Global causes of diarrheal disease mortality in children <5 years of age: a systematic review

Infection of Murine Macrophages by Salmonella enterica Serovar Heidelberg Blocks Murine Norovirus Infectivity and Virus-induced Apoptosis

Gastroenteritis caused by bacterial and viral pathogens constitutes a major public health threat in the United States accounting for 35% of hospitalizations. In particular, Salmonella enterica and noroviruses cause the majority of gastroenteritis infections, with emergence of sporadic outbreaks and incidence of increased infections. Although mechanisms underlying infections by these pathogens have been individually studied, little is known about the mechanisms regulating co-infection by these pathogens. In this study, we utilized RAW 264.7 murine macrophage cells to investigate the mechanisms governing co-infection with S. enterica serovar Heidelberg and murine norovirus (MNV). We demonstrate that infection of RAW 264.7 cells with S. enterica reduces the replication of MNV, in part by blocking virus entry early in the virus life cycle, and inducing antiviral cytokines later in the infection cycle. In particular, bacterial infection prior to, or during MNV infection affected virus entry, whereas MNV entry remained unaltered when the virus infection preceded bacterial invasion. This block in virus entry resulted in reduced virus replication, with the highest impact on replication observed during conditions of co-infection. In contrast, bacterial replication showed a threefold increase in MNV-infected cells, despite the presence of antibiotic in the medium. Most importantly, we present evidence that the infection of MNV-infected macrophages by S. enterica blocked MNV-induced apoptosis, despite allowing efficient virus replication. This apoptosis blockade was evidenced by reduction in DNA fragmentation and absence of poly-ADP ribose polymerase (PARP), caspase 3 and caspase 9 cleavage events. Our study suggests a novel mechanism of pathogenesis whereby initial co-infection with these pathogens could result in prolonged infection by either of these pathogens or both together.

Methodological Framework for World Health Organization Estimates of the Global Burden of Foodborne Disease

BACKGROUND

The Foodborne Disease Burden Epidemiology Reference Group (FERG) was established in 2007 by the World Health Organization to estimate the global burden of foodborne diseases (FBDs). This paper describes the methodological framework developed by FERG's Computational Task Force to transform epidemiological information into FBD burden estimates.

METHODS AND FINDINGS

The global and regional burden of 31 FBDs was quantified, along with limited estimates for 5 other FBDs, using Disability-Adjusted Life Years in a hazard- and incidence-based approach. To accomplish this task, the following workflow was defined: outline of disease models and collection of epidemiological data; design and completion of a database template; development of an imputation model; identification of disability weights; probabilistic burden assessment; and estimating the proportion of the disease burden by each hazard that is attributable to exposure by food (i.e., source attribution). All computations were performed in R and the different functions were compiled in the R package 'FERG'. Traceability and transparency were ensured by sharing results and methods in an interactive way with all FERG members throughout the process.

CONCLUSIONS

We developed a comprehensive framework for estimating the global burden of FBDs, in which methodological simplicity and transparency were key elements. All the tools developed have been made available and can be translated into a user-friendly national toolkit for studying and monitoring food safety at the local level.

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.

Value of Post-Licensure Data on Benefits and Risks of Vaccination to Inform Vaccine Policy: The Example of Rotavirus Vaccines

In 1999, the first rhesus-human reassortant rotavirus vaccine licensed in the U.S. was withdrawn within a year of its introduction after it was linked with intussusception at a rate of ~1 excess case per 10,000 vaccinated infants. While clinical trials of 60,000-70,000 infants of each of the two current live oral rotavirus vaccines, RotaTeq (RV5) and Rotarix (RV1), did not find an association with intussusception, post-licensure studies have documented a risk in several high and middle income countries, at a rate of ~1-6 excess cases per 100,000 vaccinated infants. However, considering this low risk against the large health benefits of vaccination that have been observed in many countries, including in countries with a documented vaccine-associated intussusception risk, policy makers and health organizations around the world continue to support the routine use of RV1 and RV5 in national infant immunization programs. Because the risk and benefit data from affluent settings may not be directly applicable to developing countries, further characterization of any associated intussusception risk following rotavirus vaccination as well as the health benefits of vaccination is desirable for low income settings.

