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Microbes

Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, Deanne Erdmann, MS, Sonia Rahmati Clayton, PhD, and James Denk, MA.

Disease Information: Tuberculosis

Tuberculosis, a disease also known as “TB,” has affected humans for thousands of years. For most of that time, there was no known cure and very little understanding of the disease. In the past, TB sometimes was called “con­sumption,” because it seemed to devour people from the inside. 

TB is one of the deadliest diseases known to man. At one point, it was the leading cause of death in the U.S. Its dark history is reflected in novels, artwork and dramas. Back in the 1800s, some people even thought TB was caused by vampires. It’s true! The symptoms of TB look like characteristics often associated with vampires (red, swollen eyes that are sensitive to bright light, pale skin, and worst of all, coughing up blood). In fact, some people thought TB sufferers caught the disease from dead family members who visited at night. 

An Invisible Enemy
We have come a long way since then, and scientists have developed effective treatments against TB. Caused by the Mycobacterium tuber­culosis bacteria, TB can be deadly for people who do not get proper treatment. The disease most often infects the lungs, because it is transmitted through the air we breathe. However, it can attack any body organ or system. 

How TB Spreads
TB spreads from person to person through the air. When someone who is infected with tuberculosis sneezes, coughs, talks or spits, TB bacteria are released into the air. Anyone nearby who breathes in these bacteria can become infected. If a person with TB does not receive treatment, he or she could infect an average of 10 to 15 people each year. 

People infected with TB bacteria may not show symptoms or develop the disease. In fact, only about 10% of otherwise healthy people infected with TB bacteria ever become sick. The other 90% are said to have a latent TB infection. These people do not get sick and do not transmit the disease.

However, some people with latent TB infection do become ill when they get older. Therefore, they may choose to take antibiotics right away to prevent the disease from occurring later in life.

Babies and young children have an increased risk for catching TB because their immune systems are not yet mature. Other people at higher risk for contracting (catching) TB are those with weakened immune systems, such as people with HIV (the virus that causes AIDS), diabetes, cancer, kidney disease or other serious medical conditions. People who abuse drugs or alcohol also are more likely to develop this illness. 

Where Things Stand Today
Until the 1940s, there was no cure for TB. But with education, improvements in public health care and the creation of new antibiotics, the numbers of deaths from TB dropped dramatically in the U.S. and Europe. To cure the disease, patients were required to take anti­biotics for six months.

However, over time, drug-resistant forms of TB began to emerge. Doctors discovered that some patients stopped taking their medicine as soon as they felt better, instead of completing the course of anti­biotics designed to kill all of the bacteria. In these cases, the surviving TB bacteria changed, or mutated, so that the original antibiotic became less effective. Eventually, the antibiotic-resistant TB bacteria were passed on to other people, who then developed forms of TB that were even more difficult to treat.

There are many reasons why TB still exists, including lack of medical facilities, cost of anti­biotics and poor hygiene.The disease remains a very serious health problem today. Each year, almost nine million new cases of TB are reported worldwide, and nearly two million people die from the disease. 

Without better treatment, it is estimated that over the next 15 years, almost one billion people will become infected with TB bacteria, more than 150 million will become sick, and more than 36 million people will die. 


Funded by the following grant(s)

Science Education Partnership Award, NIH

MicroMatters
Grant Number: 5R25RR018605