Estimated epidemiological burden of incident TB, according regions by the WHO in 2010 (World Health Organization 2011). Incidence rates were calculated for this chapter.
Tuberculosis (TB) is an infectious disease caused by different species of the genus Mycobacteria. Together with human immunodeficiency virus infection (HIV)/Acquired Immunodeficiency Syndrome (AIDS) and malaria, tuberculosis is one of the biggest killers in the Word (Rodríguez-Morales AJ et al 2008, Murcia-Aranguren MI et al 2001). Human disease is usually caused by Mycobacterium tuberculosis, also know as the Koch’s bacilli (Figure 1), which can affect any organ or tissue in the body, and in some cases due to M. bovis (Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a). Although this, pulmonary disease, with their particular hallmarks such as occurrence of cough with expectoration lasting more than 15 days, is the main corporal area affected by this mainly tropical pathogen (Rodríguez-Morales AJ et al 2008; Castañeda-Hernández DM & Rodríguez-Morales AJ 2012). In such cases, previous to a microbiological diagnosis, individuals in such state are so-called respiratory symptomatic.
Besides those symptoms/signs, disease can be manifested with hemoptisis, fever, night sweating, general malaise, thoracic pain, anorexia and weight lost. This disease is still a significant public health problem due to is highly transmissibility, but is highly potentially preventable and treatable condition (Curto et al. 2010, Dim et al. 2011, Orcau et al. 2011, Marais & Schaaf 2010, Glaziou et al. 2009). Even more, in the context of HIV and newer immunosuppressive conditions mycobacterial diseases emerge as public health threat in the World (Vargas et al. 2005).
Tuberculosis is a human threat and still a significant public health problem in the World, but particularly in developing countries. Today, together with the burden of infection due to Human Immunodeficiency Virus (HIV), this coinfection drives most of the tuberculosis morbidity and mortality in many regions (e.g. Africa) and makes more complicated its control and reduction in many terms. According to the World Health Organization (WHO) Global Tuberculosis Control Report 2011 (the most important and official document regard the epidemiology and other aspects of TB worldwide), in 2010, there were 8.8 million (range, 8.5–9.2 million) incident cases of TB, 1.1 million (range, 0.9–1.2 million) deaths from TB among HIV-negative people and an additional 0.35 million (range, 0.32–0.39 million) deaths from HIV-associated TB (World Health Organization 2011). Important new findings at the global level are: a) the absolute number of TB cases has been falling since 2006 (rather than rising slowly as indicated in previous global reports); b) TB incidence rates have been falling since 2002 (two years earlier than previously suggested); c) Estimates of the number of deaths from TB each year have been revised downwards; d) In 2009 there were almost 10 million children who were orphans as a result of parental deaths caused by TB (World Health Organization 2011).
Epidemiology of tuberculosis can be influenced by multiple not only clinical factors, but also demographical, geographical and social aspects at local or national levels, as the development of the country (Rodríguez-Morales AJ & Castañeda-Hernández DM 2012), currently measured by indicators such as the Human Development Index (HDI). Finding there, that negative relationships between both morbidity and mortality due to tuberculosis and HDI exist, with better HDI levels lower morbidity and mortality due TB is found (Rodríguez-Morales AJ & Castañeda-Hernández DM 2012). As has been reported with other diseases with high prevalence in developing countries, burden of diseases such as TB can be an impediment in achieving the Millennium Development Goals (Franco-Paredes et al 2007b). Then strategies to reduce its impact and improving the health of populations, most of the times neglected, should be implemented (Franco-Paredes et al 2007a).
In developing countries another aspect influencing this is the limited research on tuberculosis that usually is made (Castañeda-Hernández DM et al 2012a). For example scientific production on TB in Colombia is low, not just comparing it with developed countries (USA, 4.08 articles/100,000 hab.) but also with others in Latin America with even lower TB incidence such as Chile (19 cases/100,000 hab.) but with a better productivity 2.19 times higher (1.09 articles/100,000 hab.). A higher promotion of research, beginning in undergraduate studies, better interaction between public and private organizations, as well more academic and international cooperation, would allow to decrease those gaps, increase scientific publication and let that the application of that generated knowledge in the same country contribute to improve the TB epidemiology and different aspects of disease (Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a).