World Health Organization Estimates of the Global and Regional Disease Burden of 22 Foodborne Bacterial, Protozoal, and Viral Diseases, 2010: A Data Synthesis

BACKGROUND

Foodborne diseases are important worldwide, resulting in considerable morbidity and mortality. To our knowledge, we present the first global and regional estimates of the disease burden of the most important foodborne bacterial, protozoal, and viral diseases.

METHODS AND FINDINGS

We synthesized data on the number of foodborne illnesses, sequelae, deaths, and Disability Adjusted Life Years (DALYs), for all diseases with sufficient data to support global and regional estimates, by age and region. The data sources included varied by pathogen and included systematic reviews, cohort studies, surveillance studies and other burden of disease assessments. We sought relevant data circa 2010, and included sources from 1990-2012. The number of studies per pathogen ranged from as few as 5 studies for bacterial intoxications through to 494 studies for diarrheal pathogens. To estimate mortality for Mycobacterium bovis infections and morbidity and mortality for invasive non-typhoidal Salmonella enterica infections, we excluded cases attributed to HIV infection. We excluded stillbirths in our estimates. We estimate that the 22 diseases included in our study resulted in two billion (95% uncertainty interval [UI] 1.5-2.9 billion) cases, over one million (95% UI 0.89-1.4 million) deaths, and 78.7 million (95% UI 65.0-97.7 million) DALYs in 2010. To estimate the burden due to contaminated food, we then applied proportions of infections that were estimated to be foodborne from a global expert elicitation. Waterborne transmission of disease was not included. We estimate that 29% (95% UI 23-36%) of cases caused by diseases in our study, or 582 million (95% UI 401-922 million), were transmitted by contaminated food, resulting in 25.2 million (95% UI 17.5-37.0 million) DALYs. Norovirus was the leading cause of foodborne illness causing 125 million (95% UI 70-251 million) cases, while Campylobacter spp. caused 96 million (95% UI 52-177 million) foodborne illnesses. Of all foodborne diseases, diarrheal and invasive infections due to non-typhoidal S. enterica infections resulted in the highest burden, causing 4.07 million (95% UI 2.49-6.27 million) DALYs. Regionally, DALYs per 100,000 population were highest in the African region followed by the South East Asian region. Considerable burden of foodborne disease is borne by children less than five years of age. Major limitations of our study include data gaps, particularly in middle- and high-mortality countries, and uncertainty around the proportion of diseases that were foodborne.

CONCLUSIONS

Foodborne diseases result in a large disease burden, particularly in children. Although it is known that diarrheal diseases are a major burden in children, we have demonstrated for the first time the importance of contaminated food as a cause. There is a need to focus food safety interventions on preventing foodborne diseases, particularly in low- and middle-income settings.

World Health Organization Estimates of the Global and Regional Disease Burden of 11 Foodborne Parasitic Diseases, 2010: A Data Synthesis

BACKGROUND

Foodborne diseases are globally important, resulting in considerable morbidity and mortality. Parasitic diseases often result in high burdens of disease in low and middle income countries and are frequently transmitted to humans via contaminated food. This study presents the first estimates of the global and regional human disease burden of 10 helminth diseases and toxoplasmosis that may be attributed to contaminated food.

