Tuberculosis

Though the incidence of tuberculosis (TB) is and has been quite low in Virginia over the past several years, 2.9 per 100,000 individuals, two recent cases identified at a local Richmond school remind us that it is still around.

Just one hundred years ago, tuberculosis was the number one killer in the United States.  Though the infection and its symptoms have been around for millennia, it was first recognized as a single disease around the 1830’s.  The bacterium that causes TB, Mycobacterium tuberculosis, was identified by Dr. Robert Koch, the founder of modern bacteriology, in 1882.       

After determining the disease was communicable, public health measures were instituted in the U.S. to prevent the spread of TB.  Prior to antibiotic therapy, individuals diagnosed with consumption, the old term for tuberculosis, were encouraged to enter sanitariums, where they lived, worked, and most eventually died.  Unfortunately, the incidence of the disease is still quite high in many less developed countries around the world.

Tuberculosis is primarily a lung infection, but can attack other parts of the body such as the kidneys, spine, and brain.  The infection causes nodular growths, called tubercles, in the infected tissue; hence, the name.  

The bacteria are spread through the air when an infected person coughs, sneezes, or speaks.  Not everyone who contracts the bacteria becomes sick.  An individual may have a latent TB infection wherein their body’s defenses stop the growth of the bacteria and prevent symptoms from occurring.  Latent TB can become active TB if the immune system is later weakened.  Individuals with latent infection cannot spread the disease.

A person with active TB develops symptoms.  These can include a cough that lasts three weeks or longer; coughing up blood; weakness or fatigue; weight loss; loss of appetite; night sweats; fever and chills.  As you can see, many of the symptoms mimic some of the common respiratory infections we encounter throughout the year, including colds and flu.

Determining whether an individual has TB begins with an assessment of their risk for exposure to TB.  Individuals at risk for active TB include: close contacts of persons with known or suspected tuberculosis; those with HIV; residents of high-risk institutions such as nursing homes, correctional institutions, and homeless shelters; health care workers who serve high-risk individuals; foreign-born persons who have recently arrived from countries that have a high incidence of TB or those who have recently traveled to those areas; individuals taking immunosuppressive treatment; individuals who use IV, other illicit drugs, or excessive alcohol.  Some chronic medical conditions can also increase one’s risk of active TB such as diabetes, kidney failure, certain blood disorders, organ transplantation, and cancers.      

Screening for TB infection is currently recommended for individuals working in health care settings, nursing homes, daycares, and those with risk factors listed above.  A skin test (PPD) can determine if an individual has been exposed to TB.  If the test is positive, a chest x-ray is generally done to rule out pulmonary TB.       

Since TB is caused by a bacterial infection, it can be treated with antibiotic therapy.   However, Mycobacterium tuberculosis is an atypical bacterium.  This means that the antibiotics we use for typical infections, such as strep, are not as effective.  Generally, a combination of drugs is used to treat active TB and these medications are used for months instead of days.  Those who have latent TB are generally prescribed treatment to prevent them from getting active TB.       

The content in this column is for information purposes only and is not intended to be used for diagnostic or treatment purposes.  Consult your physician for appropriate individual treatment.  

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