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M W Borgdorff

Publications and source records attributed to M W Borgdorff.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Control of drug-sensitive and (multi-)resistant tuberculosis].

Tuberculosis is an important cause of death in the world. It can be controlled by applying the WHO 'directly observed therapy, short-course' (DOTS) strategy. This strategy aims at detecting at least 70% of new, smear-positive tuberculosis cases and curing at least 85% of these. At present, only 27% of tuberculosis cases are treated according to this strategy. Application of the WHO DOTS strategy can prevent multidrug-resistant (MDR) tuberculosis. However, where MDR tuberculosis has become a large problem, as it has in some Eastern European countries, additional measures may be required for its control. Important problems remain with respect to the feasibility and costs of these measures and the prevention of additional resistance.

Antitubercular Agents↗
PubMed2002

Calculation of the stability of the IS6110 banding pattern in patients with persistent Mycobacterium tuberculosis disease.

The interpretation of molecular epidemiologic data of Mycobacterium tuberculosis infection is dependent on the understanding of the stability and evolutionary characteristics of the DNA fingerprinting marker used to classify clinical isolates. This study investigated the stability of the IS6110 banding pattern in serial tuberculosis isolates collected from patients resident in an area with a high incidence of tuberculosis. Evolutionary changes were observed in 4% of the strains, and a half-life (t(1/2)) of 8.74 years was calculated, assuming a constant rate of change over time. This rate may be composed of a high rate of change seen during the early disease phase (t(1/2) = 0.57 years) and a low rate of change seen in the late disease phase (t(1/2) = 10.69 years). The early rate probably reflects change occurring during active growth prior to therapy, while the low late rate may reflect change occurring during or after treatment. We demonstrate that the calculation of these rates is strongly influenced by the time interval between onset of disease and sputum sampling. These calculations are further complicated by partial replacement of the original strain population, resulting in the sporadic appearance of clonal variants in sputum specimens. Therefore, the true extent of genetic diversity may be underestimated within each host, thereby influencing molecular epidemiological data used to establish transmission chains.

Adult↗
PubMed2002

Effect of screening of immigrants on tuberculosis transmission.

SETTING: In The Netherlands all immigrants from highly endemic countries undergo obligatory entry screening by X-ray, followed by voluntary half-yearly screening for 2 years. OBJECTIVE: To estimate the contribution of screening of immigrants to reductions in tuberculosis transmission. DESIGN: All bacteriologically confirmed tuberculosis patients diagnosed between 1994 and 1999 with mycobacterial isolates exhibiting identical DNA fingerprints were assigned to clusters. Clusters were assumed to be a consequence of recent transmission and to have had the first patient as their source case. Among patients with pulmonary tuberculosis from highly endemic countries, the characteristics of source patients were compared with those of non-clustered patients. RESULTS: Of the 1438 selected patients, 187 (13%) were the first in a cluster, 386 (27%) were in a cluster but were not the first case, and 865 (60%) were not clustered. Independent risk factors for being the first in a cluster were young age, nationality, early year of diagnosis, longer duration of treatment and no concurrent extra-pulmonary tuberculosis. In univariate analysis, passively detected patients and patients with a long duration of stay in The Netherlands were more likely to be the first in a cluster than patients detected by screening and recent arrivals, respectively. However, these variables were strongly associated. CONCLUSION: Screening of immigrants can reduce tuberculosis transmission. This effect is in part due to confounding by duration of stay.

Adolescent↗
PubMed2002

The impact of immigration on the elimination of tuberculosis in The Netherlands: a model based approach.

OBJECTIVE: To determine whether elimination of tuberculosis in the Dutch population can be achieved by the year 2030, taking into account the impact of immigration. METHODS: The incidence of tuberculosis (all forms) in the period 1970 to 2030 was estimated using a life-table model for the Dutch population without the impact of immigration. The influence of immigration on tuberculosis incidence among the Dutch was modelled using four immigrant scenarios, distinguished by the assumed contact rate between immigrants and the Dutch population, and by different projections (middle, upper) of the future size of the immigrant population in The Netherlands. RESULTS: The incidence of smear-positive tuberculosis among the Dutch is projected to be 1.4 per million in the scenario without the influence of immigrant cases, and ranging from 3.8 to 11.8 per million in the four immigrant scenarios. In all immigrant scenarios, the prevalence of tuberculosis infection will continue to decline and be less than 1% by the year 2030. At least 60% of Dutch tuberculosis cases in the year 2030 are expected to be the result of transmission from a foreign source case. CONCLUSION: Using a prevalence of tuberculosis infection of less than 1% as the elimination criterion, tuberculosis will probably be eliminated from the indigenous Dutch population by 2030. However, the incidence of smear-positive tuberculosis is expected to remain higher than 1 per million, and the majority of new tuberculosis cases among the Dutch may be attributable to recent infection from a foreign source case.

