Drug users are at high risk for tuberculosis

Drug users are at high risk for tuberculosis (TB), and they have been the drivers of TB epidemics in many countries.

ACCORDING to the National Anti-Drug Agency (NADA), there are more than 300,000 registered drug users in Malaysia. But that’s the tip of the iceberg.

Bear in mind that some local studies suggest that for every registered drug user, there are three to four who are unregistered. This could mean that there are more than a million drug users in the country.

Of the registered drug users, 79% are aged 19 to 39, 16% more than 40 years, and 5% aged 13 to 18. Notwithstanding the reported reduction in the number of registered drug users in the last two years, the health challenges remain considerable.

Drug users are at high risk for tuberculosis (TB). They have been the drivers of TB epidemics in many countries. This is especially so with injection drug users (IDUs) as they have a higher prevalence of latent TB (LTB) and active TB.

Physiological and environmental factors, as well as the risk behaviours of drug users, may all contribute to the increased prevalence of TB among them.

There are frequent associations between drug use and environmental factors, including tobacco smoking, alcohol abuse, social disadvantages and incarceration, which increase the risk of TB.

These factors may contribute to poorer outcomes – drug users are more likely to be infectious, to take longer to achieve a cure for TB, and to be at increased risk of death.

The increased prevalence of LTB and longer periods of infectivity in drug users may be responsible for the increased rates of TB transmission among them.

Immunosuppression due to human immunodeficiency viral (HIV) infection is the most important reason for the high TB incidence, especially among IDUs. It is commonly reported that there is a high prevalence of TB co-infection among HIV-positive IDUs, particularly in prisoners.

TB is the most common opportunistic infection in IDUs, even in areas where there is a low prevalence of TB. The risk of TB in IDUs peaks several years after the infection with HIV. As such, the time immediately after a diagnosis of HIV infection is made is an opportunity for TB prevention and/or treatment.

The identification and treatment of TB among drug users are crucial in controlling the disease, which has seen a resurgence in Malaysia. Its incidence increased from 64.7 per 100,000 in the population in 2000 to 71.35 per 100,000 population in 2011. The number of reported TB cases increased from 15,875 in 2005 to 20,666 in 2011.

The hopes of health professionals that TB would finally be controlled after the successes of 1970 to 2000 have all but disappeared.

The prevalence of both LTB and active TB in drug users in Malaysia was unknown until recently. Haider Abdulrazzaq Abed Al-Darraji, Adeeba Kamarulzaman et al reported in the Journal of Substance Abuse Treatment the prevalence and correlation of LTB among attendees at a voluntary drug treatment centre in Sungei Besi, Kuala Lumpur, using a standardised questionnaire and tuberculin skin testing (TST), which is the standard method of diagnosing TB.

Of the 196 attendees, who were mostly men (95%), under 40 years of age, and of whom 75% reported heroin use immediately before treatment entry, the positive TST prevalence was 86.7%, i.e. 170 out of 196 had TB!

Nine (4.6%) participants were HIV-infected. There was a significant association between TST positivity and previous arrest/incarcerations and not being HIV-infected.

The high prevalence of TB in the study group was attributed to the fact that “correctional settings are highly conducive to TB transmission given poor ventilation, lack of routine TB screening, inadequate access to health services and the concentration of people with risk factors for progression to active TB disease (HIV infection, people who use drugs, and low socio-economic background)”.

Taken together, these factors create the “perfect storm” for facilitating TB transmission and causing a high prevalence of TB (estimated to be 100 times higher compared to the general population) in these settings (World Health Organization, 2000).

The researchers concluded that “there is an urgent need to establish TB screening and treatment programmes in substance abuse treatment centres and to tailor service delivery to the complex treatment needs of patients with multiple medical and psychiatric co-morbidities”.

Drug users present a unique set of challenges for TB diagnosis and control. New diagnostic methods, which have the potential for improved diagnosis and surveillance, as well as proven treatment strategies that include direct observed therapy with treatment for drug abuse are recommended by the experts.

This would include clinical attention to co-infection with viral hepatitis and drug interactions.

The question is will policymakers act on Haider Abdulrazzaq Abed Al-Darraji, Adeeba Kamarulzaman et al’s findings, and if they do, how vigorous the efforts will be.

Dr Milton Lum is a member of the board of Medical Defence Malaysia. This article is not intended to replace, dictate or define evaluation by a qualified doctor. The views expressed do not represent that of any organisation the writer is associated with.

Disclaimer: Nothing on this blog should be considered or used as a substitute for medical advice, diagnosis or treatment. Blog visitors with personal health or medical questions should consult their health care provider.