Sun, Ventilation Reduce Tuberculosis Risk
A new report released Tuesday by the World Health Organization (WHO) finds that improved ventilation and extra sunshine may reduce the risk of tuberculosis (TB) in prisons and hospitals.
The WHO’s latest Global Tuberculosis Control report also doubled its estimate of the number of HIV-infected who catch and are killed from tuberculosis. The U.N. agency warned that particularly deadly strains of TB continue to spread throughout all regions of the world.
Since tuberculosis bacteria thrive in stagnant air, "simply opening the doors" can lessen the chances that inmates, patients and others will become infected with the contagious lung disease, according to Mario Raviglione, director of the WHO’s Stop TB department.
Tuberculosis killed about 1.8 million people in 2007, including 1.3 million HIV-negative people and 456,000 who were also infected with the AIDS virus ““ which health statistics strictly classified as HIV fatalities.
"You can only die once," said Kevin De Cock, WHO’s HIV/AIDS Director, in an interview with Reuters.
De Cock estimated that that those with HIV, whose immunity levels are weakened, are more than 20 times more likely to acquire TB than the rest of the population.
The WHO’s revised figures for the number of people with both TB and HIV are a result of "better analyses, better data, and better methodology", and not a true increase in the two infections between 2006 and 2007, said the Belgian infectious-disease expert during a news briefing with reporters in Geneva.
Those with HIV should be screened for tuberculosis and given drugs to reduce their chances of developing the disease, he said, which can be acquired by inhaling air droplets from a cough or sneeze of an infected person.
While roughly one-third of the world’s population is infected with the bacterium that causes tuberculosis, only a small percentage of those will actually develop the disease. This typically occurs when immune levels are weakened due to illness or pregnancy.
Global rates of tuberculosis were fairly stable in 2007, with 9.27 million new cases reported compared with 9.24 million cases in 2006.
Although antibiotics can cure TB, drug-resistant strains of the bacterium have spread in recent years as a result of medical errors and patients’ failure to take the total six- to nine-month antibiotic treatment course.
Worldwide, roughly 500,000 people have been diagnosed with multi-drug-resistant strains of tuberculosis, the U.N. agency said. These strains cannot be treated with two or more front-line drugs. Furthermore, 55 countries and territories have reported at least one incident of "extensively drug-resistant" tuberculosis, something known as XDR-TB. This form is virtually untreatable with current medicines, according to the report.
The true prevalence of that deadly strain is likely even higher, as many poor countries are not conducting the series of tests required to assess the extent of drug resistance in their patients, said Raviglione, who has led the WHO’s tuberculosis fight since 2003.
In 2007, an Atlanta lawyer infected with drug-resistant TB triggered an international health scare after flying to and from Europe for his wedding and honeymoon, and then entering the U.S. from Canada.
That same year, a traveler from Mexico flew across the U.S.-Mexico border 21 times, despite multiple warnings from the U.S. Centers for Disease Control and Prevention (CDC) to U.S. border officials that he was infected with a drug-resistant strain of tuberculosis.
Raviglione said that transmission risks were only highly acute for people sitting within five rows of an infected person, and on flights of durations longer than eight hours.
"In airplanes the ventilation system is actually better than in most buildings.”
Referring to research showing that ultra-violet light can kill tuberculosis bacteria, Raviglione said any efforts to increase the amount of natural light in prisons and hospitals would also help reduce threats from contagious droplets.
Improved air flow through open window, ventilation systems and doors, combined with the use of masks in stagnant areas, would also help augment screenings and antibiotic treatments to achieve the U.N.’s goal of stopping and reversing the spread of TB by 2015.
"It is feasible. What it needs is commitment, some money, and people who know what they are doing," said Raviglione.
The full WHO report can be viewed at http://www.who.int/tb/publications/global_report/2009/en/index.html.
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