Beyond its epidemiology, particularly mostly due to pulmonary disease (Figure 2), other important forms of disease represent also a significant burden in the World. When the infection affects organ other than the lung is called extrapulmonary TB. The most common form of this disease is at the pleura, followed by the lymphatic nodes. Extrapulmonary TB includes various manifestations according to the affected organ. Prognosis and time to develop disease also can vary according to the affected organ (Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a).
Disease can ranges a spectrum that can begin from a latent infection or reactivation slowly evolving into a focal or whole spread and involvement of multiple organs, which makes it difficult to diagnosis by clinicians and health care workers, who many times could not identify it timely. One of the most severe forms of extrapulmonary TB is the meningitis (TB meningitis), which occurs as a result of hematogenous spread of bacilli into the subarachnoid space. This is known as a complication of primary TB and may occur years later as an endogenous reactivation of a latent tuberculosis or as a result of exogenous reinfection (Glaziou et al. 2009, Hoek et al. 2011, Galimi 2011, Garcia-Rodriguez et al. 2011). Currently in the case of latent TB developing countries usually counts only with the PPD to diagnose this condition. However, recently new alternatives have risen for the diagnosis in these cases, using IFNγ release assays (IGRAs) to diagnose latent TB infection (LTBI). This is actually proposed for public health purposes in developing countries (Castañeda-Hernández DM et al 2012d).
Tuberculosis is a complex disease in terms of the multiple factors that are involved in its occurrence and persistence in the human societies. In first place there are factors associated with the bacillus (viability, transmissibility and virulence), with the host as a biological individual (immune status, genetic susceptibility, duration and intensity of exposure) as well, at the bacillus-host interaction (place of affection, severity of illness) (Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a).
At a second, clinical level, the occurrence of pulmonary tuberculosis undiagnosed or untreated, overcrowding, malnutrition, immunosuppresion from any cause (HIV infection, use of immunosuppressive drugs, diabetes, cancer, chronic renal failure, silicosis, alcoholism and drug addiction), are also important factors (Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a). In developing countries there are also multiple epidemiological contexts where TB can be highly prevalent in comparison with general population, such as in prisons, among homeless persons and indigenous individuals (Castañeda-Hernández DM et al 2012b, Castañeda-Hernández DM & Rodríguez-Morales AJ, 2012b).
At community public health interventional level, protective factors include the BCG (Bacille Calmette Guerin) vaccine, applied in developing countries, which provides protection before exposure and prevent severe infection forms, especially in infants and young children, reaching up to 80% of protection against the development of forms of the disease such as meningeal and miliary TB (Garcia-Rodriguez et al. 2011, Garg 2010, Black et al. 2003, Francis et al. 2002, Arbelaez et al. 2000, Ginsberg 2000).
Additional to those clinical implications, changes in the susceptibility of the etiological agent to the therapy used drugs has imposed more challenges in the management of TB. The magnitude of problem with TB now lies in the fact that one third of the world population is infected by Mycobacterium tuberculosis. Even in the 21st century, TB kills more people than any other infective agent. This, then, occurs in part as a result of a progressive decrease in its susceptibility to anti-TB drugs or resistance emergence. Cases of resistant TB, defined by the recommendations of the World Health Organization (WHO) as primary, initial, acquired multidrug resistant (MDR-TB) or extensively drug resistant TB (XDR-TB) are emerging in different areas of the World (Torres et al. 2011, Solari et al. 2011, Chadha et al. 2011, Arenas-Suarez et al. 2010, Ferro et al. 2011, Martins 2011, Robledo et al 2008).
The development of resistance in TB may result from the administration of mono-therapy or inadequate combinations of anti-TB drugs. A possible role of health care workers in the development of multi drug-resistant TB is very important. Actually, multi drug-resistant TB is a direct consequence of mistakes in prescribing chemotherapy, provision of anti-tuberculosis drugs, surveillance of the patient and decision-making regarding further treatment as well as in a wrong way of administration of anti-TB drugs. The problem of XDR-TB in the world has become very alarming. Only adequate treatment according to directly supervised short regiment for correctly categorized cases of TB can stop the escalation of MDR-TB or XDR-TB, which is actually, in large magnitude, a global threat in the 21st century (Torres et al. 2011, Solari et al. 2011, Chadha et al. 2011, Arenas-Suarez et al. 2010, Ferro et al. 2011, Martins 2011, Robledo et al 2008).
