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Biomedical subjects

D A Enarson

Publications and source records attributed to D A Enarson.

At least 73 records · Page 4Linked to original sources
PubMed2000

Classification of drug-resistant tuberculosis in an epidemic area.

BACKGROUND: Traditionally, patients with drug-resistant tuberculosis are classified as having acquired drug-resistant or primary drug-resistant disease on the basis of a history of previous tuberculosis treatment. Only cases of primary drug resistance are assumed to be due to transmission of drug-resistant strains. METHODS: This descriptive study of 63 patients with drug-resistant tuberculosis assessed the relative contribution of transmission of drug-resistant strains in a high-incidence community of Cape Town, South Africa, by restriction-fragment length polymorphism (RFLP). The RFLP results were compared with the results obtained by traditional classification methods. FINDINGS: According to RFLP definitions, 52% (33 cases) of drug-resistant tuberculosis was caused by transmission of a drug-resistant strain. The proportion of cases due to transmission was higher for multidrug-resistant (64%; 29 cases) than for single-drug-resistant (no cases) tuberculosis. By the clinical classification, only 18 (29%) patients were classified as having primary drug-resistant tuberculosis (implying transmission). The clinical classification was thus misleading in 25 patients. INTERPRETATION: The term acquired drug resistance includes patients infected with strains that truly acquired drug resistance during treatment and patients who were initially infected with or reinfected with a drug-resistant strain. This definition could lead to misinterpretation of surveillance studies, incorrect evaluation of tuberculosis programmes, and delayed diagnosis and treatment of patients with multidrug-resistant disease. The clinical term acquired drug resistance should be replaced with the term "drug resistance in previously treated cases", which includes cases with drug resistance due to true acquisition as well as that due to transmitted drug-resistant strains.

Adolescent↗
PubMed2000

Risk of tuberculosis infection and tuberculous meningitis after discontinuation of Bacillus Calmette-Guerin in Beijing.

In Beijing, the notification rate of smear-positive tuberculosis (TB) has been below 20 per 100,000 since 1986, and continues to decline. To accurately measure the risk of TB infection in a population in which the results of tuberculin skin testing were not confounded by vaccination with Bacillus Calmette-Guerin (BCG), BCG vaccination at birth was discontinued from 1988 in Shun-yi County. In 1995, the prevalence of TB infection among 12,836 primary school children aged 6 to 7 yr and without BCG scars was 1.4%, giving an estimated annual risk of infection of 0.19% (95% confidence interval: 0.16 to 0.22%). The prevalence of TB infection in children aged 5 to 9 yr in Beijing in 1950 was 46%. The number of cases of tuberculous meningitis did not increase after discontinuation of BCG. We conclude that discontinuation of BCG had no detectable harmful effects, and that control of TB in Beijing has markedly reduced the prevalence of TB infection since 1950.

BCG Vaccine↗
PubMed2000

Affordability of inhaled corticosteroids as a potential barrier to treatment of asthma in some developing countries.

SETTING: The cost and availability of the medications required for the treatment of asthma may represent potential barriers to effective management. METHOD: A survey of prices and policies for components of asthma treatment in 1998, in Algeria, Burkina Faso, Ivory Coast, Guinea, Mali, Syria, Turkey and Vietnam. RESULTS: Medications were consistently available in only four of the eight countries studied. The cost of essential medications for standard case management varied by over five times for beclomethasone and by over three times for inhaled salbutamol. In all but two countries, the cost of one year of drugs for treatment of a moderate, persistent case exceeded the monthly salary of a nurse in that country. The essential drugs list included inhaled salbutamol in five of eight countries and beclomethasone in three of eight. The costs of medications were lower where generic preparations were available and, to a lesser extent, where the medications are on the essential drugs list. CONCLUSIONS: The cost and availability of medications vary widely, and may represent an important barrier to effective management in some low and middle income countries.

Albuterol↗
PubMed2000

Tuberculosis control in Sudan against seemingly insurmountable odds.

