The 1985 beginning of the HIV/AIDS epidemic occurred as the vigilant tuberculosis (TB) prevention and control measures had been lifted. Thus, a surge of patients arose with both latent TB (infected patients who test positive but are not sick) and active TB (infected patients who test positive and are clinically symptomatic) in vulnerable groups, including prison populations, the homeless, and IV drug abusers. Added to these susceptible populations were immigrants arriving from continents and areas where TB is endemic, such as Africa, Asia, and Latin America.
Many patients were lost to follow-up or did not complete their designated drug therapy when there was marked improvement in their health. Because of the long treatment period (12 -18 months) combined with drug intolerance, patients often discontinue treatment that is not monitored. Discontinuing therapy early allows selective resistance to occur with the subsequent increased transmission of resistant strains.
To prevent transmission, a structured anti-tuberculosis regimen is mandated. Non-compliance with the prescribed regimen led to the epidemic of the superbug, a multidrug-resistant TB (MDR-TB), resistant to the most effective first-line drugs isoniazid (INH) and rifampin (RIF). Although second-line drugs are available, their action is slow, and serious side effects are common. In the 1990s, the peak of non-compliance in the U.S. culminated in a New York City epidemic resulting in a severe outbreak of MDR-TB in 350 patients who were suffering from HIV/AIDS as well.
The maps to the right, used with permission from the WHO, show the percentage of new TB cases with MDR-TB (upper) and previously treated TB cases with MDR-TB (lower) in 2016.