Another important issue in TB is the social component, related to a complex background and multiple interacting factors that internally and externally affect individuals affected by the disease, which still represents a significant stigma in many communities in the World. Given this setting, TB approach is complex and requires not only medical but also psychological and especially sociological approaches in order to improve its management from a collective medicine perspective as well better acceptability by non-affected people surrounding infected individuals at their communities or neighborhoods. In this way, programs approaching taking all these considerations in count will benefit with better strategies that allow good interactions between social actors involve in the complex social matrix in which sometimes TB can be present at societies. Taking advantage from this, regular activities, such as proper diagnosis and treatment would be achieve in a more efficient way (Murray et al. 2011, Santin & Navas 2011, Juniarti & Evans 2011).
One challenge in the current context of TB particularly in developing countries is the access to reliable diagnostic tests (Castañeda-Hernández DM et al 2012d), particularly those than allow to confirm species diagnostics as well to identify those isolates that are not fully susceptible to antimicobacterial first line drugs. However, today many diagnostic tests have been developed, but many of them are only used routinely in developed countries (e.g. IGRAs and molecular biology-based tests) (Castañeda-Hernández DM et al 2012d). Although is clear that DOTS (directly observed treatment strategy, short-course) programmes have contributed in the successful treatment of TB, particularly because this strategy includes six major components that are: (i) pursue high-quality DOTS expansion and enhancement; (ii) address TB/HIV, MDR-TB (multi-drug resistant TB), and the needs of poor and vulnerable populations; (iii) contribute to health-system strengthening based on primary health care; (iv) engage all care providers; (v) empower people with TB, and communities through partnership; and (vi) enable and promote research; it is necessary to increase its coverage and usefulness particularly in those highly TB prevalent countries in the developing World in order to achieve the goals that have been established for 2015 in the Global Plan to Stop TB (2011-2015) of the World Health Organization and the Stop TB Partnership (Castañeda-Hernández DM & Rodriguez-Morales AJ. 2012a). The epidemiological burden of TB in developing countries can be measured directly from different global and national indicators and estimators, however, those mainly to be addressed should be incidence, prevalence, mortality, MDR-TB incidence, XDR-TB (extensively drug-resistant TB) incidence, case notifications, treatment outcomes and case detection rates. In this chapter, such topics are furtherly revised and prepared in the setting of highest available evidence (evidenced-based public health) and epidemiological data, including a detailed analysis according to some highly endemic countries sources in different developing regions, suggesting also new strategies for control as well providing updated information on epidemiological tools relevant for TB in developing countries. Relevant new epidemiological settings will be also discussed, such as the importance of TB in homeless, indigenous, migrated and prison populations as has been suggested.
2. Tuberculosis in developing countries
Tuberculosis is a disease present, due the raise of HIV coinfection in most countries in the World. Until two to three decades ago, TB was decreasing in importance in the World and was predominantly endemic in developing countries. However after the origin of the AIDS pandemic in June 1981, TB has been increasing again in importance not only in these countries but also in those developed in North America and Europe. Besides this, the multiple problems that countries with a high burden of TB have to face are major in developing countries in Africa, Asia and Latin America, especially when this is also associated to other conditions and diseases, such as HIV, comorbidities, poverty and when living in resource-constrained areas where diagnosis and treatment is not prompt as in other areas.
In order to know the real burden of disease in developing countries is necessary that these make things well in epidemiology and public health regard TB. Recording and reporting of data is a fundamental component of care of patients with tuberculosis (TB) and control of the disease. Data recording and reporting is necessary to monitor trends in the TB epidemic at global, national and subnational levels; to monitor progress in the treatment of individual patients and groups (cohorts) of patients and ensure continuity of care when patients are referred between healthcare facilities; and to plan, raise funds for, implement and evaluate programmatic efforts to control TB, including forecasting the numbers of cases and the associated requirements for staffing, medicines and laboratory supplies; and analysing treatment outcomes (World Health Organization 2012).