SETTING: Sudan, Africa's largest and one of its poorest countries, in which civil disturbance, resource limitation and communications difficulties are substantial impediments to delivery of health services. OBJECTIVES: To 1) illustrate the burden of tuberculosis; 2) review measures taken to control the disease; 3) outline the introduction of the DOTS strategy; and 4) demonstrate the trend in the output of the DOTS strategy. METHODS: Published information on general health, tuberculosis and health structure provide the setting. Routine reports illustrate the trend in case notification in Sudan, and outcome of treatment by period of enrollment on treatment (cohort). RESULTS: Since 1992, sputum smear microscopy centres have been established in existing health facilities (179 of a total 290 targeted centres). By the end of the second quarter of 1998, 82,860 cases of tuberculosis had been reported, of whom 52% were sputum smear-positive cases. Of these, 89% had no history of previous treatment for as much as one month. The treatment outcomes for 11,000 new smear-positive cases were reported by the end of the second quarter of 1997; the proportion of notified cases for whom treatment results were available increased from 16% in 1994 to 63% in 1996. Of these, 72% were successfully treated, increasing from 62% in 1994 to 73% in 1996. CONCLUSIONS: Despite seemingly overwhelming odds, the DOTS strategy has been successfully commenced and is in the process of expansion throughout the country, with monitoring of the quality of diagnostic examinations and improvements in treatment outcome. Further improvement is necessary, but appears feasible.

AIDS-Related Opportunistic Infections↗
PubMed2000

The impact of directly-observed treatment on the epidemiology of tuberculosis in Beijing.

SETTING: Fully supervised chemotherapy, or directly observed treatment (DOT), for newly detected smear-positive cases in Beijing, has been successfully implemented for two decades. OBJECTIVE: To evaluate the progress made in tuberculosis control, and in particular to evaluate the impact of DOT on tuberculosis epidemiology in Beijing. DESIGN: Epidemiological parameters on tuberculosis, consisting of mortality, prevalence, notification rate, tuberculous meningitis in children and initial drug resistance rate, were collected and analysed. Their trends were evaluated and compared with DOT implemented for new smear-positive cases in Beijing from 1978 to 1996. RESULTS: The coverage of DOT for new smear-positive pulmonary tuberculosis cases has increased from 10% in 1978 to more than 90% since 1990. Since DOT was introduced in 1978, mortality from tuberculosis has declined by an average of more than 7% per year. The reduction rate of 17.2%, and the rates of chronic cases and tuberculous meningitis in children decreased dramatically. The rate of newly registered smear-positive cases decreased from 18.9/100000 in 1986 to 7.3/100000 in 1996, giving an average annual reduction rate of 9.1 during this period. Initial resistance to isoniazid and streptomycin decreased from respectively 13.9% and 12.3% in 1978-1979 to 4.2% and 5.8% by 1996. The level of multidrug resistance was low and stable, at 0.8% in 1996. CONCLUSION: The experience of the Beijing tuberculosis control programme convincingly demonstrates that it is possible to improve the epidemiological situation rapidly in a low-income country, at very low cost and in a manner that is self-sufficient and sustainable.

Adolescent↗
PubMed1999

Exogenous reinfection as a cause of recurrent tuberculosis after curative treatment.

BACKGROUND: For decades it has been assumed that postprimary tuberculosis is usually caused by reactivation of endogenous infection rather than by a new, exogenous infection. METHODS: We performed DNA fingerprinting with restriction-fragment-length polymorphism analysis on pairs of isolates of Mycobacterium tuberculosis from 16 compliant patients who had a relapse of pulmonary tuberculosis after curative treatment of postprimary tuberculosis. The patients lived in areas of South Africa where tuberculosis is endemic. Medical records were reviewed for clinical data. RESULTS: For 12 of the 16 patients, the restriction-fragment-length polymorphism banding patterns for the isolates obtained after the relapse were different from those for the isolates from the initial tuberculous disease. This finding indicates that reinfection was the cause of the recurrence of tuberculosis after curative treatment. Two patients had reinfections with a multidrug-resistant strain. All 15 patients who were tested for the human immunodeficiency virus were seronegative. CONCLUSIONS: Exogenous reinfection appears to be a major cause of postprimary tuberculosis after a previous cure in an area with a high incidence of this disease. This finding emphasizes the importance of achieving cures and of preventing anyone with infectious tuberculosis from exposing others to the disease.

