While tuberculosis (TB) has not been a widespread health issue for Americans for decades, it remains a potentially serious threat here and worldwide, say public health officials.
Up to 13 million people in the U.S. have a latent TB infection, and without treatment, they are at risk for developing full-blown TB, a bacteria that usually attacks the lungs but can also damage other parts of the body. TB is a top infectious disease killer worldwide. The tuberculosis germs are passed through the air when a person who is sick with the virus coughs and even laughs.
Each year, World TB Day is observed on March 24 by the U.S. Centers for Disease Control and Prevention  (CDC), along with public health agencies worldwide, to educate the public about the threat of the disease. It commemorates the date in 1882 when Dr. Robert Koch announced his discovery of Mycobacterium tuberculosis, the bacteria that causes TB. Here in the U.S., “we must continue to find and treat cases of active TB disease and also test and treat latent TB infection to prevent progression to disease,” states the CDC.
“Even though the curve of the rate of the infection with tuberculosis in the U.S. is dropping every year, it still continues to be an important issue,” says Carlos Torres-Viera, M.D. , an infectious disease physician with Baptist Health South Florida. “And it’s very important especially in our community here in Florida because of the Hispanic population and the immigrant population.”
The findings of a new study released this month by the National Institutes of Health , this nation’s medical research agency, found that adults with HIV in Latin America, who were diagnosed with TB at an initial clinic visit, were about twice as likely to die within 10 years — compared to those who were not initially diagnosed with TB. Investigators analyzed the clinical records of nearly 16,000 people with HIV who received care at clinics in Brazil, Chile, Haiti, Honduras, Mexico and Peru.
“Most new cases in the U.S. are on foreign-born patients,” says pulmonologist Jacky Blank, M.D. , chair of the Lung Health Program  at South Miami Hospital . “Studies have proven that these cases stem from the latent disease, meaning that these patients were infected years before and changes in their health condition allowed for the reactivation of the disease. Here, we see patients with TB, but most are imported cases from Eastern Europe, Latin America and the Caribbean.”
The CDC says that TB remains a serious threat for some in this nation, especially for people living with AIDS or those who are HIV-positive, and for people with weakened immune systems. A TB infection, combined with an HIV infection, can work together to make a person very sick. Worldwide, TB is the leading cause of death among people living with HIV. Overall, TB is the world’s top infectious disease killer, claiming 4,500 lives each day, according to the World Health Organization.
Moreover, TB can spread through the air, from person to person, when someone with the active TB disease — not the latent form — talks, coughs or sneezes. Transmission can occur between people who are in close contact for a period of time.
“And you don’t have to be that close,” emphasizes Dr. Torres-Viera. “You can inhale (the droplets of saliva in the air) and they’re so small that they pass through your nose, your trachea and get into your lungs. And then they start reproducing and that causes an inflammation in your lungs. That’s when you get tuberculosis.”
Persons with latent TB infection are not infectious and cannot spread TB to others. They usually had a mild infection that was controlled by the body, and the bacteria remains dormant similar to varicella and shingles. The only sign of TB infection is a positive reaction to the tuberculin skin test or TB blood test.
Medications now widely prescribed that are known as “biologics” can weaken the immune system, creating potential flare-ups of chronic diseases that are dormant, such as TB. Biological medicines are a newer type of medicine that are used to treat autoimmune diseases, such as rheumatoid arthritis (RA) to reduce the damaging effect of the disease on the joints. Certain biologics also treat some types of cancers, lupus, psoriasis, inflammatory bowel diseases and other conditions.
All patients taking these medications should be skin-tested for tuberculosis prior to starting biologics, and many should also be tested for chronic hepatitis.
“TB was better controlled before the AIDS epidemic helped revive it around the world, as the immune-compromised patients could not fight the disease,” says Dr. Blank. “And once they developed active TB, they could spread it to the general population. But now we have other TB concerns that affect a wider range of patients, especially those with latent TB who have no symptoms and do not feel sick.”