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C Dye

Publications and source records attributed to C Dye.

At least 37 records · Page 2Linked to original sources
PubMed2000

Standard short-course chemotherapy for drug-resistant tuberculosis: treatment outcomes in 6 countries.

CONTEXT: No large-scale study has investigated the impact of multidrug-resistant tuberculosis (TB) on the outcome of standard short-course chemotherapy under routine countrywide TB control program conditions in the World Health Organization's (WHO) directly observed treatment short-course strategy for TB control. OBJECTIVE: To assess the results of treatment with first-line drugs for patients enrolled in the WHO and the International Union Against Tuberculosis and Lung Disease's global project on drug-resistance surveillance. DESIGN AND SETTING: Retrospective cohort study of patients with TB in the Dominican Republic, Hong Kong Special Administrative Region (People's Republic of China), Italy, Ivanovo Oblast (Russian Federation), the Republic of Korea, and Peru. PATIENTS: New and retreatment TB cases who received short-course chemotherapy with isoniazid, rifampicin, pyrazinamide, and either ethambutol or streptomycin between 1994 and 1996. MAIN OUTCOME MEASURE: Treatment response according to WHO treatment outcome categories (cured; died; completed, defaulted, or failed treatment; or transferred). RESULTS: Of the 6402 culture-positive TB cases evaluated, 5526 (86%) were new cases and 876 (14%) were retreatment cases. A total of 1148 (20.8%) new cases and 390 (44.5%) retreatment cases were drug resistant, including 184 and 169 cases of multidrug-resistant TB, respectively. Of the new cases 4585 (83%) were treated successfully, 138 (2%) died, and 151 (3%) experienced short-course chemotherapy failure. Overall, treatment failure (relative risk [RR], 15.4; 95% confidence interval [CI], 10.6-22.4; P<.001) and mortality (RR, 3.73; 95% CI, 2.13-6.53; P<.001) were higher among new multidrug-resistant TB cases than among new susceptible cases. Even in settings using 100% direct observation, cases with multidrug resistance had a significantly higher failure rate than those who were susceptible (9/94 [10%] vs 8/1410 [0.7%]; RR, 16.9; 95% CI, 6.6-42.7; P<.001). Treatment failure was also higher among patients with any rifampicin resistance (n=115) other than multidrug resistance (RR, 5.48; 95% CI, 3.04-9.87; P<.001), any isoniazid resistance (n=457) other than multidrug resistance (RR, 3. 06; 95% CI, 1.85-5.05; P<.001), and among patients with TB resistant to rifampicin only (n=76) (RR, 5.47; 95% CI, 2.68-11.2; P<.001). Of the retreatment cases, 497 (57%) were treated successfully, 51 (6%) died, and 124 (14%) failed short-course chemotherapy treatment. Failure rates among retreatment cases were higher in those with multidrug-resistant TB, with any isoniazid resistance other than multidrug resistance, and in cases with TB resistant to isoniazid only. CONCLUSIONS: These data suggest that standard short-course chemotherapy, based on first-line drugs, is an inadequate treatment for some patients with drug-resistant TB. Although the directly observed treatment short-course strategy is the basis of good TB control, the strategy should be modified in some settings to identify drug-resistant cases sooner, and to make use of second-line drugs in appropriate treatment regimens. JAMA. 2000;283:2537-2545

Antitubercular Agents↗
PubMed2000

Serological and demographic evidence for domestic dogs as a source of canine distemper virus infection for Serengeti wildlife.

Following an epidemic of canine distemper virus (CDV) in Serengeti lions in 1994, the role of domestic dogs in the epidemiology of the disease was investigated by serological and demographic analyses. From 1992 to 1994, data were collected from two domestic dog populations bordering the Serengeti National Park. Several lines of evidence indicated that patterns of CDV infection differed significantly between higher-density dog populations of Serengeti District to the west of the park and lower-density populations of Ngorongoro District to the south-east: (a) CDV age-seroprevalence patterns differed significantly between years in Ngorongoro District populations but not in Serengeti District populations; (b) CDV seropositive pups (<12 months of age) were detected in Ngorongoro District only in 1994, whereas a proportion of pups in Serengeti District were seropositive in each year of the study; (c) in Ngorongoro District, the proportion of deaths attributed to disease was significantly higher in 1994 than in 1993, whereas in Serengeti District, there was no significant difference in disease-related mortality between years; (d) in Ngorongoro District, significantly more CDV seronegative dogs than seropositive dogs died in 1994, whereas there was no difference in survival of CDV seropositives and seronegatives between years in Serengeti District. We concluded that, between 1992 and 1994, CDV persisted in higher-density dog populations of Serengeti District, but occurred only sporadically in lower-density Ngorongoro District populations. Data from Ngorongoro District are consistent with exposure of dogs to CDV in 1991 and 1994, but not in 1992 and 1993. These findings suggest that higher-density domestic dog populations to the west of the Serengeti National Park were a more likely source of CDV infection for wildlife during 1994 than lower-density pastoralist dogs to the south and east of the park.