Global burden of TB in the World is estimated in 8.8 million (range, 8.5–9.2 million) incident cases of TB (Table 1) for rates ranging 123.7 to 133.9 cases/100,000 pop. (Table 1); however this can be very different among the WHO Regions in the World, being higher in Africa where those estimates can reach 250.9 to 298.7 cases/100,000 pop. (Table 1). Rates of incidence are important because can show the real populational problem of the disease. For example in South East Asia there are more crude number of cases of TB, estimated in 3.5 million (range, 3.2–3.7 million) incident cases, however the incidence rates are quite lower than in Africa, reaching 177.0 to 204.7 cases/100,000 pop. (Table 1) (Figure 4).
|Incidence(cases)||Incidence rates (cases/100,000pop)|
|WHO African Region||836,970,000||2,300,000||2,100,000||2,500,000||274.8||250.9||298.7|
|WHO South-East Asia Region||1,807,594,000||3,500,000||3,200,000||3,700,000||193.6||177.0||204.7|
|WHO Eastern Mediterranean Region||596,747,000||650,000||580,000||730,000||108.9||97.2||122.3|
|WHO Western Pacific Region||1,798,335,000||1,700,000||1,500,000||1,800,000||94.5||83.4||100.1|
|WHO European Region||896,480,000||420,000||390,000||450,000||46.8||43.5||50.2|
|WHO Region of the Americas||933,447,000||270,000||250,000||280,000||28.9||26.8||30.0|
Regard the prevalence of TB, which for some countries is still difficult to estimate and in many cases even are not reported and/or analyzed. According the WHO, for 2010 the prevalence was estimated in 12.0 million (range, 11.0–14.0 million) prevalent cases of TB (Table 2) for rates ranging 160.1 to 203.8 cases/100,000 pop. (Table 2); however this can be very different among the WHO Regions in the World, being higher in Africa where those estimates can reach 274.8 to 394.3 cases/100,000 pop. (Table 2).
|Prevalence(cases)||Prevalence rates (cases/100,000pop)|
|WHO African Region||836,970,000||2,800,000||2,300,000||3,300,000||334.5||274.8||394.3|
|WHO European Region||896,480,000||2,500,000||2,200,000||2,800,000||278.9||245.4||312.3|
|WHO Western Pacific Region||1,798,335,000||5,000,000||3,700,000||6,500,000||278.0||205.7||361.4|
|WHO Eastern Mediterranean Region||596,747,000||1,000,000||670,000||1,500,000||167.6||112.3||251.4|
|WHO Region of the Americas||933,447,000||330,000||260,000||410,000||35.4||27.9||43.9|
|WHO South-East Asia Region||1,807,594,000||560,000||430,000||720,000||31.0||23.8||39.8|
Regard the deaths, WHO estimates indicate that around 1.1 million (range, 0.9–1.2 million) deaths from TB among HIV-negative people occurred and an additional 0.35 million (range, 0.32–0.39 million) deaths from HIV-associated TB were also reported (World Health Organization 2011) (Table 3). Higher mortality rates are reported in Africa, ranging 26.3 to 33.5 deaths/100,000 pop. (Table 3), but very close to those reported by South East Asia, ranging 20.5 to 35.4 deaths/100,000 pop. (Table 3).
|Mortality(deaths)||Mortality rates (deaths/100,000pop)|
|WHO African Region||836,970,000||250,000||220,000||280,000||29.9||26.3||33.5|
|WHO South-East Asia Region||1,807,594,000||500,000||370,000||640,000||27.7||20.5||35.4|
|WHO Eastern Mediterranean Region||596,747,000||95,000||74,000||120,000||15.9||12.4||20.1|
|WHO Western Pacifi c Region||1,798,335,000||130,000||120,000||150,000||7.2||6.7||8.3|
|WHO European Region||896,480,000||61,000||48,000||75,000||6.8||5.4||8.4|
|WHO Region of the Americas||933,447,000||20,000||17,000||23,000||2.1||1.8||2.5|
Tuberculosis incidence in HIV-patients is a very relevant indicator worldwide for TB epidemiology and burden (Table 4). Africa presented the highest rates for HIV-Positive Incident TB cases, ranging from 98.0 to 117.1 cases/100,000pop. (Table 4).