Adult↗
PubMed1999

Cultural barriers to asthma management.

This article reviews published evidence which addresses the relevance of cultural factors in the delivery of health services for asthma patients. In addition, it suggests a framework within which further research could be carried out to advance our knowledge on this topic.

Adolescent↗
PubMed1999

Epidemiology of respiratory infectious diseases.

Respiratory infections are a frequent burden to health despite the fact that cost-effective methods for their prevention and cure are available. Acute respiratory infections in children under 5 years of age are the most frequent cause of death from lung disease globally, causing more than 4 million deaths annually. Tuberculosis is the most frequent cause of death from a single pathogen in persons aged 15 to 49 years (a total of 2 million to 3 million deaths annually). Respiratory infections are the most frequent complications of immune deficiency (whether due to HIV infection or induced by chemotherapy). Where a "carrier state" occurs (as with many bacterial pathogens), the level of immune function is the key determinant in appearance of disease. Where there is no carrier state (as with many viruses), exposure is the key determinant. Characteristics of the pathogen, including virulence and bacterial load where there is a carrier state, also determine the probability of respiratory infections. Modifiers of these determinants include allergy and toxic exposures including tobacco smoke and ambient pollution.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Lung health in Alberta farmers.

SETTING: A study conducted in the rural areas of two counties in east-central Alberta, Canada. OBJECTIVE: To investigate the relationship between lung health and dust exposure in farmers. DESIGN: A cross-sectional study of 781 farmers growing grain crops and raising livestock. Measurements included a questionnaire on respiratory symptoms, smoking habits and occupation, skin prick tests using common aeroallergens, and spirometry. RESULTS: Immediate skin reactivity to common aeroallergens was less prevalent in farmers with higher reported intensity of dust exposure. Respiratory symptoms suggestive of bronchitis had a significant dose-response relationship with the reported intensity of dust exposure. Respiratory symptoms consistent with bronchial responsiveness were significantly positively associated with cumulative dust exposure. There was a significant positive association between a physician's diagnosis of bronchitis and intensity of dust exposure. FEV1 and FEV1/FVC were significantly negatively associated with cumulative dust exposure. Ten years of exposure to a moderate dust level was associated with a deficit of 43 ml in the FEV1 and a deficit of 0.44% in the FEV1/FVC. CONCLUSIONS: Despite evidence of worker selection related to dust exposure, these farmers experienced respiratory symptoms, respiratory conditions, and reduced lung function associated with reported occupational dust exposure.

Adolescent↗
PubMed1998

Screening for tuberculosis infection and disease.

Screening is a health-related activity which has clear indications and guidelines which must be followed when this activity is carried out. Methods for screening for tuberculosis infection and disease are available and have been evaluated. Most of the criteria for screening are relevant to tuberculosis. However, screening for tuberculosis disease is not efficient and is not recommended for routine practice. Screening for purposes of preventing tuberculosis disease on the other hand, is efficient and may be indicated where the probability of disease is high and where preventive chemotherapy is included as an integral component of the activity. Such screening utilizes the tuberculin skin test, the chest radiograph and cultures of Mycobacterium tuberculosis. This allows the identification of groups of the population at sufficient risk of developing tuberculosis in future to warrant preventive chemotherapy. In setting guidelines for the use of preventive chemotherapy, the potential harmful effects of such treatment must be carefully considered. Screening without the use of preventive chemotherapy is unethical.

Antitubercular Agents↗