Age Factors↗
PubMed2000

Dynamics and control of the global tuberculosis epidemic.

Studies of disease burden have reaffirmed that tuberculosis is among the top 10 causes of death in the world. The tuberculosis epidemic in most countries could eventually be brought under control by implementing the World Health Organization's (WHO) directly observed therapy, short course (DOTS) strategy, although tuberculosis linked to human immunodeficiency virus (HIV) in Africa and multidrug-resistant tuberculosis (MDR-TB) in the former Soviet Union urgently demand adaptations and extensions of DOTS. Most high-incidence countries have achieved treatment success rates approaching the WHO 85% target in pilot projects. In the long term, we may have better diagnostics, drugs, and vaccines to control the disease; for the next 5 years, the central problem in global tuberculosis control is to expand DOTS coverage in high-incidence countries. Improved case finding and diagnosis, coupled with best-practice short-course chemotherapy, could quickly and dramatically cut the number of years of healthy life lost due to tuberculosis, especially by preventing death.

AIDS-Related Opportunistic Infections↗
PubMed2000

Gender and tuberculosis: a comparison of prevalence surveys with notification data to explore sex differences in case detection.

OBJECTIVE: To explore whether lower tuberculosis notification rates among women are due to a reduced access to health care, particularly diagnostic services, for women. METHODS: Age- and sex-specific tuberculosis prevalence rates of smear-positive tuberculosis were obtained from tuberculosis prevalence surveys reported to the WHO or published in the literature. Age- and sex-specific notification rates from the same countries in 1996 were used. RESULTS: Prevalence data and notifications from 29 surveys in 14 countries were used. Notification rates varied strongly among countries, but the female/male ratio was below 1 and decreased with increasing age in almost all. The female/male (F/M) prevalence ratios were less than 0.5 in surveys in the South-East Asia and Western Pacific Region, and approximately 1 in the African Region. CONCLUSION: In most countries the F/M sex ratio in prevalent cases was similar or lower than that in notified cases, suggesting that F/M differences in notification rates may be largely due to epidemiological differences and not to differential access to health care. However, available data are limited as the prevalence surveys in Africa were carried out many years ago, and in Asia notification rates may be distorted by a large private sector with deficiencies in notification.

Adolescent↗
PubMed2000

Evaluating the impact of tuberculosis control: number of deaths prevented by short-course chemotherapy in China.

BACKGROUND: Tuberculosis (TB) is still amongst the most important causes of human morbidity and mortality, killing approximately two million people each year. Standard short-course chemotherapy (SSCC) can rapidly control illness and dramatically reduce the chance of death, but the impact of treatment has rarely been evaluated in these terms. METHOD: We developed a mathematical model that makes use of routinely-collected data to calculate the number of deaths directly prevented by TB treatment (i.e. excluding those due to reduced transmission). The method was applied to the world's largest TB control programme covering over 500 million people in 12 provinces of China. RESULTS: Counties which had been enrolled in the programme since 1991 were, by 1997, preventing at least 46% (37-56%) of the TB deaths that would otherwise have occurred. If replicated across the entire TB control programme area, this would amount to 30 000 (range 26 000-59 000) deaths directly prevented each year. CONCLUSIONS: Short-course chemotherapy has substantially reduced TB mortality in half of China. The analytical method described here could be applied to TB control operations in many other countries, and should help to quantify the true burden of tuberculosis alleviated by SSCC.

Anti-Bacterial Agents↗
PubMed2000

Tuberculosis 2000-2010: control, but not elimination.

The main task of global tuberculosis (TB) control over the next decade is to dramatically reduce TB deaths, the average duration of illness, and incidence--in that order. The best possible application of chemotherapy has the potential to cut the TB burden by more than 50% in 10 years. Mass screening for active TB has not generally been recommended, but the costs and benefits of targeted active case finding deserve further investigation. Among potential new tools for TB control, the biggest prize would be a high-efficacy vaccine that can produce long-lasting immunity. Now that good control programmes are becoming more widespread, new methods and indicators are needed to evaluate epidemiological impact. Even if morbidity and mortality are significantly reduced before 2010, tuberculosis infection will persist for much longer, acting as a sensitive indicator of public health, and as a marker of the quality of health services.

