One third of the population of the world is infected with TB. The vast majority of those have latent infections.
Despite the existence of effective drugs, each year more people die of TB. Recent outbreaks have occurred in Eastern Europe, where TB deaths are increasing after many years of steady decline. The largest number of cases is in Southeast Asia.
Each year approximately eight million people get active TB. More than 1.5 million of those cases are in sub-Saharan Africa. This number is rising rapidly because of the HIV/AIDS epidemic, which makes TB easier to catch because it suppresses the body's immune defenses. Nearly three million TB cases each year are in Southeast Asia. Russian prisons have extremely high TB rates and many inmates have the drug-resistant strain. This becomes an even greater health risk when prison amnesty is granted to tens of thousands at a time and the infected prisoners are released to cause disease among civilians.
A number of factors have contributed to the rise of tuberculosis in recent years. They include the scary combination of HIV and TB infection, a rapid increase in global travel, malnutrition, overcrowding, and an increase in the number of refugees who carry the disease.
A healthy person infected with TB has a 5-10 percent chance of getting active disease in his or her lifetime. An HIV-positive person has a 5-10 percent chance of getting active TB each year.
HIV and TB are a lethal combination, with each one speeding the others' progress. HIV weakens the immune system so that if an HIV-positive person becomes infected with TB, they are much more likely to develop an active case of the disease. As a result, TB causes 15 percent of HIV deaths worldwide. In Africa, HIV is the most important factor that has led to the increased incidence of TB in the past 10 years.
Poor management of TB programs threatens to make a curable disease incurable.
Can you get TB on a plane?
Yes. It is not likely, but it is possible. There are documented cases of TB infection that have occurred on long international flights. The people exposed to and infected with TB were those who sat closest to the person with the active disease.
Today there are resistant TB strains in every country that has been surveyed, with some strains resistant to all major anti-TB drugs. In undeveloped nations, doctors sometimes prescribe the wrong medicine, don't treat with multiple drugs at one time, or their drug supply is unreliable. The rise of MDR-TB, especially in the former Soviet Union, threatens global TB control efforts. And with the cost of treating MDR-TB so prohibitive in many countries, major outbreaks are possible.
Public health officials worry that poorly supervised or incomplete treatment of TB is sometimes worse than no treatment at all. Unlike those who are treated properly and stop being infectious after a few weeks (although they aren't cured yet), people who take the wrong medicines, or don't take them for long enough, are likely to remain infectious and spread their disease to many others. Drug resistance can arise and spread through improper and/or poorly supervised treatment as well.
Global trade and travel has increased dramatically over the past 40 years, helping to spread TB and other infectious diseases. There are proven cases of people infecting others on long plane rides and cases of MDR-TB strains that have been carried by a patient from one country to another.
Another factor hastening the spread of TB is the rising number of refugees and displaced people in the world. Untreated TB spreads rapidly in crowded camps and shelters, where it is estimated that up to 50 percent of refugees may be infected. Displaced people are a danger because it is difficult to treat people who are constantly moving around; as they move, they spread the disease.
Other displaced people, like the homeless in industrialized countries, are also at risk. In 1995, close to 30 percent of San Francisco's homeless population and 25 percent of London's homeless were reported to be infected with TB. These infection rates are much higher than the rates in the general population.
Although tuberculosis is a curable disease, it continues to cause much disease and death worldwide. Without aggressive public health measures and continued research on effective treatments and vaccine development, this treatable disease will continue to run rampant.