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What You Need To Know About TB

When we think of tuberculosis, we think of Old West outlaws, novels set in 19th-century Europe and afflicted geniuses. We think of Doc Holliday, the Georgia-born dentist and gunfighter who went to the Southwest in hopes of extending his life. We think of Marguerite Gautier, the heroine of Alexandre Dumas’s novel, The Lady of the Camellias. We think of Emily Bronte and George Orwell.

Mostly, though, we don’t think of tuberculosis, or TB, at all. Reminders of the threat of TB in everyday life went by the wayside when municipalities removed their “No Spitting on Sidewalk” signs. But tuberculosis did not. Despite the misconception that it has been scratched off of the infectious diseases list, it still exists in the U.S. and around the world. More than 90 percent of people in developing countries are infected with either latent TB or active TB disease. Dr. Jose Vazquez, M.D., section chief of infectious diseases at Georgia Regents University, says, “There are about two-billion cases worldwide. Of those, there are about two-million deaths a year.” The misguided belief that it was been eradicated like polio is shattered. “We’re a long way from eliminating it,” he says. “We don’t have the capacity, the capability or the funding to eradicate it.” 

Not everyone exposed to
Mycobacterium tuberculosis will develop symptoms. 


Thanks to a better understanding of how the disease spreads and how the disease is best treated, its grip on Western culture, especially in North America, has loosened. Among the 300 million people living in the U.S., only 12,000 to 14,000 cases of TB are diagnosed each year according to Dr. Vazquez. Since 1995, the incidence of tuberculosis has dropped 50 percent. Yet recent reports naming London as the Tuberculosis Capital of the Western World and of local high school students testing positive for active tuberculosis have brought the disease out of the shadows and into the headlines.

Fear of contracting the illness grips the public’s imagination. Renewed efforts at education and dissemination of information help quell the tide of panic. Reassurance that here in the U.S. tuberculosis is comparatively well-managed is welcome.

Tuberculosis, which has been infecting people almost since they first rose from the dust, peaked in the 18th and 19th centuries. Not until the late 1800s did physicians pinpoint tuberculosis as a communicable disease spread person to person. Caused by the bacterial organism Mycobacterium tuberculosis, TB as we now know is an air-born infection and not transmitted by contact with body fluids such as saliva.

The primary treatment for tuberculosis in the 19th century was to isolate infected individuals from the population. Sanatoriums sprang up to house victims of the illness, which was often referred to as “consumption” because of the weight loss it causes. Though the tuberculosis-causing bacterium primarily affects the lungs of those with active TB disease, it can spread to other organs as well, including the spine, kidneys and brain. Symptoms of tuberculosis infection of the respiratory tract include a chronic cough that lasts more than three months, fever, night sweats, loss of appetite, unintentional weight loss, fatigue, pain in the chest and coughing up sputum or blood.

Not everyone exposed to Mycobacterium tuberculosis will develop symptoms. “You need significant exposure to the bacteria. It comes down to continuous exposure in an area with poor ventilation,” says Dr. Vazquez. Even when these conditions exist and a person does have long-term contact with an individual with active TB disease—meaning he or she exhibits symptoms—the bacteria may enter the individual’s body but not produce active illness. “The immune system walls off the bacteria and prevents it from spreading,” says Dr. Vazquez. This is referred to as latent tuberculosis and occurs in around 90 percent of individuals exposed to TB. People with latent tuberculosis are not contagious but should still receive antibiotic treatment. Dr Vazquez warns, “If not treated, a normal host has a 10 percent chance of developing active TB over his lifetime.” That risk increases dramatically if the immune system is compromised and as the individual ages.

Treatment for active tuberculosis and latent tuberculosis is highly effective if the entire six- to-nine month, out-patient course of antibiotics is completed. Patients with active TB receive four oral antibiotics for the first two months, followed by two antibiotics for the final four months. Compliance is a critical factor in curing a patient with TB infection, preventing the spread to others and combating the development of antibiotic resistant tuberculosis (about 10 percent of the tuberculosis in the U.S. is drug resistant). Every person diagnosed with active TB is placed on a directly observed therapy (DOT) program overseen by the health department to ensure compliance. Latent TB is also treated with antibiotics for six to nine months, but the medications are not administered directly by the health department since patients with latent tuberculosis do not pose an imminent threat to society.

Despite what many people believe, there is no useful vaccine for tuberculosis. It cannot be medically prevented. Though the BCG vaccine was widely used after WWI and is still in use in countries throughout the world, Dr. Vazquez says, “We do not use it in North America because it has not been shown to be effective.”

The most common diagnostic tests for latent tuberculosis are the Mantoux tuberculin skin test (TST or PPD) and the TB blood test. The skin test is the one with which most people are familiar. A small amount of tuberculin fluid is injected under the skin on the lower arm. The patient then returns within 48 to 72 hours to have the skin test read. A skin reaction indicates a need for further diagnostic screening, which includes a chest X-ray and possibly some analysis of sputum. Similarly, the blood test measures the immune system’s reaction to the disease-causing bacteria. The advantage of the blood test is that results can be obtained without the patient having to return to the office. Chest X-rays and sputum stains and cultures are also used to confirm active infection.

The skin and blood tests are very useful in detecting latent and active cases of TB, but they are not used for widespread routine screening purposes. This leaves a person to question if he or she has been exposed, if he or she is at risk and how he or she can prevent contracting tuberculosis. Consider the risk issue first. Again, it takes prolonged close contact with a person who has TB to contract latent or active forms of the illness. The national average for incidence of TB in the U.S. population is 4.2 percent. Georgia is slightly above this average and most cases occur in the HIV-infected population centered in and around Atlanta. South Carolina is right at the national average.

Not everyone exposed to
Mycobacterium tuberculosis will develop symptoms. 

Degree of exposure and the immune system’s strength and competence are key factors in determining whether someone is at greater risk than the general population. People most at risk for contracting active tuberculosis include healthcare workers, IV drug users, anyone who has been incarcerated, people who are HIV positive, chemotherapy patients and people seeking certain treatments for lupus and rheumatoid arthritis. In the United States, the majority of cases occur among people who are foreign born, low-income or of African-American or Mexican-American heritage.

“There’s no good way to protect yourself,” says Dr. Vazquez, other than avoiding people known to have active TB or who present with TB symptoms. Move away from a person with a persistent cough. Eat a healthy diet to maintain the immune system.

Though somewhat romanticized in our lore and history, tuberculosis is a serious illness. Left untreated, it can cause debilitation and death. The famous Doc Holliday didn’t go down fighting at the end of gun barrel. He suffered prolonged illness and an agonizing end. Fortunately, TB is not as common now as it was in Doc Holliday’s lifetime, and it’s easy to treat and cure. Unless you’re in a high risk category, you’re very unlikely to contract tuberculosis. So though it rears its ugly head in news sound-bites, from a personal perspective there’s little to fear. From a public health and greater good perspective, however, we all benefit from continuing to battle the disease for those at risk.
   
   

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