Pathogen-specific burdens of community diarrhoea in developing countries: a multisite birth cohort study (MAL-ED)

Impact of co-infections with enteric pathogens on children suffering from acute diarrhea in southwest China

Background

Acute diarrhea is a global health problem, resulting in high morbidity and mortality in children. It has been suggested that enteric pathogen co-infections play an important role in gastroenteritis, but most research efforts have only focused on a small range of species belonging to a few pathogen groups. This study aimed to assess the impact of co-infections with a broad range of enteric pathogens on children aged below five years who suffer from acute diarrhea in southwest China.

Method

A total of 1020 subjects (850 diarrhea cases and 170 healthy controls) were selected from four sentinel hospitals in Kunming, Yunnan province, southwest China, from June 2014 to July 2015. Stool specimens were collected to detect five virus (rotavirus group A, RVA; norovirus, NoV; Sapovirus, SaV; astrovirus, As; and adenovirus, Ad), seven bacterial (diarrheagenic Escherichia coli, DEC; non-typhoidal Salmonella, NTS; Shigella spp.; Vibrio cholera; Vibrio parahaemolyticus; Aeromonas spp.; and Plesiomonas spp.), and three protozoan (Cryptosporidium spp., Giardia lamblia, and Blastocystis hominis, B. hominis) species using standard microbiologic and molecular methods. Data were analyzed using the partial least square regression technique and chi-square test.

Results

At least one enteric pathogen was detected in 46.7 % (n = 397) of acute gastroenteritis cases and 13.5 % (n = 23) of healthy controls (χ² = 64.4, P < 0.05). Single infection with RVA was associated with acute diarrhea (26.5 % vs. 5.8 %, P < 0.05). The prevalence of a single infection with B. hominis in diarrhea cases was higher than in healthy controls (3.1 % vs. 0.5 %, OR = 4.7, 95 % CI: 1.01–112.0). Single infection with NoV GII was not associated with diarrhea (4.4 % vs. 3.5 %, OR = 1.2, 95 % CI: 0.5–3.3). Single infections with bacterial species were not observed. The prevalence of co-infections with two enteric pathogens in diarrhea cases was higher than in asymptomatic children (20.1 % vs. 5.3 %, P < 0.05). RVA-NoV GII was the most common co-infection in symptomatic children (4.4 %), with it aggravating the severity of diarrhea.

Conclusions

Although it is clear that RVA has an overwhelming impact on diarrhea illnesses in children, co-infection with other enteric pathogens appears to also aggravate diarrhea severity. These findings should serve as evidence for public health services when planning and developing intervention programs.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-016-0157-2) contains supplementary material, which is available to authorized users.

A Prospective Longitudinal Cohort to Investigate the Effects of Early Life Giardiasis on Growth and All Cause Diarrhea

BACKGROUND

Growth stunting in children under 2 years of age in low-income countries is common. Giardia is a ubiquitous pathogen in this age group but studies investigating Giardia's effect on both growth and diarrhea have produced conflicting results.

METHODS

We conducted a prospective longitudinal birth cohort study in Dhaka, Bangladesh, with monthly Giardia and continuous diarrheal surveillance.

RESULTS

629 children were enrolled within the first 72 hours of life, and 445 completed 2 years of the study. 12% of children were stunted at birth with 57% stunted by 2 years. 7% of children had a Giardia positive surveillance stool in the first 6 months of life, whereas 74% had a positive stool by 2 years. The median time to first Giardia positive surveillance stool was 17 months. Presence of Giardia in a monthly surveillance stool within the first 6 months of life decreased length-for-age Z score at 2 years by 0.4 (95% confidence interval, -.80 to -.001; P value .05) whereas total number of Giardia positive months over the 2-year period of observation did not. Neither variable was associated with weight-for-age Z score at 2 years. In our model to examine predictors of diarrhea only exclusive breastfeeding was significantly associated with decreased diarrhea (P value <.001). Concomitant giardiasis was neither a risk factor nor protective.

CONCLUSIONS

Early life Giardia was a risk factor for stunting at age 2 but not poor weight gain. Presence of Giardia neither increased nor decreased odds of acute all cause diarrhea.

