A Few Pathogens Account for Most Severe Pneumonias in African, Asian Kids

By Reuters Staff

July 05, 2019

NEW YORK (Reuters Health) - A short list of pathogens accounts for most cases of pneumonia requiring hospital admission in children without HIV infection from Africa and Asia, according to results from the PERCH study.

Pneumonia is the greatest cause of death globally in children younger than 5 years. Several pneumonia-specific interventions (empirical antibiotic treatment, effective vaccines against the leading pneumonia pathogens, and other aspects of case management) have reduced pneumonia deaths in recent decades, but further reductions could occur with the development of vaccines against the remaining common pathogens.

Dr. Katherine L. O'Brien from Johns Hopkins Bloomberg School of Public Health, in Baltimore, Maryland, and colleagues in the Pneumonia Etiology Research for Child Health (PERCH) study group assessed the causes of severe or very severe pneumonia among 3,981 children without HIV aged 1-59 months and hospitalized for pneumonia at one of nine study locations in seven countries in Africa and Asia.

Pneumonia was most commonly due to viral pathogens (61.4%), with respiratory syncytial virus (RSV) causing the greatest number of cases (31.3%). Bacterial pathogens other than Mycobacteria tuberculosis accounted for 27.3% of cases.

Other pathogens accounting for 5% or more of the etiological distribution included human rhinovirus, human metapneumovirus (HMPV) A or B, human parainfluenza virus (types 1-4 combined), S. pneumoniae, M. tuberculosis, and H. influenzae, the team reports in The Lancet, online June 27.

About one in seven pneumonia cases (14.0%) were attributable to pathogens targeted by currently licensed vaccines.

The top 10 most common pathogens at each site accounted for between 79.0% and 90.0% of the etiological fraction, while 10 "focus" pathogens (H. influenzae, M. tuberculosis, S. aureus, S. pneumoniae, HMPV, influenza, parainfluenza, rhinovirus, RSV, and P. jirovecii) accounted for 55.1% to 86.6% of the etiological fraction across sites, with heterogeneity in the site-specific rank order of each pathogen.

"Future pneumonia research needs to address the conundrum of multiple pathogens and the sequence of their role in pneumonia pathogenesis," the researchers conclude. "The findings from the PERCH study should prompt additional investments in pneumonia prevention, testing, triage, and treatment and should encourage the use of innovative design and analyses in etiology studies, especially those that can further assess pneumonia as a multipathogen disease."

"The PERCH study emphasizes that, after conjugate vaccines, the job of addressing acute lower respiratory infections is far from over," the author of a linked editorial writes.

"This job will require concerted global efforts to produce an effective vaccine against RSV (the cause of more than 30% of acute lower respiratory infections in all countries), a greater focus on public health strategies to prevent and mitigate the severity of acute lower respiratory infections, and improved case-management strategies," adds Dr. Trevor Duke of the University of Melbourne, in Australia, and the University of Papua New Guinea, in Port Moresby.

"Exclusive breastfeeding, better nutrition in the first 2 years of life, protection from indoor air pollution and smoke exposure, healthy housing, care seeking, and improving the quality of primary care and referral case management - including oxygen therapy, identifying and treating comorbidities, monitoring, and supportive care - need more emphasis as part of a strategy for the multiple different causes of acute lower respiratory infections in the conjugate vaccine era," he concludes.

Dr. O'Brien did not respond to a request for comments.

SOURCE: https://bit.ly/2Xl8pQa and https://bit.ly/2JiqkCh

Lancet 2019.