Breathing New Life into Pneumonia Diagnostics

Abstract

The date 2 November 2009 marked the first World Pneumonia Day, launched by a coalition of child health organizations to support global efforts to prioritize pneumonia treatment and prevention. Despite recent medical advances, pneumonia takes the lives of up to 2 million children under age 5 each year—more than AIDS, malaria, and measles combined (15). As with many other illnesses, the disease burden is greatest among the world's most vulnerable population: children living in developing nations. For every child who dies of pneumonia in a developed country, more than 2,000 die in developing countries (16). With safe and effective vaccines against Haemophilus influenzae type b (Hib), Streptococcus pneumoniae, and measles virus and with improvements in environment and nutrition and in case management standards, we now have several strategies to both prevent and treat pneumonia. The challenge is to ensure universal access to these life-saving interventions. Laboratory diagnostics and clinical microbiologists should play an important part in global efforts to prevent and treat pneumonia. Diagnostic testing has an essential role in ensuring the most appropriate and effective therapy for individual patients. It also plays a role in disease surveillance in defining the etiologic spectrum of pneumonia cases and deaths. This in turn forms the evidence base for strategic decisions by global decision makers (such as the World Health Organization, UNICEF, and the GAVI Alliance), vaccine manufacturers, and funders to develop and support treatment algorithms, vaccine products and programs, and other effective prevention strategies. World Pneumonia Day also reminds us that much work remains to be done in pneumonia diagnostics and that historically, even with the best of methods, we have been unable to define the microbial etiology of a significant proportion of pneumonia episodes, particularly in children. The conditions under which pneumonia mortality is greatest are also the conditions under which adequate diagnosis is least possible. Even in settings with access to state-of-the-art microbiological diagnosis, establishing the etiology of a pneumonia case is fundamentally vexed by the limited ability to obtain specimens from the site of infection without contamination by upper respiratory secretions. Lack of sensitive laboratory diagnostic tools has probably played a direct role in the delayed introduction of effective vaccines to prevent pneumonia. Vaccines against Hib and S. pneumoniae alone may prevent >50% of severe childhood pneumonia, but poor diagnostics contribute to substantial underdiagnosis, and thus, substantial efforts need to be put into place to build awareness about the potential impact of these interventions. In spite of these limitations, significant advances have been made in diagnostic technology. However, technology alone is not a panacea for pneumonia diagnostic needs: assessment of performance within clinical and epidemiologic contexts is essential.