Near real-time space-time cluster analysis for detection of enteric disease outbreaks in a community setting

OBJECTIVES

To enhance timely surveillance of bacterial enteric pathogens, space-time cluster analysis was introduced in Israel in May 2013.

METHODS

Stool isolation data of Salmonella, Shigella, and Campylobacter from patients of a large Health Maintenance Organization were analyzed weekly by ArcGIS and SaTScan, and cluster results were sent promptly to local departments of health (LDOHs).

RESULTS

During eighteen months, we identified 52 Shigella sonnei clusters, two Salmonella clusters, and no Campylobacter clusters. S. sonnei clusters lasted from one to 33 days and included three to 30 individuals. Thirty-one (60%) of the S. sonnei clusters were known to LDOHs prior to cluster analysis. Clusters not previously known by the LDOHs prompted epidemiologic investigations. In 31 of the 37 (84%) confirmed clusters, educational institutes (nursery schools, kindergartens, and a primary school) were involved.

CONCLUSIONS

Cluster analysis demonstrated capability to complement enteric disease surveillance. Scaling up the system can further enhance timely detection and control of outbreaks.

Characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age: a hospital-based cross-sectional study

Background

Acute diarrhea is a leading cause of morbidity and mortality in children, particularly in those under the age of 5 years. Rotavirus is recognized as the leading cause of acute diarrhea in children, however, the contribution of bacterial pathogens as causative agents varies throughout the world. Here we report a hospital-based prospective study to analyze the characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age.

Methods

Stool samples were collected from 508 patients with acute diarrhea under 5 years of age who presented at our hospital. Nine pathogens were isolated and identified by culturing, serology or PCR, these included Salmonella spp., Shigella spp., Vibrio cholerae, diarrheagenic Escherichia coli (DEC), Aeromonas spp., Plesiomonas spp., Vibrio parahaemolyticus, Campylobacter spp. and Yersinia enterocolitica. Antimicrobial sensitivity tests of these pathogens were conducted. The most commonly detected pathogen, Salmonella spp., was further investigated by PCR and sequencing of antibiotic resistance-related genes.

Results

Pathogens were identified in 20.1 % of the 508 samples. The most commonly detected pathogens were Salmonella spp. (8.5 %), followed by DEC (4.7 %), Campylobacter jejuni (3.0 %) and Aeromonas spp. (2.0 %). The resistance rates to ampicillin and tetracycline in Salmonella spp. were >60 %, but were <30 % to cephalosporins and quinolones. More than 50 % of DEC strains displayed resistance to ampicillin, cefotaxime and tetracycline, and 60 % of C. jejuni strains were resistant to ciprofloxacin but highly sensitive to the other antibiotics. Among 12 cephalosporin-resistant Salmonella isolates, TEM-1 and CTX-M-14 determinants were present in two (16.7 %) isolates. PCR screening for plasmid-mediated quinolone resistance genes revealed gyrA mutations in one of three highly quinolone resistant isolates.

Conclusions

Salmonella spp., DEC, Campylobacter spp. and Aeromonas spp. were the most commonly detected bacterial pathogens in children under the age of 5 years with acute diarrhea. Our findings indicate that ampicillin and tetracycline are not suitable as first line therapeutic drugs against Salmonella spp. Resistance to third generation cephalosporins and quinolones was also detected. TEM-1 and CTX-M-14 genetic determinants, and gyrA mutations, were the major mechanisms associated with high levels of cephalosporin and quinolone resistance, respectively, in Salmonella isolates.

The Burden of Cryptosporidium Diarrheal Disease among Children < 24 Months of Age in Moderate/High Mortality Regions of Sub-Saharan Africa and South Asia, Utilizing Data from the Global Enteric Multicenter Study (GEMS)

Background

The importance of Cryptosporidium as a pediatric enteropathogen in developing countries is recognized.

