From Our Archives
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
In May 2007, the U.S. Centers for Disease Control and Prevention (CDC) issued an order to quarantine a man who flew on two transatlantic flights with a rare, dangerous form of tuberculosis and potentially exposed passengers and crew to the infection.
The Atlanta man was believed to be infected with the form of the tuberculosis bacteria known as "extensively drug-resistant" TB, abbreviated XDR TB. Tuberculosis is a bacterial infection that primarily affects the lungs, and the infection is spread via air droplets released during coughing, spitting, sneezing, or talking. XDR TB causes the same symptoms that a person would develop with TB. If TB disease is present, cough and fever would be the predominant symptoms. XDR TB is a rare form of the disease that is resistant to the drugs routinely used to treat tuberculosis infections and is extremely difficult to treat. The few treatment options available for XDR TB are less effective and associated with worse outcomes than traditional antibiotic therapies for TB. In 2006, there were two documented cases of XDR TB in the U.S.
Health authorities were aware of the man's condition and had warned the man against traveling, but he stated that compelling personal reasons led him to fly from Atlanta to Paris on May 13. On May 24, he returned to North America on a flight from Prague to Montreal and entered the U.S. by car. While it is not certain that passengers and crew on board the flights were infected, the CDC recommended that passengers and crew on those flights be tested for TB infection. Particularly those seated within two rows of the infected man are at greatest risk for infection.
After his return to the U.S., the man cooperated with authorities and voluntarily entered a hospital in Atlanta and was placed in respiratory isolation to prevent spread of the infection. This event marked the first time since 1963, when a patient with smallpox was quarantined, that the CDC issued this type of isolation order.
On July 3, 2007, however, a further statement was issued that downgraded the man's condition. Based on further and extensive testing of different isolates of the TB organisms cultured from the man, authorities were able to demonstrate that he did not have XDR TB. He does have multi-drug resistant TB (MDR TB), or TB that is resistant to at least two of the best anti-TB medications, isoniazid and rifampin, which are considered first-line drugs used to treat all people with drug-susceptible TB. MDR TB may be treated with some of the second-line drugs used to treat TB, although this treatment is much less effective and more toxic than the first-line medications normally used to treat TB. XDR TB is a relatively rare type of TB that is resistant to nearly all medicines used to treat TB disease, including many of the second-line drugs that may still be used to treat MDR TB.
Testing of multiple isolates of the TB bacteria taken from the same patient may at times produce differing results, especially in the evaluation of their resistance to second-line drugs to treat TB. It is also possible that a given patient may be infected with more than one strain of the TB bacteria, which could also be responsible for changes in the drug-resistance testing results.
The CDC defends its actions against the Atlanta man, noting that while not as rare as XDR TB, MDR TB is a serious medical condition: "Regardless of the revisions of the patient's drug susceptibility at this time, the public health actions that CDC took in this case, and are continuing to case - to take are sound and appropriate. After all, the public health response to drug-resistant TB infections, either MDR TB or XDR TB is the same under the World Health Organization's TB and airline travel guidelines that were published in 2005."
Not all people who are infected with the TB bacteria develop the disease, but all TB infections must still be treated. Spread of the infection is only possible by people who have developed the disease. Infection with TB, and particularly MDR TB or XDR TB, is a particularly serious concern for those who have compromised immune systems, such as people with HIV disease or those receiving chemotherapy for cancer or immunosuppressant drugs.