**2. Patch 1: Chiapas, Mexico**

In this sense, we understand as social vulnerability that set of economic, political, social and cultural conditions which determine that some individuals become infected by the TB bacillus while others do not, depending on the structural conditions which favor or hinder exposure

TB disease while others do not, and among those with TB disease some are cured (whether spontaneously or as a result of anti-TB treatment), others remain chronically ill (possibly with multi-drug resistance) while others die (generally those presenting the worst socioeconomic

Nevertheless, TB prevention and control programmes are designed as if the disease behaved in a homogeneous way in all countries and regions, based almost solely on biological and medical factors, without taking into account socio-cultural, economic and political factors, such as poverty, malnutrition, health services accessibility and quality, as well as intra and inter-

This approach impedes acting on the particularities of marginal populations, which are precisely the ones presenting the highest rates of morbidity and mortality of this disease, manifesting various gradients of exposure and susceptibility. This leads governments to act on the basis of global estimates, even when their interpretation of these is limited and partial,

Furthermore, this way of tackling TB does not reflect the reality of the different regions within a given country, because local or regional variations in rates of morbidity and mortality are disguised. Such variability could easily be quantified by, at the very least, providing the standard deviation corresponding to the global values of these rates for each country. Conse‐ quently, areas which should be given priority, paradoxically receive only limited resources for

In this sense, it is important to point out that TB, like HIV/AIDS, is one of the diseases for which estimations of impact in terms of incidence and prevalence are frequently based only on the registered cases. While it is true that published national and international figures often include estimates of sub-notification, they do not usually include gradients of the magnitude of the disease, or of the intra- or inter-regional under-notification rates, nor the differential rates between different population groups. According to several authors, calculation of the number of cases of TB disease is possible based on the expected evolution of cases of infection [2] or through linear regression modeling involving age-specific prevalence values across a range of differently aged populations [3]. Although this calculation technique for the frequency of TB and HIV status has been considered [4], there are currently no models in which population

In summary, in general terms, national and international policies to cope with TB ignore this reality, applying criteria of homogeneity in the calculation of objectives, materials, costs and logistics, among other aspects. While it is well known that marginal groups are the ones presenting the highest TB morbidity and mortality rates, their characterisation is not usually

1 According to World Health Organization calculations, one third to the human population is infected with TB bacillus

because the differential exposures and true extent of TB are unknown.

as well as those differential aspects by which, among those infected, some get

to the disease,1

interventions.

conditions and poorer health in general).

444 Tuberculosis - Current Issues in Diagnosis and Management

community political conflicts, among others.

impact has been measured in terms of social factors.

Chiapas is one of the poorest states in Mexico, and has one of the highest rates of indigenous margination as well as an acute lack of health care resources. According to official government statistics, Chiapas ranks almost last among all Mexican states in terms of health and socioe‐ conomic indicators [6]. It is precisely in Chiapas where, due to the conditions of social exclusion, poverty, malnutrition and high mortality from infectious contagious diseases, the Zapatista National Liberation Army (EZLN) initiated an armed rising against the Mexican government in 1994, which drew attention, both nationally and internationally, to the preca‐ rious living and health conditions of the indigenous and peasant populations, not only in Chiapas, but throughout the entire country.

Several studies have been carried out by our team in areas of high levels of poverty in Chiapas: Our first attempt to analyze the pulmonary tuberculosis (PTB) situation arose out of the discovery that in the only hospital (Comitán General Hospital, Ministry of Health) in the region of the border with Guatemala for patients not covered by insurance (the majority of whom are indigenous),2 there was empirical evidence of a high prevalence of PTB cases. In 1994, active case finding of patients with chronic cough (15 days or more) was carried out among all patients aged over 14 years seeking care in the hospital for whatever reason [7]. In this study

