TB vs Bird Flu: who poses the biggest threat?
Starting today, representatives from the World Health Organization (WHO) will attend two days of meeting with other tuberculosis (TB) experts in South Africa to discuss how to address the emergence of virulent new strains of multidrug resistant TB. In a statement released on September 5th, 2006, the WHO expressed serious concern about the emergence of extensive (or extreme) drug-resistant strains of TB, dubbed XDR-TB. While TB strains that resist treatment by the two major front-line antibiotics have been around for sometime, the emergence of XDR-TB is very worrisome because they are additionally resistant to at least three of the six remaining classes of secondary treatment options, rendering them virtually untreatable with existing antibiotics.
TB already poses a serious world health threat and the latest findings will not improve matters. A joint study by the WHO and the US Centers for Disease Control and prevention (CDC) found that XDR-TB are present in every region of the world. The WHO estimates that approximately 1.7 million people die annually from TB infections, which affect the respiratory system and are spread through airborne transmission routes. The problem is greatest in the developing world were access to medical aid is sporadic and costly drugs are inaccessible or prohibitively expensive.
I find it very encouraging that the WHO, and others (eg. Bill and Melinda Gates Foundation, Stop TB Partnership, etc.) are continuing to take a serious interest in the world’s TB problem, but I fear it will never receive as much press attention as bird flu (avian influenza) strain H5N1 has received in recent years. This somehow seems strangely out of proportion with the current level of risk posed by each disease. Let’s compare some facts:
Bird flu H5N1 virus has infected 241 and killed 141 people since 2003 (August 23, 2006 figures).
In 2004, 14.6 million people were currently infected with TB, of which 8.9 million were newly diagnosed cases, and nearly 1.7 million people died from TB infections.
H5N1 virus could potentially mutate into a form that may be transmissible between humans (there are isolated cases in several families that suggest this might be occurring).
TB is transmitted from person to person through coughing and sneezing.
Treatment of H5N1 infection with agents such as neuraminidase inhibitors shows limited success.
Increasingly drug resistant strains of TB are making the disease clinically “untreatable” in a growing number of cases.
H5N1 virus has now been found in 17 countries.
TB is a world-wide problem. XDR-TB strains have been identified in all regions of the world.
So why then all the recent fuss about bird flu? Could it be that the developed world is by and large unaffected by TB (except for HIV carriers) so it is considered a poor man’s disease? Is the press not interested in an “old” disease like TB because it isn’t sexy? Yes I realize that the overall mortality rate of TB is much lower than H5N1 virus and it could be a major health concern if it mutates. But it has not mutated yet, and until it does so I think the hyperbole needs to be reined in. Even some within the WHO itself seems to be blinded by the limelight. Last March a widely circulated story from the Associated Press attributed an absurd statement to a WHO official who declared that bird flu represented a bigger challenge to world health systems than AIDS! Did I miss something? Has a cure for AIDS been found and I didn’t hear about it? Have the 38.6 million people living with HIV made miraculous recoveries? Did 2.8 million people not die of AIDS last year? Thankfully there are many people working behind the scenes to make sure that diseases like TB will not be forgotten for sexy new diseases like bird flu and SARS (does anyone still remember that world killer?).