METHODS AND FINDINGS

Data were abstracted from 16 systematic reviews or similar studies published between 2010 and 2015; from 5 disease data bases accessed in 2015; and from 79 reports, 73 of which have been published since 2000, 4 published between 1995 and 2000 and 2 published in 1986 and 1981. These included reports from national surveillance systems, journal articles, and national estimates of foodborne diseases. These data were used to estimate the number of infections, sequelae, deaths, and Disability Adjusted Life Years (DALYs), by age and region for 2010. These parasitic diseases, resulted in 48.4 million cases (95% Uncertainty intervals [UI] of 43.4-79.0 million) and 59,724 (95% UI 48,017-83,616) deaths annually resulting in 8.78 million (95% UI 7.62-12.51 million) DALYs. We estimated that 48% (95% UI 38%-56%) of cases of these parasitic diseases were foodborne, resulting in 76% (95% UI 65%-81%) of the DALYs attributable to these diseases. Overall, foodborne parasitic disease, excluding enteric protozoa, caused an estimated 23.2 million (95% UI 18.2-38.1 million) cases and 45,927 (95% UI 34,763-59,933) deaths annually resulting in an estimated 6.64 million (95% UI 5.61-8.41 million) DALYs. Foodborne Ascaris infection (12.3 million cases, 95% UI 8.29-22.0 million) and foodborne toxoplasmosis (10.3 million cases, 95% UI 7.40-14.9 million) were the most common foodborne parasitic diseases. Human cysticercosis with 2.78 million DALYs (95% UI 2.14-3.61 million), foodborne trematodosis with 2.02 million DALYs (95% UI 1.65-2.48 million) and foodborne toxoplasmosis with 825,000 DALYs (95% UI 561,000-1.26 million) resulted in the highest burdens in terms of DALYs, mainly due to years lived with disability. Foodborne enteric protozoa, reported elsewhere, resulted in an additional 67.2 million illnesses or 492,000 DALYs. Major limitations of our study include often substantial data gaps that had to be filled by imputation and suffer from the uncertainties that surround such models. Due to resource limitations it was also not possible to consider all potentially foodborne parasites (for example Trypanosoma cruzi).

CONCLUSIONS

Parasites are frequently transmitted to humans through contaminated food. These estimates represent an important step forward in understanding the impact of foodborne diseases globally and regionally. The disease burden due to most foodborne parasites is highly focal and results in significant morbidity and mortality among vulnerable populations.

Immunogenicity and protective efficacy of a recombinant adenoviral based vaccine expressing heat-stable enterotoxin (STa) and K99 adhesion antigen of enterotoxigenic Escherichia coli in mice

The diarrheal disease of domestic animals or in humans caused by enterotoxigenic Escherichia coli (ETEC) infections remains a major issue for public health in developing countries. Unfortunately, there is no effective vaccine available for preventing from an ETEC infection. Therefore, the development of a safe and effective vaccine against ETEC is urgently needed. In the present study, A recombinant adenoviral vector Ad5-STa-K99 that capable of expressing a fusion protein of heat-stable enterotoxin (STa) and K99 adhesion antigen of ETEC was generated and its immunogenicity was evaluated in a murine model. The intestinal mucosal secretory IgA(sIgA), serum anti-STa-K99 antibody responses, antigen-specific CD4(+) and CD8(+) T cells frequencies, as well as T-cell proliferation of mice immunized with the viral vector were determined as immunological indexes. The results demonstrated that Ad5-STa-K99 was able to enhance humoral responses with a dramatically augmented antigen-specific serum IgG antibody, and an elevated production of intestinal sIgA in immunized mice, suggesting the elicitation of both of humoral and mucosal immune responses. In addition, this adenoviral vector could significantly promote splenic T cell proliferation and increase the frequencies of CD4(+) and CD8(+) T cell populations in mice, indicative of a capacity to activate T cell responses. More importantly, vaccination of the Ad5-STa-K99 showed a potential to evoke a protective effect from ETEC challenge in mice. These data indicate that the Ad5-STa-K99 is a highly immunogenic vector able to induce a broad range of antigen-specific immune responses in vivo, and evoke a protective immune response against ETEC infections, implying that it may be a novel vaccine candidate warranted for further investigation.

High prevalence of G12P[8] rotavirus strains in Rio Branco, Acre, Western Amazon, in the post-rotavirus vaccine introduction period

