Comparative analysis of tuberculosis incidence during childhood and adolescence in 1993 and 1997 in Paraíba Valley, State of São Paulo (Brazil)

ORIGINAL ARTICLE

Comparative analysis of tuberculosis incidence during childhood and adolescence in 1993 and 1997 in Paraíba Valley, State of São Paulo (Brazil)^*

Luiz Fernando Costa Nascimento^I; Renata T. Lobato^II

IAssistant Professor of the Department of Medicine

^IIResident of the Pediatrics of the Department of Medicine.

^{Correspondence}

ABSTRACT

OBJECTIVE: To describe and to compare the incidence of tuberculosis in childhood and adolescence in the Paraíba Valley (State of São Paulo, Brazil) in 1993 and 1997.

METHOD: Descriptive study with secondary records obtained from the Tuberculosis Division of the Health Department of the State of São Paulo (Divisão de Tuberculose da Secretaria de Saúde de São Paulo). The variables were the type of case, age, form of detection, diagnosis confirmation, clinical presentation, X-ray results, and anti-HIV test results.

RESULTS: The global incidence of tuberculosis in all age ranges was of 97.3 cases/100,000 inhabitants in 1993, and 127.6 cases/100,000 inhabitants in 1997. In the age group up to 15 years old, there were 93 new cases in 1993, and 68 new cases in 1997, representing an incidence of 11.7 cases/100,000 inhabitants in 1993 and 7.9 cases/100,000 inhabitants in 1997. The most common clinical presentation was the pulmonary form; the most important form of detection was by searching communicants; the most frequent diagnosis confirmation was by X-ray, and there was an increasing number of anti-HIV tests between 1993 and 1997. The distribution by age range was similar to the literature data in both years analyzed.

CONCLUSION: The values of tuberculosis incidence in childhood and adolescence found in this study are higher than those existing in developed countries.

Key words: Tuberculosis, epidemiology. Child. Adolescence. Incidence.

Abbreviations used in this study

HIV – Human immunodefficiency virus

CGB – Calmette-Guérin bacillus

WHO – World Health Organization

Introduction

Tuberculosis is still a major cause of morbidity and mortality among children worldwide. Tuberculosis during childhood and adolescence results necessarily from a recent infection and, mainly in infants and pre-school children, reflects the continuous transmission in the community. In several developing countries, the rates remain unaltered, and in industrialized countries, where the incidence had dropped between the 30’s and 80’s as a reflex of the improved social conditions, of the introduction of tuberculostatic drugs, and of CGB vaccination, the incidence has increased in the last years ⁽¹⁾.

In many African and Asian regions, the incidence is approximately 220 cases/100,000 inhabitants, of which 15% occur in children aged 15 or younger ⁽²⁾.

The World Health Organization (WHO) estimates there are 1.3 million new cases and 450,000 deaths every year in 15 year-old children or younger, in developing under development ⁽³⁾. According to the WHO, the estimate of new annual cases, at all ages, is eight million, with approximately 2 million deaths ⁽⁴⁾.

In England, the incidence of tuberculosis in people up to 18 years of age was estimated at 3.9 cases/100,000 inhabitants, in a study assessing tuberculosis cases between 1982 and 1997 ⁽⁵⁾.

In 1998, a survey carried out by the Public Health Laboratory Service in England, revealed an incidence of 3.6 cases/100,000 inhabitants, which is lower than the number found in the 1988 and 1993 surveys, despite the case increase in London ⁽⁶⁾. This same study showed that the pulmonary form was less frequent in children than in adults (35% compared to 65% in adults). A population-based study performed in Greenland identified an increase of tuberculosis incidence from 85 to 172 cases/100,000 inhabitants, between 1990 and 1997, with a six-fold increase in children’s cases ⁽⁷⁾.

In Cuba, data on the incidence of childhood tuberculosis between 1983 and 1998 revealed about five cases/100,000 inhabitants ⁽⁸⁾.

In Brazil there are few studies on the incidence of tuberculosis, especially in the pediatric and adolescence age range, although tuberculosis is a disease of compulsory notification, and data are concentrated in State Health Departments.

Thus, collecting the information on 560 charts of tuberculosis patients between zero and 14 years of age, Oliveira et al. ⁽⁹⁾ found 6.6% of childhood tuberculosis cases among the notifications in Rio de Janeiro, in 1993, with predominance of approximately 70% of pulmonary cases. Alves et al ⁽¹⁰⁾ used secondary data from Rio de Janeiro Health Department, and found an incidence of 27 cases/100,000 inhabitants between 1989 and 1993, where the incidence at all ages in 1993 was of 151 cases/100,000 inhabitants.