|HIV-Positive Incident TB Cases||Rates (Cases/100,000pop)|
|WHO African Region||836,970,000||900,000||820,000||980,000||107.5||98.0||117.1|
|WHO South-East Asia Region||1,807,594,000||190,000||140,000||230,000||10.5||7.7||12.7|
|WHO Region of the Americas||933,447,000||35,000||31,000||38,000||3.7||3.3||4.1|
|WHO European Region||896,480,000||20,000||19,000||22,000||2.2||2.1||2.5|
|WHO Eastern Mediterranean Region||596,747,000||12,000||9,800||15,000||2.0||1.6||2.5|
|WHO Western Pacifi c Region||1,798,335,000||35,000||26,000||45,000||1.9||1.4||2.5|
Even more, difference in all these aspect can differ among countries and be higher. For example in Colombia, TB is still a significant public health problem. Figure 3 shows the WHO profile for TB in Colombia for 2010.
3. Tuberculosis incidence in high burden developing countries
As has been stated TB is highly endemic in many developing countries, particularly of Africa and Asia highest rates of TB are located. These 22 countries, summarizing 62.9% of the World population (4,321,966,000 pop) concentrated 81.5% of the incident cases of TB in the World (7,169,000 cases), reaching mean incidence rates higher than in the rest of the World, 165.9 cases/100,000pop. (Table 5). However in many of these countries those numbers are higher. India (although considered not official data) in 2010 reported 2,300,000 incident cases (ranging from 2,000,000 to 2,500,000 cases) (Table 5), followed by China with 1,000,000 incident cases (ranging from 910,000 to 1,200,000 cases) (Table 5) and South Africa with 490,000 incident cases (ranging 400,000 to 590,000 cases) (Table 5). Although that, again rates are higher in this last country, South Africa, where for the same year were reported between 797.9 to 1176.9 cases/100,000 pop. (7.9 to 11.8 cases/1,000 pop or 0.8 to 1.2 cases/100 pop) (Table 5). For Asia the country with highest rates is Cambodia (374.9 to 509.3 cases/100,000 pop.) (Table 5). For Latin America the country with highest rates (and the only from that region in this list) is Brazil (35.9 to 51.3 cases/100,000 pop.) (Table 5) (Figure 4).
|Incidence (cases)||Incidence rates (cases/100,000pop)|
|% from global burden||62.9||81.5||69.0||91.2||-||-||-|
4. Tuberculosis prevalence in high burden developing countries
For prevalence a similar epidemiological situation is seen. These 22 countries, concentrated 83.1% of the prevalent cases of TB in the World (9,972,000 cases), reaching mean prevalence rates higher than in the rest of the World, 230.7 cases/100,000pop. (Table 6). However in many of these countries those numbers are higher. India (although considered not official data) in 2010 reported 3,100,000 prevalent cases (ranging from 2,000,000 to 4,600,000 cases) (Table 6), followed by China with 1,500,000 prevalent cases (ranging from 1,300,000 to 1,700,000 cases) (Table 6) and Indonesia with 690,000 prevalent cases (ranging 300,000 to 1,200,000 cases) (Table 6). Although that, again rates are higher in other countries, such as South Africa, where for the same year were reported between 359.0 to 1256.7 cases/100,000 pop. (3.6 to 12.6 cases/1,000 pop or 0.4 to 1.3 cases/100 pop) (Table 6). For Asia the country with highest prevalence rates is Cambodia (297.1 to 1061.0 cases/100,000 pop.) (Table 6). For Latin America the country with highest rates (and the only from that region in this list) is Brazil (17.4 to 82.1 cases/100,000 pop.) (Table 6).
