25 March 2009

Let sunshine in to fight TB

Ventilation and some sunshine could go a long way to reduce tuberculosis risks in hospitals and prisons, two strongholds of the contagious lung disease, the WHO said.

Ventilation and some sunshine could go a long way to reduce tuberculosis risks in hospitals and prisons, two strongholds of the contagious lung disease, the World Health Organisation said.

In its latest Global Tuberculosis Control report, released on Tuesday, the United Nations agency also doubled its estimate of how many HIV-infected people catch and die from tuberculosis, and warned especially deadly strains are continuing to spread in all corners of the world.

Mario Pavilion, director of the WHO's Stop TB department, said that because tuberculosis bacteria thrive in stagnant air, "simply opening the doors" can reduce the chances that patients, inmates and others will become infected with the disease that killed about 1.8 million people in 2007.

That global tuberculosis death toll includes 1.3 million HIV-negative people and 456 000 who were also infected with the Aids virus, deaths which are strictly classified in health statistics as HIV fatalities.

"You can only die once," explained Kevin De Cock, the WHO's HIV/Aids Director, who estimated HIV patients whose immunity levels are weak are more than 20 times more likely to catch tuberculosis than the rest of the population.

Better data
The WHO's large revision of the number of people with both HIV and tuberculosis reflected "better analyses, better data, and better methodology" and not a real increase in the twin infections between 2006 and 2007, De Cock told a Geneva news briefing.

HIV patients should be screened for tuberculosis and given drugs to reduce their risks of developing the disease, which can be caught by breathing in air droplets from a cough or sneeze of an infected person, the Belgian infectious-disease expert said.

About a third of the world's population is infected with the bacterium that causes tuberculosis, but only a small percentage of people develop the disease, which normally arises when immune levels are weakened due to pregnancy or illness.

The global prevalence of tuberculosis was nearly stable in 2007, with 9.27 million new cases reported compared to 9.24 million in 2006.

Development of drug-resistance
Although antibiotics can cure tuberculosis, drug-resistant strains of the disease have proliferated in recent years as a result of medical errors and the failure of patients to take the full six- to nine-month drug treatment course.

The WHO said that about 500 000 people worldwide have been diagnosed with multi-drug-resistant strains of tuberculosis, which cannot be treated with two or more front-line drugs.

And 55 countries and territories worldwide have reported at least one case of "extensively drug-resistant" tuberculosis or XDR-TB, which is virtually untreatable with today's medicines, according to the WHO study.

The actual prevalence of that lethal strain is probably even higher, as few poor countries are currently doing the series of tests required to evaluate the extent of drug resistance in their patients, Pavilion told the Geneva briefing.

Aeroplanes safer than buildings
In 2007 an Atlanta lawyer infected with drug-resistant tuberculosis flew to and from Europe for his wedding and honeymoon, and then entered the United States from Canada, triggering an international health scare about the disease.

The same year, a Mexican traveller flew across the US-Mexico border 21 times despite warnings from the Centres for Disease Control and Prevention to US border officials that he also had a drug-resistant tuberculosis strain.

Pavilion, who has led the WHO's tuberculosis fight since 2003, said that transmission risks were only highly acute on flights lasting more than eight hours, and for people sitting within five rows of an infected person.

"In airplanes the ventilation system is actually better than in most buildings," he said.

UV also fights TB
Citing research showing that ultra-violet light can zap tuberculosis bacteria, Raviglione said all efforts to improve natural light in prisons and hospitals could help reduce threats from contagious droplets.

Better air flow through ventilation systems or open windows and doors, and the use of masks in stagnant areas, would also help supplement screenings and antibiotic courses to accomplish the UN's goal of halting and reversing the spread of tuberculosis by 2015.

"It is feasible. What it needs is commitment, some money, and people who know what they are doing," Raviglione said. - (Laura McGinnis/Reuters Health)

Read more:
Drug-resistant TB an uphill battle
UV thwarts TB infection in hospital


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