Methods

Data from the Global Enteric Multicenter Study (GEMS), a 3-year, 7-site, case-control study of moderate-to-severe diarrhea (MSD) and GEMS-1A (1-year study of MSD and less-severe diarrhea [LSD]) were analyzed. Stools from 12,110 MSD and 3,174 LSD cases among children aged <60 months and from 21,527 randomly-selected controls matched by age, sex and community were immunoassay-tested for Cryptosporidium. Species of a subset of Cryptosporidium-positive specimens were identified by PCR; GP60 sequencing identified anthroponotic C. parvum. Combined annual Cryptosporidium-attributable diarrhea incidences among children aged <24 months for African and Asian GEMS sites were extrapolated to sub-Saharan Africa and South Asian regions to estimate region-wide MSD and LSD burdens. Attributable and excess mortality due to Cryptosporidium diarrhea were estimated.

Findings

Cryptosporidium was significantly associated with MSD and LSD below age 24 months. Among Cryptosporidium-positive MSD cases, C. hominis was detected in 77.8% (95% CI, 73.0%-81.9%) and C. parvum in 9.9% (95% CI, 7.1%-13.6%); 92% of C. parvum tested were anthroponotic genotypes. Annual Cryptosporidium-attributable MSD incidence was 3.48 (95% CI, 2.27–4.67) and 3.18 (95% CI, 1.85–4.52) per 100 child-years in African and Asian infants, respectively, and 1.41 (95% CI, 0.73–2.08) and 1.36 (95% CI, 0.66–2.05) per 100 child-years in toddlers. Corresponding Cryptosporidium-attributable LSD incidences per 100 child-years were 2.52 (95% CI, 0.33–5.01) and 4.88 (95% CI, 0.82–8.92) in infants and 4.04 (95% CI, 0.56–7.51) and 4.71 (95% CI, 0.24–9.18) in toddlers. We estimate 2.9 and 4.7 million Cryptosporidium-attributable cases annually in children aged <24 months in the sub-Saharan Africa and India/Pakistan/Bangladesh/Nepal/Afghanistan regions, respectively, and ~202,000 Cryptosporidium-attributable deaths (regions combined). ~59,000 excess deaths occurred among Cryptosporidium-attributable diarrhea cases over expected if cases had been Cryptosporidium-negative.

Conclusions

The enormous African/Asian Cryptosporidium disease burden warrants investments to develop vaccines, diagnostics and therapies.

Cryptosporidium is a protozoan that causes diarrhea and malnutrition in young children in developing countries, and is associated with diarrhea cases and outbreaks in developed countries. To date, limited information exists on the burden of Cryptosporidium diarrheal disease in sub-Saharan Africa and South Asia, where most diarrheal disease deaths occur. We estimated the burden of Cryptosporidium-diarrhea and associated deaths in these regions using data from the Global Enteric Multicenter Study (GEMS). Cryptosporidium was associated with diarrhea mainly in children aged <24 months. Infections began in the first few months of life but clinical episodes of Cryptosporidium-associated diarrhea illness peaked at age 6–11 months. The annual number of Cryptosporidium-attributable diarrhea episodes was estimated at 2.9 and 4.7 million in children aged <24 months in sub-Saharan Africa and in the India/Pakistan/Bangladesh/Afghanistan/Nepal region of South Asia, respectively. In both regions combined, Cryptosporidium is estimated to contribute to approximately 202,000 deaths per year, and to ~59,000 more deaths in Cryptosporidium-attributable cases than if those cases had been negative for Cryptosporidium. Our study highlights the enormous burden attributable to Cryptosporidium in Africa and Asia, which underscores the need for developing vaccines and treatments to reduce this burden.

Untangling the Impacts of Climate Change on Waterborne Diseases: a Systematic Review of Relationships between Diarrheal Diseases and Temperature, Rainfall, Flooding, and Drought

