The evolution of tuberculosis infection among schoolchildren in Barcelona and the HIV epidemic

[Trends in the prevalence of tuberculosis among six-year-olds in Albacete (Spain)]

OBJECTIVES

To analyze the prevalence and evolution of tuberculous infection among 6-year-olds in Albacete and its relation to socioeconomic status of the family.

METHOD

A tuberculin test (2UT RT-23 Tween 80) was given to 6-year-old school children in and around Albacete in 1992 and 1999. We calculated the prevalence of tuberculosis and the relation to family socioeconomic level as assessed by the parents' level of education of the area of residence.

RESULTS

The tuberculin test was given to 2,783 children, 1,532 in 1992 (8% bacille-Calmette-Guerin-vaccinated) and 1,251 in 1999. The prevalence of tuberculosis infection among non-vaccinated children was 0.78% in 1992 (3.37% among vaccinated children, p = 0.012) and 0.72% in 1999. No significant differences between the two screenings were found except for the vaccinated and non-vaccinated children. The annual decline was 1.1% and the annual decrease in risk of tuberculosis infection was 0.12%. No significant differences related to level of parental education or area of residence were detected.

CONCLUSIONS

The prevalence of tuberculosis infection among 6-year-old school children in Albacete is low, although there is a very slight non-significant downward trend, which may be biased by the inclusion of bacille-Calmette-Guerin-vaccinated children. No differences related to family socioeconomic level were found.

Tuberculosis infection and disease among schoolchildren: the influence of the HIV epidemic and of other factors

BACKGROUND

The HIV/AIDS epidemic has caused an excess of tuberculosis cases in Spain and in other countries, but its impact on tuberculosis infection is less well understood. This study presents a massive screening undertaken to estimate the prevalence of tuberculous infection in a cohort of primary school entrants. The evolution of the risk of infection is studied by comparison with previous data in the same population.

METHODS

Tuberculin skin test screening with 2TU of PPD RT 23 of first grade students in the primary schools of Barcelona, in the 1994-95 school year (cohort born in 1988). Information was also sought from families of unscreened children. Contacts of PPD+ children were traced to locate index cases. The results were also linked to the case registry of the tuberculosis control programme.

RESULTS

The prevalence of tuberculin reactors free of BCG vaccination among the 11,080 schoolchildren screened belonging to the 1988 cohort was 0.76%. A 3% annual decline in the annual risk of infection is estimated by comparison with previous data. The identification of 24 cases with a previous history of tuberculosis disease and of 13 cases with active disease diagnosed after the screening was possible by the follow up of these tuberculin positive children and of the information provided by families of unscreened pupils. The screening detected 1.5 new cases of tuberculosis per 1000 tuberculin tests performed. Tuberculosis infection could be traced to HIV infected tuberculosis cases for at least 6% of the positive schoolchildren.

CONCLUSIONS

The decline of the annual risk of infection continues in Barcelona, although at a slower pace than before the HIV/AIDS epidemic, probably attributable to the influence of injecting drug users with smear positive tuberculosis and HIV/AIDS.

HIV in children

Because children acquire HIV infection differently than adults, this article begins with a discussion of the epidemiology of AIDS in children. This is followed by a discussion of factors related to progression of the disease and survival in pediatric AIDS. A discussion of the pulmonary manifestations in children is followed by a suggested approach to the HIV-infected child with respiratory symptoms.

Evaluation of a social health intervention among homeless tuberculosis patients

SETTING

Homeless and other fringe groups are a priority in the global strategies of tuberculosis prevention and control in big cities, as a consequence of their generally poor adherence to treatment and concurrent multiple social and health problems.

OBJECTIVE

To evaluate a social care and health follow-up programme targeting homeless tuberculosis patients in Ciutat Vella District, Barcelona, which covered 210 patients from 1987 to 1992. During directly observed treatment, primary health care and, if necessary, accommodation was provided.

DESIGN

The differential tuberculosis incidence rate between Ciutat Vella and the other districts of Barcelona, the percentage of successfully completed treatments and the days of hospitalization saved by the programme were measured.

RESULTS

There was a significant decrease in the tuberculosis incidence rate among homeless patients in Ciutat Vella (from 32.4 per 10(5) inhabitants in 1987, to 19.8 per 10(5) in 1992, P = 0.03), compared to an unchanged rate elsewhere (1.6 per 10(5) inhabitants in 1987, compared to 1.7 per 10(5) in 1992, P = 0.34). A smaller than expected proportion, 19.6%, of patients failed to complete their treatment, and a decrease in the mean period of hospitalization for tuberculosis in the district hospital was recorded, falling from a mean 27.1 days in 1986 to a mean 15.7 days in 1992.

CONCLUSION

The programme appears to be both effective and efficient, as it has enabled a large number of homeless patients to complete their treatment successfully, at the same time saving twice the amount of funds invested.

[The prevalence of tuberculous infection in the 6- to 7-year-old schoolchild population in Albacete]

To analyze the prevalence of tuberculosis infection, tuberculin tests were given to 3,292 elementary school children in the first and second grades in the environs of Albacete (Spain) in 1992. There were 1,532 children aged 6 (122 vaccinated with BCG) and 1,760 children aged 7 (162 vaccinated); 51 children tested positive (20 who had been vaccinated and 31 who had not been). The prevalence of infection was 0.78% at 6 years of age and 1.25 at 7 years of age in non vaccinated children, a rate similar to that found by earlier national surveys. One case of active pulmonary tuberculosis was identified. Inclusion of the 8.6% who had been vaccinated caused significant distortion of the initial prevalences. The annual rate of infection, estimated based on an annual decline of 4%, was 0.143 %. Differences in tuberculosis infection by family socioeconomic level, as indicted by level of parental studies or place of residence, were not statistically significant, although we did observe a slightly greater rate among children living in poorer areas and with parents with only elementary school education. Our results confirm a downward trend in the prevalence of tuberculosis infection in the population studied, as well as the importance of carrying out this type of survey to provide a reference for active control and for taking an active stand.

The epidemiology of Mycobacterium bovis infections in animals and man: a review

Tuberculosis is primarily a respiratory disease and transmission of infection within and between species is mainly by the airborne route. Mycobacterium bovis, the cause of bovine-type tuberculosis, has an exceptionally wide host range. Susceptible species include cattle, humans, non-human primates, goats, cats dogs, pigs, buffalo, badgers, possums, deer and bison. Many susceptible species, including man, are spillover hosts in which infection is not self-maintaining. In countries where there is transmission of infection from endemically infected wildlife populations to cattle or other farmed animals, eradication is not feasible and control measures must be applied indefinitely. Possible methods of limiting spread of infection from wildlife to cattle including the use of vaccines are outlined. The usefulness of DNA fingerprinting of M. bovis strains as an epidemiological tool and of BCG vaccination of humans and cattle as a control measure are reviewed. The factors determining susceptibility to infection and clinical disease, and the infectiousness of infected hosts and transmission of infection, are detailed. Reports of the epidemiology of M. bovis infections in man and a variety of animal species are reviewed. M. bovis infection was recognised as a major public health problem when this organism was transmitted to man via milk from infected cows. The introduction of pasteurization helped eliminate this problem. Those occupational groups working with M. bovis infected cattle or deer, on the farm or in the slaughter house, are more likely to develop pulmonary disease than alimentary disease. In recent years, tuberculosis in farmed cervidae has become a disease of economic as well as public health importance in several countries. Nowadays, the human immunodeficiency virus (HIV) is associated with a greatly increased risk of overt disease in humans infected with Myobacterium tuberculosis. It is believed this increased risk also occurs in the case of M. bovis infections in humans.