What is it?
Tuberculosis (TB) is an infection caused by the organism called Mycobacterium tuberculosis. It is spread via respiratory droplets, and therefore anybody who comes in close contact with an infected individual is at risk of getting the disease.
The course
Primary TB is usually latent. What happens is that people inhale the organism and the immune system fights it without there being an active infection. The organism thus remains latent in the lungs. When reinfection occurs, or when the existing TB is reactivated then an active infection will ensue. Reactivation occurs when a person’s immune system is compromised. This may be due to illness, or medications that suppress the immune system. Upon reactivation or reinfection the TB may remain in the lungs or may spread to other tissues and organs, and this is termed disseminated TB.
Risk factors
Because TB is spread via respiratory droplets a big risk factor is close contact. This happens in places that are overcrowded. The poor, homeless, prison inmates, patients in nursing homes, and healthcare workers are most at risk because they are most exposed to people with active TB. Also at risk are alcoholics and those who use drugs intravenously.
Symptoms
The symptoms will depend on the organ involved. Generally all types of TB will be accompanied by constitutional symptoms, that is, weight loss, loss of appetite, fever and night sweats. If it involves the lungs there will be a productive cough. If it involves the gastrointestinal symptoms there will be vomiting and diarrhea. People with a compromised immune system are also at risk, like those with cancer, diabetes and HIV.
Diagnosis
Most often the presenting symptoms will lead the doctor to a high suspicion of TB. The first thing that will be done is a chest x-ray to see if there are any features of TB. Then sputum will be sent of for microscopy and culture to see of there are any TB organisms present. Doctors may also do a tuberculin skin test that will show evidence of an active infection.
If other organs are involved the appropriate specimen will be sent to the lab. If it involves the kidney then a urine specimen will be sent, and if it involves the gastrointestinal system then a stool sample will be sent. TB in lymph nodes will require a fine needle aspiration, which will be put on a slide to view under a microscope. If the TB has spread to the brain and formed a tuberculoma then a CT scan will be useful.
Treatment
There is a range of medication that can be used to treat TB but they are arranged in regimens. First-line treatment is for active TB and involves a course of rifampicin, isoniazid, pyrazinamide, and ethambutol. The course is for six months. Then there are other lines of treatment for people who fail to complete the first course or who end up with drug resistant TB. The downside of TB drugs is that they come with a range of side effects like damage to peripheral nerves and the liver.