The present study aimed to provide a molecular characterization of circulating rotavirus (RVA) strains in Rio Branco, Acre, in the post-rotavirus vaccination period, particularly with regard to the emerging, increasingly prevalent G12P[8] genotype. A total of 488 fecal specimens from diarrheic and non-diarrheic children were obtained between January and December 2012. RVA detection was initially performed using enzyme-linked immunosorbent assay (ELISA) method, followed by reverse-transcription polymerase chain reaction (RT-PCR) using specific primers. RVA was detected in 18.3% (44/241) of the children with acute diarrhea and in 1.2% (3/247) of the non-diarrheic children (P < 0.001), with overall RVA-positivity of 9.6% (47/488). The most common genotype was G2P[4] with 43.2% (19/44) of the diarrheic cases, followed by G12P[8] (27.3%, 12/44), G3P[6] (18.2%, 8/44), G3P[8] (4.5%, 2/44), and G12P[6] (2.3%, 1/44). G12 samples belonged to lineage III and were from children aged 4-52 months. All of these children had acute diarrhea associated with fever (83.3%, 10/12) and vomiting (66.7%, 8/12). Most of the cases occurred in August (58.3%, 7/12), 75% (9/12) of which having received the full vaccination scheme with Rotarix™. For the first time G12 was reported at relative high prevalence in Brazil. Our findings warrant further monitoring studies on the molecular characterization of circulating RVA strains after rotavirus vaccine introduction in Brazil and elsewhere, since the occurrence of either unusual our emerging genotypes may pose a challenge to vaccination strategies.

Interventions to improve water quality for preventing diarrhoea

BACKGROUND

Diarrhoea is a major cause of death and disease, especially among young children in low-income countries. In these settings, many infectious agents associated with diarrhoea are spread through water contaminated with faeces.In remote and low-income settings, source-based water quality improvement includes providing protected groundwater (springs, wells, and bore holes), or harvested rainwater as an alternative to surface sources (rivers and lakes). Point-of-use water quality improvement interventions include boiling, chlorination, flocculation, filtration, or solar disinfection, mainly conducted at home.

OBJECTIVES

To assess the effectiveness of interventions to improve water quality for preventing diarrhoea.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register (11 November 2014), CENTRAL (the Cochrane Library, 7 November 2014), MEDLINE (1966 to 10 November 2014), EMBASE (1974 to 10 November 2014), and LILACS (1982 to 7 November 2014). We also handsearched relevant conference proceedings, contacted researchers and organizations working in the field, and checked references from identified studies through 11 November 2014.

SELECTION CRITERIA

Randomized controlled trials (RCTs), quasi-RCTs, and controlled before-and-after studies (CBA) comparing interventions aimed at improving the microbiological quality of drinking water with no intervention in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. We used meta-analyses to estimate pooled measures of effect, where appropriate, and investigated potential sources of heterogeneity using subgroup analyses. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

Forty-five cluster-RCTs, two quasi-RCTs, and eight CBA studies, including over 84,000 participants, met the inclusion criteria. Most included studies were conducted in low- or middle-income countries (LMICs) (50 studies) with unimproved water sources (30 studies) and unimproved or unclear sanitation (34 studies). The primary outcome in most studies was self-reported diarrhoea, which is at high risk of bias due to the lack of blinding in over 80% of the included studies. Source-based water quality improvementsThere is currently insufficient evidence to know if source-based improvements such as protected wells, communal tap stands, or chlorination/filtration of community sources consistently reduce diarrhoea (one cluster-RCT, five CBA studies, very low quality evidence). We found no studies evaluating reliable piped-in water supplies delivered to households. Point-of-use water quality interventionsOn average, distributing water disinfection products for use at the household level may reduce diarrhoea by around one quarter (Home chlorination products: RR 0.77, 95% CI 0.65 to 0.91; 14 trials, 30,746 participants, low quality evidence; flocculation and disinfection sachets: RR 0.69, 95% CI 0.58 to 0.82, four trials, 11,788 participants, moderate quality evidence). However, there was substantial heterogeneity in the size of the effect estimates between individual studies.Point-of-use filtration systems probably reduce diarrhoea by around a half (RR 0.48, 95% CI 0.38 to 0.59, 18 trials, 15,582 participants, moderate quality evidence). Important reductions in diarrhoea episodes were shown with ceramic filters, biosand systems and LifeStraw® filters; (Ceramic: RR 0.39, 95% CI 0.28 to 0.53; eight trials, 5763 participants, moderate quality evidence; Biosand: RR 0.47, 95% CI 0.39 to 0.57; four trials, 5504 participants, moderate quality evidence; LifeStraw®: RR 0.69, 95% CI 0.51 to 0.93; three trials, 3259 participants, low quality evidence). Plumbed in filters have only been evaluated in high-income settings (RR 0.81, 95% CI 0.71 to 0.94, three trials, 1056 participants, fixed effects model).In low-income settings, solar water disinfection (SODIS) by distribution of plastic bottles with instructions to leave filled bottles in direct sunlight for at least six hours before drinking probably reduces diarrhoea by around a third (RR 0.62, 95% CI 0.42 to 0.94; four trials, 3460 participants, moderate quality evidence).In subgroup analyses, larger effects were seen in trials with higher adherence, and trials that provided a safe storage container. In most cases, the reduction in diarrhoea shown in the studies was evident in settings with improved and unimproved water sources and sanitation.

