination policy and the tuberculosis epidemiological situation; and differences in BCG vaccination policy between Western and Central-Eastern European countries. The results obtained (from 41 (82%) of the 50 countries) revealed that BCG vaccination programmes met WHO recommendations in 44% of European countries. Mass primary vaccination and general revaccination were extremely common in countries where the prevalence of tuberculosis was high. A highly significant difference was found between Western and Central-Eastern European countries in terms of their adhesion to WHO recommendations. Within Central-Eastern Europe no difference was found between countries that had or had not been part of the former Soviet Union. The implementation of WHO recommendations into national tuberculosis programmes must be intensified, based on the available body of evidence. Preventive methods whose cost-effectiveness has not been properly established should be discouraged.

[Tuberculosis in the Czech Republic in 1994. Does compulsory notification give a true picture of tuberculosis morbidity?]. / Tuberkulóza v Ceské republic v roce 1994. Je notifikace v povinných hláseních skutecným obrazem nemocnosti na tuberkulózu?

In the Czech Republic in 1994 a total of 1960 new cases of TB of all forms and localizations were notified, i.e. 19.0 patients per 100,000 population. This number comprised 1644 cases of TB of the respiratory system (15.2 patients/100 000 population). Bacteriological tests were made in 1058 new cases of respiratory TB (10.2/100,000, whereby in 524 patients in sputum acid resistant rods were detected under the microscope. Extrapulmonary forms accounted for 16% of all notified cases of TB and relapses of TB accounted for less than 3% of the total number of notified cases. The TB mortality varied near 0.8 deaths/100,000 population. These numbers did not differ significantly from data for 1992 and 1993 and it may be concluded that the stagnating trend of tuberculosis in this country persists. The notified data made it possible to create a set of direct and indirect epidemiological indicators (age distribution, notifications, prevalence of severe forms, regional distribution, mortality rate and comparison of hospital admission on account of TB), which helped to show that the validity of notification has not changed much in recent years. The data assembled in notifications can therefore be used for comparative studies and they can be considered a measure of the TB morbidity. However, every evaluation of morbidity based on notification cells for verification of the validity of the presented data.

[Tuberculosis in Central Europe. Comparison of the present situation and development of tuberculosis in the Czech Republic and in Germany 1991-1993]. / Tuberkulóza ve Strední Evrope. Porovnání soucasné situace a vývoje tuberkulózy v Ceské republice a ve Spolkové republice Nemecko v letech 1991-1993.

Comparison of the position as regards tuberculosis in the Czech Republic (CR) and in the Federal German Republic (FRG), two neighbouring countries of the Central European region was made possible by an approximation of systems of health services in the two countries and by the common effort to standardize definitions of indicators of the epidemiological situation as regards tuberculosis according to international recommendations. The relative number of newly assessed diseases of all forms and at all sites was equal in the two countries in 1993 and did not differ significantly during the past three years. No significant differences were found on comparison of indicators of incidence classified by bacteriological confirmation, site and age distribution. In the GRF the position as regards TB during the past three years is considered stabilized without apparent changes; the same applies also to the CR. In the GRF TB in the domestic population (German population) and foreigners is evaluated separately, as foreigners account for 7.3% of the prevalence. Tuberculosis of foreigners influences in a significant way the general incidence in the GRF, in particular in younger age groups. It is due to the adverse situation as regards TB in countries from which immigrants come. Logistic comparison of indicators of the incidence revealed that the traditional stabilized system of health services in the GRF as well as the newly introduced system in the CR are biased by the same error as regards mandatory notification of all new cases of TB. The findings make it possible to assess priorities specific for the Central European area in the amended system of surveillance of TB in the CR.

Validation of the surveillance system for new cases of tuberculosis in a province of northern Italy. Varese Tuberculosis Study Group.