Antitubercular Agents↗
PubMed1999

Intra and inter-specific microsatellite variation in the Leishmania subgenus Viannia.

Leishmania species of the subgenus Viannia are responsible for a large proportion of New World leishmaniasis. Here we report the development of a set of microsatellite markers which are able to discriminate between all species within the subgenus Viannia, including the closely related species pairs: Leishmania (V.) braziliensis and Leishmania (V.) peruviana; Leishmania (V.) panamensis and Leishmania (V.) guyanensis. Potential species hybrids were uncovered in the analysis. These markers are sufficiently polymorphic such that within-species epidemiological, population and genetic studies are theoretically possible for all species analyzed.

Animals↗
PubMed1999

Consensus statement. Global burden of tuberculosis: estimated incidence, prevalence, and mortality by country. WHO Global Surveillance and Monitoring Project.

OBJECTIVE: To estimate the risk and prevalence of Mycobacterium tuberculosis (MTB) infection and tuberculosis (TB) incidence, prevalence, and mortality, including disease attributable to human immunodeficiency virus (HIV), for 212 countries in 1997. PARTICIPANTS: A panel of 86 TB experts and epidemiologists from more than 40 countries was chosen by the World Health Organization (WHO), with final agreement being reached between country experts and WHO staff. EVIDENCE: Incidence of TB and mortality in each country was determined by (1) case notification to the WHO, (2) annual risk of infection data from tuberculin surveys, and (3) data on prevalence of smear-positive pulmonary disease from prevalence surveys. Estimates derived from relatively poor data were strongly influenced by panel member opinion. Objective estimates were derived from high-quality data collected recently by approved procedures. CONSENSUS PROCESS: Agreement was reached by (1) participants reviewing methods and data and making provisional estimates in closed workshops held at WHO's 6 regional offices, (2) principal authors refining estimates using standard methods and all available data, and (3) country experts reviewing and adjusting these estimates and reaching final agreement with WHO staff. CONCLUSIONS: In 1997, new cases of TB totaled an estimated 7.96 million (range, 6.3 million-11.1 million), including 3.52 million (2.8 million-4.9 million) cases (44%) of infectious pulmonary disease (smear-positive), and there were 16.2 million (12.1 million-22.5 million) existing cases of disease. An estimated 1.87 million (1.4 million-2.8 million) people died of TB and the global case fatality rate was 23% but exceeded 50% in some African countries with high HIV rates. Global prevalence of MTB infection was 32% (1.86 billion people). Eighty percent of all incident TB cases were found in 22 countries, with more than half the cases occurring in 5 Southeast Asian countries. Nine of 10 countries with the highest incidence rates per capita were in Africa. Prevalence of MTB/HIV coinfection worldwide was 0.18% and 640000 incident TB cases (8%) had HIV infection. The global burden of tuberculosis remains enormous, mainly because of poor control in Southeast Asia, sub-Saharan Africa, and eastern Europe, and because of high rates of M tuberculosis and HIV coinfection in some African countries.

AIDS-Related Opportunistic Infections↗
PubMed1999

A cost-benefit analysis of BCG revaccination in the Czech Republic.

We assessed the direct and indirect economic costs and benefits of the current policy of revaccinating tuberculin-negative schoolchildren in the Czech Republic. The analysis is conducted from the perspective of the payer for health care. In considering whether revaccination should be discontinued, we consistently made assumptions which tend to favor revaccination. The direct costs of revaccination are estimated at Czech Koruna (KCR) 15.0 million (US$0.46 million) annually. The direct benefits are the treatment costs saved for future cases averted by revaccination. These range from KCR 0.5 million (US$0.015 million, ambulatory care, excluding transmission benefits) to KCR 13.7 million (US$0.4 million, hospitalization, including transmission benefits). Costs exceed benefits even if children are revaccinated without prior tuberculin testing. The major indirect cost is the loss of work output attributable to tuberculosis morbidity. Counting the averted loss in output as a benefit does not change the results qualitatively, although there is a 50% chance that the benefits will be greater than costs if treatment continues to be hospital-based. Thus, the costs of revaccination in the Czech Republic are found to exceed benefits over most, plausible variations in parameter values. The cost-benefit ratio is especially large if patients are given ambulatory treatment, as recommended by the World Health Organization.

