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D A Enarson

Publications and source records attributed to D A Enarson.

At least 19 recordsLinked to original sources
PubMed2001

The tuberculosis pandemic today: routes of transmission and new target groups.

Tuberculosis, a disease that has been with us since the dawn of time, shows little sign of disappearing. Declines in death rates observed for several centuries prior to 1960 have been reversed in recent decades. This is in spite of the fact that efficient means of controlling the disease have been available during this period. This article reviews experience in 3 communities: among the Inuit, who live in the region of the North Pole; in the Beijing Municipality in the People's Republic of China; and in a socially isolated community in South Africa. In the first 2 communities, dramatic declines in the burden of disease have been observed: in the Inuit community, this occurred after substantial intervention; in the Beijing Municipality it was done with limited resources. The third community in South Africa illustrates an alarming trend, with tuberculosis being seen in a variety of locations but in the absence of external agents such as HIV infection. Clearly we need to refocus our efforts to control this disease, making use of the new tools that are rapidly becoming available. This must be done without delay, before influences such as HIV infection put the possibility of control completely out of reach.

Arctic Regions↗
PubMed2001

Analysis for a limited number of gene codons can predict drug resistance of Mycobacterium tuberculosis in a high-incidence community.

Correct and rapid diagnosis is essential in the management of multidrug-resistant tuberculosis (MDR-TB). In this population-based study of 61 patients with drug-resistant tuberculosis, we evaluated the frequency of mutations and compared the performance of genotypic (mutation analysis by dot blot hybridization) and phenotypic (indirect proportion method) drug resistance tests. Three selected codons (rpoB531, rpoB526, and katG315) allowed identification of 90% of MDR-TB cases. Ninety percent of rifampin, streptomycin, and ethambutol resistance and 75% of isoniazid resistance were detected by screening for six codons: rpoB531, rpoB526, rrs-513, rpsL43, embB306, and katG315. The performance (reproducibility, sensitivity, and specificity) of the genotypic method was superior to that of the routine phenotypic method, with the exception of sensitivity for isoniazid resistance. A commercialized molecular genetic test for a limited number of target loci might be a good alternative for a drug resistance screening test in the context of an MDR "DOTS-plus" strategy.

Bacterial Proteins↗
PubMed2001

Exogenous reinfection with tuberculosis on a European island with a moderate incidence of disease.

The frequency and determinants of exogenous reinfection and of endogenous reactivation of tuberculosis in patients previously treated are poorly understood. In Gran Canaria Island, Spain, between 1991 and 1996, 962 tuberculosis cases were confirmed by culture. Drug susceptibility testing was performed on available bacterial isolates and IS6110-based RFLP genotyping was carried out. Twenty-three patients (2.4%) had two positive cultures separated by at least 12 mo, 18 of whom had bacterial DNA available for genotypic analysis. The initial and final isolates from eight (44%) were different genotypes, indicating exogenous reinfection. Six of them were retreated after cure and two retreated after default. Six were HIV seronegative and two were HIV seropositive. Endogenous reactivation was seen in the remaining 10 patients of whom eight were retreated after default and two after cure. Three of the eight (38%) being retreated after default developed multidrug resistance. One genotype was responsible for a second episode of tuberculosis in five cases, three exogenous reinfections and two endogenous reactivations. In the context of a moderate incidence of tuberculosis, exogenous reinfection is an important cause of TB recurrence, even in HIV-seronegative patients.

Adult↗
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↗