<sup>2</sup> In Chiapas, over 80% of population is not covered by social security [6]

a rate of 21 positive PTB smears per hundred patients was found (95% CI=15.5-26.6), and the main factors associated with PTB were age (35-44 years), occupation (engaged in agricultural) and weight loss. Through a logistic regression model, we found that the subgroup of chronic cough patients aged 35-44 years, agricultural workers and who had lost weight, had the greatest likelihood of being PTB positive (68.7% compared to the overall average of 21% in the studied patients).

government communities, and divided communities, i.e. which contained both opposition and

Pulmonary Tuberculosis in Latin America: Patchwork Studies Reveal Inequalities in Its Control – The Cases of Chiapas

(Mexico), Chine (Ecuador) and Lima (Peru) http://dx.doi.org/10.5772/54950 447

This investigation identified serious deficiencies in both detection and treatment of PTB. In the 46 studied communities (n=2,997 households), we detected 29 cases of PTB among the population aged over 14 years. This means a rate of PTB of 85.3 per 100,000 in the general population, and of 161.2 among those aged 15 and older, almost three times the rate reported for the entire state. In this sense, only 13 (45%) cases of the 29 detected, had been identified by health services and were being treated. Of these 13 cases, one had not received any anti-TB

We also carried out two evaluations of a cohort of patients aged over 14 years diagnosed with PTB from January 1998 to July 2005, and found poor survival among them. In the first followup (performed during 2004-2006), the principal factors associated with PTB mortality were: age (45 years and over, OR=1.3; 95% CI=0.98-1.3), 0-3 years of schooling (OR=3.3; 95% CI=1.1-4.4), not living in the main village of their municipality (OR=1.2; 95% CI=1.0-1.3), living in a rural community (OR=2.7; 95% CI=1.1-6.8), not having been treated in DOTS (OR=1.2; 95%

In the second follow-up (carried out in 2008-2009), the factors associated with PTB mortality were age (45 years and over) and anti-TB treatment duration of under six months. The median survival time of those patients aged 45 and over who died was 718 days (range 0 to 3,185), while the median survival time in the reference group consisting of patients aged 15-34 years, was 688 days (range 8-1,841). With regard to the duration of anti-TB treatment, the median survival time among patients with incomplete treatment was 261 days (range 0-1,658), whereas among those dying in the reference group (with treatment completed), the median survival

The mortality rate in the patients studied was 4.6 per 100 person-years. Of the 78 deaths from PTB documented in this study, 25% occurred during the first six months following diagnosis (in other words, during treatment), 38% by the end of the first year from the date of diagnosis,

During the decade from 1997 to 2006, inequalities of wealth and human development were extremely marked in Ecuador. The indigenous population, such as that residing in the central Andean province of Cotopaxi, has the highest poverty rates, and has many of its basic needs unmet. In Ecuador, up until 2006, the TB Prevention and Control Program was based on passive case finding of patients with respiratory symptoms (health personnel would check whether a patient visiting a health center had a productive cough of more than 15 days of duration). In contrast to what happens in cities, in rural areas the organization and functioning of the program relies on the presence of basic rural health teams; this means that is not

53% had died by the end of the second year, and 72% after three years.

The most important features of these studies are shown in Table 1.

CI=1.0-1.3) and having defaulted from treatment (OR=11.5; 95% CI=5.3-24.8) [13].

pro-government groups.

treatment and six had defaulted from anti-TB treatment.

time was 1,137 days (range 202-3,185) [14].

**3. Patch 2: Chine, Ecuador**

In addition, we noted that in the case of men, patients came to the hospital from near, far and very far distant communities, but in the case of women, the majority of them only came from communities which were near or very near. So we decided to carry out other studies in the hospital's area of influence, with the aim of analyzing factors related with the high PTB prevalence among users of secondary level care, not only in terms of health system aspects, but of demographic and socioeconomic characteristics:

a) In 1997 active case-finding was carried out among all patients aged over 14 years seeking consultation in a random sample of seven primary care centers [8]. We found a PTB positivity rate of 11.1 (95% CI=6.6-17.2) per hundred patients studied. The factors associated with PTB were size and poverty level of the locality of residence. Of the coughers identified, 56% sought care for non-respiratory symptoms.

