**1. Introduction**

Tuberculosis is a chronic granulomatous bacterial infection with a global occurrence [1–3]. This preventable and curable infectious disease has afflicted man since antiquity [4]. Many parts of the world especially the developing nations are still witnessing a rise in the number of new tuberculosis cases with its attendant consequences [3]. This rising prevalence trend of *Mycobacterium tuberculosis* infection is without prejudice to the strides and efforts in infection control [3].

Estimates have it that every minute someone somewhere gets infected with *Mycobacterium tuberculosis* making it a common globally transmitted disease [5, 6]. Epidemiologically, the World Health Organization (WHO) and other multinational health organization have reported tuberculosis as a worldwide pandemic [3, 7].

A recent report by WHO revealed a global tuberculosis incidence of 6.3 million for 2016 reflecting a rise from the preceding year [3]. In the same vein, sub Saharan Africa has a substantial burden of tuberculosis related morbidity and mortality as reported in the 2016 WHO global tuberculosis report [3].

demerits of old conventional and advanced molecular/immunological methods would be carried out to ascertain what best serve the purpose of prompt and

*Diagnostic Evaluation of Tuberculosis: Existing Challenges and Merits of Recent Advances*

*Mycobacterium tuberculosis* infection remains a significant public health challenge despite the modest achievements in its control at the global, regional and country levels [3]. The alarming global prevalence rate of *Mycobacterium tuberculosis* infection has been put at one-third of the world population [1, 3]. Sub-Saharan Africa, South East Asia, and West Pacific region is home to most of the 22 countries

World Health Organization reported that 6.3 million cases of tuberculosis were notified in 2016 which might be under-estimation owing to the non-health seeking behavior and poor documentation in some regions [3]. This tuberculosis epidemiological pattern calls for sustained surveillance and prompt treatment to improve the

The rising number of drug-resistant form of tuberculosis poses an additional challenge on the inadequate resources allocated to healthcare delivery. In the year 2015, over 100 countries reported extensively drug-resistant tuberculosis [2]. Estimates by the WHO revealed that 490,000 individual developed multidrug-resistant tuberculosis in the year 2016 and only a fraction received treatment [3]. The threat of drug-resistant tuberculosis as affirmed by 2016 global report on tuberculosis may possibly be a consequence of inappropriate anti-tuberculosis medication use [3]. This emerging menace of drug resistant tuberculosis if not properly managed could

The global distribution of tuberculosis infection is in close association with poverty, immunosuppression and social deprivation [3, 5, 8, 17]. Sub Saharan Africa has the world highest tuberculosis incidence of 356 per 100,000 populations per year [2, 3]. Similarly, the social and clinical determinants of tuberculosis which include HIV infection, diabetes mellitus, under-nutrition, migration and smoking have been reported to preferentially afflict the young adult population [3, 5]. Nevertheless, tuberculosis infection generally has no age, gender, racial or regional bias. Mycobacteria consist of different pathogenic and saprophytic mycobacteria species that are isolated from humans and the general environment [18, 19]. The two broad groups of mycobacteria which are tuberculous and non-tuberculous mycobacteria share some features but are largely distinguishable by molecular analysis and the utilization of some microbiological test which include niacin reduction test, nitrate test, and urease test [18, 19]. Lack of identification of the species of mycobacteria infection from the outset has a clinical, management and prognostic implication. The importance of mycobacteria speciation lie in their differing epidemiology, response to anti-tuberculosis, course of disease and long term

Literally, tuberculosis could affect any organ system of the body and clinical presentation depends on the site of involvement. The human host immune system influences the clinical pattern of tuberculosis presentation. Tuberculosis is generally described as pulmonary if it involves the lungs and extra-pulmonary when there is

highly burdened by tuberculosis, and this ranking seldom change [3, 17].

efficient detection of *Mycobacterium tuberculosis* infection.

**4. Literature review**

consequences [18, 19].

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**4.1 Global burden of tuberculosis**

*DOI: http://dx.doi.org/10.5772/intechopen.81882*

disease related morbidity and mortality [3].

retard the progress made in the fight against tuberculosis.

**4.2 Pulmonary and extra-pulmonary tuberculosis**

The current epidemiological profile of tuberculosis in Sub-Saharan Africa seems to have an established association of the disease with poverty and social deprivation [3, 5, 8]. Similarly, the burden of tuberculosis remains an obstacle to socioeconomic development with a staggering direct and indirect cost of health financing [3, 9, 10]. The relationship between tuberculosis and social deprivation in addition to the adverse socioeconomic developmental effect of tuberculosis creates a vicious cycle of disease, poverty and poor productivity among the most disadvantaged in the society.

*Mycobacterium tuberculosis* is the causative organism of tuberculosis which was discovered by Robert Koch [11]. This granuloma forming microorganism is well adapted to live in a man and cause disease under favorable condition(s). In the same token, *Mycobacterium tuberculosis* is ubiquitous and has some unique features in its genetic makeup and cell wall constituents that not only distinct it from other organisms but also confers it with the strength of survival under harsh and stressful conditions [12, 13].

The *Mycobacterium tuberculosis* genome is composed of insertion sequences (IS) and phages which serve as unique features for its identification and speciation [12]. The type of IS that is abundant in *Mycobacterium tuberculosis* is IS6110 [12]. The knowledge of *Mycobacterium tuberculosis* genome is used in assessment of rate of transmission, identification of a regional circulating strain and detection of transborder spread of the disease.

The main stay of *Mycobacterium tuberculosis* diagnosis has been the sputum microscopy (Ziehl Neelsen) and the solid media culture (Lowestein-Jensen medium) [14]. Although, these conventional methods of *Mycobacterium tuberculosis* identification and isolation are still in use, newer methods of tuberculosis diagnostics which include Ampiclor *M. tuberculosis* PCR test and Cephid GeneXpert is fast gaining relevance and acceptance [15, 16]. The merits of use of molecular and immunological techniques cannot be overemphasized in view of its additional benefit of infectious organism speciation, isolate antimicrobial sensitivity and detection of specific mutations that confer drug resistance (i.e., rpoB and KatG mutation) [15, 16]. The acquisition and deployment of molecular tuberculosis diagnostics in priority high disease burden areas would eventually increase rate of *Mycobacterium tuberculosis* infection identification. This is predicated on the fact that early detection and treatment of smear positive tuberculosis is attributed to improved cure rate [15].