|Prevalence (cases)||Prevalence rates (cases/100,000pop)|
|% from global burden||62.9||83.1||53.7||107.6||-||-||-|
5. Tuberculosis mortality in high burden developing countries
For mortality a similar epidemiological situation is seen. These 22 countries, concentrated 78.0% of the deaths due to TB in the World (857,800 deaths, ranging 581,900 to 1,229,000 deaths), reaching mean mortality rates higher than in the rest of the World, 19.8 deaths/100,000pop. (Table 7). However in many of these countries those numbers are higher. India (although considered not official data) in 2010 reported 320,000 deaths (ranging from 210,000 to 470,000) (Table 7), followed by Indonesia with 64,000 deaths (ranging from 42,000 to 91,000 deaths) (Table 7) and Bangladesh with 64,000 deaths (ranging 47,000 to 85,000 deaths) (Table 7). Although that, again rates are higher in other countries, such as Cambodia, where for the same year were reported between 43.9 to 84.9 deaths/100,000 pop. (Table 7). For Africa the country with highest mortality rates is DR Congo (40.9 to 68.2 deaths/100,000 pop.) (Table 7). For Latin America the country with highest rates (and the only from that region in this list) is Brazil (1.6 to 4.3 deaths/100,000 pop.) (Table 7).
|Mortality (deaths)||Mortality rates (deaths/100,000pop)|
|% from global burden||62.9||78.0||63.3||102.4||-||-||-|
6. Tuberculosis-HIV incidence in high burden developing countries
Coinfection in high burden developing countries is one the main problems those countries should face in the public health threat that TB represents. These 20 countries, concentrated 78.1% of the cases of TB-HIV in the World (859,600 cases, ranging 636,200 to 1,128,900 cases), reaching mean TB-HIV rates higher than in the rest of the World, 20.4/100,000pop. (Table 8). However in many of these countries those numbers are higher. Africa in 2010 reported 300,000 cases TB-HIV (ranging 240,000 to 350,000) followed by India (although considered not official data) in 2010 reported 110,000 cases TB-HIV (ranging from 75,000 to 160,000) (Table 8), and Mozambique with 77,000 cases (ranging 53,000 to 110,000) (Table 8). Although that, again rates are higher in other countries. South Africa is the country with highest rates of TB-HIV, 478.7 to 698.1 cases/100,000 pop. (Table 8). For Asia the country with highest TB-HIV rates is Myanmar (43.8 to 118.8 cases/100,000 pop.) (Table 8). For Latin America the country with highest rates (and the only from that region in this list) is Brazil (5.1 to 14.4 cases/100,000 pop.) (Table 8) (Figure 5).
|HIV-positive incident TB cases||HIV-TB rates (cases/100,000 pop)|
|% from global burden||61.2||78.1||63.6||94.1||-||-||-|
7. Multidrug resistant tuberculosis in high burden developing countries
Multidrug resistant (MDR) tuberculosis is a public health problem (Gotuzzo E 2011, Tamaru et al 2012). Its burden particularly in developing countries is a relevant issue to be addressed. In some countries, proportions as high as 26% of the new TB cases can be MDR-TB (Figure 6).
MDR strains arose over the past 30 years as a variety of antituberculosis drugs were introduced in medicine, and they largely discount the results of chemotherapy for tuberculosis. The most dangerous of them are strains with extensive drug resistance (XDR), which are resistant to four or five different drugs on average. The molecular mechanisms that make a strain resistant are considered. XDR and MDR strains result from successive and usually independent resistance mutations, which arise in various regions of the mycobacterial genome. In addition, the formation of resistant strains is affected by the phenomenon of tolerance and mycobacterial latency in infected tissues (Prozorov AA et al 2012).
The increasing emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) in the era of human immunodeficiency virus (HIV) infection presents a major threat to effective control of TB. Drug resistance in Mycobacterium tuberculosis arises from spontaneous chromosomal mutations at low frequency. Clinical drug-resistant TB largely occurs as a result of man-made selection during disease treatment of these genetic alterations through erratic drug supply, suboptimal physician prescription and poor patient adherence. Molecular mechanisms of drug resistance have been elucidated for the major first- and second-line drugs rifampicin, isoniazid, pyrazinamide, ethambutol, the aminoglycosides and the fluoroquinolones. The relationship between drug resistance in M. tuberculosis strains and their virulence/transmissibility needs to be further investigated. Understanding the mechanisms of drug resistance in M. tuberculosis would enable the development of rapid molecular diagnostic tools and furnish possible insights into new drug development for the treatment of TB (Zhang Y & Yew WW, 2009).
