Surveillance of pneumococcal-associated disease among hospitalized children in Khanh Hoa Province, Vietnam

Retrospective database analysis for clinical diagnoses commonly associated with pneumococcal diseases in the Malaysian healthcare system over a 3-year period (2013-2015)

BACKGROUND

Pneumococcal disease caused by Streptococcus pneumoniae is an important cause of morbidity and mortality across all ages, particularly in younger children and older adults. Here, we describe pneumococcal disease hospitalizations at Ministry of Health (MoH) facilities in Malaysia between 2013 and 2015.

METHODS

This was a retrospective databases analysis. Tabular data from the Malaysian Health Data Warehouse (MyHDW) were used to identify microbiologically confirmed, pneumococcal disease hospitalizations and deaths during hospitalization, using hospital-assigned ICD-10 codes (i.e., classified as meningitis, pneumonia, or non-meningitis non-pneumonia). Case counts, mortality counts, and case fatality rates were reported by patient age group and by Malaysian geographic region.

RESULTS

A total of 683 pneumococcal disease hospitalizations were identified from the analysis: 53 pneumococcal meningitis hospitalizations (5 deaths and 48 discharges), 413 pneumococcal pneumonia hospitalizations (24 deaths and 389 discharges), and 205 non-meningitis non-pneumonia pneumococcal disease hospitalizations (58 deaths and 147 discharges). Most hospitalizations occurred in children aged < 2 years. Crude mortality was highest among children aged < 2 years (for all three disease categories), among adults aged ≥ 65 years (for pneumococcal pneumonia), or among adults aged 65-85 years (for non-meningitis non-pneumonia pneumococcal disease). The case fatality rate, all ages included, was 5.8% for pneumococcal pneumonia, 9.1% for pneumococcal meningitis, and 28.3% for non-meningitis non-pneumonia pneumococcal disease.

CONCLUSIONS

Our study is the first to document pneumococcal disease hospitalizations and deaths during hospitalization in Malaysia. Although this database analysis likely underestimated case counts, and the true disease burden could be even greater, the study demonstrates a substantial burden of pneumococcal disease. Public health measures, including vaccination, would significantly contribute to the prevention of hospitalizations and deaths associated with pneumococcal disease in Malaysia.

Epidemiology and Phylogenetic Analysis of Viral Respiratory Infections in Vietnam

Acute respiratory infections (ARIs) impose a major public health burden on fragile healthcare systems of developing Southeast Asian countries such as Vietnam. The epidemiology, genetic diversity and transmission patterns of respiratory viral pathogens that circulate in this region are not well characterized. We used RT-PCR to screen for 14 common respiratory viruses in nasal/throat samples from 4326 ARI patients from 5 sites in Vietnam during 2012-2016. 64% of patients tested positive for viruses; 14% tested positive multiple co-infecting viruses. The most frequently detected viruses were Respiratory syncytial virus (RSV, 23%), Human Rhinovirus (HRV, 13%), Influenza A virus (IAV, 11%) and Human Bocavirus (HBoV, 7%). RSV infections peaked in July to October, were relatively more common in children <1 year and in the northernmost hospital. IAV infections peaked in December to February and were relatively more common in patients >5 years in the central region. Coinfection with IAV or RSV was associated with increased disease severity compared with patients only infected with HBoV or HRV. Over a hundred genomes belonging to 13 families and 24 genera were obtained via metagenomic sequencing, including novel viruses and viruses less commonly associated with ARIs. Phylogenetic and phylogeographic analyses further indicated that neighboring countries were the most likely source of many virus lineages causing ARIs in Vietnam and estimated the period that specific lineages have been circulating. Our study illustrates the value of applying the state-of-the-art virus diagnostic methods (multiplex RT-PCR and metagenomic sequencing) and phylodynamic analyses at a national level to generate an integrated picture of viral ARI epidemiology.