AUTHORS' CONCLUSIONS

Interventions that address the microbial contamination of water at the point-of-use may be important interim measures to improve drinking water quality until homes can be reached with safe, reliable, piped-in water connections. The average estimates of effect for each individual point-of-use intervention generally show important effects. Comparisons between these estimates do not provide evidence of superiority of one intervention over another, as such comparisons are confounded by the study setting, design, and population.Further studies assessing the effects of household connections and chlorination at the point of delivery will help improve our knowledge base. As evidence suggests effectiveness improves with adherence, studies assessing programmatic approaches to optimising coverage and long-term utilization of these interventions among vulnerable populations could also help strategies to improve health outcomes.

The epidemiology of all-cause and rotavirus acute gastroenteritis and the characteristics of rotavirus circulating strains before and after rotavirus vaccine introduction in Yemen: analysis of hospital-based surveillance data

Background

Rotavirus (RV) vaccine was added to Yemen’s childhood vaccination schedule in late 2012. We evaluated the effect of vaccination on the epidemiology of acute gastroenteritis (AGE) and the characteristics of circulating RV strains.

Methods

Surveillance data was obtained at two sentinel hospitals from 5,691 children with acute gastroenteritis (AGE) who were under 5 years of age. Data collected before (2007–2011) and after (2013–2014) RV vaccine introduction were retrospectively analyzed. Treatment outcome, presence of severe dehydration, and the proportion of all-cause AGE due to RV-antigen positive AGE were calculated for each period and compared. Binominal generalized linear models were used to calculate adjusted odds ratios (ORs) and 95 % confidence intervals (CIs). We also compared severe RVAGE and severe dehydration proportions in hospitalized children with severe AGE and characterized RV circulating strains in available specimens from the two periods.

Results

Before RV vaccination, mean RVAGE prevalence peaked in October (58.8 %), November (69.5 %), and December (56.4 %). In 2013–2014, the variation became less defined, with only a few RVAGE cases. The average annual prevalence of severe RVAGE needing hospitalization was 42.9 % in 2007–2011, decreased to 21.1 % in 2013, and to 18.5 % in 2014, representing declines of 50.8 % (95 % CI: 36.4–65.0) and 56.9 % (95 % CI: 42.1–70.5). The proportion of children <12 months of age with all-cause AGE decreased significantly after introduction of RV vaccination (58.7 % vs. 62.3 %; p = 0.042), severe dehydration decreased by 50 % (14.7 % vs. 21.7 %; OR = 0.501, p < 0.0001), and RVAGE proportion decreased by 48 % (19.9 % vs. 41.6 %; OR = 0.52, p < 0.0001). The proportion of severe RVAGE in hospitalized patients decreased by 67 % (20.1 % vs. 43.5 %; OR = 0.33, p < 0.0001), and severe dehydration decreased by 58 % (17.2 % vs. 33.1 %; OR = 0.42, p < 0.0001). Non-RV AGE prevalence significantly increased, with ORs of 2.8–3.1 in favor of non-RV AGE in 2013–2014. Analysis of 128 available stool specimens revealed that circulation of the G1 genotype did not change following vaccination (33.3 % vs. 41.3 %; p = 0.366). G2 significantly decreased in 2013–2014 (4.2 % vs. 42.5 % p = 0.0001), and G9 increased (29.2 % vs. 6.3 %; p = 0.001). G1P[8] and G2P[4] remained prevalent, and G9P[8] and G9P[4], which were not detected in the pre-vaccine period appeared in 2013–2014. G and [P] mixed genotypes became more prevalent in 2013–2014. It is not known if this predominance is related to the vaccine introduction or attributable to normal genotype fluctuations.

