Why TB Remains a Modern and Deadly ProblemTuberculosis is an ancient disease, with afflictions recorded as far back as Egypt's pharaohs. Despite effective antibiotic treatments, TB very much remains a pressing global health issue.
Sick with tuberculosis, inmates at a Siberian prison wash down their medicine with milk while a masked nurse monitors them.
The United States has seen a decline in the number of tuberculosis cases from 27,700 in 1980 to 14,100 in 2005.
A 1939 poster asks for contributions to help prevent tuberculosis.
Swim Ink 2, LLC/Corbis
Swim Ink 2, LLC/Corbis
Until German physician Robert Koch first identified the bacteria behind tuberculosis in 1882, the often fatal, wasting disease of the chest was known simply as consumption or the white plague. Even after Koch found the disease's cause, doctors could do little for patients beyond keeping them well-nourished and in a clean environment. A cure remained another half-century away, with the discovery of an effective antibiotic in the mid-1940s.
Today, treatments for tuberculosis are threatened by the emergence of strains of the disease resistant to multiple lines of drugs. In a first since 1963, federal public health officials this month ordered a quarantine for Andrew Speaker, a 31-year-old Atlanta lawyer, who has been diagnosed with an extremely drug-resistant form of the disease. The patient currently is at the National Jewish Medical Research Center in Denver for treatment.
Such hard-to-cure strains are rare in the United States, but are gaining a foothold in countries like Russia and South Africa.
Here, a look at the state of TB in the United States and around the world:
Isn't tuberculosis a disease of the past?
TB is indeed ancient – it has been around at least since the pharaohs. Some scientists suggest it has been living with the human species for 3 million years. But it's also very much a disease of the present. It remains widespread around the world, with one in three people infected, according to the World Health Organization. But 90 percent of people infected with the germ never develop the disease. The bacteria are usually held in check by the immune system. The infection is more likely to develop into a disease when a person's immune system is compromised, for instance, due to HIV, other illnesses or aging.
How is TB spread?
People with TB disease can spread the bacteria through coughing, sneezing or simply talking. But infection usually happens only after prolonged exposure, according to Dr. Martin Cetron, director of the global migration and quarantine division at the Centers of Disease Control and Prevention.
"By and large, TB is spread through prolonged contact. This is not the type of pathogen that is transmitted by short, casual contact," Cetron said.
Only 10 percent of those infected with the germ go on to develop the disease.
Drug-resistant TB is not more infectious than other forms of TB. But repeated exposure to large concentrations of infected people – such as happens in prisons, overcrowded houses and hospitals – can increase a person's chance of infection. An immune system weakened by disease or even certain types of medication can also increase a person's risk of developing full-blown TB.
A person also becomes less infectious after the first week of treatment.
How widespread is TB in the United States?
TB has been on the decline here for decades, with the number of cases in 2006 – 13,767 – at an all-time low since national reporting began in 1953. But the rate of decline has slowed, a point of concern to public health officials, given the rise of TB strains resistant to multiple drugs.
Immigrants and minority groups continue to have higher rates of infection than whites in the United States. And the number of regular TB as well as multidrug-resistant cases is increasing in foreign-born people living in the United States.
How widespread is TB globally?
In 2005, WHO estimated 8.8 million cases worldwide, with 1.6 million deaths. About 200,000 of those deaths were patients with HIV. The majority of cases – 7.4 million – are in Asia and sub-Saharan Africa. In the Americas, there were approximately 352,000 cases in 2005, with 49,000 deaths.
If treatments exist, why is TB still such a problem?
Access to treatment and diagnosis in poorer countries is an ongoing obstacle. The HIV pandemic also complicates attempts to eradicate TB: The AIDS virus, which attacks the immune system, increases the likelihood that a TB infection will become a full-blown disease. HIV is considered the single most important factor in the increase of TB in Africa since 1990. Emerging drug-resistant strains of TB are also hampering efforts to stamp out both diseases.