Predicting the impact of pneumococcal conjugate vaccine programme options in Vietnam

Although catch-up campaigns (CCs) at the introduction of pneumococcal conjugate vaccines (PCVs) may accelerate their impact, supply constraints may limit their benefit if the need for additional PCV doses results in introduction delay. We studied the impact of PCV13 introduction with and without CC in Nha Trang, Vietnam – a country that has not yet introduced PCV – through a dynamic transmission model. We modelled the impact on carriage and invasive pneumococcal disease (IPD) of routine vaccination (RV) only and that of RV with CCs targeting <1y olds (CC1), <2y olds (CC2) and <5y olds (CC5). The model was fitted to nasopharyngeal carriage data, and post-PCV predictions were based on best estimates of parameters governing post-PCV dynamics. With RV only, elimination in carriage of vaccine-type (VT) serotypes is predicted to occur across all age groups within 10 years after introduction, with near-complete replacement by non-VT. Most of the benefit of CCs is predicted to occur within the first 3 years with the highest impact at one year, when IPD incidence is predicted to be 11% (95%CrI 9 – 14%) lower than RV with CC1, 25% (21 – 30 %) lower with CC2 and 38% (32 – 46%) lower with CC5. However, CCs would only prevent more cases of IPD insofar as such campaigns do not delay introduction by more than about 6, 12 and 18 months for CC1, CC2 and CC5. Those findings are important to help guide vaccine introduction in countries that have not yet introduced PCV, particularly in Asia.

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.

Cost-effectiveness of Haemophilus influenzae type b vaccine in Vietnam

BACKGROUND

With GAVI support, Vietnam introduced Haemophilus influenzae type b (Hib) vaccine in 2010 without evidence on cost-effectiveness. We aimed to analyze the cost-effectiveness of Hib vaccine from societal and governmental perspectives.

METHOD

We constructed a decision-tree cohort model to estimate the costs and effectiveness of Hib vaccine versus no Hib vaccine for the 2011 birth cohort. The disease burden was estimated from local epidemiologic data and literature. Vaccine delivery costs were calculated from governmental reports and 2013 vaccine prices. A prospective cost-of-illness study was conducted to estimate treatment costs. The human capital approach was employed to estimate productivity loss. The incremental costs of Hib vaccine were divided by cases, deaths, and disability-adjusted life years (DALY) averted. We used the WHO recommended cost-effectiveness thresholds of an intervention being highly cost-effective if incremental costs per DALY were below GDP per capita.

RESULT

From the societal perspective, incremental costs per discounted case, death and DALY averted were US$ 6252, US$ 26,476 and US$ 1231, respectively; the break-even vaccine price was US$ 0.69/dose. From the governmental perspective, the results were US$ 6954, US$ 29,449, and US$ 1373, respectively; the break-even vaccine price was US$ 0.48/dose. Vietnam's GDP per capita was US$ 1911 in 2013. In deterministic sensitivity analysis, morbidity and mortality parameters were among the most influential factors. In probabilistic sensitivity analysis, Hib vaccine had an 84% and 78% probability to be highly cost-effective from the societal and governmental perspectives, respectively.

CONCLUSION

Hib vaccine was highly cost-effective from both societal and governmental perspectives. However, with GAVI support ending in 2016, the government will face a six-fold increase in its vaccine budget at the 2013 vaccine price. The variability of vaccine market prices adds an element of uncertainty. Increased government commitment and improved resource allocation decision making will be necessary to retain Hib vaccine.

Population based cohort study for pediatric infectious diseases research in Vietnam

A population-based cohort study on pediatric infectious diseases was established at Khanh Hoa Province, central Vietnam in 2006, to determine the etiology and risk factors for severe pediatric infectious diseases (SPID) such as acute respiratory infection (ARI), diarrhea and dengue which are the major causes of under 5 mortality. A population census survey was conducted in Nha-Trang and Ninh-Hoa to collect demographic, social-behavioral data and disease burden on SPID. The study site covered a population of 353,525 residing in 75,826 households with 24,781 children less than 5 years. Hospital databases from two hospitals covering the region were obtained. Linking the census and hospital databases, we were able to investigate on a variety of SPID such as environmental tobacco smoking exposure and increased risked of pediatric pneumonia hospitalization, population density, water supply and risk of dengue fever and animal livestock and risk of hospitalized diarrhea. To determine incidence, viral etiology and risk factors for pediatric ARI/pneumonia, we setup a population based prospective hospitalized Pediatric ARI surveillance at Khanh Hoa General Hospital, Nha-Trang in February 2007. The study has revealed RSV, rhinovirus and influenza A as major viral pathogens, role of multiple viral infection and its interaction with bacteria in the development of pneumonia. In addition, we are also conducting a birth cohort study to investigate the incidence of congenital infection and its impact on physical-neurological development, and role of host genetic polymorphism on SPID hospitalization in Vietnam. Population mobility, high cost of regular census update and low mortality are the challenges.