Conclusions

Rotarix substantially reduced the prevalence of RVAGE, with a 67 % reduction of severe RVAGE hospitalizations, and over 50 % reduction of diarrhea with severe dehydration. Circulation of RV G and [P] mix strains was significantly increased in 2013–2014 and needs continuous monitoring.

Detection of Rotavirus Genotypes in Korea 5 Years after the Introduction of Rotavirus Vaccines

Rotavirus (RV) is one of the most important viral etiologic agents of acute gastroenteritis (AGE) in children. Although effective RV vaccines (RVVs) are now used worldwide, novel genotypes and outbreaks resulting from rare genotype combinations have emerged. This study documented RV genotypes in a Korean population of children with AGE 5 yr after the introduction of RVV and assessed potential genotype differences based on vaccination status or vaccine type. Children less than 5-yr-old diagnosed with AGE between October 2012 and September 2013 admitted to 9 medical institutions from 8 provinces in Korea were prospectively enrolled. Stool samples were tested for RV by enzyme immunoassay and genotyped by multiplex reverse-transcription polymerase chain reaction. In 346 patients, 114 (32.9%) were RV-positive. Among them, 87 (76.3%) patients were infected with RV alone. Eighty-six of 114 RV-positive stool samples were successfully genotyped, and their combinations of genotypes were G1P[8] (36, 41.9%), G2P[4] (12, 14.0%), and G3P[8] (6, 7.0%). RV was detected in 27.8% of patients in the vaccinated group and 39.8% in the unvaccinated group (P=0.035). Vaccination history was available for 67 of 86 cases with successfully genotyped RV-positive stool samples; RotaTeq (20, 29.9%), Rotarix (7, 10.4%), unvaccinated (40, 59.7%). The incidence of RV AGE is lower in the RV-vaccinated group compared to the unvaccinated group with no evidence of substitution with unusual genotype combinations.

Hospitalizations and Deaths Because of Respiratory and Diarrheal Diseases Among Haitian Children Under Five Years of Age, 2011-2013

BACKGROUND

Respiratory and diarrheal diseases are leading causes of morbidity and mortality among children younger than 5 years in developing countries. Data on the burden of these diseases in Haiti are scarce.

METHODS

We conducted a retrospective review of hospital admission registries during January 1, 2011-December 31, 2013 for children younger than 5 years in 6 hospitals in Haiti. We recorded the number of all-cause, respiratory and diarrheal disease admissions and deaths by epidemiologic week and age.

RESULTS

A total of 31,565 hospital admissions and 1763 deaths were recorded among children aged <5 years during the study period. Respiratory diseases accounted for 9183 (29%) hospitalizations and 301 (17%) deaths. Children aged 6-23 months had the highest percentage of hospitalizations attributable to respiratory diseases (38%), whereas children aged 36-47 months had the highest proportion of deaths attributable to respiratory diseases (37%). Respiratory disease hospitalizations followed a bimodal seasonal pattern, with peaks during May-June and October-December. Diarrheal diseases accounted for 8063 (26%) hospitalizations and 224 (13%) deaths. Children aged 6-11 months had the highest percentage of diarrhea-associated hospitalizations (39%) and deaths (29%). Diarrheal disease admissions peaked in January-April before the rainy season.

CONCLUSIONS

Respiratory and diarrheal diseases contributed to more than half of hospitalizations and almost a third of deaths in children younger than 5 years in Haiti. These data are essential to assess the impact of pneumococcal and rotavirus vaccines and other interventions in Haiti.

Phylogenetic analysis of human group C rotavirus in hospitalized children with gastroenteritis in Belém, Brazil

Group C rotavirus (RVC) is potentially an important pathogen associated with acute gastroenteritis (AG), especially in outbreaks. This study aims to detect and molecularly characterize RVC in hospitalized children with AG in Belém, Brazil. From May 2008 to April 2011, 279 stools were subjected to reverse-transcription polymerase chain reaction targeting VP7, VP6, VP4, and NSP4 genes. RVC positivity rate was 2.1% (6/279) and phylogenetic analysis of positive samples yields genotype G4-P[2]-I2-E2. No evidence of zoonotic transmission and VP7 gene demonstrated close relationship with Asian strains. RVC surveillance is worth to expand information on evolutionary and epidemiological features of this virus.

