New Screening Technique Increases Identification of Patients Migrating to the United States with Infectious TB by 30 Percent
Russian Cure Rates Near Global Target in First Year of DOTS Demonstration Project
Growing HIV Epidemic Hampers TB Control Efforts in Latvia
Once-a-Week Regimen Successfully Cures TB in Select Patients
Note to Editors/Reporters: Dr. Kenneth G. Castro, assistant surgeon general and director of CDC's TB Elimination Program, and authors noted here, are available for interviews. Please call Cynthia Glocker Crick, (770) 527-6239 to schedule interview during the World Congress.
NEW SCREENING TECHNIQUE INCREASES IDENTIFICATION OF PATIENTS MIGRATING TO THE U.S. WITH INFECTIOUS TB BY 30 PERCENT
Increase in Smear Sensitivity Following Processing With C18-Carboxypropylbetaine Compared to Direct Acid Fast Staining in an Immigrant Population in Viet Nam, Dr. Kayla Laserson and Colleagues
New data released today by the CDC suggests the addition of a simple processing technique to current procedures for testing sputum specimens - phlegm coughed up from deep within a TB patient's lungs - could lead to significant increases in the identification of infectious TB among prospective immigrants. The study, conducted among more than 300 Vietnamese applying for U.S. immigration, found that the new technique, which involves applying the detergent C18-carboxypropylbetaine (CB-18) to the patient's sputum sample 24 hours prior to the traditional acid-fast bacilli (AFB) smear staining method, identified 30 percent more cases of infectious TB.
While researchers stress the need to further evaluate and refine the test prior to widespread use, this type of increased sensitivity, the ability to correctly detect those individuals who have active TB, could have profound implications for reducing TB in the United States, where half of all new tuberculosis cases are diagnosed among foreign-born individuals. Two-thirds of U.S. TB cases are among immigrants from Mexico, the Philippines, Vietnam, China, India, Haiti or South Korea. A key strategy for reducing this toll is improved diagnosis of active TB disease in the immigrant's country of origin, where the vast majority are infected.
The CB-18 technique was evaluated on one to three specimens collected from 344 individuals applying to emigrate from Vietnam to the United States. Each specimen was initially analyzed by direct AFB staining method and then split in half - one half was cultured, while the other half was treated with CB-18 for 24 hours before being processed with the traditional staining method. While the process increased sensitivity by 30 percent, there was a 10 percent reduction in specificity, the ability to correctly identify those patients who do not have active TB. To guard against individuals being incorrectly diagnosed with active TB (false-positives), a follow-up study is in progress to investigate the nature of the loss in specificity as a result of the CB-18 method.
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RUSSIAN CURE RATES NEAR GLOBAL TARGET IN FIRST YEAR OF DOTS DEMONSTRATION PROJECT
Encouraging Outcomes in the First Year of a DOTS Demonstration Programme: Orel Oblast, Russia-1999-2000, Dr. Lorna Thorpe and Colleagues
CDC data released today suggest that TB treatment programs in Russia that use the World Health Organization's (WHO) strategy of directly observed treatment, short-course (DOTS) can achieve the global target of 85 percent cure rate. In a retrospective evaluation of a DOTS demonstration project in the Orel Oblast region of Russia, researchers documented an 80 percent treatment success rate (75 percent cure and 5 percent treatment completion) among infectious TB patients in the program's first full year of implementation.
TB patients are considered infectious if their sputum smear tests positive on a laboratory test. The program achieved a 91 percent cure rate among TB patients diagnosed with clinical symptoms only. Because these patients cannot produce (cough-up) sputum from their lungs, they are not believed to be as infectious as smear-positive patients.
The study evaluated treatment outcomes of 745 TB patients diagnosed and treated between October 1999 and September 2000, following the 1999 launch of the DOTS demonstration project. Launched with assistance from CDC and WHO, the Orel demonstration project was initiated to help fight the growing TB epidemic in Russia, where TB rates increased nearly three fold between 1991 and 1998 from 32 cases per 100,000 people to 84 cases per 100,000 people.
Success rates among patients being retreated for TB - individuals who came into the project having previously failed TB treatment - were lower at 68 percent. The increased rate of treatment failure among these patients was likely the result of a higher prevalence of multidrug-resistant (MDR) TB or interruption of treatment. MDR-TB is not susceptible to the two most effective TB drugs, isoniazid and rifampin. In this study, 17 percent of retreatment patients were diagnosed with MDR-TB compared to three percent among new smear positive patients. Factors often associated with interruption of therapy include social and economic problems, such as alcoholism, homelessness and unemployment.
While additional steps, such as social support for retreatment patients, are needed, the high overall success rate demonstrates that the DOTS strategy is possible in Russia. However, there has been some resistance to adopting this WHO strategy because of long-standing traditions in Russian TB control, including hospital-based TB care and use of individualized treatment regimens. To address the growing TB problem in Russia, a new national committee is developing a national TB control policy and a strategy to coordinate efforts of international partners working to control TB.
Russia, which is almost twice the size of the United States, is among the 22 countries that account for a majority of the world's TB, with an estimated incidence of 132 cases per 100,000 people in 2000. Only 12 percent of the TB cases occurring in Russia are treated using the WHO strategy, compared to 100 percent in Vietnam. In the global ranking of countries by the number of TB cases, Russia ranks number 10. In July 2001, Russia had a population of more than 145 million.
