Page 15 - Delaware Medical Journal - March/April 2020

PUBLIC HEALTH
INTRODUCTION
Tuberculosis (TB) is a disease many think of in the past tense, as if it did not still live among us, but it does. In fact, the WHO tells us that TB remains the 10th leading cause of death worldwide.1 Successful public health efforts in the United States have helped drive down domestic TB incidence rates, but they have also had
the unfortunate side effect of removing it from many providers’ minds. Lowering the threshold for suspicion in providers is now one of our biggest challenges in getting providers to think TB!
In 2018, Delaware had 22 cases of TB disease, and an incidence rate of 2.3 cases per 100,000 population, lower than the national average but still ranking us 19th in the nation for TB disease incidence. among the three counties, though Kent County has had the highest incidence
rate since 2016. In keeping with national demographics, Delaware sees more cases in those born outside the United States. In 2018, Delaware’s U.S.-born and non-U.S. born incidence rates were 0.9 and 12.8 per 100,000 population, compared to national incidence rates of 1.0 and 14.3 per 100,000.3
LATENT TB INFECTION (LTBI)
There are two TB-related conditions: LTBI and TB disease. Those with LTBI were exposed to someone with infectious TB disease and are infected with M. tuberculosis, but they do not have the active form of TB disease. Those with LTBI do not have symptoms of TB disease and are not contagious to others. If tested for TB using either the tuberculin skin test (TST) or an interferon gamma release assay (IGRA), patients with LTBI will likely have a positive result with a normal chest x-ray and negative sputum test.
It is important to treat those with LTBI
because if left untreated, the average patient with a normal, healthy immune system still has a 5% to 10% chance of progressing to TB disease during his or her lifespan. To eliminate TB disease, the medical community must appropriately diagnose and treat those with LTBI. The risk for progression is much higher in those with compromised immune systems, such as persons with HIV or diabetes, or those under 5 years of age.4
TB DISEASE SYMPTOMS
TB most often attacks the lungs (pulmonary TB), but it can occur anywhere in the body, including the eyes, brain, kidneys, lymphatic system, or bones and joints (extrapulmonary TB). It is possible to have both pulmonary and extrapulmonary TB at the same time.
TB spreads via airborne respiratory droplet nuclei that must be inhaled by an exposed individual, so extrapulmonary TB, except for laryngeal TB, is not typically contagious. Of note, there
have been cases in which transmission occurred from extrapulmonary sites “during aerosol-producing procedures, such as autopsies and tissue irrigation.”5 If extrapulmonary TB is suspected, initiate airborne infection isolation
(AII) precautions prior to aerosol- producing procedures. Symptoms of extrapulmonary TB depend on where the disease has manifested but may also include general TB disease symptoms, such as unexplained weight loss, loss of appetite, night sweats, fever, fatigue, and chills.
According to the Centers for Disease Control and Prevention (CDC), “not all persons with TB disease have symptoms; however, most persons with TB disease have one or more symptoms that lead them to seek medical care.” 5 Adults with pulmonary TB may exhibit the above symptoms, as well as:
■ A cough lasting three weeks or longer, ■ Pain in the chest, and
■ Hemoptysis or a cough-producing sputum.
Children are more often asymptomatic and less infectious than adults due to a reduced bacterial load and less tussive force. Infants and young children
are, however, more likely than adults and older children “to develop life- threatening forms of TB disease (e.g., disseminated TB, TB meningitis).”6 When children exhibit symptoms of pulmonary TB, the symptoms are similar to those of adults, with emphasis placed on failure to gain weight,
weight loss, and/or delays in growth.”7 Pediatric TB is a public health issue of recent transmission.
For the 0-4 and 5-14 age groups, in 2018, the CDC reported national incidence rates of 0.9 and 0.5 per 100,000 population, respectively.3 Delaware, in 2018, reported just a single case in the 5-14 range and three cases under 5 years old in 2019. All three 2019 pediatric cases were contacts of infectious parents.
TB RISK FACTORS: EXPOSURE AND PROGRESSION
Those infected with M. tuberculosis may develop TB disease soon after infection, before their immune system can contain the bacteria, or they may get sick months or even years later. Those at highest risk for progression fall into one of two categories: those recently infected and those with medical conditions that weaken the immune system.
Risk factors for recent exposure include:
Del Med J | March/April 2020 | Vol. 92 | No. 2
63