Antibody-mediated disruption of the mechanics of CS20 fimbriae of enterotoxigenic Escherichia coli

Preventive vaccines against enterotoxigenic Escherichia coli (ETEC) are being developed, many of which target common fimbrial colonization factors as the major constituent, based on empirical evidence that these function as protective antigens. Particularly, passive oral administration of ETEC anti-fimbrial antibodies prevent ETEC diarrhea. Little is, however, known regarding the specific mechanisms by which intestinal antibodies against ETEC fimbriae function to prevent disease. Using coli surface antigen 20 (CS20) fimbriae as a model ETEC colonization factor, we show using force spectroscopy that anti-fimbrial antibodies diminish fimbrial elasticity by inhibiting their natural capacity to unwind and rewind. In the presence of anti-CS20 antibodies the force required to unwind a single fimbria was increased several-fold and the extension length was shortened several-fold. Similar measurements in the presence of anti-CS20 Fab fragments did not show any effect, indicating that bivalent antibody binding is required to reduce fimbrial elasticity. Based on these findings, we propose a model for an in-vivo mechanism whereby antibody-mediated disruption of the biomechanical properties of CS20 fimbriae impedes sustained adhesion of ETEC to the intestinal mucosal surface. Further elucidation of the role played by intestinal antibodies in mechanical disruption of fimbrial function may provide insights relevant to ETEC vaccine development.

Norovirus immunology: Of mice and mechanisms

Noroviruses (NoVs) are the most common cause of sporadic and epidemic gastroenteritis in the United States and Europe and are responsible for 20% of acute gastroenteritis worldwide. Over the past decade, the understanding of NoV immunology has grown immensely. Studies of the natural immune response to NoV in humans and animal models have laid the foundation for innovations in cell culture systems for NoV and development of new therapeutics. Evidence from animal models, NoV surrogates, observational human research, and human challenge studies suggest that the innate immune response is critical for limiting NoV infection but is insufficient for viral clearance. NoV may antagonize the innate immune response to establish or prolong infection. However, once a robust adaptive immune response is initiated, the immune system clears the infection through the action of T and B cells, simultaneously generating highly specific protective immunologic memory. We review here both the current knowledge on NoV immunity and exciting new developments, with a focus on ongoing vaccine development work, novel cell culture systems, and advances in understanding the role of the gut microbiome. These changes reinforce the need for a better understanding of the human immune response to NoV and suggest novel hypotheses.

Comparative analysis of antimicrobial resistance in enterotoxigenic Escherichia coli isolates from two paediatric cohort studies in Lima, Peru

BACKGROUND

Antibiotic resistance is increasing worldwide, being of special concern in low- and middle-income countries. The aim of this study was to determine the antimicrobial susceptibility and mechanisms of resistance in 205 enterotoxigenic Escherichia coli (ETEC) isolates from two cohort studies in children <24 months in Lima, Peru.

METHODS

ETEC were identified by an in-house multiplex real-time PCR. Susceptibility to 13 antimicrobial agents was tested by disk diffusion; mechanisms of resistance were evaluated by PCR.

RESULTS

ETEC isolates were resistant to ampicillin (64%), cotrimoxazole (52%), tetracycline (37%); 39% of the isolates were multidrug-resistant. Heat-stable toxin producing (ETEC-st) (48%) and heat-labile toxin producing ETEC (ETEC-lt) (40%) had higher rates of multidrug resistance than isolates producing both toxins (ETEC-lt-st) (21%), p<0.05. Only 10% of isolates were resistant to nalidixic acid and none to ciprofloxacin or cefotaxime. Ampicillin and sulfamethoxazole resistance were most often associated with blaTEM (69%) and sul2 genes (68%), respectively. Tetracycline resistance was associated with tet(A) (49%) and tet(B) (39%) genes. Azithromycin inhibitory diameters were ≤15 mm in 36% of isolates, with 5% of those presenting the mph(A) gene.

