Managing tuberculosis in people who use and inject illicit drugs

Abstract

People who use and inject illicit drugs are at high risk of contracting tuberculosis, whether or not they are infected with the human immunodeficiency virus (HIV). Studies conducted before and after the emergence of HIV infection show that, when compared with the general population, people who use illicit drugs have a higher risk not just of getting tuberculosis infection, but also of developing active disease.1,2 Similarly, outbreaks of drug-susceptible and multidrug resistant (MDR) tuberculosis are common in this group.1 Although the higher risk of tuberculosis observed in people who inject illicit drugs is usually the result of associated HIV infection, in people who use illicit drugs without injecting this higher risk is primarily attributable to the sharing of drug equipment, such as marijuana water pipes, and to living in cramped conditions or in dwellings with poor ventilation.1 Co-infection with the hepatitis B and hepatitis C viruses is also common among patients who inject illicit drugs, particularly among those who are also co-infected with the tuberculosis bacillus and HIV.2 Although most reports on hepatitis among people who use illicit drugs have come from high-income settings, some alarming reports have also been produced about middle- and low-income settings. For example, in a study among people using illicit drugs in Chennai, India, hepatitis B and C showed a prevalence of 11.9% and 94.1%, respectively.3 Illicit drug use is often associated with alcoholism, which also increases the risk of becoming infected with the tuberculosis bacillus and of developing active tuberculosis. It also complicates tuberculosis diagnosis and treatment. Furthermore, drug use is criminalized in many settings. In a study by Hayashi et al., up to 80% of the study subjects who injected illicit drugs had been incarcerated at least once.4 Prisons are well established breeding sites for tuberculosis and HIV infection, especially in settings where no preventive measures are in place and where illicit drug use and drug equipment sharing are common among prisoners.2 As a result, the risk of becoming infected with the tuberculosis bacillus and the risk of developing active tuberculosis are 26 and 23 times higher, respectively, among prisoners than among members of the general population.2 These factors, combined with an increased risk of tuberculosis-related morbidity and mortality among people using illicit drugs, complicate the clinical management of tuberculosis patients and the administration of tuberculosis programmes. Diagnosing tuberculosis is more complicated in a high-risk population, such as people who use illicit drugs. The recent introduction of a rapid diagnostic test (Xpert MTB/RIF) offers an ideal opportunity to improve diagnosis in such groups because it detects tuberculosis twice as effectively as smear microscopy without any significant difference in performance as a function of HIV status.2 The World Health Organization recommends it as the initial diagnostic test in individuals suspected of having MDR-tuberculosis or tuberculosis associated with HIV infection. The test may therefore expedite the diagnosis of tuberculosis among people who use illicit drugs, since MDR-tuberculosis and HIV infection are common among them. At the same time, little evidence has been generated in terms of the clinical management of people who use illicit drugs and who also have either drug-susceptible or drug-resistant tuberculosis, HIV infection or hepatitis. The management of these co-morbid conditions requires sound clinical judgment; treatment should be guided by the patient’s clinical condition and by the possibility of drug side-effects and interactions. Additive adverse effects, overall pill burden and adherence to treatment require special attention as well. The prevention, diagnosis and treatment of tuberculosis among people who use illicit drugs have been neglected and require immediate attention. Open dialogue on policy in this area should be encouraged, and a coordinated programme response from stakeholders working in prisons and in harm reduction, HIV infection, hepatitis and tuberculosis services should be sought. People who use illicit drugs and prisoners should be provided with evidence-based, integrated tuberculosis, HIV, hepatitis and harm reduction services that fully respect basic human rights.