Prospective surveillance study of invasive pneumococcal disease among urban children in the Philippines

BACKGROUND

Worldwide, invasive pneumococcal disease (IPD) causes considerable morbidity and mortality among children, but incidence data in Asia are lacking. This 2-year hospital-based, prospective, surveillance study was conducted at 3 study sites in urban areas of the Philippines to estimate IPD and pneumonia incidence in children and describe the serotype distribution of invasive Streptococcus pneumoniae isolates.

METHODS

Children aged 28 days to <60 months residing within the 3 surveillance areas presenting with possible IPD were enrolled. Initial diagnosis, history of pneumococcal vaccine receipt and previous antimicrobial treatment were recorded. Blood specimens were collected for S. pneumoniae identification and serotyping. Final diagnosis was determined for hospitalized subjects, subjects whose culture yielded S. pneumoniae and subjects with clinically suspected meningitis.

RESULTS

A total of 5940 subjects were enrolled, 47 IPD cases identified. IPD site rates were 33.49 per 100,000, 25.38 per 100,000 and 25.85 per 100,000. Chest radiograph-confirmed pneumonia incidence ranged from 633.74 to 1683.59 per 100,000. Highest chest radiograph-confirmed pneumonia incidence occurred in those 28 days to <6 months of age at 2 sites (2166.16 and 3891.94 per 100,000) and those 6-12 months of age at the third site (3847.52 per 100,000). Thirty-five S. pneumoniae isolates were serotyped; most commonly identified were serotypes 1, 2, 5, 6B, 14 and 18F. One serotype 14 isolate was erythromycin resistant. Previous antibiotic therapy was documented in 17-53% of subjects; 2 subjects had received pneumococcal vaccine. At 2 sites, one-third of IPD subjects died.

CONCLUSIONS

IPD is an important cause of morbidity and mortality among urban children in the Philippines. Our data support the expectation that widespread immunization would decrease IPD disease burden.

Incidence of radiologically-confirmed pneumonia and Haemophilus influenzae type b carriage before Haemophilus influenzae type b conjugate vaccine introduction in Central Vietnam

OBJECTIVES

To determine the incidence of radiologically-confirmed pneumonia (RCP) and Haemophilus influenzae type b (Hib) carriage in central Vietnam as a baseline data before Hib conjugate vaccine introduction.

STUDY DESIGN

In the context of ongoing population-based prospective, hospitalized acute respiratory infection surveillance study, a cross-sectional Hib carriage study was conducted among 1000 children < 5 years of age living in NhaTrang, Vietnam in June 2010, 1 month before the nationwide introduction of Hib conjugate vaccine in Vietnam.

RESULTS

The incidence of RCP hospitalizations among children < 5 years of age was 3.3 per 1000 children. The highest incidence was observed among children 12-23 month age group (8.3 per 1000). Haemophilus influenzae carriage was detected in 37% of the children and Hib carriage rate was 3%. Eighty-two percent of the Haemophilus influenzae had TEM β-lactamase resistance gene. The presence of 6 or more family members was associated with an increased rate of Hib carriage (P = .04).

CONCLUSIONS

Incidence of RCP and Hib carriage in this cross-sectional survey are lower compared with other studies. Continued surveillance for invasive Hib disease and sequential Hib carriage surveys are needed to support future assessments of the impact of Hib conjugate vaccine in Vietnam.

Global and regional burden of hospital admissions for severe acute lower respiratory infections in young children in 2010: a systematic analysis

BACKGROUND

The annual number of hospital admissions and in-hospital deaths due to severe acute lower respiratory infections (ALRI) in young children worldwide is unknown. We aimed to estimate the incidence of admissions and deaths for such infections in children younger than 5 years in 2010.

METHODS

We estimated the incidence of admissions for severe and very severe ALRI in children younger than 5 years, stratified by age and region, with data from a systematic review of studies published between Jan 1, 1990, and March 31, 2012, and from 28 unpublished population-based studies. We applied these incidence estimates to population estimates for 2010, to calculate the global and regional burden in children admitted with severe ALRI in that year. We estimated in-hospital mortality due to severe and very severe ALRI by combining incidence estimates with case fatality ratios from hospital-based studies.