Adolescent↗
PubMed2001

Transmission of Mycobacterium tuberculosis depending on the age and sex of source cases.

This study estimated to what extent tuberculosis transmission in the Netherlands depends on the age and sex of source cases. DNA fingerprints of Mycobacterium tuberculosis isolates were matched to patient information in the Netherlands Tuberculosis Register for 1993-1998. Clusters were defined as groups of patients with pulmonary tuberculosis whose isolates had identical DNA fingerprints. Source cases were assigned by using two models. The first-case model assumed that the first diagnosed case was the source case. The incidence rate model estimated source case probabilities from the incidence rates of potential source cases and the time of diagnosis. DNA fingerprints of 6,102 isolates were matched to patient information on 5,080 (83%) cases, 3,479 of whom had pulmonary disease. According to both models, the number of infectious cases generated per source case was lower for female than for male source cases and decreased with increasing age of the source case. The authors concluded that transmission of tuberculosis is associated with the age and sex of source cases as well as the age of secondary cases. Increased transmission among immigrant groups in the Netherlands is largely attributable to the relatively young age of immigrant source cases.

Adult↗
PubMed2001

[Tuberculosis screening coverage of immigrants: marked attrition in follow-up screenings].

OBJECTIVE: To estimate the coverage of bi-annual follow-up screening for tuberculosis amongst immigrants, excluding asylum seekers. DESIGN: Retrospective cohort study. METHODS: Participation in bi-annual chest X-ray screening during the first 18 months was recorded for immigrants who underwent entry screening in 1996 in the following Dutch municipal health services (MHS's): Zuid-Kennemerland (Haarlem), Flevoland (Lelystad), Midden-Brabant (Tilburg) en West-Friesland (Hoorn). The number of immigrants that had left the country before the subsequent screening was taken into account in the Zuid-Kennemerland MHS data on screening coverage. RESULTS: Of the 2147 immigrants who underwent entry screening in 1996 (48% men and 52% women; 68% aged 15-34 years), 1075 (50%; range: 29-76) returned for the first follow-up screening and 620 (29%; 21-61) returned for the second. In MHS Zuid-Kennemerland, 113 of the 777 immigrants who had a chest X-ray at entry had left the country before the first follow-up screening, and another 89 had left before the second. Of the remaining persons, who were probably still in the Netherlands, 454 (68%; 454/777 = 58%) returned for the first follow-up screening, and 166 (29%; 166/777 = 21%) returned for the second. CONCLUSION: The coverage of screening for tuberculosis in immigrants decreased after the obligatory entry screening, even when corrected for those who left the country.

Adolescent↗
PubMed2001

Logistic discrimination of mixtures of M. tuberculosis and non-specific tuberculin reactions.

Interpretation of the Mantoux test for tuberculous infection can be complicated by cross-reactions caused by infection with non-specific mycobacteria. Thus, the distribution of positive indurations is a mixture of two distributions. To estimate tuberculous infection prevalence, the marginal distribution of indurations needs to be separated into its component distributions. Observations from several populations with different mixes of the two types of infection are required. Homogeneity across populations of distributions of indurations for each type of infection is assumed. A logistic model is specified for the probability of having tuberculous infection conditional on the observed induration size. No other assumptions about the two distributions are made. Maximum likelihood is used to estimate the logistic function. Goodness-of-fit criteria are discussed. The method is applied to a series of tuberculin surveys carried out in (South) Korea. Estimated infection prevalence agrees reasonably well with several ad hoc criteria. The goodness-of-fit test rejects underlying assumptions of homogeneity. One reason appears to be a decline over time in induration sizes caused by tuberculous infection. However, not all reasons for this rejection are obvious. The proposed method of mixture analysis provides an additional tool for the interpretation of prevalence survey data where the diagnostic test lacks specificity as a result of cross-reactions.

Adolescent↗
PubMed2001

The effect of age and study duration on the relationship between 'clustering' of DNA fingerprint patterns and the proportion of tuberculosis disease attributable to recent transmission.

