Active and passive screening for tuberculosis in Vaud Canton, Switzerland.

This retrospective study compared the bacteriological and clinical presentation of tuberculosis and the outcome of treatment in immigrants notified for TB after active screening by chest X-ray at the border with other patients detected by passive screening. Retrospective study of all patients notified for TB in Vaud Canton in 2001 and 2002. In Vaud Canton 78% of the 179 patients notified for TB were foreign-born. Among 71 asylum seekers actively screened at the border, 49.3% [CI 37.4-61.2] were symptom-free vs 17.6% [CI 10.3-24.9] among 108 passively screened patients. In the passively screened group, the proportion of asymptomatic patients was 15.4% for Swiss patients, 8.6% for foreign workers, and 29.4% for other foreigners. The average duration of symptoms before diagnosis among patients with complaints was 2 months in actively screened foreign-born, compared to 2.5 months in passively screened patients (no significant difference by Wilcoxon-Mann-Whitney test). The proportion of pulmonary TB cases with positive smear or culture was 63.4% in actively screened patients vs 70.4% in passively detected cases. Among actively screened patients with bacteriological confirmation, 42.2% [CI 27.2-57.2] were asymptomatic compared to 13% [CI 5.31-20.7] for passively screened patients. Considering only smear positive patients, the proportion of symptom-free patients was 22.2% [CI 9.6-34.8] in 45 actively screened cases vs 11.7% [4.4-19.0] for 77 passive screening. Cure and treatment completion rate for new cases reached 88% for foreign workers, 83% for asylum seekers, 85% for Swiss patients, and 78% for other foreigners. Actively screened patients were more frequently asymptomatic than passively detected cases, even when considering only patients with bacteriological confirmation. The active screening by chest X-ray of an immigrant population with a high prevalence of tuberculosis allows the early detection and treatment of tuberculosis. This may contribute to the protection of the resident population from infection. The outcome of treatment for tuberculosis was satisfactory in all population groups

Directly observed therapy for tuberculosis in a low prevalence region: first experience at the Tuberculosis Dispensary in Lausanne.

AIM: Evaluation of first experience of the directly observed therapy (DOT) programme for tuberculosis introduced in the Canton of Vaud in 1997. METHOD: Retrospective analysis of tuberculosis patients included in a DOT programme from October 1997 to March 2000 under the supervision of the TB Dispensary in Lausanne. RESULTS: 54 patients were included, 49 of whom were new cases and 5 relapses. 70% were asylum seekers and illegal immigrants. The indications for DOT were immigrant status, social problems, and physical or psychiatric comorbidities. Treatment was fully supervised in 67% and partially in 33%. The outcome was favourable (cure or treatment completion) in 88.9% and unfavourable in 11.1%. A similar success rate was observed in full and partial DOT and there was no difference in success rates between the various structures where DOT was administered. By comparison, the success rate in a historical group from the same institution was 70% in 1990. The biggest problem was communication with the patients and within the team. CONCLUSION: Treatment of tuberculosis under DOT in the Canton of Vaud resulted in improvement of the treatment success rate

Screening and treatment for latent tuberculosis infection among asylum seekers entering Switzerland.

AIM OF THE STUDY: To evaluate the compliance of doctors and patients with the current recommendations for screening and preventive treatment of immigrants with a positive tuberculin skin test (TST) suggestive of latent tuberculosis infection (LTBI). METHODS: Retrospective cohort study of all asylum seekers entering Switzerland between 1 January 1993 and 31 December 1993 and assigned to the cantons of Aargau, Fribourg, Geneva, Neuchâtel, Valais and Vaud, who underwent a TST at the border. The medical documents of all individuals with a TST size suggestive of LTBI (> or = 10 mm in children <15 years, > or = 18 mm in young adults aged 15-25 years) were reviewed for final diagnosis, therapeutic decision, compliance with treatment if prescribed, and notification for tuberculosis within the next 3 years. RESULTS: Among 2515 asylum seekers, 172 had a positive TST suggestive of LTBI. The documents of 93 persons were available. The final diagnosis was LTBI in 71 cases, possible tuberculosis in 10 cases, an effect of BCG immunisation in 10 cases, and other diagnoses in 2 cases. Among 82 individuals with normal chest X-ray or no radiological examination, only 37 (46%) received a preventive treatment and one a full course of antituberculosis drugs. Among 11 persons with an abnormal chest X-ray, 2 received a full course of antituberculosis drugs, 7 a preventive therapy and 2 had no treatment prescribed. Among the 44 subjects in whom a preventive treatment was prescribed, 30 adhered to the treatment regimen. One case (without prescribed treatment) was notified for tuberculosis two years after entry. CONCLUSIONS: Compliance of doctors and patients with current recommendations for examination and treatment of immigrants with a TST suggestive of LTBI is unsatisfactory. New guidelines are needed to provide a clearer definition of the indications and explain the benefits of treating LTBI

Outcome of treatment of pulmonary tuberculosis in Switzerland in 1996.

