Tuberculosis is such a health threat because not only is it contagious, but it spreads through the air. (CBC)

Ever heard of White Plague? What about Pott's disease? Lupus Vulgaris? King's evil? No? OK then, surely you've heard of consumption. All of these diseases are actually the same disease, better known today as tuberculosis — TB for short.

Tuberculosis is caused by a germ called Mycobacterium tuberculosis. What makes TB such a health threat is that it is not only contagious, but it spreads through the air. So when infected individuals cough, sneeze, spit or even just talk, they're spreading the bacteria. Other people become infected when they breathe in the now airborne bacteria.

This is why the World Health Organization reports that about nine million people around the world become newly infected each year. Once infected, the bacteria can lie dormant inside the body for years.

Most cases are reported in Africa and Asia. The disease kills approximately 1.5 million people every year.

Canada and other countries that had at least one case of extensively drug-resistant tuberculosis in 2008 are indicated in orange. (Courtesy: World Health Organization)

Most people don't even realize they are infected. They don't feel sick and don't show any symptoms. In fact, 90 to 95 per cent of people who get infected never get sick.

It's the other five to 10 per cent who have to worry. These are people who have weaker-than-normal immune systems, such as children, the elderly or people with immune-deficiency diseases like HIV.

When the bacteria become active, they can attack any part of the body, although they commonly go for the lungs. Once there, the bacteria begin to grow and move through the blood to other parts of the body, such as the kidneys, spine and brain.

Watch for coughing, chest pain

If you suffer from a persistent cough — one that lasts longer than two weeks — along with chest pain, and are coughing up blood and phlegm, you may have TB. Other symptoms include weight loss, fatigue, lack of appetite, chills and fever.

Tuberculosis has been around a long time. Tissue samples from ancient gravesites and the examination of an Egyptian mummy suggest people were infected by tuberculosis as far back as 5,400 years, but scientists believe the bacteria are probably three times as old.

Documentation of TB goes back to the ancient Greeks, who identified what they called "phthisis" as the most widespread disease of the time, one that was almost always fatal.

But it wasn't until 1546 that the idea that TB is contagious began to be accepted as medical fact. And it took almost another 200 years before scientists realized that the disease didn't just attack people who had certain physical attributes.

In 1882, German bacteriologist Robert Koch identified the tuberculosis bacillus, the bacteria at the root of the disease. Koch's work won him the Nobel Prize in physiology or medicine in 1905.

WHO plan aims to tackle TB

The WHO's Global Plan to Stop TB aims to cut the number of deaths from tuberculosis in half by 2015, saving 14 million lives between 2006 and 2015. The plan sets out strategies for making sure that people in underserviced areas get access to quality TB diagnosis and treatment. Regions especially hard hit are sub-Saharan Africa, where HIV is also prevalent, and parts of Eastern Europe.

In June 2008, the WHO announced plans to begin using a DNA-based test to diagnose drug-resistant forms of the disease in Africa. The tests will be used in Ethiopia, Ivory Coast, Congo and Lesotho and are expected to shorten the diagnosis time from months to hours.

In most of the world, people with active tuberculosis can be treated and cured if medical help is accessible, and infected people who aren't sick can take medicine to avoid developing TB.

People who think they may have TB can get a TB skin test, in which a health-care worker injects a small amount of testing fluid just under the skin on an arm. After a couple of days, the spot where the needle was injected is examined for a positive or negative reaction.

If the person tests positive, usually meaning he or she has TB, the person can get medicine that will kill the bacteria before they become active. One such drug is called isoniazid. Most people usually have to take the drug for at least six months.

There is also a vaccine called BCG, which is often used to prevent children from getting tuberculosis, although it's not always effective.

Meanwhile, Canadian researchers are invovled in an international study to see if inactive — or latent — TB can be treated more effectively with a drug regime that takes half the time as standard treatment. The new drug may also reduce the risk of side effects.

The study will follow 6,000 people in five cities across Canada as well as in the West African countries of Benin and Guinee, in Brazil, South Korea, Australia and Saudi Arabia.

Half will receive the current treatment — the once-a-day drug isoniazid — for nine months. The other half will receive rifampin for four months.

Researchers will monitor the two groups for 28 months to see how many go on to develop active TB. It's exepcted to take about seven years to determine whether the new treatment offers any advantages to the current treatment.

Cure within easy reach

People who develop TB can almost always be cured provided the proper medical treatment is available. Unfortunately, this is not the case in many countries where TB is killing thousands.

But recently, the WHO has identified a new strain of extremely drug-resistant tuberculosis that leaves patients "virtually untreatable." Extensive drug-resistant TB or XDR-TB is emerging, in which the bacteria resist not only front-line drugs, but also three of the more than six classes of second-line drugs. While more potent, these medications have more serious side-effects, are more expensive and may need to be taken for as long as two years.

On average, about one per cent of all strains are drug-resistant, and of those, between five and 15 per cent are extensively drug-resistant, said Dr. Anne Fanning, a professor emeritus at the University of Alberta's faculty of medicine.

"It is of grave concern if it is not appropriately addressed," Fanning told CBC Newsworld. "Drug resistance happens if treatment is not handled well. Good TB treatment in the first instance cures. Poor treatment creates drug resistance."

A survey by the U.S. Centers for Disease Control found that the strain is showing up around the world — not just in areas with poor access to quality care. Although no numbers are yet available, the Canadian Lung Association (formerly the Canadian Tuberculosis Association) says cases of XDR-TB were detected in Canada in 2006.

In May 2007, a man previously diagnosed with extensively drug-resistant tuberculosis sparked an international stir when he ignored doctors' orders and flew from Europe to the U.S. via Canada.

Tests later showed that Andrew Speaker had the less dangerous multi-drug-resistant form of TB. No one on the flight was infected, but some fellow passengers are suing Speaker for putting them at risk.

In March 2009, the WHO said more money and better science are urgently needed to address the growing threat of drug-resistant TB. The WHO estimates there were more than half a million cases of multidrug-resistant TB around the world in 2007, resulting in 130,000 deaths. The organization says the world is at "a turning point" in addressing the problem.

Winning TB fight

Overall, Canada has done pretty well in its fight against tuberculosis. The rate of the disease has dropped from about 120 cases per 100,000 people in the 1940s, to 5.2 cases per 100,000 people in 2002.

Of the 1,634 cases reported in 2002, 115 patients were reported to have died, but only 68 of the deaths were linked to TB.

Not bad for a population of 30 million, but not quite the elimination of the disease that was predicted to be achieved by 2000.

In October 2008, public health officials searched for passengers considered at "moderate" risk of having contracted tuberculosis during a Greyhound bus trip to Windsor, Ont.

As in Speaker's case, a passenger on the bus had infectious tuberculosis and may have passed it on by coughing while in close contact with others. Airports routinely screen passengers for signs of infectious diseases, but bus and train companies often don't.

The Canadian Lung Association says there are three reasons Canada hasn't managed to shake the disease. The first is that because tuberculosis bacterium is a living organism, it is in a constant fight to survive in its changing environment. This is why new strains of the bacteria adapt to resist drugs.

The second reason is that, due to the nature of Canada's population — with immigrants from around the world — the disease is brought over from countries where drug treatments for TB are not readily available. In 2005, 63 per cent of TB cases in Canada occurred in people born outside the country.

Lastly, there exists a reservoir for TB among people considered at high risk of infection — those with weak immune systems or living in communities that lack the proper health services.