The burden of respiratory syncytial virus in adults: a systematic review and meta-analysis.

Respiratory syncytial virus (RSV) is the most common pathogen associated with acute lower respiratory tract infections in young children. RSV is also a major viral pathogen causing severe lung disease in the adult population, particularly among the elderly. We conducted a review of adult RSV studies published from January 1970 to February 2017 to determine the burden of disease among adults worldwide. There were no restrictions on health care setting or definition of RSV infection. A total of 1530 published studies were identified, 95 of which were included in this review. The incidence rates of hospitalised RSV acute respiratory tract infection (ARI) in adults >65 years old ranged from 7.3 to 13.0/105 population in Africa and Asia and from 190 to 254/105 population in the USA. Higher incidence rates (195-1790/105 population) were observed in adults ≥50 years old for outpatient or emergency visits in the USA. Of all ARI patients, RSV accounted for 1-10% in adults and 2-14% in patients with chronic diseases or transplantation. Given the limitations in the existing data, significant efforts should be made to generate evidence on the burden of RSV infections in adults and to estimate the potential impact of future preventive interventions.

Evaluation of chest radiography, lytA real-time PCR, and other routine tests for diagnosis of community-acquired pneumonia and estimation of possible attributable fraction of pneumococcus in northern Togo.

Streptococcus pneumoniae (Spn) is a leading cause of community-acquired pneumonia (CAP), yet existing diagnostic tools remain inadequate. We aimed to evaluate laboratory and radiological methods for detecting pneumococcal aetiology in CAP patients and to estimate Spn prevalence in this group. All-aged patients hospitalized with clinically defined CAP in northern Togo were enrolled during 2010-2013. Latent class analysis pooled results of semi-automated blood culture (SABC), whole blood lytA real-time polymerase chain reaction (rt-PCR), serum C-reactive protein (CRP), and chest radiography (CXR) and categorized patients as likely pneumococcal or non-pneumococcal CAP. We enrolled 1684 patients; 1501 had results for all tests. CXR, SABC, lytA rt-PCR and CRP >71·2 mg/l had sensitivities of 94% [95% confidence interval (CI) 87-100], 13% (95% CI 10-16), 17% (95% CI 14-21) and 78% (95% CI 75-80), and specificities of 88% (95% CI 84-93), 100% (95% CI 99-100), 97% (95% CI 96-99) and 77% (95% CI 75-79), respectively. Pneumococcal attributable proportion was 34% (95% CI 32-37), increasing with age and in men. We estimated that Spn caused one third of CAP. Whole blood lytA rt-PCR was more sensitive than SABC; both had low sensitivity and high specificity. Conversely CXR was highly sensitive and reasonably specific; it could be a useful tool for epidemiological studies aiming to define Spn pneumonia incidence across all ages.

Streptococcus pneumoniae serotype 1 burden in the African meningitis belt: exploration of functionality in specific antibodies.

Streptococcus pneumoniae serotype 1 (Sp1) constitutes an important cause of seasonal endemic meningitis in all age groups in the African meningitis belt. Despite a higher meningitis incidence, the Burkinabé population has an Sp1-specific antibody seroprevalence similar to that reported in the United Kingdom (UK). We aimed to establish whether the opsonophagocytic activity (OPA) of pneumococcal IgG naturally present in Burkina Faso differs from that seen in individuals in the UK and to compare the OPAs generated by natural and vaccine-induced immunity. Samples collected from pneumococcal vaccine-naive Burkinabé and UK subjects were matched for age (1 to 39 years) and anti-Sp1 IgG level, analyzed for OPA to 3 S. pneumoniae serotypes (1, 5, and 19A), and compared to postvaccine samples. Furthermore, the Burkinabé samples were assessed for IgG avidity and serotype-specific IgM concentrations. One hundred sixty-nine matched serum samples from both populations were selected. A greater proportion of Burkinabé subjects aged 1 to 19 years had functional Sp1 activity (OPA ≥ 8) compared to UK subjects (12% versus 2%, P < 0.001); however, the proportions were similar among adults (9%). The correlation between Sp1 IgG concentration and OPA was good (P < 0.001), but many individuals had nonfunctional IgG, which was not related to avidity. While the Sp1 IgM concentrations correlated with OPA, not all of the function in serum samples with low IgG could be attributed to IgM. Finally, vaccine-induced Sp1-specific IgG was more functional than equivalent amounts of naturally occurring IgG. In conclusion, despite a substantially higher pneumococcal meningitis incidence, no decreased functional immunity to Sp1 could be evidenced in the Burkinabé population compared to that in the population from the UK. Furthermore, the naturally induced antibodies were less functional than vaccine-induced antibodies.