Ambulatory Care↗
PubMed1999

Progress in global tuberculosis control 1995-1996, with emphasis on 22 high-incidence countries. Global Monitoring and Surveillance Project.

OBJECTIVE: To review global tuberculosis case notifications and treatment outcomes, and to assess progress in TB control 1995-1996, especially in the 22 countries that carry 80% of all incident cases. DESIGN: Compilation of case notifications; cohort analysis of treatment outcomes in DOTS and non-DOTS programmes. RESULTS: The 181 of 212 countries (85%) that reported data to WHO in 1997 covered 97% of the global population. They reported 3.81 million cases of tuberculosis, of which 1.29 million were smear-positive, representing case detection rates of approximately 39% and 51%, respectively. DOTS programmes diagnosed 67% of new pulmonary cases to be smear-positive (65% expected), compared with 30% in other control programmes. They evaluated a higher fraction of registered cases (94% vs 55%), achieved higher treatment success rates (78% vs 45%), and a higher fraction of patients was shown to be cured by smear conversion (72% vs 23%). Despite the apparent advantages of DOTS, only 12% of all estimated cases, and only 15% of smear-positive cases, were treated in such programmes. CONCLUSION: With the exceptions of Vietnam, Peru and Tanzania, none of the 22 highest-incidence countries achieved WHO targets for TB control. The slow progress is of greatest concern in 16 countries, including India, Indonesia, Nigeria and Pakistan.

Antitubercular Agents↗
PubMed1999

Estimate of the global market for rifampicin-containing fixed-dose combination tablets.

SETTING: Despite WHO and IUATLD recommendations to use fixed-dose combination (FDC) tablets for treatment of tuberculosis, more than 75% of all rifampicin used in the public sector globally is administered as single drug tablets. OBJECTIVE: To estimate the potential global market for rifampicin-containing FDCs in the public and private sectors. DESIGN: The public sector market for FDCs was calculated from the number of tuberculosis cases notified to WHO for 1996 and from information on treatment regimens currently used in each country. The private sector market was calculated from the estimated number of treated tuberculosis cases and the treatment regimens presumed to be used in the private sector. RESULTS: The potential global market for the four-drug FDC tablet (rifampicin 150 mg, isoniazid 75 mg, pyrazinamide 400 mg and ethambutol 275 mg) is 305 (90%CI 145-505) million tablets per year, 105 (90%CI 50-160) and 200 (90%CI 95-345) million of which would be distributed in the public and private sectors, respectively. The uncertainty of the estimate remains considerable, as shown by the 90% confidence intervals. CONCLUSION: The study demonstrated a large potential global market for FDCs that should encourage pharmaceutical manufacturers to produce WHO-recommended dosages of FDCs at affordable prices.

Antibiotics, Antitubercular↗
PubMed1998

Prospects for worldwide tuberculosis control under the WHO DOTS strategy. Directly observed short-course therapy.

BACKGROUND: WHO advocates the use of directly observed treatment with a short-course drug regimen as part of the DOTS strategy, but the potential effect of this strategy worldwide has not been investigated. METHODS: We developed an age-structured mathematical model to explore the characteristics of tuberculosis control under DOTS, and to forecast the effect of improved case finding and cure on tuberculosis epidemics for each of the six WHO regions. FINDINGS: In countries where the incidence of tuberculosis is stable and HIV-1 absent, a control programme that reaches the WHO targets of 70% case detection and 85% cure would reduce the incidence rate by 11% (range 8-12) per year and the death rate by 12% (9-13) per year. If tuberculosis has been in decline for some years, the same case detection and cure rates would have a smaller effect on incidence. DOTS saves a greater proportion of deaths than cases, and this difference is bigger in the presence of HIV-1. HIV-1 epidemics cause an increase in tuberculosis incidence, but do not substantially reduce the preventable proportion of cases and deaths. Without greater effort to control tuberculosis, the annual incidence of the disease is expected to increase by 41% (21-61) between 1998 and 2020 (from 7.4 million to 10.6 million cases per year). Achievement of WHO targets by 2010 would prevent 23% (15-30) or 48 million cases by 2020. INTERPRETATION: The potential effect of chemotherapy (delivered as DOTS) on tuberculosis is greater in many developing countries now than it was in developed countries 50 years ago. To exploit this potential, case detection and cure rates urgently need to be improved in the main endemic areas.

Communicable Disease Control↗
PubMed1997

Cycles of malaria associated with El Niño in Venezuela.

