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H L Rieder

Publications and source records attributed to H L Rieder.

At least 19 recordsLinked to original sources
PubMed2005

A method to determine the utility of the third diagnostic and the second follow-up sputum smear examinations to diagnose tuberculosis cases and failures.

SETTING: Forty-two laboratories in four countries. OBJECTIVE: To determine the number of sputum smear examinations required to identify one additional case of tuberculosis from a third serial diagnostic smear or one additional treatment failure from a second serial follow-up smear. MATERIAL AND METHODS: Country-specific prevalence of new cases and failures among 59 665 examinees were determined, as well as the incremental yield from serial smears. The reciprocal value of the product of the prevalence of cases or failures and the respective incremental yield from the last serial smear provided the number of slides that have to be examined to identify one additional case or failure. RESULTS: The expected prevalence of cases among suspects ranged from 5.4% to 32.8%; the incremental yield from a third serial smear ranged from 0.7% to 7.2%. Between 122.7 and 796.3 smears were required to identify one additional case with the third serial smear. The prevalence of failures among follow-up examinees ranged from 1.0% to 2.5%; the incremental yield from the second follow-up serial smear ranged from 4.5% to 26.9%. Between 164.8 and 2133.4 slides were required to identify one additional failure with the second serial smear. CONCLUSION: The utility of serial smears can be rationally determined by careful review of program data.

Follow-Up Studies↗
PubMed2005

Prevalence and trends of infection with Mycobacterium tuberculosis in Djibouti, testing an alternative method.

SETTING: Djibouti, 1994 and 2001. OBJECTIVE: To estimate the prevalence of tuberculosis (TB) and average annual risk of TB infection (ARTI) and trends, and to test a new method for calculations. METHODS: Tuberculin surveys among schoolchildren and sputum smear-positive TB patients. Prevalence of infection was calculated using cut-off points, the mirror image technique, mixture analysis, and a new method based on the operating characteristics of the tuberculin test. Test sensitivity was derived from tuberculin reactions among TB patients and test specificity from a comparison of reaction size distributions among children with and without a BCG scar. RESULTS: The ARTI was estimated to lie between 2.6% and 3.1%, with no significant changes between 1994 and 2001. The close match of the distributions between children tested in 1994 and patients justifies the utilisation of the latter to determine test sensitivity. This new method gave very consistent estimates of prevalence of infection for any induration for values between 15 and 20 mm. Specificity was successfully determined for 1994, but not for 2001. Mixture analysis confirmed the estimates obtained with the new method. CONCLUSION: Djibouti has a high ARTI, and no apparent change over the observation time was found. Using operating test characteristics to estimate prevalence of infection looks promising.

Bayes Theorem↗
PubMed2004

[Recommendations for personal respiratory protection in tuberculosis].

These recommendations of the German Central Committee against Tuberculosis give an overview of the current scientific knowledge on the tuberculosis risk of health service employees and on the risk of infection in individual areas of work. The efficacy of face masks and their benefit in tuberculosis control is discussed. There are no reliable data on the efficacy of face masks in preventing infection with M. tuberculosis, nor can such data be expected in the near future, due to the complex interaction of infection-preventing measures. As rapid case finding, isolation, and immediate, effective treatment of infected patients already greatly diminish the risk of transmission, we consider face masks to be of limited use in reducing this risk. However, they may be beneficial in certain areas of work and in certain situations, particularly in the presence of elevated aerosol concentrations. The benefit of face masks depends largely on their correct application. The choice of a particular type of mask requires knowledge of the current epidemiological situation, and a competent assessment of the risk in the area of work for which it is chosen, taking into account the closeness of contact with potentially infectious tuberculosis patients.

Germany↗
PubMed2004

[Latent tuberculosis infection: recommendations for preventive therapy in adults in Germany].

