July 3 (Reuters) - U.S. doctors treating a man who sparked international concern because he flew after being diagnosed with a dangerous form of tuberculosis said he in fact is infected with a somewhat milder form, multidrug-resistant TB, or MDR TB. Here are some facts about MDR TB: -- An estimated 500,000 people globally have MDR TB, according to the World Health Organization.-- In MDR TB, the bacteria that cause the disease are resistant to the two most powerful anti-TB drugs, isoniazid and rifampicin. -- MDR TB is called extensively drug-resistant TB or XDR TB if it also resists antibiotics in a class called fluoroquinolones, and at least one of three injectable second-line drugs -- capreomycin, kanamycin, and amikacin. -- Only 70 percent of MDR TB cases are cured and only 30 to 40 percent of XDR TB cases can be cured. -- WHO says there is probably no difference in the transmission of XDR-TB and any other forms of TB. The risk of becoming infected increases over time with contact.-- Up to 90 percent of people infected with TB bacteria never develop TB disease, including those with MDR and XDR forms.-- Symptoms of active disease include a cough with thick, cloudy mucus, sometimes with blood, for more than 2 weeks; fever, chills, and night sweats; fatigue and muscle weakness; weight loss; and in some cases shortness of breath and chest pain.
