Drug Resistant Tuberculosis Scare: The Cliff Notes
Last week I had a chance to talk tuberculosis with Neil Cavuto on the Fox News Channel. Recently, a traveler entering the United States from India was identified as having an extensively drug resistant form of TB. Not only may she have exposed fellow passengers in flight, she traveled to multiple states before finally seeking treatment for her symptoms in Chicago. As a result of this latest news story, your patients may have questions about the disease
Here are a few quick notes about drug resistant tuberculosis to help you field questions in your practice.
What is drug-resistant tuberculosis?
Just like bacteria causing infections like cellulitis and urinary tract infections can develop resistant to antibiotics over time, some strains of Mycobacterium tuberculosis, the bug responsible for TB, have also developed defenses against the drugs commonly used to treat it.
The most common form of drug-resistant tuberculosis is referred to as multidrug-resistant tuberculosis, or MDR-TB. This strain of the disease is resistant to both isoniazid and rifampin, the two most potent TB medications. Extensively drug-resistant tuberculosis, or XDR-TB, is a subtype of MDR-TB. XDR-TB is resistant not only to first line therapies, but also most second line TB drugs making treatment difficult. Only 30 to 50 percent of patients with XDR-TB are treated effectively.
How is drug-resistant TB spread?
Drug-resistant TB can be spread in one of two ways. First, an infected individual with the disease may spread it to another by coughing, sneezing, or even speaking as the disease is airborne. Second, when an individual undergoing treatment for tuberculosis does not complete their treatment regimen or take anti-TB medications as prescribed, resistance can develop further spreading resistant strains of the disease. Treatment regimens for tuberculosis require that patients take medications for months, and sometimes for up to two years, making compliance difficult.
Who gets tuberculosis?
Similarly to many other infectious diseases, individuals with compromised immune systems such as those with HIV are most at risk for contracting TB. About one-third of the world's population is infected with tuberculosis. In most cases, the disease remains latent in the body without causing symptoms. Individuals with latent disease cannot spread the infection and may never develop an active case of tuberculosis.
In about 10 percent of individuals, latent tuberculosis develops into active disease anywhere from a few months to years after initial infection. 9 million individuals worldwide become ill with active TB each year including about 9,000 in the United States.
How easily is tuberculosis spread on an airplane?
The CDC and World Health Organization have looked at the spread of tuberculosis among passengers on aircraft. Retrospective studies indicate that TB has spread on aircraft in a few instances. A greater length of air travel, over 8 hours, increased the risk of TB transmission as close and prolonged contact is typically required to spread infection.
The air on planes is not as infectious as most people believe. Airplanes do recirculate about 50 percent of air but this air is passed through HEPA filters sterilizing it before it returns to the cabin. Overall, passengers seated more than six feet away from an infected individual are not at risk for disease transmission.
If you missed my clip on The Fox News Channel last week, check it out here.
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