This study aimed to identify areas of risk for the diagnosis of TB in children and the possible relationships to the social inequalities noted in areas of Southeast Brazil. It is important to note that children are dependent on an adult for the treatment of TB or any other condition. Thus, it is essential that health professionals engage in a treatment strategy with the responsible caregivers so that there is adherence to the treatment and, consequently, a lower number of abandonments. Furthermore, it is necessary to guide the caregiver about the adverse effects that may occur as a result medications . According to the study conducted with caregivers of children with TB, knowledge about the treatment and pathophysiology of the disease favors treatment adherence .
This study also points out that there are several difficulties faced by caregivers, such as guilt from feeling responsible for the child's illness, fear of death as an outcome, and the suffering and prejudice faced by the lack of knowledge about TB. Caregivers also experience financial difficulties because in most cases one of the parents stops working to accompany the child to treatment. It is crucial for the health team to understand this situation. Caregiver experience contributes to the continuity of treatment and reduces the risk of abandonment prior to completion of interventions .
According to this study, the majority of TB cases were new and the most common outcome was cure (63.3%), a rate that is lower than the 85% goal set out by the End TB Strategy, which aims to cure 85% of TB cases by 2035 . The mortality rate due to TB as a basic cause was extremely high (6.1%), a rate that reflects the late diagnosis of the disease. Although, in this study, the majority of TB cases were not related to other clinical factors such as TB-HIV co-infection, mental illness, drug addiction, alcoholism, or smoking, it may be valid to highlight these risk factors.
The use of illicit or licit drugs, such as alcohol, can contribute to a poor prognosis for TB treatment. Dependency on drugs may delay and/or prolong treatment. Drug use may be related to the concomitant process of chemical dependency, which, in addition to the responsibility for taking medications and regular visits to health services, makes it difficult to continue treatment, in addition to forgetting to take the medication and potentiating the hepatotoxic effects .
With the use of serial analytical techniques and time trends, the results showed that TB diagnosis in children under 15 years of age had remained stable throughout the study period. However, this trend may indicate that new cases are not being diagnosed and/or reported and, in this context, may serve as an alert for municipal epidemiological surveillance to identify situations in which the reported data may be misrepresentative of true incidences of the disease .
More data are required to investigate the health of the adults in close contact with these children to rule out any undiagnosed or untreated TB in the household. Considering that this result represents the reality of the municipality, it still serves as an alert for epidemiological surveillance to investigate the close contacts of these children, as surely there is an undiagnosed or untreated bacilliferous adult.
When analyzing the statistics, there was an area in which children have a 3.14 fold greater risk of TB than in other areas of the municipality. This area is localized in the central, the western, and the southern regions. The central district is one of the oldest districts of the municipality; its most striking feature is the large number of homeless people in the municipality, part of a serious public health problem. The western district, on the other hand, has many slums and many residents per household; the middle economic class predominates. The southern district is the largest group in number of residents with a predominance of the middle-low economic class .
The findings lead us to show that children may only be infected through close contact with a person with active bacilliferous TB. Based on the literature, after 14 days of treatment the infected person no longer transmits the disease to others. Therefore, the diagnosis of TB in a child is considered a sentinel event that indicates the presence of people (usually adults) in the child's environment who are not diagnosed or who are not undergoing treatment for TB.
Our findings follow the results from the study by Cano et al. ; those researchers identified an adult with TB in 37.2% of the cases of children diagnosed with TB. Gathering an accurate and current medical and social history of the person with TB allows the identification of household contacts. Contact tracing is considered a key to protect those considered vulnerable to TB and can limit secondary cases (index case contacts) and break the transmission chain of the TB to other patients.
If a person is diagnosed with TB, it becomes necessary for all contacts (including children) to be evaluated by a specialist and, if necessary, initiate treatment for latent TB. This protocol is recommended by the WHO for all infected household contacts, regardless of age .
Dodd et al.  used mathematical modeling and identified that the management of household contacts, including the detection of secondary cases and latent infection and the carrying out prophylactic treatment, would prevent almost 160,000 cases of TB and almost 110,000 deaths of children under the age of 15 (with most of these preventable deaths for those under 5 years of age living in endemic areas). Therefore, it is essential that the active search for patients be carried out at home and in the places of greatest contact whenever a child is diagnosed with TB.
Of the tested explanatory models, the ZIP model was the one that best fit the data according to the pre-established criterion (lowest AIC value). This model revealed that children living in census sections that have more than 85 private and collective households (OR 6.55), the proportion of households with per capita income lower than 0.6 (OR 1.78), and the proportion of private households with nominal income of up to one quarter of the minimum wage greater than 48.6 (OR 2.77) have a higher risk of contracting TB. The influence of living conditions on the transmission of TB persists and highlights the image of socioeconomic inequalities that result in medical and health inequities .
The model also revealed that locations with a proportion of more than 5 children from 0 to 5 years in the population (OR 3.09) is a probable risk factor for TB. This may be related to the immaturity of the immune system itself; studies have shown that environmental and even food antigens induce the body to produce its own immunoglobulins. The child’s immune system is considered immature and more vulnerable to the disease until the maternal antibodies have decreased and his or her own body produces antibodies. This process should occur until the age of five years . In 2015, TB caused the death of 210,000 children worldwide, and 80% (191,000) of these deaths occurred in children under the age of 5 years . A systematic review of the subject indicated that changes in TB incidence rates are more associated with variations in socioeconomic indices and consequent change in the general health status of the population than in health services variables .
One of the variables identified as protective is the proportion of women responsible for the household under 30 years old and over 69 years old (OR 0.31). This protective factor can be explained, according to research carried out by the Brazilian Institute of Geography and Statistics (IBGE), by the fact that women are having children later . According to a survey conducted between 2008 and 2018 by the IBGE, the number of women under 30 years who had children decreased 16.1%, while the number of women who became mothers after the age of 30 years increased (increase and 36% the number of births for mothers between 30 and 44 years old). In addition, those who had children after the age of 45 years dropped by 14.9% . Thus, it could be deemed reliable to assume that maternal age under 30 years would serve as a protective factor for the child’s resistance to TB.
Also identified as a protective factor for childhood TB contraction is the average income greater than BRL 2,344 for women responsible for the household (OR 0.04); this can be justified by the close relationship that TB has with the social determinants of health. A study by San Pedro and Oliveira  identified that low income increases vulnerability to TB, reflecting unequal access to information, and unequal access to consumer goods and health services . Conversely, increasing income tends to decrease vulnerability to disease.
Among the limitations of the study are the use of secondary data sources that may lead to incomplete data or writing errors, because the data obtained through the TB notification forms were already tabulated and the researchers had no contact with the participants of this research to verify information. In addition, the main limitation of an ecological study is ecological fallacy: Analyses are carried out at the aggregate level and their results cannot be interpreted at the individual level.
The authors encourage new studies and approaches be carried out to better characterize the relationship between children with TB and cases reported in the same family, as it is a very important and little explored aspect in the literature and new studies should be conducted in order to fill the gaps that still remain on the topic. This study showed areas of risk for the occurrence of TB in children. The study is in line with the End TB Strategy and the 2030 Agenda, which aims to support a strategic agenda for action and, therefore, save the lives of children through the systematic, intensified, and comprehensive identification of children with TB respiratory symptoms in the community.
Therefore, TB continues to be a problem linked to living conditions, as it shows a marked and persistent influence from socioeconomic and cultural factors that worsen the rates of social inequalities and inequities.