b) In 1998 active case-finding was carried out among those aged over 14 years who had a cough of 15 days or more of duration, in a convenience sample of 1,894 households in 32 communities chosen at random based on the level of poverty and on travel time to reach the nearest health services (< 1 hour, 1 hour and over). In this study we found a rate of 276.9 per 100,000 persons studied (95%CI: 161-443) and that the only factor associated with PTB was blood in sputum, probably due to the homogenous conditions of extreme poverty among the populations studied [9].

Additionally, we found that the sensitivity of the smear testing was slightly lower than 50% in the primary care centers and in communities, and that the proportion of patients with active PTB that was receiving treatment was only 50% in the primary care centers, and 10.5% in the studied communities [10]. Also, we found high rates of anti-TB treatment defaulting [11], and very high levels of PTB multidrug-resistance (MDR): 4.6% and 29.2% primary and secondary MDR-TB, respectively. In fact, 14% of all studied PTB patients had MDR.

According to the logistic regression model fitted, the main variables associated with MDR were: having received anti-TB treatment previously, cough of three years or more of duration and not being indigenous. This is the only occasion in all our studies, which the condition of being indigenous appeared as a protective factor [12].

In 2000-2001 our team, together with Right to Health Defense Group and Physicians for Human Rights, carried out a population-based study to assess health conditions, and access to health services in the conflict zone initiated in 1994 between the EZLN and the Mexican government [6]. We found that the most affected regions by the armed conflict have fared even worse than the rest of Chiapas State. We performed a household survey in the municipalities most affected by the armed conflict among three types of communities: opposition communities, progovernment communities, and divided communities, i.e. which contained both opposition and pro-government groups.

This investigation identified serious deficiencies in both detection and treatment of PTB. In the 46 studied communities (n=2,997 households), we detected 29 cases of PTB among the population aged over 14 years. This means a rate of PTB of 85.3 per 100,000 in the general population, and of 161.2 among those aged 15 and older, almost three times the rate reported for the entire state. In this sense, only 13 (45%) cases of the 29 detected, had been identified by health services and were being treated. Of these 13 cases, one had not received any anti-TB treatment and six had defaulted from anti-TB treatment.

We also carried out two evaluations of a cohort of patients aged over 14 years diagnosed with PTB from January 1998 to July 2005, and found poor survival among them. In the first followup (performed during 2004-2006), the principal factors associated with PTB mortality were: age (45 years and over, OR=1.3; 95% CI=0.98-1.3), 0-3 years of schooling (OR=3.3; 95% CI=1.1-4.4), not living in the main village of their municipality (OR=1.2; 95% CI=1.0-1.3), living in a rural community (OR=2.7; 95% CI=1.1-6.8), not having been treated in DOTS (OR=1.2; 95% CI=1.0-1.3) and having defaulted from treatment (OR=11.5; 95% CI=5.3-24.8) [13].

In the second follow-up (carried out in 2008-2009), the factors associated with PTB mortality were age (45 years and over) and anti-TB treatment duration of under six months. The median survival time of those patients aged 45 and over who died was 718 days (range 0 to 3,185), while the median survival time in the reference group consisting of patients aged 15-34 years, was 688 days (range 8-1,841). With regard to the duration of anti-TB treatment, the median survival time among patients with incomplete treatment was 261 days (range 0-1,658), whereas among those dying in the reference group (with treatment completed), the median survival time was 1,137 days (range 202-3,185) [14].

The mortality rate in the patients studied was 4.6 per 100 person-years. Of the 78 deaths from PTB documented in this study, 25% occurred during the first six months following diagnosis (in other words, during treatment), 38% by the end of the first year from the date of diagnosis, 53% had died by the end of the second year, and 72% after three years.

The most important features of these studies are shown in Table 1.