FINDINGS

We identified 89 eligible studies and estimated that in 2010, 11·9 million (95% CI 10·3-13·9 million) episodes of severe and 3·0 million (2·1-4·2 million) episodes of very severe ALRI resulted in hospital admissions in young children worldwide. Incidence was higher in boys than in girls, the sex disparity being greatest in South Asian studies. On the basis of data from 37 hospital studies reporting case fatality ratios for severe ALRI, we estimated that roughly 265,000 (95% CI 160,000-450,000) in-hospital deaths took place in young children, with 99% of these deaths in developing countries. Therefore, the data suggest that although 62% of children with severe ALRI are treated in hospitals, 81% of deaths happen outside hospitals.

INTERPRETATION

Severe ALRI is a substantial burden on health services worldwide and a major cause of hospital referral and admission in young children. Improved hospital access and reduced inequities, such as those related to sex and rural status, could substantially decrease mortality related to such infection. Community-based management of severe disease could be an important complementary strategy to reduce pneumonia mortality and health inequities.

FUNDING

WHO.

Safety and reactogenicity of primary vaccination with the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine in Vietnamese infants: a randomised, controlled trial

BACKGROUND

Pneumococcal infections are major causes of child mortality and morbidity worldwide and antibiotic resistance of Streptococcus pneumoniae is a major concern, especially in Asian countries. The present study was designed to evaluate the reactogenicity and safety of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) when co-administered with the licensed diphtheria, tetanus, acellular pertussis, hepatitis B virus, inactivated poliovirus and H. influenzae type b vaccine (DTPa-HBV-IPV/Hib) in a 3-dose primary vaccination course in Vietnamese infants.

METHODS

This phase III, open, randomised study was conducted in one centre in Ho Chi Minh City between February and July 2011. Healthy infants (N=300) were randomised (2:1) to receive either PHiD-CV co-administered with DTPa-HBV-IPV/Hib (PHiD-CV group) or DTPa-HBV-IPV/Hib alone (Control group) at 2, 3, and 4 months of age.

RESULTS

Within 31 days post-vaccination, 8.2% of overall doses in the PHiD-CV group and 3.0% of overall doses in the Control group were followed by at least one solicited and/or unsolicited, local and/or general adverse event of grade 3 intensity. Pain at injection site was the most common grade 3 solicited symptom, which was reported following 6.5% and 1.0% of overall doses in the PHiD-CV and Control groups, respectively. Within 4 days post-vaccination, the most common solicited local and general symptoms reported with any intensity were pain (48.9% and 31.0% of doses in the PHiD-CV and Control groups) and irritability (58.0% and 40.4% of doses in the PHiD-CV and Control groups). Within 31 days post-vaccination, the incidence of unsolicited symptoms was comparable in both groups (following 12.3% and 14.8% of doses in the PHiD-CV and Control groups, respectively). Throughout the study, 13 serious adverse events (SAEs) were reported in 9 infants in the PHiD-CV group and 11 SAEs in 6 infants in the Control group. None of them were fatal or considered causally related to vaccination.

CONCLUSIONS

PHiD-CV had a clinically acceptable safety profile when co-administered with DTPa-HBV-IPV/Hib in Vietnamese infants. The reactogenicity of PHiD-CV was comparable to that observed in other South-East Asian populations.

An expanded age range for meningococcal meningitis: molecular diagnostic evidence from population-based surveillance in Asia

Background

To understand epidemiologic patterns of meningococcal disease in Asia, we performed a retrospective molecular analysis of cerebrospinal fluid (CSF) specimens collected in prospective surveillance among children aged < 5 years of age in China, South Korea, and Vietnam.

Methods

A total of 295 isolates and 2,302 CSFs were tested by a meningococcal species- and serogroup-specific polymerase chain reaction (PCR) assay targeting the Neisseria meningitidis (Nm) ctrA gene. Multi-locus sequence typing (MLST) was performed in Nm gene amplification analysis and incidence rates for meningococcal meningitis were estimated.

Results

Among 295 isolates tested, 10 specimens from Vietnam were confirmed as serogroup B and all were Sequence Type (ST) 1576 by MLST. Among the 2,032 CSF specimen tested, 284 (14%) were confirmed by PCR (ctrA gene), including 67 (23.6%) from China, 92 (32.4%) from Korea, and 125 (44.0%) from Vietnam. Neonates and infants aged < 6 months of age accounted for more than 50% of Nm-PCR positive CSF. Two CSF specimens from Vietnam were identified as serogroup B using MLST. In addition, 44 specimens underwent sequencing to confirm meningococcal serogroup; of these, 21 (48%) were serogroup C, 12 (27%) were serogroup X, 9 (20%) were serogroup Y and 2 (5%) were serogroup B. The incidence rates of meningococcal meningitis among children < 5 years of age was highest in Vietnam (7.4/100,000 [95% CI, 3.6—15.3] followed by Korea (6.8/100,000 [95% CI, 3.5-13.5] and China (2.1/100,000) [95% CI, 0.7-6.2]).