What is drug-resistant TB?
MDR-TB, or multidrug-resistant TB, is a form of the TB bacteria that is resistant to two of the most powerful TB drugs – isoniazid and rifampsicin. When these so-called first line drugs don't work, doctors resort to a second line of drugs. But these aren't as fast-acting, cause more side effects and are more expensive. One U.S. case of drug-resistant TB last year cost nearly $500,000 to treat.
When the bacteria become resistant to the second line of drugs, too, the disease is considered to be XDR-TB, or extensively drug-resistant TB. At that point, treatment options are seriously limited. (Extensively drug-resistant TB is the form Andrew Speaker has. Speaker is currently in isolation in Denver.)
Between 1993 and 2006, there were 200,000 confirmed cases of TB reported in the United States. Of these, nearly 3,000 cases were classified as multidrug-resistant (MDR).
Of those 3,000 cases, 49 were extensively drug-resistant (XDR) TB, with 32 cases reported between 1993 and 1999, and 17 cases between 2000 and 2006.
The CDC doesn't have a confirmed outcome on eight of the 49 patients who had XDR TB. Among the other 41 patients, 12 people died. At least 10 of those who died were HIV positive.
Can extensively drug-resistant TB (XDR-TB) be cured?
About 30 percent of cases can be cured, according to the CDC. The severity of the disease, underlying medical conditions and a physician's access to treatment options all factor into a patient's ability to be cured.
Is XDR-TB rare?
TB that is resistant to nearly forms of drugs (XDR-TB) is rare. But in 2004, there were an estimated half a million cases globally of TB resistant to some drugs. Multidrug-resistant TB remains rare in the United States; the CDC recorded 124 cases out of more than 13,000 TB infections in 2005.
How does TB become drug resistant?
Resistance to antibiotics happens in two ways – a person either is infected with a resistant strain, or during treatment, the bacteria mutate or pickup resistance genes from other organisms. For most strains of the disease, the CDC recommends a course of drugs over a six- to nine-month period. (For multidrug-resistant strains, treatment can take up to two years.) If the drugs aren't taken precisely as prescribed, that could give the bacteria a window of opportunity to become resistant. This can be a serious problem in developing countries, where those infected may not have access to medical care.
What are the symptoms?
A skin test can detect whether a person has TB even before the full-blown disease appears. Symptoms are the same for normal TB as XDR-TB. Among the signs: a cough with thick, cloudy mucus, sometimes with blood, for more than two weeks; fever, chills and night sweats; fatigue, muscle weakness and weight loss.
For now, extremely drug-resistant TB remains rare in the United States — with 49 cases confirmed over the last 15 years. But these dangerous, hard-to-cure strains are gaining a foothold around the globe.
A 31-year-old Atlanta attorney who went to Europe while infected with a hard-to-treat strain of tuberculosis said Friday that health officials told him it was safe to travel.
Andrew Speaker, who was quarantined this week, said on ABC's Good Morning America that although the Centers for Disease Control knew he had TB, he was given the green-light to fly to Europe for his wedding and honeymoon.
Speaker said health officials told him they would rather he didn't fly but didn't forbid it. His father, also a lawyer, taped that meeting, he said.
"My father said, 'OK, now are you saying, (you) prefer (him) not to go on the trip because he's a risk ... or are you simply saying that to cover yourself?' And they said, 'we have to tell you that to cover yourself, but he's not a risk,'" Speaker told ABC.
He also apologized to fellow passengers who might have been exposed to him. "I feel awful," he said through a mask at his hospital room in Denver. "I don't expect those people to ever forgive me. I just hope they understand that I truly never meant them any harm."
According to The Associated Press, even though U.S. officials had put Speaker on a warning list. After he completed the first leg of his trip to Europe, he caught a second flight to Montreal and then drove across the U.S. border on May 24 at Champlain, N.Y. A border inspector who checked him disregarded a computer warning to stop Speaker, officials said Thursday.