Global climate change is expected to affect waterborne enteric diseases, yet to date there has been no comprehensive, systematic review of the epidemiological literature examining the relationship between meteorological conditions and diarrheal diseases. We searched PubMed, Embase, Web of Science, and the Cochrane Collection for studies describing the relationship between diarrheal diseases and four meteorological conditions that are expected to increase with climate change: ambient temperature, heavy rainfall, drought, and flooding. We synthesized key areas of agreement and evaluated the biological plausibility of these findings, drawing from a diverse, multidisciplinary evidence base. We identified 141 articles that met our inclusion criteria. Key areas of agreement include a positive association between ambient temperature and diarrheal diseases, with the exception of viral diarrhea and an increase in diarrheal disease following heavy rainfall and flooding events. Insufficient evidence was available to evaluate the effects of drought on diarrhea. There is evidence to support the biological plausibility of these associations, but publication bias is an ongoing concern. Future research evaluating whether interventions, such as improved water and sanitation access, modify risk would further our understanding of the potential impacts of climate change on diarrheal diseases and aid in the prioritization of adaptation measures.

Norovirus Infection and Acquired Immunity in 8 Countries: Results From the MAL-ED Study

BACKGROUND

Norovirus is an important cause of childhood diarrhea. We present data from a longitudinal, multicountry study describing norovirus epidemiology during the first 2 years of life.

METHODS

A birth cohort of 1457 children across 8 countries contributed 7077 diarrheal stools for norovirus testing. A subset of 199 children contributed additional asymptomatic samples (2307) and diarrheal stools (770), which were used to derive incidence rates and evaluate evidence for acquired immunity.

RESULTS

Across sites, 89% of children experienced at least 1 norovirus infection before 24 months, and 22.7% of all diarrheal stools were norovirus positive. Severity of norovirus-positive diarrhea was comparable to other enteropathogens, with the exception of rotavirus. Incidence of genogroup II (GII) infection was higher than genogroup I and peaked at 6-11 months across sites. Undernutrition was a risk factor for symptomatic norovirus infection, with an increase in 1 standard deviation of length-for-age z score associated with a 17% reduction (odds ratio, 0.83 [95% confidence interval, .72-.97]; P = .011) in the odds of experiencing diarrhea when norovirus was present, after accounting for genogroup, rotavirus vaccine, and age. Evidence of acquired immunity was observed among GII infections only: Children with prior GII infection were found to have a 27% reduction in the hazard of subsequent infection (hazard ratio, 0.727; P = .010).

CONCLUSIONS

The high prevalence of norovirus across 8 sites in highly variable epidemiologic settings and demonstration of protective immunity for GII infections provide support for investment in vaccine development.

Early-life enteric infections: relation between chronic systemic inflammation and poor cognition in children

The intestinal microbiota undergoes active remodeling in the first 6 to 18 months of life, during which time the characteristics of the adult microbiota are developed. This process is strongly influenced by the early diet and enteric pathogens. Enteric infections and malnutrition early in life may favor microbiota dysbiosis and small intestinal bacterial overgrowth, resulting in intestinal barrier dysfunction and translocation of intestinal bacterial products, ultimately leading to low-grade, chronic, subclinical systemic inflammation. The leaky gut-derived low-grade systemic inflammation may have profound consequences on the gut-liver-brain axis, compromising normal growth, metabolism, and cognitive development. This review examines recent data suggesting that early-life enteric infections that lead to intestinal barrier disruption may shift the intestinal microbiota toward chronic systemic inflammation and subsequent impaired cognitive development.

Norovirus Epidemiology in Africa: A Review

Norovirus (NoV) is recognised as a leading cause of gastroenteritis worldwide across all age groups. The prevalence and diversity of NoVs in many African countries is still unknown, although early sero-prevalence studies indicated widespread early infection. Reports on NoVs in Africa vary widely in terms of study duration, population groups and size, inclusion of asymptomatic controls, as well as genotyping information. This review provides an estimate of NoV prevalence and distribution of genotypes of NoVs in Africa. Inclusion criteria for the review were study duration of at least 6 months, population size of >50 and diagnosis by RT-PCR. As regions used for genotyping varied, or genotyping was not always performed, this was not considered as an inclusion criteria. A literature search containing the terms norovirus+Africa yielded 74 publications. Of these 19 studies from 14 out of the 54 countries in Africa met the inclusion criteria. Data from studies not meeting the inclusion criteria, based on sample size or short duration, were included as discussion points. The majority of studies published focused on children, under five years of age, hospitalised with acute gastroenteritis. The mean overall prevalence was 13.5% (range 0.8–25.5%) in children with gastroenteritis and 9.7% (range 7–31%) in asymptomatic controls, where tested. NoV GII.4 was the predominant genotype identified in most of the studies that presented genotyping data. Other prevalent genotypes detected included GII.3 and GII.6. In conclusion, NoV is a common pathogen in children with diarrhoea in Africa, with considerable carriage in asymptomatic children. There is however, a paucity of data on NoV infection in adults.