Conclusions

These results suggest that there is a previously undetected, yet substantial burden of meningococcal meningitis among infants and young children. Standardized, sensitive and specific molecular diagnostic assays with Nm serogrouping capacity are needed throughout Asia to understand the true burden of N. meningitidis disease.

A literature review and survey of childhood pneumonia etiology studies: 2000-2010

The Pneumonia Etiology Research for Child Health (PERCH) project is the largest multicountry etiology study of childhood pneumonia since the Board on Science and Technology in International Development studies of the 1980s. However, it is not the only recent or ongoing pneumonia etiology study, and even with seven sites, it cannot capture all epidemiologic settings in the developing world. Funding providers, researchers and policymakers rely on the best available evidence to strategically plan programs, new research directions and interventions. We aimed to describe the current landscape of recent pneumonia etiology studies in children under 5 years of age in the developed and developing world, as ascertained by a literature review of relevant studies with data since the year 2000 and a survey of researchers in the field of childhood pneumonia. We collected information on the study population, study design, case definitions, laboratory samples and methods and identified pathogens. A literature review identified 88 studies with child pneumonia etiology results. As of June 2010, our survey of researchers identified an additional 65 ongoing and recently completed child pneumonia etiology studies. This demonstrates the broad existing context into which the PERCH study must be placed. However, the landscape analysis also reveals a multiplicity of case definitions, levels of clinician involvement, facility types, specimen collection, and laboratory techniques. It reinforces the need for the standardization of methods and analyses for present and future pneumonia etiology studies in order to optimize their cumulative potential to accurately describe the microbial causes of childhood pneumonia.

Rapid assessment of Hib disease burden in Vietnam

Background

Several countries have applied the Haemophilus influenzae type b (Hib) rapid assessment tool (RAT) to estimate the burden of Hib disease where resources for hospital- or population-based surveillance are limited. In Vietnam, we used the Hib RAT to estimate the burden of Hib pneumonia and meningitis prior to Hib vaccine introduction.

Methods

Laboratory, hospitalization and mortality data were collected for the period January 2004 through December 2005 from five representative hospitals. Based on the WHO Hib RAT protocol, standardized MS Excel spreadsheets were completed to generate meningitis and pneumonia case and death figures.

Results

We found 35 to 77 Hib meningitis deaths and 441 to 957 Hib pneumonia deaths among children < 5 years of age annually in Vietnam. Overall, the incidence of Hib meningitis was estimated at 18/100,000 (95% confidence interval, CI, 15.1-21.6). The estimated Hib meningitis incidence in children < 5 years age was higher in Ho Chi Minh City (22.5/100,000 [95% CI, 18.4-27.5]) compared to Hanoi (9.8/100,000 [95% CI, 6.5-14.8]). The Hib RAT suggests that there are a total of 883 to 1,915 cases of Hib meningitis and 4,414 to 9,574 cases of Hib pneumonia per year in Vietnam.

Conclusions

In Hanoi, the estimated incidence of Hib meningitis for children < 5 years of age was similar to that described in previous population-based studies of Hib meningitis conducted from 1999 through 2002. Results from the Hib RAT suggest that there is a substantial, yet unmeasured, disease burden associated with Hib pneumonia in Vietnamese children.

Global prevailing and emerging pediatric pneumococcal serotypes

Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths among children younger than 5 years of age worldwide. The 7-valent pneumococcal conjugate vaccine (PCV7) is currently licensed in more than 90 countries and has contributed to significant declines in the incidence of invasive pneumococcal disease (IPD). Recent studies report an increased incidence of IPD caused by non-PCV7 vaccine serotypes (NVTs). Seroepidemiology of IPD caused by NVTs following the introduction of PCV7 is of interest, and this article provides a comprehensive global summary of the prevailing and emerging serotypes causing IPD in children. Currently, globally emerging or persistent NVTs include serotypes 1, 3, 5, 6A, 7F and 19A. Serotypes included in the recently licensed 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) account for pneumococcal disease burdens in most developed countries of 65-85% and 80-90%, respectively. The seroprevalence of NVTs after widespread use of PCV10 and PCV13 requires ongoing monitoring.

