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Atypical mycobacteria in extrapulmonary disease among children. Incidence in Sweden from 1969 to 1990, related to
V Romanus1, H O Hallander, P Wåhlén
1Swedish Institute for Infectious Disease Control, Stockholm, Sweden.
Insights
BCG vaccination may protect children against atypical mycobacterial infections. Studies show a lower incidence in vaccinated versus unvaccinated children, suggesting a protective role.
Area of Science:
- Pediatric infectious diseases
- Mycobacterial infections
- Vaccinology
Background:
- Sweden transitioned from general newborn BCG vaccination to selective vaccination for high-risk groups in 1975.
- Atypical mycobacterial diseases pose a health concern in children.
Purpose of the Study:
- To investigate the relationship between BCG vaccination and the incidence of atypical mycobacterial disease in children.
- To assess the protective effect of BCG vaccination against extrapulmonary atypical mycobacterial infections.
Main Methods:
- A nationwide survey in Sweden (1969-1990) identified 390 children under 15 with bacteriologically confirmed atypical mycobacteria.
- Incidence rates were analyzed based on BCG vaccination status and age cohorts.
Main Results:
- The incidence of atypical mycobacterial disease in children under 5 increased significantly after 1975.
- Children vaccinated with BCG had a substantially lower cumulative incidence rate (4.6/100,000) compared to unvaccinated children (26.8/100,000) before age 5.
- Mycobacterium avium-intracellulare was the most common pathogen (83%); most cases involved localized lesions, with a few fatal disseminated infections.
Conclusions:
- BCG vaccination appears to offer protection against localized atypical mycobacterial diseases in children.
- The findings support a role for BCG in preventing certain mycobacterial infections beyond tuberculosis.
Setting:
In April 1975, the general BCG vaccination of newborns in Sweden was replaced by selective vaccination of groups at increased risk of tuberculosis.
Objective:
To relate the incidence of atypical mycobacterial disease in children to BCG vaccination.
Design:
A nationwide survey in Sweden during the period 1969-90 disclosed 390 children under 15 years of age with bacteriologically confirmed atypical mycobacteria from extrapulmonary lesions.
Results:
The average, annual incidence of atypical mycobacterial disease per 100,000 children under 5 years of age increased from 0.06 during the period 1969-74 to a maximum level of 5.7 during 1981-85. Among the cohorts born in Sweden in the period 1975-85, the cumulative incidence rate before 5 years of age was estimated at 26.8 per 100,000 non-BCG-vaccinated children and at 4.6 among those BCG-vaccinated, ratio 5.9 (95% confidence limits 1.6, 48.5). Mycobacterium avium-intracellulare was found in 83%. Disseminated, fatal disease developed in 3 children. The remaining ones suffered from local infections, most often lymph-node or soft-tissue lesions. The observed incidence of bacteriologically confirmed diagnosis was estimated to represent approximately 40% of the 'true' number, if patients with diagnosis based on histological, clinical and epidemiological findings only were included.
Conclusion:
The present study indicates that BCG vaccination plays a role in protection against localized disease caused by atypical mycobacteria in children.