In São Paulo, the incidence of tuberculosis between 1993 and 1997 for all ages was about 51 cases/100,000 inhabitants, ⁽¹¹⁾ and in 1999, about 4% of tuberculosis cases notified in the State of São Paulo were children up to 14 years of age, with predominance of the pulmonary form, followed by the ganglionic form ⁽¹²⁾.

The purpose of the present study was to describe and to compare new cases of children’s tuberculosis in 1993 and 1997, in the Middle Paraíba Valley, São Paulo, Brazil.

Methods

This is a descriptive study, using secondary data from the Tuberculosis Division of the São Paulo Health Department, corresponding to the notifications of São Paulo Middle Paraíba Valley. This region encompasses 28 townships, with a population of about 900,000 inhabitants, located between São Paulo and Rio de Janeiro States. The study includes the years of 1993 and 1997.

The study variables were age of the patients, later grouped from zero to four years, five to nine years, and 10 to 15 years of age; the diagnosis was confirmed by X-ray, positive bacterioscopy, histopathology, and others (including culture, clinical, and other exams), type of case considered new, early relapse, return after drop-out, no information, and others (including re-notification and late relapse), clinical form, including pulmonary, peripheral ganglionic, pleural, without information, and others (including meningeal, milliar, genital, bone, ophthalmologic, intestinal and disseminated), type of identification, result of the X-ray and of anti-HIV test. These variables are included in the Notification Chart of Tuberculosis Cases of the Tuberculosis Division of the São Paulo State Health Department.

Tables for these variables were built for the years 1993 and 1997, with the respective percentages. In the tables of the Results session, the data source was from the Tuberculosis Division of São Paulo State Health Department.

Data was analyzed by Epi-Info 6.04.

Results

Seven hundred and seventy two new tuberculosis cases were notified in 1993 and 1,098 new cases in 1997 in Paraíba Valley. The incidence of tuberculosis in 1993 was of 97.3 cases/100,000 inhabitants, and in 1997 of 127.6 cases/100,000 inhabitants. In the age range up to 15 years, 180 cases of tuberculosis were recorded, being 105 in 1993 and 75 in 1997. These figures represent respectively 13.6% and 6.8% of the cases recorded in these years,.

Of these 180 cases, 93 were new cases in 1993, and 68 in 1997. The incidence of tuberculosis in the age range up to 15 years of age was of 11.7 cases/100,000 inhabitants in 1993, and 7.9 cases/100,000 inhabitants in 1997, a drop of a little over 30%.

Table 1 shows the case distribution according to the type. A considerable rate of return to treatment after drop-out in 1993 and a reduction in 1997 was noticed.

Table 2 shows the distribution of new cases, according to age, form of detection and form of confirmation. In 1993, the most prevalent age range to the results was zero to four years of age, representing an important part in 1997 as well. The main form of detection was by control of communicants in both years studied; the X-ray was the exam most commonly used to confirm the diagnosis.

After diagnosis confirmation, it was noticed that the most frequent form was pulmonary, representing approximately 80% of the cases in both years, followed by the peripheral ganglionic form. No case of meningeal form of tuberculosis was notified; one milliar form in a two-year old patient was recorded, without the possibility of determining his vaccination status.

The X-ray result, except for the "no information" status, was altered in 88.0% of the recorded cases in 1993 and in 85.0% of the notified cases in 1997; the lack of information on the X-ray exam was remarkable in both years (25.8% and 45.3%, in 1993 and 1997).

There was an increase in anti-HIV exams made from 10.8% in 1993 to 36.8% in 1997 (Table 2).

Discussion

Childhood tuberculosis must be seen as a sentinel-event in public health, due to the fact that it considers a recent infection produced by a bacillus-infected person. The description of age ranges at risk, as well as the forms, type of case, and type of diagnosis confirmation can show how the Tuberculosis Program is working.

Although there are possible disadvantages in a study with secondary data, we consider them to be an important source of information, not only in the local context, but also to be analyzed by the core level of the Health Department, given the lack of this kind of study in the State of São Paulo.

Of the 180 cases of childhood and adolescence tuberculosis recorded, 161 (89.4%) were new occurrences, with a remarkable amount of treatment drop-outs. The incidences revealed in the present study are above those of other studies on this issue, ^(5,6,8) and above the numbers found in the State of São Paulo ⁽¹²⁾.