8. Tuberculosis in Colombia and in a city of the country: Pereira
In Colombia for 2010 incident cases were 16,000 cases (ranging 13,000 to 19,000 cases) for a rate of 34 cases/100,000 pop (28 to 41 cases/100,000 pop). Prevalence was estimated in 22,000 cases (9,100 to 37,000 cases) for a rate of 48 cases/100,000 pop (ranging 20 to 81 cases/100,000 pop.). Mortality was estimated in 1,300 deaths (ranging 800 to 1,900 deaths) for a mortality rate of 2.8 deaths/100,000 pop. (1.7 to 4.2 deaths/100,000 pop.). All these figures are excluding HIV cases. TB incidence in HIV positive patients is 1,100 cases (ranging 750 to 1,500 cases) for a rate of 2.4 cases/100,000 pop. (ranging from 1.6 to 3.3 cases/100,000 pop.).
As an example of place where the burden of TB is high, Pereira, a city in Colombia can be presented. Pereira is the capital municipality of the Department of Risaralda (Figure 7). It stands in the center of the western region of the country, located in a small valley that descends from a part of the western Andes mountain chain. Its strategic location in the coffee producing area makes the city an urban center in Colombia, as does its proximity to Bogotá, Cali and Medellín.
For 2011, Pereira municipality has an estimated population of 459,690. Official reported records for TB in Risaralda registered a disease incidence for 2010 of 25 cases per 100,000 pop (which is above the national average rate of 24 cases per 100,000 pop). Pereira is divided into 19 urban submunicipalities: Ferrocarril, Olímpica, San Joaquín, Cuba, Del Café, El Oso, Perla del Otún, Consota, El Rocío, El poblado, El Jardín, San Nicolás, Centro, Río Otún, Boston, Universidad, Villavicencio, Oriente and Villasantana. Additionally also has rural townships which include Altagracia, Arabia, Caimalito, Cerritos, La Florida, Puerto Caldas, Combia Alta, Combia Baja, La Bella, Estrella, La Palmilla, Morelia and Tribunas. The municipality of Pereira has a diversified economy: the primary sector accounts for 5.7% of domestic product, the secondary sector shows a relative weight of 26.2%, while the tertiary sector is the most representative with a 68.1%. The GDP of Pereira grew by 3.7% in 2004. For 2010, Pereira reported 301 cases of TB (incidence rate of 65.85 cases per 100,000pop). In Pereira, previously reported interventions have been developed and working intersectorially with the academia in order to increase the impact of activities in TB control (Castañeda-Hernández DM et al. 2012c, Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a).
In the country, the strategic plan “Colombia Libre de Tuberculosis para la Expansión y Fortalecimiento de la Estrategia Alto a la TB, 2010-2015” (Colombia Free of TB for the Expansion and Enhancement of the Strategy Stop TB, 2010-2015), define as goal the achievement of notifications of new positive baciloscopy cases in more than 70% and a curation rate of at least 85%. In this context the routine surveillance allow to follow management and measurement of the impact of the realized actions by the control programs at municipal, departmental and national level, in order to generate interventions that contribute to achievement of the established goals to stop the advance of TB in the country.
In Pereira, control of TB among homeless have found that between 2007 and 2010, 74 homeless persons with TB were evaluated, from a total of 1,470 registered homeless persons (from the Social Development Secretary of Pereira) (cumulated incidence=50.3 cases/1,000pop., range 5.44 to 22.44; year 2010=16.32). Outcome condition was in 43.2% treatment self-withdrawal (range 36.4%-55.6%), therapeutical failure, 4.1%(0.0-9.1%), deaths, 2.7%(0.0%-8.3%), cured, 39.2%(33.3%-42.4%) and finished treatments, 10.8%(4.2%-25.0%). Comparing the 2010 TB incidence among homeless persons with that of the general population (0.6585/1,000pop.) that is 76.45 times higher in that risk population. In the same way, case fatality rate in 2010 was 2.5 times higher than in the general population (3.3%). These results have important implications in public health as well in the management and evolution of TB in these individuals, persistence of infection, drug-resistance and potential transmission to those that can be around these populations (Castañeda-Hernández DM & Rodríguez-Morales AJ, 2012b).