Characterization of a multicomponent live, attenuated Shigella flexneri vaccine

Shigella flexneri is a leading cause of diarrheal disease in children under five in developing countries. There is currently no licensed vaccine and broad spectrum protection requires coverage of multiple serotypes. The live attenuated vaccines CVD 1213 and CVD 1215 were derived from two prominent S. flexneri serotypes: S. flexneri 3a and S. flexneri 6. To provide broad-spectrum immunity, they could be combined with CVD 1208S, a S. flexneri 2a strain that demonstrated promising results in phase I and II clinical trials. Each strain contains a mutation in the guaBA operon. These vaccine candidates were tested in vitro and in vivo and were found to be auxotrophic for guanine and defective in intracellular replication, but capable of inducing cytokine production from both epithelial cells and macrophages. Both strains were attenuated for virulence in the guinea pig Serény test and induced robust serotype-specific antibody responses following immunization. Each strain induced homologous serotype protection against challenge and a mixed inoculum of the three S. flexneri vaccines conferred protection against all three virulent wild-type strains. These data support the use of CVD 1213, CVD 1215 and CVD 1208S in a multivalent vaccine to confer broad protection against disease caused by Shigella flexneri.

The Vast and Varied Global Burden of Norovirus: Prospects for Prevention and Control

Globally, norovirus is associated with approximately one-fifth of all diarrhea cases, with similar prevalence in both children and adults, and is estimated to cause over 200,000 deaths annually in developing countries. Norovirus is an important pathogen in a number of high-priority domains: it is the most common cause of diarrheal episodes globally, the principal cause of foodborne disease outbreaks in the United States, a key health care-acquired infection, a common cause of travel-associated diarrhea, and a bane for deployed military troops. Partly as a result of this ubiquity and burden across a range of different populations, identifying target groups and strategies for intervention has been challenging. And, on top of the breadth of this public health problem, there remain important gaps in scientific knowledge regarding norovirus, especially with respect to disease in low-income settings. Many pathogens can cause acute gastroenteritis. Historically, rotavirus was the most common cause of severe disease in young children globally. Now, vaccines are available for rotavirus and are universally recommended by the World Health Organization. In countries with effective rotavirus vaccination programs, disease due to that pathogen has decreased markedly, but norovirus persists and is now the most common cause of pediatric gastroenteritis requiring medical attention. However, the data supporting the precise role of norovirus in low- and middle-income settings are sparse. With vaccines in the pipeline, addressing these and other important knowledge gaps is increasingly pressing. We assembled an expert group to assess the evidence for the global burden of norovirus and to consider the prospects for norovirus vaccine development. The group assessed the evidence in the areas of burden of disease, epidemiology, diagnostics, disease attribution, acquired immunity, and innate susceptibility, and the group considered how to bring norovirus vaccines from their current state of development to a viable product that will benefit global health.

Status of vaccine research and development for norovirus

The global health community is beginning to gain an understanding of the global burden of norovirus-associated disease, which appears to have significant burden in both developed- and developing-country populations. Of particular importance is the growing recognition of norovirus as a leading cause of gastroenteritis and diarrhea in countries where rotavirus vaccine has been introduced. While not as severe as rotavirus disease, the sheer number of norovirus infections not limited to early childhood makes norovirus a formidable global health problem. This article provides a landscape review of norovirus vaccine development efforts. Multiple vaccine strategies, mostly relying on virus-like particle antigens, are under development and have demonstrated proof of efficacy in human challenge studies. Several are entering phase 2 clinical development. Norovirus vaccine development challenges include, but are not limited to: valency, induction of adequate immune responses in pediatric and elderly populations, and potential for vaccine-strain mismatch. Given current strategies and global health interest, the outlook for a norovirus vaccine is promising. Because a norovirus vaccine is expected to have a dual market in both developed and developing countries, there would likely be scale-up advantages for commercial development and global distribution. Combination with or expression by another enteric pathogen, such as rotavirus, could also enhance uptake of a norovirus vaccine.