Though it is recognized that the extent of 'clustering' of isolates from tuberculosis cases in a given population is related to the amount of disease attributable to recent transmission, the relationship between the two statistics is poorly understood. Given age-dependent risks of disease and the fact that a long study (e.g. spanning several years) is more likely to identify transmission-linked cases than a shorter study, both measures, and thus the relationship between them, probably depend strongly on the ages of the cases ascertained and study duration. The contribution of these factors is explored in this paper using an age-structured model which describes the introduction and transmission of M. tuberculosis strains with different DNA fingerprint patterns in The Netherlands during this century, assuming that the number of individuals contacted by each case varies between cases and that DNA fingerprint patterns change over time through random mutations, as observed in several studies. Model predictions of clustering in different age groups and over different time periods between 1993 and 1997 compare well against those observed. According to the model, the proportion of young cases with onset in a given time period who were 'clustered' underestimated the proportion of disease attributable to recent transmission in this age group (by up to 25% in males); for older individuals, clustering overestimated this proportion. These under- and overestimates decreased and increased respectively as the time period over which the cases were ascertained increased. These results have important implications for the interpretation of estimates of the proportion of disease attributable to recent transmission, based on 'clustering' statistics, as are being derived from studies of the molecular epidemiology of tuberculosis in many populations.

Adolescent↗
PubMed2001

Attention to gender issues in tuberculosis control.

Although a seventy per cent excess of male over female TB cases are reported globally each year, the reasons for this difference are unclear. Generally, women in poor countries confront more barriers than men in accessing health care services. Yet, research is lacking to explain the impact of gender inequalities in access to care on reported sex ratios for TB. A review of the limited available literature and field visits to TB programmes offered insights and suggested a framework to study gender differentials in TB. This paper considers the role of gender at various steps in effective TB care. A research strategy to study and account for gender differences in TB control is proposed.

Adult↗
PubMed2001

Trend in HIV prevalence among tuberculosis patients in Tanzania, 1991-1998.

OBJECTIVE: To determine the trend in human immunodeficiency virus (HIV) prevalence among tuberculosis patients in Tanzania and estimate what proportion of the increase in notification rates between the surveys was directly attributable to HIV infection. METHODS: Consecutive tuberculosis patients were enrolled over 6-month periods in most regions. Demographic and clinical data were collected on standard forms and a single HIV ELISA test performed. Trends in tuberculosis incidence were estimated from regional notification data. RESULTS: Of 10612 eligible tuberculosis patients, 44% had HIV infection, compared with 32% in the previous survey. The largest increase was observed in the youngest birth cohorts, suggesting active HIV transmission. Approximately 60% of the increase in notification rates of smear-positive tuberculosis between surveys was directly attributable to HIV infection. CONCLUSION: The HIV epidemic has had a strong influence on tuberculosis incidence. However, since 1995, tuberculosis notification data have increased less steeply, AIDS notifications have gone down, and HIV prevalence in blood donors has not increased a great deal. Another survey among tuberculosis patients in 5 years' time may show whether the HIV epidemic in Tanzania has reached a maximum or steady state.

Adolescent↗
PubMed2001

Screening for pulmonary tuberculosis among immigrants: estimated effect on severity of disease and duration of infectiousness.

OBJECTIVE: To estimate the effect of tuberculosis screening among recent immigrants on the severity of disease at diagnosis and on the duration of the infectious period. DESIGN: Comparison of pulmonary tuberculosis cases among immigrants detected through screening with those detected passively, using information from the Netherlands Tuberculosis Register. PARTICIPANTS: Immigrants from highly endemic countries diagnosed with culture-positive pulmonary tuberculosis within 30 months after arrival in The Netherlands, 1993 through 1998. OUTCOME MEASURES: Severity of disease (smear-positive disease, hospitalisation, case fatality) and duration of symptomatic period. RESULTS: A total of 882 bacteriologically confirmed tuberculosis patients from highly endemic countries had been in The Netherlands less than 30 months, and were detected through screening (454), or passively (368). Compared with patients detected passively, patients found through screening were less often sputum smear-positive (OR 0.5, 95%CI 0.3-0.8) and less often hospitalised (OR 0.2, 95%CI 0.1-0.2). Those detected through screening had a shorter symptomatic period. Screening is estimated to have reduced the infectious period by approximately 33%. CONCLUSION: The screening programme detected cases earlier, resulting in fewer hospital admissions, shorter duration of symptoms and therefore probably reduced tuberculosis transmission.

Adolescent↗
PubMed2001

Tuberculosis and patient gender in Bangladesh: sex differences in diagnosis and treatment outcome.