CONTEXT: Malaria has been increasing globally, and epidemics tend to occur when weather conditions favor this vector-borne disease. Long-term meteorologic forecasting using El Niño Southern Oscillation (ENSO) may assist in anticipating epidemics and targeting scarce resources. OBJECTIVE: To determine whether malaria epidemics in Venezuela are related to ENSO and rainfall and to determine whether such a relationship could be used to predict outbreaks. DESIGN: Retrospective analysis of national malaria morbidity (1975-1995) and mortality (1910-1935) data in the coastal zone and interior of Venezuela in relation to El Niño events and rainfall. MAIN OUTCOME MEASURE: Correlation between malaria mortality and morbidity and sea surface temperatures (SSTs) in the Eastern Tropical Pacific, a parameter of ENSO. RESULTS: Malaria mortality and morbidity have increased by an average of 36.5% (95% confidence interval, 3.7%-69.3%; P=.004) in years following recognized El Niño events. A moderate correlation was found between Pacific tropical SST during a Niño event and malaria 1 year later (r=0.50, P<.001). Malaria mortality is more strongly related to drought in the year preceding outbreaks than to rainfall during epidemic years. CONCLUSIONS: Historic and recent data from Venezuela demonstrate that malaria increases by an average of about one third in the year following a Nino event; change in malaria risk can be predicted from Pacific SSTs in the previous year. Therefore, the occurrence of an El Niño event may help predict malaria epidemics in this part of South America.

Disease Outbreaks↗
PubMed1997

Infectious disease persistence when transmission varies seasonally.

The generation reproduction number, R0, is the fundamental parameter of population biology. Communicable disease epidemiology has adopted R0 as the threshold parameter, called the basic case reproduction number (or ratio). In deterministic models, R0 must be greater than 1 for a pathogen to persist in its host population. Some standard methods of estimating R0 for an endemic disease require measures of incidence, and the theory underpinning these estimators assumes that incidence is constant through time. When transmission varies periodically (e.g., seasonally), as it does for most pathogens, it should be possible to express the criterion for long-term persistence in terms of some average transmission (and hence incidence) rate. A priori, there are reasons to believe that either the arithmetic mean or the geometric mean transmission rate may be correct. By considering the problem in terms of the real-time growth rate of the population, we are able to demonstrate formally that, to a very good approximation, the arithmetic mean transmission rate gives the correct answer for a general class of infection functions. The geometric mean applies only to a highly restricted set of cases. The appropriate threshold parameter can be calculated from the average transmission rate, and we discuss ways of doing so in the context of an endemic vector-borne disease, canine leishmaniasis.

Animals↗
PubMed1997

Assessment of worldwide tuberculosis control. WHO Global Surveillance and Monitoring Project.

BACKGROUND: Because worldwide tuberculosis (TB) control had never been assessed, WHO set up a surveillance and monitoring project in 1995. The objectives were to assess the performance of national TB programmes; to assess the extent of implementation of the WHO strategy of TB control; and to attempt a comparison between regions that had adopted the WHO strategy and those that had not. METHODS: In June, 1996, we sent data-collection forms requesting information on national TB programmes' control policies, 1995 case notifications, and 1994 treatment results to 216 countries, areas, and territories. We assessed the performance of national TB programmes by comparing case notifications with estimated incidence and by outcome of treatment in cohorts of patients. We also investigated worldwide treatment success and case detection among sputum-smear-positive patients. FINDINGS: 180 (83%) of the 216 countries, areas, and territories surveyed replied to WHO (98% of the worldwide population). In 1995, the WHO control strategy had been implemented in 75 countries, and in 39 of these implementation was countrywide. UP to 23% of the worldwide population lived in regions where the strategy was available. In 1995, 3 297 688 cases of TB (all types) were reported, of which 1161411 (35%) were sputum-smear positive. 54% of all reported cases in countries that used the WHO strategy were sputum-smear positive, compared with 30% in other countries. The worldwide case-detection rate of new sputum-smear-positive cases was 35%. 92% of cases registered for treatment in 1994 in regions that used WHO strategy were assessed for outcome and 76% were treated successfully, compared with 54% and 42%, respectively, in regions that had not implemented the WHO strategy. Among cases reported worldwide in 1994, the documented treatment-success rate was 43%. INTERPRETATION: National TB programmes that have adopted the WHO TB control strategy achieve higher cure rates, but their impact on TB is modest on a worldwide scale. Wider continuous coverage with the WHO strategy is needed for effective worldwide TB control.

Communicable Disease Control↗