The inspector ran Speaker's passport through a computer, and a warning - including instructions to hold the traveler, don a protective mask in dealing with him, and telephone health authorities - popped up, officials said. About a minute later, Speaker was instead cleared to continue on his journey, according to officials who spoke with the AP. The inspector has since been removed from border duty.
Colleen Kelley, president of the union that represents customs and border agents, declined to comment on the specifics of the case, but told the AP that "public health issues were not receiving adequate attention and training" within the agency.
The next day, Speaker became the first infected person to be quarantined by the U.S. government since 1963.
Federal authorities have spent much of this week looking for people who might have come into contact with a man who has a drug-resistant form of tuberculosis.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, talks to NPR's Steve Inskeep about drug-resistant disease strains and how difficult they are to treat.
Are there other diseases out there that you would describe as being drug resistant?
Oh, plenty. Drug-resistant TB is one of many, many examples of microbes that develop a resistance to the standard antimicrobials that are generally used successfully against them. In fact, it has really put a damper on the extraordinary advances that have been made over decades and decades of antimicrobial agents, antibiotics, antivirals — because, sooner or later, microbes have the capability of being able to evolve toward protecting themselves from what we do to blunt them.
What are some other diseases that people didn't worry much about 10 or 20 years ago that now have strains that can kill you?
Staphylococcus is the prime example of that — typical staph infections. Some of them are more severe than others. Within a few years of the introduction of the penicillins, back in the 1950s, these staphylococci developed resistance. Then a new generation of drugs, methicillin, was developed, and they were very well treated with methicillin. Then, very soon thereafter, methicillin-resistant staphylococcus came in. Over a period of time, when you use antibiotics, you can actually make the resistance phenomenon come in sooner rather than later.
How does that happen? You kill off the weak ones and the strong ones survive?
Microbes, as they replicate, are continually able to mutate and divert themselves around. If you go with an antibiotic that's successfully treating a microbe, there will always be a small fraction of the microbe that, under most circumstances, wouldn't be a problem. But when you get rid of all of the sensitive microbes with the antibiotic, then those other strains that were generally minor strains start to take over. The problem is, they're resistant to the antibiotic, and then they become predominant microbes in a particular infection.
Are we accelerating this process by the way we use antibiotics?
Unfortunately, yes. There is a considerable amount of what we call inappropriate use of antibiotics. People come into a doctor's office. They don't have a bacterial infection. They have a viral infection, but they want an antibiotic, thinking it's going to make them better more quickly. If you inappropriately treat somebody with antibiotics, you will select for the less benign component of that.
You will get rid of the ones you don't have to worry about, and the ones you do have to worry about will have room to grow?
Is the pharmaceutical industry coming up with new antibiotics as rapidly as the old ones become less useful?
Unfortunately, the answer to that is no. There is not that much of an incentive for pharmaceutical companies to make new antibiotics because, first of all, antibiotics generally are not used on a daily basis, year-round. Pharmaceutical companies like to get a new blockbuster drug that you and I will use every day: lipid-lowering agents, blood-pressure agents, new types of Viagra — the things that people use over a long period of time. Antibiotics are effective, but they are not a long-term, major investment usually. Occasionally, you get a brand new blockbuster antibiotic, but that is more unlikely than it is likely.
Can you anticipate a time when we might have to accept much higher rates of infectious diseases and death, perhaps like we had a century ago?
No. ... It's a threat. I will not submit that we have to accept that one day that's going to happen. I have confidence that the research community will keep up, but it's not going to happen automatically. It's going to be kind of an agreement between the fundamental research community and the developmental community and the pharmaceutical organizations. If we get asleep at the switch, then it's going to happen. But we should not allow that to happen.
This story contains only a portion of the conversation, and excerpts have been edited for clarity. To hear the entire conversation, click the "Listen" button at the top of the page.