Adequate treatment of pulmonary tuberculosis cures patients and reduces transmission. The study assesses treatment outcomes under current conditions in Switzerland. Retrospective cohort study including all TB cases with positive sputum cultures notified to the national surveillance system between July 1996 and June 1997. Ten months after notification, treating physicians reported the outcomes using WHO categories. Of 265 patients, 209 (79%) completed at least 6 months' treatment, 3 (1%) were treatment failures, 23 (9%) died, 8 (3%) defaulted from treatment and 22 (8%) left the country. The proportion of successful treatments did not significantly differ between the 103 Swiss-born (80%) and the 162 foreign-born (78%) patients. There were 19 deaths (18%) in the Swiss-born and 4 (2%) in the foreign-born groups; death was caused by TB in two patients, 10 died of other causes (cause unknown in 11). In the foreign-born group there were 31 (19%) potentially unsatisfactory outcomes (treatment failure, default from treatment, transfer abroad) and in the Swiss-born group 2 (2%). Default from treatment involved 8 patients, 6 of whom were asylum seekers. In a multivariate analysis potentially unsatisfactory outcomes were not significantly associated with foreign origin but with status as a foreigner of irregular or unknown legal status (adj. OR 8.8; 95% CI 1.4 to 53.7). Overall treatment success rates are satisfactory and similar to those of other western European countries. Potentially unsatisfactory outcomes are more common in foreign-born persons of irregular legal status. Tracking of non-adherent patients by health workers could further improve outcomes

Contact tracing investigation after professional exposure to tuberculosis in a Swiss hospital using both tuberculin skin test and IGRA.

SETTING: A 950 bed teaching hospital in Switzerland. AIM: To describe the result of a contact investigation among health care workers (HCW) and patients after exposure to a physician with smear-positive pulmonary tuberculosis in a hospital setting using standard tuberculin skin tests (TST) and Interferon-gamma release assay (IGRA). METHOD: HCW with a negative or unknown TST at hiring had a TST two weeks after the last contact with the index case (T0), repeated six weeks later if negative (T6). All exposed HCW had a T-SPOT.TB at T0 and T6. Exposed patients had a TST six weeks after the last contact, and a T-SPOT.TB if the TST was positive. RESULTS: Among 101 HCW, 17/73 (22%) had a positive TST at T0. TST was repeated in 50 at T6 and converted from negative to positive in eight (16%). Twelve HCW had a positive T-SPOT.TB at T0 and ten converted from negative to positive at T6. Seven HCW with a positive T-SPOT.TB reverted to negative at T6 or at later controls, most of them with test values close to the cut-off. Among 27 exposed patients tested at six weeks, ten had a positive TST, five of them confirmed by a positive T-SPOT.TB. CONCLUSIONS: HCW tested twice after exposure to a case of smear-positive pulmonary TB demonstrated a possible conversion in 10% with T-SPOT and 16% with TST. Some T-SPOT.TB reverted from positive to negative during the follow-up, mostly tests with a value close to the cut-off. Due to the variability of the test results, it seems advisable to repeat the test with values close to the cut-off before diagnosing the presence of a tuberculous infection

Influence of bacille Calmette-Guerin vaccination on size of tuberculin skin test reaction: to what size?

BACKGROUND: Previous bacillus Calmette-Guerin (BCG) vaccination can confound the results of a tuberculin skin test (TST). We sought to determine a cutoff diameter of TST induration beyond which the influence of BCG vaccination was negligible in evaluating potential Mycobacterium tuberculosis infection in a population of health care workers with a high vaccination rate and low incidence of tuberculosis. METHODS: From 1991 through 1998, all new employees at the University Hospital of Lausanne, Switzerland, underwent a 2-step TST at entry visit. We also gathered information on demographic characteristics, along with factors commonly associated with tuberculin positivity, including previous BCG vaccination, history of latent M. tuberculosis infection, and predictors for M. tuberculosis infection. RESULTS: Among the 5117 investigated subjects, we found that influence of BCG vaccination on TST results varied across categories of age (likelihood ratio test, 0.0001). Prior BCG vaccination had a strong influence on skin test results of <or=18 mm in diameter among persons <40 years old, compared with the influence of factors predictive of M. tuberculosis infection. Prior latent M. tuberculosis infection and travel or employment in a country in which tuberculosis is endemic also had significant influences. CONCLUSIONS: Interpretation of TST reactions of <or=18 mm among BCG-vaccinated persons <40 years of age must be done with caution in areas with a low incidence of tuberculosis. In such a population, except for persons who have never been vaccinated, TST reactions of <or=18 mm are more likely to be the result of prior vaccination than infection and should not systematically lead to preventive treatment

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Latent tuberculosis: which test in which situation?

Detection of latent tuberculosis infection (LTBI) is a cost-effective procedure in patients at high risk of developing tuberculosis later and who could benefit from preventive treatment. The commonest situation where screening is indicated is the search for infected contacts of an index case with pulmonary tuberculosis. As a screening procedure the current tendency is to replace the time-honoured tuberculin skin test by one of the new blood tests measuring the release of interferon gamma by sensitised T lymphocytes after stimulation by specific peptides from M. tuberculosis. The main advantage of the new tests is the absence of interference with BCG and non-tuberculous mycobacteria, which confers high specificity on the test. This allows a more selective choice of persons for whom preventive treatment is indicated. Some controversial issues remain, such as sensitivity in children and immunocompromised subjects, the predictive value of the blood test and interpretation of possible changes in test results over time. The technical aspects required for performance of the tests must be considered