World TB Day 2013: A Fearsome Disease, Hope for New Vaccines

 written by Dr. Pamela Peacock, Museum Curator 

I spent much of 2012 thinking about tuberculosis.  As Curator at the Museum of Health Care, I was tasked with developing an online exhibit on the disease, covering how it works and spreads, as well as how we have worked to prevent, diagnose, and treat TB over time.

When I first started this project, I knew very little about tuberculosis.  The most obvious image I could conjure was of a figure coughing up blood into handkerchief.  The more I learned about TB and how it worked, the more concerned I became.  When people broke out into coughing fits around me, I would cringe a little – what IF they did not have a common cold?  What IF I caught TB?  The thought is disturbing, even if the actuality is highly unlikely.

A TB patient is depicted coughing up blood.  Image from the US National Library of Medicine.
A TB patient is depicted coughing up blood. Image from the US National Library of Medicine.

TB most commonly infects the lungs, though it can infect almost any part of the body, including the heart, the bones, or the brain.  Typically, the immune system is able to form a protective layer – a tubercle – around the bacterial infection, but in some people the bacteria are able to continue to replicate in the tubercle until it bursts, damaging lung tissue and releasing bacteria that spread further into the lung and body.  In other cases, the bacteria are contained, dormant but not dead, in the tubercle until the immune system is weakened, at which point the bacteria are able to burst out of the weakened tubercle.  The image of bacterial time-bombs in the lungs is frightening.  Even more so, perhaps, when you consider that for most of history there was no effective treatment for TB.  Or, that increasingly tuberculosis bacteria are becoming resistant to the treatments that are currently available.

Like many people, I suspect, I had a historical image of the disease, a disease that was past its prime and on its way to eradication.  How wrong I was!  Though many scholarly works do address the effects of the disease on past populations, articles and websites bring home the damage this disease is doing to individual lives and communities around the world.

It is estimated that one third of the world’s population has been infected with tuberculosis.  The world does not bear this burden equally – twenty two countries across Africa, Asia, Eastern Europe and South America account for 80% of all tuberculosis cases.  1.4 million people died from TB in 2010.  Roughly 3,800 people die from TB each day!  This, despite the fact that the majority of TB cases are drug-susceptible and can be cured with appropriate drug therapy.  Yet, drug resistant cases of the disease are on the rise, complicating treatment and escalating its cost.  Many such cases are misdiagnosed and mistreated, widening the drug resistance.

Children are vaccinated with the BCG vaccine.  WHO image, US National Library of Medicine A014051.
Children are vaccinated with the BCG vaccine. WHO image, US National Library of Medicine A014051.

Although these facts should disturb you, there is also great hope for the development of new preventative measures, specifically vaccines, and new drugs to treat the disease.  The BCG vaccine was introduced in 1921 and remains the only TB vaccine today.  Still used in many countries, BCG has proven to be effective in children; however, its protective effects wear off with time and it is not as effective in adults.  Thus, for many years researchers have sought a new vaccine.  Aeras, a non-profit development corporation that works with a number of partners, has six vaccinations in trial.  Unfortunately, the most advanced vaccine in trials, MVA85A, was recently shown to be no more effective than the BCG vaccine at protecting infants.  Two other vaccines are in large trials.  Hope must be maintained.

For many North Americans, tuberculosis is a disease of past-generations and that rarely crosses their minds.  This is a luxury.  In many parts of the world TB remains an ever-present danger.  Vaccination and drug development are needed to prevent and control the spread of TB.  As our global community is woven more and more tightly together, the goal of stopping the TB epidemic should be one shared by us all.  Money and resources must be committed to solving the problem.

TB is a frightening disease.  But there is also great hope that we can soon find better tools to fight it.

To find out more about tuberculosis and the efforts to improve diagnosis and treatment please explore our web exhibit, “Fighting for Breath: Stopping the TB Epidemic”: http://museumofhealthcare.ca/explore/exhibits/breath/  See also two blogs posted in 2012 for World TB Day.  The Museum will open an exhibit this fall on the role of vaccinations in controlling several diseases in the 20th century.

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