Association between nasopharyngeal load of Streptococcus pneumoniae, viral coinfection, and radiologically confirmed pneumonia in Vietnamese children

BACKGROUND

The interplay between nasopharyngeal bacterial carriage, viral coinfection, and lower respiratory tract infections (LRTIs) is poorly understood. We explored this association in Vietnamese children aged less than 5 years.

METHODS

A hospital-based case-control study of pediatric LRTIs was conducted in Nha Trang, Vietnam. A total of 550 hospitalized children (274 radiologically confirmed pneumonia [RCP] and 276 other LRTIs) were enrolled and 350 healthy controls were randomly selected from the community. Polymerase chain reaction-based methods were used to measure bacterial loads of Streptococcus pneumoniae (SP), Haemophilus influenzae, and Moraxella catarrhalis and to detect 13 respiratory viruses and bacterial serotypes in nasopharyngeal samples of study participants.

RESULTS

The median nasopharyngeal bacterial load of SP was substantially higher in children with RCP compared with healthy controls or children with other LRTIs (P < 0.001). SP load was 15-fold higher in pneumonia children with viral coinfection compared with those children without viral coinfection (1.4 x 10⁷/mL vs. 9.1 x 10⁵/mL; P 0.0001). SP load was over 200-fold higher in serotypeable SP compared with nontypeable SP (2.5 x 10⁶/mL vs. 1 x 10⁴/mL; P < 0.0001). These associations were independent of potential confounders in multiple regression models. No clear association was found between nasopharyngeal load of Haemophilus influenzae or Moraxella catarrhalis and viral coinfection in either RCP or other LRTIs groups.

CONCLUSIONS

An increased load of SP in the nasopharynx was associated with RCP, viral coinfection, and presence of pneumococcal capsule.

Enhanced determination of Streptococcus pneumoniae serotypes associated with invasive disease in Laos by using a real-time polymerase chain reaction serotyping assay with cerebrospinal fluid

A prospective hospital-based study was undertaken to define the incidence of invasive pneumococcal disease (IPD) and circulating serotypes in Laos. Of 10,799 patients with hemocultures and 353 patients with cerebrospinal fluid samples, 0.21% and 5.4%, respectively, were positive for Streptococcus pneumoniae, giving a total of 35 IPD patients. We developed a real-time polymerase chain reaction to detect serotypes represented in the 13-valent pneumococcal vaccine. A blinded evaluation comparing serotype as defined by the Quellung reaction versus the polymerase chain reaction demonstrated 100% concordance. The most frequent serotype (n = 33 patients) was 1 (n = 6), followed by serotypes 5, 6A/B/C, 14, and 23F. Serotypes represented in the 7-valent polysaccharide-protein conjugate vaccine (PCV-7) infected 39% of patients, with 73% coverage for the PCV-10 and PCV-13 vaccines. Although the sample size is small, these data suggest that the PCV-7 vaccine may have relatively low efficacy in Laos. Further studies are urgently needed to guide pneumococcal vaccine policy in Laos.

Invasive pneumococcal disease in Fiji: clinical syndromes, epidemiology, and the potential impact of pneumococcal conjugate vaccine

Invasive pneumococcal disease (IPD) epidemiology and the potential impact of the pneumococcal conjugate vaccine in Fiji are documented. The annual incidence was 26.5 and 10.9 in those aged <5 and > or =55 years per 100,000, respectively. The case fatality rate was 9.4% and 67% in <5 and >65 year olds, respectively. One pneumococcal death and case would be prevented in <5 years olds for every 1930 and 128 infants vaccinated with 7vPCV, respectively.