The immunologic mechanisms of latent tuberculosis (TB) infection are complex and hitherto not completely understood. The lifelong risk of an immunocompetent individual of developing active TB after infection with M. tuberculosis is 5-10 % and highest during the first two years after infection. Various factors may considerably increase the risk of developing active TB, e. g., immunosuppressive disease or immunosuppressive medication. However, the development of active TB may be avoided by preventive chemotherapy, the therapy of choice being isoniazid over a 9-month period. Alternative treatment regimens may be indicated in special cases, but it must be borne in mind that the efficacy of these regimens has not been studied sufficiently while they seem to be less well tolerated than isoniazid monotherapy. The tuberculin skin test is still the only sufficiently documented method to detect latent infection with M. tuberculosis which is also suitable for routine application. This test today should be performed exclusively as described by Mendel and Mantoux. Its sensitivity and specificity depend on the prevalence of tuberculosis infection. It should therefore be restricted to individuals at increased risk of latent TB infection. When interpreting the tuberculin skin test, it is necessary to know whether an individual belongs to one of the defined risk groups or has an elevated risk of developing active TB. Among the risk groups are individuals who may have been infected recently with M. tuberculosis (contacts of contagious TB patients) or in whom other factors increase their risk of developing active TB. The indication for chemotherapy for latent TB infection must be based on a careful individual risk-benefit analysis and, besides patient compliance, requires full information of the patient and careful monitoring during therapy. Before initiating treatment, active TB must always be excluded by the proven methods.

Adult↗
PubMed2004

Scanty AFB smears: what's in a name?

SETTING: A tuberculosis control project in Bangladesh. OBJECTIVE: To document the frequency and diagnostic value of smears with scanty acid-fast bacilli (AFB) (IUATLD/WHO scale, < 10/100 high power fields), and to assess the appropriateness of the current positivity threshold. DESIGN: Analysis of databases of laboratory registers, patient records and the diagnostic yield of sputum collection strategies. RESULTS: Scanty smears constituted about 10% of suspect and almost 50% of follow-up smears. In suspect series, 10% of scanty 1-9/100 were not confirmed by another positive or scanty AFB sputum, compared to 7.5% of results at the current cut-off value of 10/100. Considering such results as positive by adopting a lower cut-off as low as the 1/100 used in the ATS scale added 1.5% false positives at the most. In return, the gain in confirmed positive cases was up to 10%, and that in positive results exceeded the incremental yield of the third diagnostic sputum. Significance of scanty follow-up smears at the end of the intensive phase was suggested by their association with treatment failure and unfavourable outcome overall. CONCLUSIONS: Scanty results (IUATLD/WHO scale) are not rare and should not be ignored. Adoption of a considerably lower positivity threshold would be appropriate in control programmes where basic conditions for reliable AFB microscopy, including regular quality assessment, are present.

Bacteriological Techniques↗
PubMed2004

A tuberculin skin test survey among Afghan children in Kabul.

SETTING: Kabul, Afghanistan, October to November 2000. OBJECTIVE: To determine the prevalence and the average annual risk of infection with Mycobacterium tuberculosis (ARTI). METHODS: A cluster sampling method was selected to carry out the survey. Sub-divisions of Kabul's districts were chosen, and door-to-door visits were carried out to register the children. The prevalence of tuberculous infection was determined using a cut-off point to denote infection and mixture analysis. The average ARTI was derived algebraically from the prevalence estimates. RESULTS: The tuberculin skin test was administered and read in 89% of registered children. Utilising a cut-off point of > or = 8 mm in duration, the estimated prevalence of tuberculous infection was 4.3% and the calculated average ARTI was 0.61%. Using mixture analysis, the average ARTI was estimated to be 0.34% (95% credibility interval 0.23-0.54). This indicates a substantial decrease from the estimated ARTI of 2.55% calculated in the 1963 survey. CONCLUSIONS: There has been a large decrease in the risk of tuberculous infection in Kabul since the last assessment. The adverse situation in the past decades does not appear to have severely affected the epidemiological situation.