Treatment drop-out is a major factor for the development of resistance to the drugs used to treat tuberculosis ⁽¹³⁾. In regard to this aspect, there was an improvement in the treatment adherence in 1997 when compared to 1993. The significant return rate after drop-out recorded in 1993 may reflect the carelessness with which this disease is regarded by the family or the fact that the health professionals were unable to sensitize those in charge of the children.

The incidence of tuberculosis in this age range, i.e., 11.7 cases/100,000 inhabitants in 1993 and 7.9 cases/100,000 inhabitants in 1997 are similar to the values observed in Al-Marri in Qatar ⁽¹⁴⁾ in 1983 and 1996. However, they are above those found by Rosen et al. ⁽⁶⁾ in England, of 3.5 cases/100,000 inhabitants.

Oliveira et al. ⁽⁹⁾ studied new cases in Rio de Janeiro in 1993, and found 6,7% new cases between zero and 14 year olds. Our findings showed 13.6% cases in patients up to 15 years of age in 1993, and 6.8% in 1997, being closer to the incidence found in Rio de Janeiro.

Regarding the distribution by age range, the literature ⁽¹⁵⁾ reports higher incidence in the first years of life, decreasing considerably until adolescence, when there is a new increase. The present study reports an age-related incidence very similar to the one reported by Comstock et al. ⁽¹⁵⁾.

The most important form of detection, in both years of the study, was by searching communicants, including everybody, whether relatives or not, who live with a tuberculosis patient; the communicants of bacillus-infected patients are at the highest risk of getting infected. This manner of detection contributed with approximately 40% of the findings in both years. Table 2 shows an increase in spontaneous presentation of nearly 50% in 1997.

The most frequent confirmation of tuberculosis was made by X-rays, because it is the easiest to be performed; this finding confirms what was reported by Oliveira et al. ⁽⁹⁾. X-rays were made in more than 75% of the cases, and were altered in 88% of them in 1993 and in 85% of the cases in 1997. Reports without information increased almost 60% between 1993 and 1997, an unexplained fact, maybe because this category includes cases in which X-rays were not performed and, consequently, no radiological reports could be made.

Bacillus search in sputum was scarcely used to confirm the cases. This technique is known for low sensitivity (25%) because children are usually not bacillus-infected and the best way to isolate M. tuberculosis is from gastric aspiration ⁽¹⁶⁾, a technique seldom used by the public service because it is more complex and demanding.

The pulmonary form was the most prevalent in both years analyzed; these data agree with findings described in previous papers ^(5,14,17).

The analysis also showed that there was a clear increase in anti-HIV exams; there were almost 12% of exams made in 1993, and in 1997, the reported cases increased to 37%. HIV-positive cases also decreased in 1997. This finding is important because HIV infection increases the risk of developing active tuberculosis, being 10 times higher in co-infected than in non-infected patients ⁽¹⁸⁾.

Therefore, tuberculosis continues to be a severe problem to be solved, because children and adolescents are still getting sick, and this only happens by contact with infected people. Possible causes, as mentioned by Alves et al. ⁽¹⁰⁾, include a lower socioeconomic level, malnutrition, a quality drop in the public health service, and lack of notification and follow-up of tuberculosis patients.

Although the years of 1993 and 1997 are far from the present, we must consider that consolidated data on tuberculosis in the State of São Paulo, i.e., free from possible biases, date from 1999 ⁽¹²⁾.

The notification chart on tuberculosis does not provide information on CGB vaccination status; however, CGB vaccination in the State of São Paulo is 100% ⁽¹⁹⁾. Despite its specificity, the tuberculin exam is not performed.

Although there are few studies on the incidence of tuberculosis in childhood and adolescence, future data in this same region or in others in the State of São Paulo, using the data from theTuberculosis Division of the State Health Department and from other Brazilian states, it will be possible to compare these with the ones from 1993 and 1997, in order to analyze the response to the care given to childhood and adolescence tuberculosis.

Acknowledgements

The authors would like to thank Dr. V. Galesi, from the Tuberculosis Division of the Epidemiological Vigilance Center "Prof. Alexandre Vraniak" of the São Paulo State Health Department, and Prof. Dr. Margarida M.M.B. de Almeida, of the Public Health School of USP, for their review and suggestions.

Received for publication on 1/22/03.

Approved, after revision, on 3/18/03.

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*

Work performed in the Department of Medicine of Universidade de Taubaté, SP.

Publication Dates

• Publication in this collection
  24 Sept 2003
• Date of issue
  June 2003

History

• Received
  22 Jan 2003
• Accepted
  18 Mar 2003