Use of serology and urine antigen detection to estimate the proportion of adult community-acquired pneumonia attributable to Streptococcus pneumoniae.

Streptococcus pneumoniae is a common cause of community-acquired pneumonia (CAP) but existing diagnostic tools have limited sensitivity and specificity. We enrolled adults undergoing chest radiography at three Indian Health Service clinics in the Southwestern United States and collected acute and convalescent serum for measurement of PsaA and PspA titres and urine for pneumococcal antigen detection. Blood and sputum cultures were obtained at the discretion of treating physicians. We compared findings in clinical and radiographic CAP patients to those in controls without CAP. Urine antigen testing showed the largest differential between CAP patients and controls (clinical CAP 13%, radiographic CAP 17%, control groups 2%). Serological results were mixed, with significant differences between CAP patients and controls for some, but not all changes in titre. Based on urine antigen and blood culture results, we estimated that 11% of clinical and 15% of radiographic CAP cases were due to pneumococcus in this population.

Measuring the incidence of adult community-acquired pneumonia in a Native American community.

Few population-based studies have investigated the epidemiology of adult community-acquired pneumonia (CAP). We aimed to determine the incidence of CAP in a population at high-risk for pneumococcal disease and to evaluate a standardized method for interpreting chest radiographs adapted from the World Health Organization paediatric chest radiograph interpretation guidelines. We reviewed radiology records at the two healthcare facilities serving the White Mountain Apache tribe to identify possible pneumonia cases > or =40 years of age. We categorized patients with clinical criteria and a physician diagnosis of pneumonia as clinical CAP and those with clinical criteria and an acute infiltrate as radiographic CAP. We identified 100 (27/1000 person-years) and 60 (16/1000 person-years) episodes of clinical and radiographic CAP, respectively. The incidence of CAP increased with age. Both radiographic and clinical CAP were serious illnesses with more than half of patients hospitalized. Our case definitions and methods may be useful for comparing data across studies and conducting vaccine trials.

Invasive pneumococcal disease in Kanti Children's Hospital, Nepal, as observed by the South Asian Pneumococcal Alliance network.

BACKGROUND: Pneumonia accounts for approximately 2 million deaths annually among children aged <5 years, with most of these deaths occurring in Africa and southern Asia. The South Asian Pneumococcal Alliance (SAPNA) network in Nepal is generating local epidemiological data to assist in the development of national and regional policies for prevention of pneumococcal and Haemophilus influenzae (Hib) disease. METHODS: Children aged 2 months to 5 years with suspected invasive bacterial disease were recruited from Kanti Children Hospital, Kathmandu, Nepal. Specimens of blood, CSF, and normally sterile body fluids were cultured, and analysis of antimicrobial susceptibility patterns and serotyping of Streptococcus pneumoniae isolates were performed. CSF specimens were also tested for S. pneumoniae and Hib antigens by a latex agglutination test and an immunochromatographic test of pneumococcal antigen (NOW S. pneumoniae Antigen Test; Binax). RESULTS: A total of 2528 children with suspected invasive bacterial disease were recruited, of whom 82% had pneumonia, 9.6% had meningitis, 2% had very severe disease, and 0.4% had bacteremia; the remainder received another diagnosis. Before hospitalization, 26.7% had received antibiotic treatment. Fifty children had S. pneumoniae identified as the etiological agent of invasive disease. Of 2461 blood cultures performed, 22 were positive for S. pneumoniae. Of 33 cases of S. pneumoniae meningitis, 11 were detected by CSF culture, and 21 were detected by latex agglutination and pneumococcal antigen tests. The rate of detection of S. pneumoniae in CSF was 3.6% by culture, compared with 7.8% by latex agglutination and 10% by pneumococcal antigen testing. The rate of detection of H. influenzae in CSF was 1.7% by culture and 6.5% by latex agglutination. The most common serotypes found were 1, 5, 2, and 7F, followed by 12A, 19B, and 23F. Of all the invasive isolates, 3.8% were resistant to penicillin, and 68% were resistant to trimethoprim-sulfamethoxazole. CONCLUSIONS: The SAPNA network has identified Hib and pneumococci as causes of significant disease in Nepal.