Report from the World Health Organization's Product Development for Vaccines Advisory Committee (PDVAC) meeting, Geneva, 7-9th Sep 2015

There are more vaccines in development, against a greater number of pathogens, than ever before. A challenge with this exceptional level of activity and investment is how to select and resource the most promising approaches to have the most significant impact on public health. The WHO Product Development for Vaccines Advisory Committee (PDVAC) was established in 2014 to provide strategic advice and recommendations to WHO for vaccines in clinical development that could have a significant impact on public health in low and middle income countries. On 7-9th September 2015, PDVAC was convened for the second time, when the committee reviewed vaccine developments in 24 disease areas. This report summarises the key recommendations from that consultation.

Status of vaccine research and development for enterotoxigenic Escherichia coli

Enterotoxigenic Escherichia coli (ETEC) is one of the most common bacterial causes of diarrhea-associated morbidity and mortality, particularly among infants and young children in developing countries. Still, the true impact on child and traveler health is likely underestimated. There are currently no licensed vaccines for ETEC, but studies indicate high public health impact, cost-effectiveness, and feasibility of immune protection through vaccination. ETEC vaccine development remains a World Health Organization priority. Traditionally, ETEC vaccine development efforts have focused on inducing antitoxin and anticolonization antigen immunity, as studies indicate that antibodies against both antigen types can contribute to protection and thus have potential for vaccines. Leading cellular vaccine candidates are ETVAX (a mixture of four inactivated strains) and ACE527 (a mixture of three live attenuated strains), both of which have been found to be safe and immunogenic in Phase 1/2 trials. ETVAX is the furthest along in development with descending-age studies already underway in Bangladesh. Other ETEC vaccine candidates based on protein subunits, toxoids (both LT and ST), or novel, more broadly conserved ETEC antigens are also under development. Of these, a protein adhesin-based subunit approach is the most advanced. Impact and economic models suggest favorable vaccine cost-effectiveness, which may help expand market interest in ETEC vaccines. Combination vaccine formulations may help improve the economic case for development and use, and better point-of-care diagnostics will help to raise awareness of the true health burden of ETEC and highlight the potential public health benefit of ETEC vaccine introduction. Better diagnostics and vaccine demand forecasting will also improve vaccine development financing and support accelerated uptake once a licensed vaccine becomes available.

Status of vaccine research and development for Campylobacter jejuni

Campylobacter jejuni is one of the leading causes of bacterial diarrhea worldwide and is associated with a number of sequelae, including Guillain-Barre Syndrome, reactive arthritis, irritable bowel syndrome and growth stunting/malnutrition. Vaccine development against C. jejuni is complicated by its antigenic diversity, a lack of small animal models, and a poor understanding of the bacterium's pathogenesis. Vaccine approaches have been limited to recombinant proteins, none of which have advanced beyond Phase I testing. Genomic analyses have revealed the presence of a polysaccharide capsule on C. jejuni. Given the success of capsule-conjugate vaccines for other mucosal pathogens of global importance, efforts to evaluate this established approach for C. jejuni are also being pursued. A prototypical capsule-conjugate vaccine has demonstrated efficacy against diarrheal disease in non-human primates and is currently in Phase I testing. In addition to proof of concept studies, more data on the global prevalence of capsular types, and a better understanding of the acute and chronic consequences of C. jejuni are needed to inform investments for a globally relevant vaccine.