Also, as part of the integrative control of TB in special populations, surveillance have included control in a prison. Evaluating TB among prisoners between 2010 and 2012, seven prisoners with TB (AFB+), from a total of 1,508 registered prisoners at the penitentiary were diagnosed (cumulated incidence=4.64 cases/1,000pop., 2.99 in 2010 and 2.13 in 2011). Mean age was 40.5 y-old (100% males), all were pulmonary disease. All of them received voluntary counseling and testing for HIV, one of them was HIV+. Three of them are under anti-TB treatment, 2 were transferred, 1 finished treatments and 1 was a therapeutical failure. Comparing the 2011 TB incidence among prisoners with that of the general population (0.67/1,000pop.) that was 3.19 times higher in that risk population. In 2010 in Pereira was 0.66/1,000pop., then being 4.55 times higher in prisoners (Castañeda-Hernández DM et al 2012b). These results have important implications in public health as well in the management and evolution of TB in these individuals, persistence of infection, drug-resistance and potential transmission to those that can be around these prisoners. This is in agreement with recent data indicating that TB incidence rates among prisoners can be as higher as approximately 5 to 50 times higher them than in general population. In Brazil this has been reported as high as 61.8 times higher for latent TB and 36.08 for active TB. Prisoners are at risk rapidly progress to a latent TB or have an active TB posterior a recent infection or reactivation due to latent coexisting pathologies, particularly HIV infection, IV drug use and poor nutritional status. It has been shown that workers in such facilities as well the community, are at risk. For these reasons strategies oriented to bring an integral, social, epidemiological, clinical, diagnostic and therapeutic management, are proposed and for the Americas, the Pan-American Health Organization (PAHO) guideline for the TB control in population in prisons should be followed (OPS 2008).
Tuberculosis control in the XXI century requires new approaches and interventions, particularly those based in education and prevention with a community-based orientation to continuously progress in the achieved reduction of burden of disease in the region of the Americas, including in countries such as Colombia. Different approach programs such the development of social networks for control program, as has been developed in Pereira, Colombia (Castañeda-Hernández DM & Rodríguez-Morales AJ 2012a), should performed in other highly endemic places. As the WHO recommends to pursue the ACMS (advocacy, communication and social mobilization), strategies as the social network allow to enhance particularly the communication and social mobilization components. Unfortunately at many national plans of TB control, how translate the ACMS in specific actions is not well defined in most occasions.
As has been previously stated, in the establishment of a social network for TB, previous diagnosis, including geo-referenced characterization, it is necessary to select the areas where the nodes will be established, taking also in consideration the suitability as the willingness of the potential participants of the network in each area and node. Finally, with the mining of the activities described, but also beginning with the idea of raise the awareness about the disease, taking in consideration a high level of diversity on the activities, as has been stated in order to warrant the continuous interest and participation of the network members on it.
In the future, in order to enhance the function and structure of the whole social network, further meetings between the nodes are expected. As now, only nodes interact internally, but the idea for the future activities in this setting is increase the links internally, but also between the main nodes in order to potentially increase the participation in the whole network.
Activities such as the development of social network of TB in Pereira will enhance the prevention, education and surveillance in the community, allowing a better integrated approach to the TB control in these scenarios and increasing the health profile in the community decreasing the lost opportunities for diagnosis and treatment of TB cases, finally leading to an improvement of the TB prevention and control.
Integrating additionally control in populations were TB is highly prevalent such as in prisons and homeless persons (Figure 8) (Castañeda-Hernández DM et al 2012b, Castañeda-Hernández DM & Rodríguez-Morales AJ, 2012b), an integrative control of disease can be achieved and finally control and reduce the burden of disease in a developing country.