Afghanistan↗
PubMed2003

Isoniazid resistance among tuberculosis patients by birth cohort in Germany.

SETTING: Germany, 1997-2000. OBJECTIVE: To determine the prevalence of isoniazid resistance by year of birth among previously treated and untreated tuberculosis patients by country of birth. DESIGN: Univariate and multivariate analyses of data on 8658 cases from a nationally representative sample. RESULTS: The crude prevalence of isoniazid resistance was 2.4% and 9.9% among Germany-born patients respectively without and with a prior treatment history. Among those without a history, there was virtually no difference between quartiles of birth cohorts, while among those with, a large decrease from the oldest to the youngest was observed. Among foreign-born patients, the prevalence of isoniazid resistance increased from 3.8% to 11.8% from the oldest to the youngest among those without, and more than doubled from less than 20% to more than 40% among those with prior treatment. CONCLUSION: This analysis suggests a remarkably constant and low prevalence of isoniazid resistance among never treated Germany-born patients. In contrast, among the diverse group of foreign-born patients, the prevalence increases appreciably from the oldest to the youngest birth cohorts. This indicates that tuberculosis treatment policies in Germany have been sound and that great care is needed to prevent acquisition of additional resistance among foreign-born patients.

Adolescent↗
PubMed2003

Contacts of tuberculosis patients in high-incidence countries.

The risk of acquiring infection with Mycobacterium tuberculosis correlates with duration of exposure to an infectious source of tuberculosis. Contact identification is therefore a comparatively high-yield activity. However, in resource-poor settings tuberculin is rarely available, and even where it is available, non-specific cross-reactions to tuberculin resulting from BCG vaccination complicate the interpretation of tuberculin test results. The identification of a putative infection with M. tuberculosis in a contact must result in intervention. Excluding active tuberculosis is mandatory before preventive therapy is provided. This might prove difficult in areas where the most and often only affordable diagnostic means is microscopy. The International Union Against Tuberculosis and Lung Disease (IUATLD) has thus proposed to target preventive therapy to healthy children below the age of 5 years living in the same household as a sputum smear-positive tuberculosis case, with the sole recourse to clinical contact examination. While this approach will lead to treatment of a considerable proportion of uninfected children, the advantages are several-fold: first, these are the easiest identifiable contacts; second, they are particularly prone to progression to disease if infected; third, emerging drug resistance is of little concern at that age; fourth, administration of preventive treatment can be delegated to the source case. This approach is safe, simple, and affordable.

Carrier State↗
PubMed2002

European framework for tuberculosis control and elimination in countries with a low incidence. Recommendations of the World Health Organization (WHO), International Union Against Tuberculosis and Lung Disease (IUATLD) and Royal Netherlands Tuberculosis Association (KNCV) Working Group.

As countries approach the elimination phase of tuberculosis, specific problems and challenges emerge, due to the steadily declining incidence in the native population, the gradually increasing importance of the importation of latent tuberculosis infection and tuberculosis from other countries and the emergence of groups at particularly high risk of tuberculosis. Therefore, a Working Group of the World Health Organization (WHO), the International Union Against Tuberculosis and Lung Disease (IUATLD) and the Royal Netherlands Tuberculosis Association (KNCV) have developed a new framework for low incidence countries based on concepts and definitions consistent with those of previous recommendations from WHO/IUATLD Working Groups. In low-incidence countries, a broader spectrum of interventions is available and feasible, including: 1) a general approach to tuberculosis which ensures rapid detection and treatment of all the cases and prevention of unnecessary deaths; 2) an overall control strategy aimed at reducing the incidence of tuberculosis infection (risk-group management and prevention of transmission of infection in institutional settings) and 3) a tuberculosis elimination strategy aimed at reducing the prevalence of tuberculosis infection (outbreak management and provision of preventive therapy for specified groups and individuals). Government and private sector commitment towards elimination, effective case detection among symptomatic individuals together with active case finding in special groups, standard treatment of disease and infection, access to tuberculosis diagnostic and treatment services, prevention (e.g. through screening and bacille Calmette-Guéria immunization in specified groups), surveillance and treatment outcome monitoring are prerequisites to implementing the policy package recommended in this new framework document.