SETTING: The public health sector of Bangladesh. OBJECTIVE: To assess gender differences in access to tuberculosis diagnosis and in tuberculosis treatment outcome in Bangladesh. METHODS: Information on the age and sex of a sample of patients in 1997 was collected from out-patient registers and tuberculosis laboratory and treatment registers in 59 thanas in three divisions in Bangladesh. RESULTS: The female/male ratio was 0.79 among 42,877 out-patients with respiratory complaints, 0.51 among 5,665 tuberculosis suspects undergoing sputum smear microscopy, 0.36 among 869 tuberculosis suspects with positive sputum smears, and 0.35 among 5,632 patients registered for tuberculosis treatment. Treatment was successful (cured or treatment completed) in 86% of female and 84% of male patients. CONCLUSION: Women in Bangladesh appear to have less access to public out-patient clinics than men, and if they present with respiratory symptoms they are less likely to undergo sputum smear examination. If examined, women are less likely than men to be smear-positive. No gender bias was observed in tuberculosis treatment outcome. It is recommended to focus further research on exploration of sex differences in the incidence of respiratory conditions, identification of constraints among women in accessing out-patient clinics and verification of the quality of sputum submitted by women for examination.

Adolescent↗
PubMed2000

Mutations at amino acid position 315 of the katG gene are associated with high-level resistance to isoniazid, other drug resistance, and successful transmission of Mycobacterium tuberculosis in the Netherlands.

The prevalence of mutations at amino acid (aa) position 315 in the katG gene of isoniazid (INH)-resistant Mycobacterium tuberculosis isolates in The Netherlands and the mutation's association with the level of INH resistance, multidrug resistance, and transmission were determined. Of 4288 M. tuberculosis isolates with available laboratory results, 295 (7%) exhibited INH resistance. Of 148 aa 315 mutants, 89% had MICs of 5-10 microg/mL, whereas 75% of the other 130 INH-resistant strains had MICs of 0.5-1 microg/mL. Of the aa 315 mutants, 33% exhibited monodrug resistance, compared with 69% of other INH-resistant strains (P<.0001). Multidrug resistance was found among 14% of the aa 315 mutants and 7% of the other INH-resistant strains (P>.05). The probability of being in an IS6110 DNA restriction fragment length polymorphism cluster was similar for aa 315 mutants and INH-susceptible strains, but the probability was reduced in other INH-resistant strains. Thus, aa 315 mutants lead to secondary cases of tuberculosis as often as INH-susceptible strains do.

Antitubercular Agents↗
PubMed2000

HIV incidence and HIV-associated mortality in a cohort of factory workers and their spouses in Tanzania, 1991 through 1996.

OBJECTIVE: To describe HIV incidence and HIV-associated mortality in a cohort of factory workers and their spouses with access to adequate sexually transmitted diseases (STD) treatment services and moderate exposure to sexual health interventions. METHODS: Follow-up visits at 4-month intervals and home follow-up of those who failed to keep appointments were used to estimate HIV incidence and mortality in a cohort of factory workers and their spouses in Mwanza, Tanzania, during 1991 to 1996. RESULTS: HIV prevalence at intake was 10.5% and 15.3% among 1,594 men and 880 women, respectively. HIV incidence was just over 1/100 person-years (PY) in 1,427 men and 1.9/100 PY in 745 women. The main risk factors were related to sexual behavior and clinical evidence of an STD, although only one seventh of those with HIV seroconversions had had an STD during the period following the second-from-last follow-up visit. HIV incidence among discordant couples was 5.0 and 8.3/100 PY for 41 men and 37 women, respectively. Mortality rates were 9.0 and 7.8/1,000 PY for men and women, respectively, and 65% of male and 60% of female deaths were attributable to HIV infection. CONCLUSIONS: In this factory population with good access to and use of STD treatment and with a moderate level of exposure to HIV prevention education, HIV incidence among men and women is still over 1/100 PY, which suggests a relatively high level of program effort is needed to lower incidence. More than half of all adult deaths were attributable to HIV, but greater increases in HIV-associated mortality are likely.

Adult↗
PubMed2000

Tuberculosis screening among immigrants in The Netherlands: what is its contribution to public health?

Understanding the epidemiology of tuberculosis in migrant communities and designing adequate and comprehensive control strategies is a major challenge facing public health authorities in many low-prevalence countries. In The Netherlands, screening immigrants from tuberculosis high prevalence countries has been conducted since 1966. In this paper, we review risk factors for tuberculosis in migrant populations, the public health importance of tuberculosis and the current screening policy in The Netherlands. TB treatment outcome in migrant populations and operational considerations that ought to be taken into account to optimize current screening practices are also reviewed. The article recommends the setting-up of an information system to evaluate the effectiveness of screening immigrants in The Netherlands, and adjustment of screening policies where needed.

Emigration and Immigration↗