Evaluation of Luminex xTAG Gastrointestinal Pathogen Panel Assay for Detection of Multiple Diarrheal Pathogens in Fecal Samples in Vietnam

Diarrheal disease is a complex syndrome that remains a leading cause of global childhood morbidity and mortality. The diagnosis of enteric pathogens in a timely and precise manner is important for making treatment decisions and informing public health policy, but accurate diagnosis is a major challenge in industrializing countries. Multiplex molecular diagnostic techniques may represent a significant improvement over classical approaches. We evaluated the Luminex xTAG gastrointestinal pathogen panel (GPP) assay for the detection of common enteric bacterial and viral pathogens in Vietnam. Microbiological culture and real-time PCR were used as gold standards. The tests were performed on 479 stool samples collected from people admitted to the hospital for diarrheal disease throughout Vietnam. Sensitivity and specificity were calculated for the xTAG GPP for the seven principal diarrheal etiologies. The sensitivity and specificity for the xTAG GPP were >88% for Shigellaspp.,Campylobacterspp., rotavirus, norovirus genotype 1/2 (GI/GII), and adenovirus compared to those of microbiological culture and/or real-time PCR. However, the specificity was low (∼60%) for Salmonella species. Additionally, a number of important pathogens that are not identified in routine hospital procedures in this setting, such as Cryptosporidiumspp. and Clostridium difficile, were detected with the GPP. The use of the Luminex xTAG GPP for the detection of enteric pathogens in settings, like Vietnam, would dramatically improve the diagnostic accuracy and capacity of hospital laboratories, allowing for timely and appropriate therapy decisions and a wider understanding of the epidemiology of pathogens associated with severe diarrheal disease in low-resource settings.

Prevention and Control of Childhood Pneumonia and Diarrhea

Pneumonia and diarrhea are the 2 leading infectious causes of death in children younger than 5 years worldwide, most of which occur in low- and middle-income countries (LMICs) in sub-Saharan Africa and Southern Asia. The past decade has seen large reductions in global childhood mortality, partly due to expansion of nonspecific public health interventions and vaccines against Streptococcus pneumoniae, Haemophilus influenzae, and rotavirus in LMICs. Further progress in this field depends on the international community's commitment to fund and implement programs using currently available vaccines and development of new vaccines against pathogens common to children in LMICs.

Clinical implications of reduced susceptibility to fluoroquinolones in paediatric Shigella sonnei and Shigella flexneri infections

Objectives

We aimed to quantify the impact of fluoroquinolone resistance on the clinical outcome of paediatric shigellosis patients treated with fluoroquinolones in southern Vietnam. Such information is important to inform therapeutic management for infections caused by this increasingly drug-resistant pathogen, responsible for high morbidity and mortality in young children globally.

Methods

Clinical information and bacterial isolates were derived from a randomized controlled trial comparing gatifloxacin with ciprofloxacin for the treatment of paediatric shigellosis. Time–kill experiments were performed to evaluate the impact of MIC on the in vitro growth of Shigella and Cox regression modelling was used to compare clinical outcome between treatments and Shigella species.

Results

Shigella flexneri patients treated with gatifloxacin had significantly worse outcomes than those treated with ciprofloxacin. However, the MICs of fluoroquinolones were not significantly associated with poorer outcome. The presence of S83L and A87T mutations in the gyrA gene significantly increased MICs of fluoroquinolones. Finally, elevated MICs and the presence of the qnrS gene allowed Shigella to replicate efficiently in vitro in high concentrations of ciprofloxacin.

Conclusions

We found that below the CLSI breakpoint, there was no association between MIC and clinical outcome in paediatric shigellosis infections. However, S. flexneri patients had worse clinical outcomes when treated with gatifloxacin in this study regardless of MIC. Additionally, Shigella harbouring the qnrS gene are able to replicate efficiently in high concentrations of ciprofloxacin and we hypothesize that such strains possess a competitive advantage against fluoroquinolone-susceptible strains due to enhanced shedding and transmission.

Prevalence of Shigella among diarrheic children under-5 years of age attending at Mekelle health center, north Ethiopia

BACKGROUND

Shigellosis is recognized as a major global public health problem especially in developing countries particularly in children under-5 years of age. Therefore; the objective of this study was to determine the prevalence of Shigella among diarrheic children under-5 years of age attending at Mekelle health center, north Ethiopia.

METHODS

A cross-sectional study was conducted among diarrheic children under-5 years of age from March to May, 2012. Structured questionnaire was used to collect the data. Study participants were recruited by convenience sampling technique. Shigella was isolated and identified using standard bacteriological techniques.