The five elements of the WHO strategy include: political commitment, case detection using sputum microscopy among people seeking care for prolonged cough, standardized short-course chemotherapy under proper case-management conditions including directly observed therapy, the provision of a regular drug supply, and a standardized recording and reporting system that allows assessment of individual patients as well as overall program performance. Cultures also can be used as an additional diagnostic tool.
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GROWING HIV EPIDEMIC HAMPERS TB CONTROL EFFORTS IN LATVIA
Implications of the Growing HIV Epidemic on Control of Tuberculosis and Multidrug-Resistant Tuberculosis in Latvia, Dr. Charles Wells and Colleagues
The growing HIV epidemic in Latvia could undermine progress made in controlling tuberculosis, including multidrug-resistant strains, according to a new study released today by the researchers from CDC, the Latvian National Center for TB and Lung Disease and the Center for Infectious Disease in Latvia.
The analysis of trends between 1998 and 2001 found a 14-fold increase in HIV prevalence among TB patients, and an even more dramatic increase in HIV prevalence among patients with multidrug-resistant TB (MDR-TB).
Among the more than 90 percent of TB patients tested annually for HIV, the proportion infected with the virus increased from 0.1 percent in 1998 to 1.4 percent in 2001. The level of HIV was even higher among patients with MDR-TB, with HIV prevalence increasing from zero to 5.6 percent. More than 80 percent of the cases co-infected with MDR-TB and HIV - 13 of the 16 identified - were identified in 2001, the most recent year studied.
Available data also indicate an increase in HIV prevalence overall. In Latvia, the number of people living with HIV was 3.5 times higher in 2001 than it was in 1998 (from 260 cases per 100,000 in 1998 to 906 cases per 100,000 in 2001). Roughly 80,000 to 100,000 people are screened annually for HIV in Latvia.
Health officials fear these dramatic increases in HIV prevalence among TB patients could offset significant gains made in the late 1990s in reducing TB, especially drug-resistant strains. In 1996, Latvia had the highest level of MDR-TB in the world -14.4 percent of all newly diagnosed cases were MDR-TB1. Latvia responded to this threat by implementing the WHO's strategy of DOTS in 1996 and a special DOTS-plus program - a strategy for controlling MDR-TB - in 1998. The country was able to reduce levels of MDR-TB by one-third, to just over 9 percent by 2000.
Study researchers stress that progress made to date in controlling TB and MDR-TB will be reversed without effective HIV prevention, especially among injection drug users and young people, the populations most impacted by HIV. During the study period, 72 percent of HIV cases reported in the country were among injection drug users and 69 percent were among people 16 to 29 years of age.
Latvia is a little larger than the U.S. state of West Virginia. The country is located in Eastern Europe, bordering the Baltic Sea, between Estonia and Lithuania, adjacent to Russia. In July 2001, Latvia had a population of nearly 2.5 million.
1Anti-Tuberculosis Drug Resistance in the World, The WHO/IUATLD (International Union Against TB and Lung Disease) Global Project on Anti-Tuberculosis Drug Resistance Surveillance 1994-1997
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ONCE-A-WEEK REGIMEN SUCCESSFULLY CURES TB IN SELECT PATIENTS
TBTC Study 22/Once-Weekly Isoniazid/Rifapentine (HP1) Vs Twice-Weekly Isoniazid/Rifampin (HR2) in HIV-Negative TB Patients - in Whom Can Once-Weekly Therapy Be Safely Used?, Dr. Andrew Vernon and Colleagues
A once-weekly TB regimen, initiated after the first eight weeks of therapy, is a viable option for selected patients being treated for active disease, suggests a new study today from CDC's Tuberculosis Trials Consortium (TBTC). The study, called Study 22, evaluated a regimen of once-weekly isoniazid and rifapentine given during the continuation phase of therapy (from the ninth to twenty-fourth week of treatment), as an alternative to the standard twice-weekly regimen among a group of HIV-negative TB patients.
Among HIV-negative patients with no lung cavities identifiable on chest x-ray, the once-weekly regimen was found to be safe and effective. While researchers stress the need to confirm results in routine clinical settings, this approach could help simplify TB treatment and lower the cost of care in the United States and Canada.
To identify those patients in whom a weekly therapy would be possible, more than 1,000 HIV-negative patients completed eight weeks of intensive TB therapy with the four frontline TB drugs - isoniazid, rifampin, pyrazinamide and ethambutol - before being randomly assigned to one of two groups during the 16-week continuation phase of TB treatment. One trial group received isoniazid and rifapentine - the first new TB drug approved by the Food and Drug Administration in 30 years - once a week, while the other group received the standard therapy of twice-weekly isoniazid and rifampin.
Both groups of patients were then followed for two years. Nine percent (46 patients) of those who took the once-a-week regimen either relapsed or experienced treatment failure. Six percent (28 patients) who took the twice-weekly regimen relapsed or had a treatment failure. The relapse rate in the once-weekly arm was slightly higher overall. However, when researchers only reviewed data on patients who did not have signs of advanced disease - such as lung cavitation - the relapse rates were comparable. Therefore, researchers were able to identify a group of HIV-negative patients in whom the once-a-week therapy would be successful.
Supported by CDC, the Tuberculosis Trial Consortium is a network of 23 clinical sites in the United States and Canada in which principal investigators are recognized experts in tuberculosis treatment and prevention. TBTC's mission is to conduct research concerning the diagnosis, clinical management, and prevention of latent TB infection and active TB disease. For more information on TBTC, please visit: http://www.cdc.gov/nchstp/tb/tbtc/default.htm.
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