|
| ||||||||
| ||||||||
|
Biosecurity Briefing
New WHO Survey Finds Global Increase in Drug-Resistant TB Infections By Jennifer Nuzzo, February 29, 2008 On February 26, 2008, the World Health Organization (WHO) released the Fourth Global Report entitled Anti-Tuberculosis Drug Resistance in the World,1 which, according to an accompanying WHO news release, “presents findings from the largest survey to date on the scale of drug resistance in tuberculosis.”2 Unlike previous versions of the report, the latest global survey includes analysis of extensively drug-resistant tuberculosis (XDR-TB), a form of tuberculosis that is resistant to nearly all drugs used to treat tuberculosis infection. The fourth global survey includes drug susceptibility information from 91,577 tuberculosis patients from “93 settings in 81 countries and 2 Special Administrative Regions (SARs) of China collected between 2002-2006,” which represents “35% of the global total of notified new smear-positive TB cases.”1 The survey also includes data from 33 countries that were not included in the WHO’s previous global reports. The WHO survey found that the proportion of reported tuberculosis cases that exhibited any antibiotic resistance “ranged from 0% in two Western European countries to 56.3% in Baku, Azerbaijan.”1 The overall proportion of reported cases that could be classified as multidrug resistant tuberculosis (MDR-TB), which is defined as tuberculosis that is resistant to two first-line antibiotics, was 5.3%, with ranges of 0-35% of reported TB cases, depending on the country.1 Based on the survey data, the WHO estimates that there are “nearly half a million new cases of MDR-TB a year.”2 The WHO report notes that the epidemic of MDR-TB is most “serious and widespread” in several former-Soviet countries such as in Baku, Azerbaijan, where MDR-TB was responsible for nearly 25% of all new TB cases). High rates of MDR-TB were also reported by some provinces in China.1 The report also found that XDR-TB, which is “more expensive and difficult to treat than MDR-TB,” is “widespread with 45 countries having reported at least one case.”1 However, the WHO report cautions that “few countries are currently equipped to diagnose” XDR-TB; therefore, it is difficult to estimate the true extent of XDR-TB infection.2 In Africa, where TB incidence rates are among the highest in the world, only 6 countries were able to provide drug resistance data for the global survey due to lack of equipment and trained staff to carry out these investigations. The WHO report also found an association between HIV infection and drug resistant TB, but suggests that such a link may be “more closely related to environmental factors such as transmission in congregate settings rather than biological factors.”1 The WHO did find that progress has been made in controlling TB in some areas. In particular, Estonia and Latvia, which were once “singled out by WHO as drug-resistant TB ‘hotspots’” have been able to stabilize the rates of new TB cases “following a substantial investment and sustained assault on MDR-TB.”1 The WHO estimates that “US$ 4.8 billion is needed for overall TB control in low- and middle-income countries in 2008, with US$ 1 billion for MDR-TB and XDR-TB.” However, there is currently “a total finance gap of US$ 2.5 billion, including a US$ 500 million gap for MDR-TB and XDR-TB.”1 In the WHO press release, Dr. Mario Raviglione, Director of the WHO Stop TB Department, stressed that “TB drug resistance needs a frontal assault. If countries and the international community fail to address it aggressively now we will lose this battle.”2 Specifically, the WHO calls for immediate improvement in diagnosing TB and treating cases until cured, which is “the best way to prevent the development of drug resistance.”2 References
|