Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis. Early identification of TB is vital to the patient’s morbidity and mortality and decreasing the potential transmission to others.
Around 33% of the population has latent TB; this means they have been infected by the TB bacteria but are not ill with the disease nor can they transmit the disease. Latent TB does not normally transition to the symptomatic version; however, people with compromised immune systems, such as people with HIV, malnutrition or diabetes, or people who use tobacco, have a much higher risk of falling ill.
When a person develops active TB, the symptoms (such as cough, fever, night sweats, or weight loss) may be mild for many months. This can lead to delays in seeking care, and results in transmission of the bacteria to others. People with active TB can infect 10–15 other people through close contact over the course of a year. Active TB is especially dangerous in people with compromised immune systems. Without proper treatment, 45% of HIV-negative people with TB and nearly all HIV-positive people with TB will die.
Classic clinical features associated with active pulmonary TB are cough, hemoptysis, fever, night sweats, weight loss, chest pain, and fatigue. Upon physical examination, the patient may show signs of shortness of breath, abnormal breath sounds (especially in the upper lobes), and dullness on percussion. Many will appear weak and malnourished. Though TB is primarily thought to be a disease of the pulmonary system, if left untreated the bacteria can migrate to other parts of the body, changing from a latent to an active stage.
When TB spreads throughout the body, several local complications may arise. Spinal (spondylitis) tuberculosis or Pott’s Disease cause back or extremity pain and stiffness. Tuberculous involvement of the spine has the potential to cause serious morbidity, including permanent neurologic deficits and severe deformities. Tuberculous arthritis usually affects the hips and knees, but can affect any joint with pain, swelling and decrease mobility. When involving the brain (e.g. tuberculous meningitis), symptoms may include a headache lasting from days to weeks and mental status changes that may be initially subtle but can progress to coma. Brain abscess followed by seizures are also seen. Any array of focal findings may be seen depending on the location of the infection. Cardiac tuberculosis infects the tissues that surround the heart, causing inflammation, myocarditis, and fluid collections that may lead to cardiac tamponade. Electrocardiogram evidence of myocarditis may be seen. Most patients will exhibit shortness of breath, chest pain, and distended neck veins. In the cases of renal infection more than 90% of patients are asymptomatic, but can have sterile pyuria, which can be accompanied by microscopic hematuria. Few patients have symptoms of renal colic. The classical symptoms of TB (fever, sweats, and weight loss) are not common in patients with renal TB. Symptoms of gastrointestinal TB are specific to the infected site. Anorexia and nausea that are hallmark signs of active TB may be accentuated. Non-healing ulcers, malabsorption, pain, dysphasia, and diarrhea are the most common symptoms in this version of TB.
The absence of any significant physical findings does not exclude active TB. Classic symptoms are often absent in high-risk patients, particularly those who are immunocompromised, elderly or in children. Obtaining an accurate medical history, especially in regards to patient travel and potential exposure, can often assist in diagnosing these asymptomatic patients.
References:
Tuberculosis. Retrieved from http://www.who.int/mediacentre/factsheets/fs104/en/.
Tuberculosis. Retrieved from https://emedicine.medscape.com/article/230802-overview.
Recent Comments