**Emerging Public Health Issues in Drug-Resistant Tuberculosis**

Adeola Orogade

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61269

#### **Abstract**

Drug Resistance is a major challenge in the control of Tuberculosis which itself re‐ mains a global public health problem. Resistance is commonly encountered as MDR TB but a subset, XDR TB which has about a comparatively fivefold increase in mortal‐ ity is now identified in 84 countries worldwide and increasing rates are currently re‐ ported from 65 countries. The actual burden of MDR TB is unknown though estimates have been made based on notification of cases which are usually underreported. More so there is under diagnosis in non HIV immune suppressed adults and pediatric pop‐ ulations largely due to lack of readily accessible diagnostic tools. In some case series, MDR TB has been found occurring mostly in newly diagnosed patients or relapse cas‐ es after previous cure and completion of treatment rather than in patients with im‐ properly treated disease. Clinical and laboratory monitoring once therapy has been instituted have also been a daunting task both from institutional and patient points of view. The impact of these factors are highlighted and discussed as the world moves towards attainment of the 2015 global target to halve TB prevalence and death rates within the context of Millennium Development Goals (MDGs).

**Keywords:** Tuberculosis, Drug Resistant, Public Health

### **1. Introduction**

#### *The man who moves a mountain begins by carrying away small stones* – Confucius.

Drug resistance is a major challenge in the control of Tuberculosis (TB), which itself remains a global public health problem. Resistance is commonly encountered as Multidrug-Resistant Tuberculosis (MDR TB), but a subset, Extensively Drug-Resistant Tuberculosis (XDR TB), which has about a comparatively fivefold increase in mortality, is now identified in 84 countries worldwide and increasing rates are currently reported from 65 countries. The World

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**.**

1

Figures are based on the most recent year for which data have been reported, which varies Figures are based on the most recent year for which data have been reported, which variesamong countries.

among countries. **Figure 1 Percentage of new TB cases with MDR-TB (Adapted from WHO Global TB Report, 2014) Figure 1.** Percentage of new TB cases with MDR-TB (Adapted from WHO Global TB Report, 2014)

Health Organization (WHO) has designated 22 countries of the world as high-burden countries for Tuberculosis (HBCTB) and 27 as high-burden countries for multidrug-resistant Tubercu‐ losis (HBC MDR TB), making a total of 36 countries in either of these categories [1]. The latter are countries where at least 4,000 cases of MDR TB are identified per year and/or at least 10% of newly registered TB cases are MDR TB.

MDR TB and XDR TB epidemics are largely driven by transmission and are mainly found in new cases and patients with TB relapse [2]. Since 1994, WHO has been receiving and analyzing data on anti-TB drug resistance from countries via its Drug Resistance Surveillance Project, which depends on continuous data based on rapid molecular diagnostics and drug sensitivity testing (DST). However, neither is widely or routinely available due to prohibitive costs involved, especially in low- and middle-income economies that are also high-burden countries. In these low- and middle-income high TB burden countries, cases of MDR TB are identified mainly through special surveys rather than continuous surveillance reporting. In 2013, only 11 of the 36 HBCTB/HBC MDRTB had up-to-date data through these drug-resistance surveys. From these surveys it is clearly understood that the MDR TB burdens attributed to these countries are only estimates based on notification of cases which in most countries is incom‐ plete and as such may only be the tip of the iceberg (Figures 1 & 2).  **Percentage of cases 0-2.9 3-5.9 6-11.9 12-17.9 ≥18 No data Subnational data only Not applicable** 

Despite these shortfalls in the determination of exact incidences, especially where TB burden is highest, there have been recent global efforts to bridge the gap between diagnosis and appropriate therapy with second- and third-line drugs. Treatment after diagnosis of MDR TB and follow-up of confirmed cases is however bedeviled with unavailability of human resour‐ ces, accessibility to second-line drugs in high MDR TB areas, and logistics. Global treatment Percentages of previously treated TB cases with MDR-TB in Bahrain, Bonaire, Israel, Saint Eustatius and Saba, and Sao Tomé and Principe refer to only a small number of notified cases (range: 1-8 notified previously treated TB cases). **Figure 2. Percentage of previously treated TB cases with MDR-TB (Adapted from WHO Global TB Report, 2014)** 

 **Percentage of cases** 

 **6-11.9 12-17.9 ≥18** 

 **0-2.9 3-5.9** 

 **Not applicable Subnational data only**  1

Figures are based on the most recent year for which data have been reported, which varies

 **No data** 

Percentages of previously treated TB cases with MDR‐TB in Bahrain, Bonaire, Israel, Saint Eustatius and Saba, and Sao Tomé and Principe refer Percentages of previously treated TB cases with MDR‐TB in Bahrain, Bonaire, Israel, Saint Eustatius and Saba, and Sao Tomé and Principe refer to only a small number of notified cases (range: 1‐8 notified previously treated TB cases).

to only <sup>a</sup> small number of notified cases (range: 1‐8 notified previously treated TB cases). **Figure 2.** Percentage of previously treated TB cases with MDR-TB (Adapted from WHO Global TB Report, 2014)

targets have not been met. but there are concerted efforts to achieve them through restructuring of programs and Programmatic Management of Drug-Resistant TB (PMDT). **Figure 2. Percentage of previously treated TB cases with MDR-TB (Adapted from WHO Global TB Report, 2014)** 

The key to overcoming MDR TB and XDR TB will eventually lie in the balance between prompt diagnosis and treatment of cases on one hand and prevention of transmission of drug-resistant bacilli to vulnerable populations with whom they are in contact on the other. Particular attention needs to be given to unrecognized groups: the pediatric patients in whom a high degree of clinical skill must be displayed to ensure prompt laboratory diagnosis and the health care workers whose infection can be prevented through deliberate control methods.