Communicable Disease Control↗
PubMed2002

Dosages of anti-tuberculosis medications in the national tuberculosis programs of Kenya, Nepal, and Senegal.

SETTING: National tuberculosis programs in Kenya, Nepal, and Senegal. OBJECTIVES: To ascertain adequacy of initial prescriptions of dosages of anti-tuberculosis medications in the three national tuberculosis programs. METHODS: Collection of patient treatment cards in a representative sample of treatment centers in Kenya, Nepal, and Senegal. Calculation of drug dosages in milligram per kilogram body weight of isoniazid, rifampicin, and pyrazinamide and comparison with international recommendations for dosage of these medications. RESULTS: A total of 12,346 patient treatment cards were available. Yet of these only 8640 were analyzed: 5575 (65% of total) from Kenya, 612 (53% of total) from Nepal, and 2453 (95% of total) from Senegal had the patient's weight recorded and were given a nationally recommended treatment regimen. The proportions of patients receiving an internationally recommended isoniazid dosage were 34%, 15%, and 15%, respectively in Kenya, Nepal and Senegal; the corresponding figures for rifampicin were 77%, 77%, and 93% and for pyrazinamide 25%, 3% and 75%, respectively, in the three countries. The majority of errors were over-dosage, but some cases of under-dosage were also identified. CONCLUSIONS: This study shows that over-dosage was a frequent event in all three countries. Two major reasons for this error are inadequate drug combinations in Kenya and Senegal, and in all three countries recommendations for weight brackets that did not ideally fit internationally recommended dosages. It is vital to address these problems to reduce both the risk of unnecessary drug toxicity on one end of the spectrum, and suboptimal drug levels on the other.

Adolescent↗
PubMed2001

Risk of travel-associated tuberculosis.

Infection with Mycobacterium tuberculosis might be acquired at home or during travel. The risk is determined by exposure frequency to a source case and the duration of the exposure. Thus, whether travel increases the background risk depends on origin, destination, and duration of travel. Infection might be acquired indoors or outdoors, but the overall risk seems small, whatever the setting. Bacille Calmette-Guérin vaccination and preventive therapy have both been discussed as possible preventive interventions, but the disadvantages associated with both approaches appear to outweigh any benefits. Because the risk of acquisition of infection with M. tuberculosis is small, the most rational approach is likely to delay intervention until a traveler presents with clinically active tuberculosis, as is done with any other patient.

Humans↗
PubMed2001

Global trends in resistance to antituberculosis drugs. World Health Organization-International Union against Tuberculosis and Lung Disease Working Group on Anti-Tuberculosis Drug Resistance Surveillance.