Summary of invasive pneumococcal disease burden among children in the Asia-Pacific region

Invasive pneumococcal disease (IPD) burden is significant in the Asia-Pacific region. This review describes the epidemiology and Streptococcus pneumoniae (SP) serotype distribution of IPD in children in the Asia-Pacific region from studies published from 1999 to 2010. IPD incidence varies widely in Asia-Pacific countries depending on the method of surveillance, the population studied, and the time period. Incidences are highest for younger children, with rates near 100-200 cases per 100,000 children aged <1 or 2 years. Incidences of preventable disease are estimated to be 6-200 cases per 100,000. Heptavalent pneumococcal conjugate vaccine (PCV7) serotype coverage shows a very wide range over the Asia-Pacific region. Ten countries have high vaccine serotype coverage (>70%), and six countries have low vaccine serotype coverage (<50%). The majority of SP serotypes in children with IPD in most countries in the Asia-Pacific region are susceptible to penicillin (intermediate and resistant <50%); a few countries have SP serotypes with high level resistance to penicillin (intermediate and resistant >50%). Japan, Taiwan, and Thailand have high PCV7 serotype coverage. Countries with low pneumococcal resistance to antimicrobials have shown increasingly higher nonsusceptibility with time. National vaccination programmes that include PCV7, 10-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV would significantly affect IPD burden in children aged <5 years in the Asia-Pacific region, as well as the burden of penicillin-nonsusceptible IPD.

A systematic review and critical evaluation of invasive Haemophilus influenzae type B disease burden studies in Asia from the last decade: lessons learned for invasive bacterial disease surveillance

In Asia, questions regarding the burden of Haemophilus influenzae type b (Hib) disease have delayed decision-making on introduction of Hib vaccine. However, over the past decade many studies have been published regarding Hib disease burden in Asia. We conducted a systematic literature review of all reports of Hib disease burden in Asia between 1998 and 2009, and critically reviewed their methods and data quality. We identified 94 studies from 28 countries in Asia presenting data on Hib disease burden. Of the 94 studies reviewed, 49 (52%) used a case definition consistent with World Health Organization standards, and 47 (50%) described laboratory methodology used. Twenty-seven surveillance studies presented data on incidence of Hib disease, with 8 (30%) accounting for missed cases, 6 (15%) accounting for cases with missed diagnostic tests, and 2 (7%) that considered prior antibiotic use. Of the 21 studies that provided incidence data for Hib meningitis, 10 (48%) used active, prospective, population-based surveillance, and found unadjusted incidence rates of Hib meningitis ranging from a low of 0.98 per 100,000 child-years in children aged less than 5 years in China to a high of 28 per 100,000 child-years in children less than 5 years in Mongolia. Of 49 studies that reported the etiology of bacterial meningitis, 30 (60%) identified Hib as the most common cause. This review highlights the importance of using rigorous methodologies, including standardized surveillance methods and appropriate laboratory diagnostic tests, when conducting studies measuring the burden of invasive bacterial diseases including those caused by Hib. When poorly conducted, studies can underestimate disease burden and lead to inappropriate decisions about vaccine introduction.

PCR using blood for diagnosis of invasive pneumococcal disease: systematic review and meta-analysis

The use of molecular-based methods for the diagnosis of bacterial infections in blood is appealing, but they have not yet passed the threshold for clinical practice. A systematic review of prospective and case-control studies assessing the diagnostic utility of PCR directly with blood samples for the diagnosis of invasive pneumococcal disease (IPD) was performed. A broad search was conducted to identify published and unpublished studies. Two reviewers independently extracted the data. Summary estimates for sensitivity and specificity with 95% confidence intervals (CIs) were calculated by using the hierarchical summary receiver operating characteristic method. The effects of sample processing, PCR type, the gene-specific primer, study design, the participants' age, and the source of infection on the diagnostic odds ratios were assessed through meta-regression. Twenty-nine studies published between 1993 and 2009 were included. By using pneumococcal bacteremia for case definition and healthy people or patients with bacteremia caused by other bacteria as controls (22 studies), the summary estimates for sensitivity and specificity were 57.1% (95% CI, 45.7 to 67.8%) and 98.6% (95% CI, 96.4 to 99.5%), respectively. When the controls were patients suspected of having IPD without pneumococcal bacteremia (26 studies), the respective values were 66.4% (95% CI, 55.9 to 75.6%) and 87.8% (95% CI, 79.5 to 93.1%). With lower degrees of proof for IPD (any culture or serology result and the clinical impression), the sensitivity of PCR decreased and the specificity increased. All analyses were highly heterogeneous. The use of nested PCR and being a child were associated with low specificity, while the use of a cohort study design was associated with a low sensitivity. The lack of an appropriate reference standard might have caused underestimation of the performance of the PCR. Currently available methods for PCR with blood samples for the diagnosis of IPD lack the sensitivity and specificity necessary for clinical practice.