In Italy tuberculosis (TB) surveillance is hampered by several problems (inconsistency of data and underreporting). A tuberculosis surveillance system was established in Varese Province (VSS) in 1992. The aim of the present study was, using VSS, to estimate: 1) coverage and validity of data collected by the national Compulsory Surveillance System (CSS); 2) validity of diagnosis and risk factors for tuberculosis; 3) tuberculosis incidence. A specifically designed form, including the same items as the CSS form and 10 more questions on risk factors and diagnostic issue, was completed in all the existing health facilities in the province for each new tuberculosis case diagnosed, collected by the study co-ordinator during monthly supervision after a review of clinical records, and stored in a database at the co-ordinating centre. Routine notifications collected at national level by CSS for the province were nominally linked with VSS data. To evaluate coverage and data validity, a comparison was made between VSS and CSS data after removal of duplicates. Quality of data, risk factors and incidence were evaluated on VSS data (gold standard). CSS coverage was 63% with a significant underreporting of extrapulmonary cases. Within CSS, 20% of data were missing (particularly diagnostic information: 42-72%). According to VSS, smear was performed on 88% of cases and culture on 66%. Half of the cases had no risk factors. The overall incidence of tuberculosis in Varese Province was 15 per 100,000. We estimated the coverage and validity of the data collected by CSS, validity of diagnosis, risk factors for and incidence of tuberculosis and proposed several suggestions to improve CSS nationwide.

Six years' experience with the discontinuation of BCG vaccination. 4. Protective effect of BCG vaccination against the Mycobacterium avium intracellulare complex.

SETTING: In 1986, mass BCG vaccination of newborns was discontinued in an extensive territorial sample of neonates in the Czech Republic (30,000 infants annually). The non-vaccinated children have since been tuberculin tested at two-year intervals; those with continual or repeated intensive contact with animals in households or on farms were also tested with Mycobacterium avium intracellulare complex sensitin in addition to tuberculin. OBJECTIVE: Within the frame work of the surveillance programme the incidence of infection and disease caused by M. avium intracellulare complex (M. avium complex) was evaluated and the protective effect of BCG vaccination analysed. DESIGN: In 1986-93, out of 190,874 non-vaccinated children, 36 were found to be infected by M. avium complex; 27 of them developed disease, i.e. mycobacteriosis other than tuberculosis (MOTT). RESULTS: The annual risk of infection with M. avium complex was 4.8/100,000 children per year, of whom 3.6/100,000 developed mycobacteriosis. 24 patients suffered from swelling of cervical lymph nodes, 2 of mediastinal lymph nodes and one child had the disease localized both in cervical and mediastinal lymph nodes. The disease was verified bacteriologically in 9 children. Most of the diseased children had impaired immunity; a marked skin reactivity of M. avium complex sensitin was present in all infected children. Animal sources infected by M. avium complex were detected in 5 cases. Another 14 children also had close contact with animals but without proven M. avium complex infection. CONCLUSION: In non-BCG vaccinated children the incidence of lymphadenitis caused by M. avium complex was considerably higher than in vaccinated children. BCG cells possess antigenic determinants which confer protective immunity probably both against M. tuberculosis and against M. avium complex infections. It may thus be assumed that BCG vaccination protects both against pathogenic tubercle bacilli and M. avium complex. This should be taken into consideration before recommending discontinuation of mass BCG vaccination of newborns in areas with a high prevalence of M. avium complex infection.

Six years' experience with the discontinuation of BCG vaccination. 3. Transmission of tubercle bacilli in an unvaccinated population.

SETTING: Mass BCG vaccination of newborns has been discontinued since 1986 in one third of the Czech Republic (30,000 newborns annually) except for babies with a high risk of tuberculosis. OBJECTIVE: The transmission and risk of tuberculosis infection were evaluated in non-BCG-vaccinated children representing a population living in satisfactory socio-economic conditions. DESIGN: In 1986-92, of 184,648 children tuberculin tested at 2-year intervals, 283 were infected. RESULTS: The risk of infection was low (0.04%). Infections very rarely occurred in children below the age of 1 year and the highest rate was in children 2-3 years old. The sources of infection were found in the families of only one half of the youngest children and in 10% of the older ones. In the remaining children occasional contacts with sources outside the family must be taken into account, but the mode of contact and transmission of infection were not identified. The only factor contributing to tuberculosis transmission was the high population density. CONCLUSION: The risk of infection was low and identified sources of tuberculosis were rare in a stable population of children without evident risk factors. Children were infected by occasional contact with tuberculous cases outside of their families. The unfavourable factors associated with living in overcrowded industrialised settlements contributed to the risk of infection of non-BCG-vaccinated children.