Modelling the unidentified mortality burden from thirteen infectious pathogenic microorganisms in infants.

Official statistics routinely underestimate mortality from specific microorganisms and deaths are assigned to non-specific syndromes. Here we estimate mortality attributed to specific pathogens by modelling non-specific infant deaths from laboratory reports and codes on death certificates for these pathogens, 1993-2000 in England and Wales using a generalized linear model. In total, 22.4-59.8% of non-specific deaths in infants (25-66 deaths a year) are attributable to specific pathogens. Yearly deaths from Bordetella pertussis in neonates are 6.8 [95% confidence interval (CI) 1.5-11.9]. In post-neonates 9.4 (95% CI 2.3-16.6) deaths a year are attributable to Neisseria meningitidis, 7.3 (95% CI 2.4-12.3) to Streptococcus pneumoniae, from 2.8 (95% CI 0.8-4.9) to 15.1 (95% CI 9.4-20.9) to respiratory syncytial virus (RSV) and 3 (95% CI 0.3-5.9) to parainfluenza type 2. Our results suggest there is substantial hidden mortality for a number of pathogens in infants. A considerable proportion of deaths classified to infectious syndromes are non-infectious, suggesting low specificity of death certification. Laboratory reports were the more reliable source, reinforcing the asset of strong surveillance systems.