There are drugs that can kill it.
So, why has tuberculosis been so difficult to eradicate in our modern world?
Numbers released this month by the World Health Organization (WHO) show how pervasive tuberculosis (TB) still is.
The health agency reports that in 2015 there were more than 10 million new cases of TB worldwide.
Almost 6 million of those cases were men and 3.5 million were women. Another 1 million were children. People with HIV accounted for 1.2 million of the new TB cases.
In addition, there were 580,000 new cases of drug resistant TB.
About 1.8 million people died in 2015 from the infectious disease that primarily attacks the lungs.
In the United States, 9,563 cases of TB were reported in 2015. More than 500 people in the United States die each year of the disease.
After decades of decline, the incidence of TB has leveled off in the past few years. A major reason is the emergence of the drug resistant strains.
WHO officials say they are behind in their campaign goal, started in 2014, to reduce TB cases by 80 percent and reduce TB deaths by 90 percent by 2030.
Early diagnosis crucial
TB as an organism is a tough customer.
Jeffrey D. Cirillo, Ph.D., a professor at the Texas A&M College of Medicine, says it doesn't take much of a foothold for tuberculosis to get going.
Most pathogens require hundreds, even thousands, of organisms for the disease to start growing inside the human body.
Tuberculosis requires 10 or fewer.
"It is one of the most successful pathogens in history," Cirillo told Healthline. "It's very, very effective once it gets in."
TB is also a slow-growing disease.
It can be inside a person for several months or even a year or two before symptoms, such as severe coughing, begin to show up.
"It can take a long time to manifest," Dr. Dana J. Hawkinson, an internal medicine and infectious disease specialist at The University of Kansas Hospital, told Healthline.
In addition, it can be several months after the initial infection before the disease will be evident in lab tests.
Meanwhile, a person, unaware they are infected, can pass the airborne disease along to others without knowing it.
Even people who don't develop symptoms can infect others. It's estimated that one-third of the world's population carries this "latent tuberculosis."
"The disease has the ability to hide under our radar," said Cirillo.
Cirillo said the most commonly used diagnostic lab test is simple and low-tech, so it can be used in a lot of countries.
However, many times it takes one to two weeks to get results.
In the United States, there are tests that produce results the same day.
Cirillo notes that both tests can increase the lapse time between infection and treatment.
Cirillo has been working on a new test called TB REaD. It targets an enzyme produced by the bacteria that cause TB.
The test makes this enzyme glow when it is spotted in a saliva or mucus sample.
The results can be produced in 10 minutes, so a patient can be given medication before they leave the doctor's office.
"We want to complete the diagnosis while the patient is still there," said Cirillo.
Vaccine and treatments
Once the disease has been identified, it needs to be treated.
That is easier said than done.
First, access to treatment can be difficult in some developing countries.
In addition, people with TB need to take daily medication for six to nine months. Sometimes, they stop taking the drugs when they start to feel better.
That's when a drug resistant strain can develop.
In addition, treatment can be tricky to administer to someone with HIV and TB.
"There are a lot of factors at play here," said Hawkinson.
There is a vaccine available, but there are some limitations.
Hawkinson said the inoculation is not used in the United States because it can affect the ability to screen someone for latent TB.
Cirillo added the vaccination doesn't work all that well in adults, although it is efficient in infants.
That makes it difficult in countries such as India, which currently has more than a quarter of the world's TB infections, to reduce the spread of the disease among adults.
Both medical experts agree that education about the disease, better access to resources, more efficient diagnostic tests, and shorter-term treatments are needed to combat TB.
"It is definitely a health hazard," said Hawkinson.
By David Mills
The original article was published on Healthline.com.
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