RESULTS

A total of 241 study participants were included in the study. The overall prevalence of Shigella in this study was 13.3% (32/241). High prevalence of Shigella (22.6%) was revealed from the age group of 12-23 months. No Shigella was isolated from the age group of 0-5 months. Majority of the isolates of Shigella were from bloody and mucoid diarrhea.

CONCLUSION

There was high prevalence of Shigella infection in this study. Children among the age group of 12-23 months were highly affected. Therefore; responsible bodies should work hard on preventive measures to reduce or eradicate the problem occurred due to shigellosis.

Aetiology-Specific Estimates of the Global and Regional Incidence and Mortality of Diarrhoeal Diseases Commonly Transmitted through Food

Background

Diarrhoeal diseases are major contributors to the global burden of disease, particularly in children. However, comprehensive estimates of the incidence and mortality due to specific aetiologies of diarrhoeal diseases are not available. The objective of this study is to provide estimates of the global and regional incidence and mortality of diarrhoeal diseases caused by nine pathogens that are commonly transmitted through foods.

Methods and Findings

We abstracted data from systematic reviews and, depending on the overall mortality rates of the country, applied either a national incidence estimate approach or a modified Child Health Epidemiology Reference Group (CHERG) approach to estimate the aetiology-specific incidence and mortality of diarrhoeal diseases, by age and region. The nine diarrhoeal diseases assessed caused an estimated 1.8 billion (95% uncertainty interval [UI] 1.1–3.3 billion) cases and 599,000 (95% UI 472,000–802,000) deaths worldwide in 2010. The largest number of cases were caused by norovirus (677 million; 95% UI 468–1,153 million), enterotoxigenic Escherichia coli (ETEC) (233 million; 95% UI 154–380 million), Shigella spp. (188 million; 95% UI 94–379 million) and Giardia lamblia (179 million; 95% UI 125–263); the largest number of deaths were caused by norovirus (213,515; 95% UI 171,783–266,561), enteropathogenic E. coli (121,455; 95% UI 103,657–143,348), ETEC (73,041; 95% UI 55,474–96,984) and Shigella (64,993; 95% UI 48,966–92,357). There were marked regional differences in incidence and mortality for these nine diseases. Nearly 40% of cases and 43% of deaths caused by these nine diarrhoeal diseases occurred in children under five years of age.

Conclusions

Diarrhoeal diseases caused by these nine pathogens are responsible for a large disease burden, particularly in children. These aetiology-specific burden estimates can inform efforts to reduce diarrhoeal diseases caused by these nine pathogens commonly transmitted through foods.

A systematic review and meta-analysis of ambient temperature and diarrhoeal diseases

BACKGROUND

Global climate change is expected to increase the risk of diarrhoeal diseases, a leading cause of childhood mortality. However, there is considerable uncertainty about the magnitude of these effects and which populations bear the greatest risks.

METHODS

We conducted a systematic review using defined search terms across four major databases and, additionally, examined the references of 54 review articles captured by the search. We evaluated sources of heterogeneity by pathogen taxon, exposure measure, study quality, country income level and regional climate, and estimated pooled effect estimates for the subgroups identified in the heterogeneity analysis, using meta-analysis methods.

RESULTS

We identified 26 studies with 49 estimates. Pathogen taxa were a source of heterogeneity. There was a positive association between ambient temperature and all-cause diarrhoea (incidence rate ratio (IRR) 1.07; 95% confidence interval (CI) 1.03, 1.10) and bacterial diarrhoea (IRR 1.07; 95% CI 1.04, 1.10), but not viral diarrhoea (IRR 0.96; 95% CI 0.82, 1.11). These associations were observed in low-, middle- and high-income countries. Only one study of protozoan diarrhoea was identified.

CONCLUSIONS

Changes in temperature due to global climate change can and may already be affecting diarrhoeal disease incidence. The vulnerability of populations may depend, in part, on local pathogen distribution. However, evidence of publication bias and the uneven geographical distribution of studies limit the precision and generalizability of the pooled estimates.