BACKGROUND: Data on global trends in resistance to antituberculosis drugs are lacking. METHODS: We expanded the survey conducted by the World Health Organization and the International Union against Tuberculosis and Lung Disease to assess trends in resistance to antituberculosis drugs in countries on six continents. We obtained data using standard protocols from ongoing surveillance or from surveys of representative samples of all patients with tuberculosis. The standard sampling techniques distinguished between new and previously treated patients, and laboratory performance was checked by means of an international program of quality assurance. RESULTS: Between 1996 and 1999, patients in 58 geographic sites were surveyed; 28 sites provided data for at least two years. For patients with newly diagnosed tuberculosis, the frequency of resistance to at least one antituberculosis drug ranged from 1.7 percent in Uruguay to 36.9 percent in Estonia (median, 10.7 percent). The prevalence increased in Estonia, from 28.2 percent in 1994 to 36.9 percent in 1998 (P=0.01), and in Denmark, from 9.9 percent in 1995 to 13.1 percent in 1998 (P=0.04). The median prevalence of multidrug resistance among new cases of tuberculosis was only 1.0 percent, but the prevalence was much higherin Estonia (14.1 percent), Henan Province in China (10.8 percent), Latvia (9.0 percent), the Russian oblasts of Ivanovo (9.0 percent) and Tomsk (6.5 percent), Iran (5.0 percent), and Zhejiang Province in China (4.5 percent). There were significant decreases in multidrug resistance in France and the United States. In Estonia, the prevalence in all cases increased from 11.7 percent in 1994 to 18.1 percent in 1998 (P<0.001). CONCLUSIONS: Multidrug-resistant tuberculosis continues to be a serious problem, particularly among some countries of eastern Europe. Our survey also identified areas with a high prevalence of multidrug-resistant tuberculosis in such countries as China and Iran.

Antitubercular Agents↗
PubMed2000

Trends in the prevalence of infection with mycobacterium tuberculosis in Korea from 1965 to 1995: an analysis of seven surveys by mixture models.

SETTING: Korea. OBJECTIVE: Estimation of the prevalence of tuberculous infection from tuberculin skin test surveys can be difficult if cross-reactions resulting from infection with environmental mycobacteria outweigh reactions resulting from tuberculous infection. Mixture analysis was thus chosen as a novel approach for estimating the prevalence of tuberculous infection in Korea. DESIGN: Seven tuberculin skin test surveys conducted between 1965 and 1995 were analyzed by mixture models, a statistical methodology used either to estimate a prevalence or to classify individuals into predefined homogeneous sub-populations. A Bayesian approach including prior information on component distributions was taken. The final model was selected based on the fit to observed values, and the analysis was therefore stratified by sex and year of survey and included age as a covariate. RESULTS: The results showed a large decrease in tuberculous infection in the population below 30 years of age: among 10- to 14-year-old boys (girls), infection prevalence decreased from 74.5% (67.9%) in 1965 to 16.5% (16.9%) in 1995. Additionally, the mean induration for individuals with tuberculous infection decreased by 2mm between 1965 and 1995, indicating a changing sensitivity of tuberculin over time. CONCLUSIONS: Mixture analysis is a promising approach for determining the prevalence of tuberculous infection in the presence of substantial interference from infection with environmental mycobacteria and changing tuberculin reaction sizes over time.

Adolescent↗
PubMed2000

Standardization of antituberculosis drug resistance surveillance in Europe. Recommendations of a World Health Organization (WHO) and International Union Against Tuberculosis and Lung Disease (IUATLD) Working Group.

Surveillance of antituberculosis drug resistance is an essential tool for evaluating the quality of tuberculosis control programmes. Consensus-based recommendations on uniform reporting of antituberculosis drug resistance surveillance data in Europe have been developed by a Working Group of the World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (IUATLD). Laboratories should use standardized methods for testing drug susceptibility with a quality assurance programme including national and international proficiency testing. The proportion of drug resistance, particularly resistance to isoniazid, rifampicin or both (multidrug resistance) among all definite, i.e. culture-positive, tuberculosis cases at the start of treatment is the major indicator of interest. It should be calculated separately among patients treated previously and among those who have never been treated with > or = 1 month of combined antituberculosis drugs. The Working Group recommends that, in countries in which resources allow, laboratories report drug susceptibility test results on all isolates of the Mycobacterium tuberculosis complex. Test results of the specimen at the start of treatment and clinical data from the notification should be linked using a suitable identifier. Results should be presented by calendar year and analysed by age, sex, place of birth, site of disease and sputum smear results. In countries in which a routine system cannot be organized, representative surveys or sentinel systems are possible alternatives. In some countries, the annual prevalence of multidrug-resistant tuberculosis may be estimated through a national laboratory reporting system.

Antitubercular Agents↗