A race is on for health officials to track down potentially hundreds of people who may have been in contact with a woman battling a rare and deadly form of hard-to-treat tuberculosis.

The woman, who arrived in the U.S. from India seven weeks ago, has an extremely drug-resistant form of the disease, known as XDR-TB, which is immune to most TB drugs, authorities revealed on Tuesday.

Health officials in Illinois were working with the Centers for Disease Control and Prevention to find people with whom the woman may have had prolonged direct contact, in close quarters.

The woman, who arrived in the U.S. seven weeks ago from India, has an extremely drug-resistant form of the disease, known as XDR-TB, which is immune to most TB drugs. She is being treated in a specialized respiratory unit at the National Institutes of Health in Bethesda, Maryland (pictured)

A female patient arrived from India to the U.S. in April through Chicago O'Hare. The TB sufferer then spent seven weeks in Illinois, Missouri and Tennessee before being admitted and isolated at a Chicago hospital. She is now being cared for at the National Health Institute in Bethesda, Maryland

TB is not as easily spread as diseases like the flu or measles. But it is a dangerous illness, especially for people with weakened immune systems like those with HIV, and health officials are taking the situation seriously, CDC spokesman Tom Skinner said.

In April, the woman flew from India to the U.S., arriving at Chicago's O'Hare International Airport.

She spent time in Missouri, Tennessee and Illinois before growing sick and being admitted to an isolation unit at a suburban Chicago hospital, seven weeks after arriving in the U.S.

FIGHTING A FEROCIOUS KILLER: HOW DO WE BATTLE XDR-TB? X-ray of lungs affected with pulmonary TB Extensively Drug-Resistant Tuberculosis, (shortened to XDR-TB), is a rare type of the multi-drug resistant disease which cannot be fought by even some of the most potent TB drugs. The disease is spread by coughs, sneezes, shouting or someone singing and droplets of the bacteria can float in the air for several hours. It is NOT spread by shaking hands, sharing food and drink, toilet seats, bed linens, sharing toothbrushes or kissing. XDR TB's resistance to most of the strongest TB drugs means that treating the disease means options have more side effects and cost more. Those with HIV or disease that weaken the immune system are at greater risk from XDR-TB. This rare form of TB is more common in people who do not correctly take TB meds, have had TB in the past or come from a part of the world where drug-resistant TB is more common. XDR-TB has a cure rate of around 30-50 per cent. Success depends on how drug resistant the patient is, how serious the XDR-TB has become and how weak the patient is. Source: CDC Advertisement

She is now being cared for in a specialized isolation unit for people with respiratory problems at a National Institutes of Health (NIH) hospital in Bethesda, Maryland, where she is in stable condition.

She was transported to the center by air and ground ambulance.

The CDC did not release other details about her age or nationality.

In a statement to Daily Mail Online, the CDC said: 'The CDC is working with the Illinois Department of Health to identify individuals who may have recently been exposed to a person in Illinois diagnosed with extensively drug-resistant tuberculosis (XDR TB) based on prior documented medical history and molecular‎ testing.

'The patient traveled in April from India to the United States through Chicago O’Hare airport.

'The patient also spent time in Missouri and Tennessee. Seven weeks after arriving in the United States, the patient sought treatment for and was diagnosed with active TB.

'The patient is currently in stable condition at the National Institutes of Health (NIH) Clinical Center in Maryland.'

The woman is facing months and even years of treatment for the disease which has around a 30-50 per cent cure rate. Some patients must even have pockets of the infection surgically removed.

Tuberculosis is caused by bacteria spread from person to person through the air.It usually affects the lungs and can lead to symptoms such as chest pain and coughing up blood.

However it is possible for people to have TB for weeks before they become acutely ill.

TB has been declining in the U.S. But globally, each year it sickens about 9 million people and is a cause of 1.5 million deaths.

The WHO said last year multidrug-resistant TB was at 'crisis levels', with about 480,000 new cases in 2013.

It is a man-made problem caused by regular TB patients given the wrong medicines or doses, or failing to complete their treatment, which is highly toxic and can take up two years.

Three to four cases are reported each year in the United States, on average.

The fight against TB, the world's second deadliest infectious disease after HIV, is also hampered by a lack of an effective vaccine.