CONCLUSIONS

ETEC from Peruvian children are often resistant to older, inexpensive antibiotics, while remaining susceptible to ciprofloxacin, cephalosporins and furazolidone. Fluoroquinolones and azithromycin remain the drugs of choice for ETEC infections in Peru. However, further development of resistance should be closely monitored.

Perception of drinking water safety and factors influencing acceptance and sustainability of a water quality intervention in rural southern India

BACKGROUND

Acceptance and long-term sustainability of water quality interventions are pivotal to realizing continued health benefits. However, there is limited research attempting to understand the factors that influence compliance to or adoption of such interventions.

METHODS

Eight focus group discussions with parents of young children--including compliant and not compliant households participating in an intervention study, and three key-informant interviews with village headmen were conducted between April and May 2014 to understand perceptions on the effects of unsafe water on health, household drinking water treatment practices, and the factors influencing acceptance and sustainability of an ongoing water quality intervention in a rural population of southern India.

RESULTS

The ability to recognize health benefits from the intervention, ease of access to water distribution centers and the willingness to pay for intervention maintenance were factors facilitating acceptance and sustainability of the water quality intervention. On the other hand, faulty perceptions on water treatment, lack of knowledge about health hazards associated with drinking unsafe water, false sense of protection from locally available water, resistance to change in taste or odor of water and a lack of support from male members of the household were important factors impeding acceptance and long term use of the intervention.

CONCLUSION

This study highlights the need to effectively involve communities at important stages of implementation for long term success of water quality interventions. Timely research on the factors influencing uptake of water quality interventions prior to implementation will ensure greater acceptance and sustainability of such interventions in low income settings.

Progress toward norovirus vaccines: considerations for further development and implementation in potential target populations

Human norovirus infection causes significant medical and financial costs in the USA and abroad. Some populations, including young children, the elderly, and the immunocompromised, are at heightened risk of infection with this virus and subsequent complications, while others, such as healthcare workers and food handlers are at increased risk of transmitting it, and some are at risk of both. Human noroviruses are heterogeneous with new strains emerging periodically. In addition to viral diversity, incompletely understood characteristics, such as virus-host cell binding and duration of immunity after infection add to the challenges of creating a norovirus vaccine. Although much progress has been made in recent years, many questions remain to be answered. In this review, we discuss the important areas and relevant literature in considering human norovirus vaccine development and potential targets for implementation.

Enteropathogenic E. coli: breaking the intestinal tight junction barrier

Enteropathogenic E. coli (EPEC) causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions.

Enteropathogenic E. coli: breaking the intestinal tight junction barrier

Enteropathogenic E. coli (EPEC) causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions.

Current Progress in Developing Subunit Vaccines against Enterotoxigenic Escherichia coli-Associated Diarrhea

Diarrhea continues to be a leading cause of death in children <5 years of age, and enterotoxigenic Escherichia coli (ETEC) is the most common bacterial cause of children's diarrhea. Currently, there are no available vaccines against ETEC-associated diarrhea. Whole-cell vaccine candidates have been under development but require further improvements because they provide inadequate protection and produce unwanted adverse effects. Meanwhile, a newer approach using polypeptide or subunit vaccine candidates focusing on ETEC colonization factor antigens (CFAs) and enterotoxins, the major virulence determinants of ETEC diarrhea, shows substantial promise. A conservative CFA/I adhesin tip antigen and a CFA MEFA (multiepitope fusion antigen) were shown to induce cross-reactive antiadhesin antibodies that protected against adherence by multiple important CFAs. Genetic fusion of toxoids derived from ETEC heat-labile toxin (LT) and heat-stable toxin (STa) induced antibodies neutralizing both enterotoxins. Moreover, CFA-toxoid MEFA polypeptides, generated by fusing CFA MEFA to an STa-LT toxoid fusion, induced antiadhesin antibodies that broadly inhibited adherence of the seven most important ETEC CFAs associated with about 80% of the diarrhea cases caused by ETEC strains with known CFAs. This same antigen preparation also induced antitoxin antibodies that neutralized both toxins that are associated with all cases of ETEC diarrhea. Results from these studies suggest that polypeptide or subunit vaccines have the potential to effectively protect against ETEC diarrhea. In addition, novel adhesins and mucin proteases have been investigated as potential alternatives or, more likely, additional antigens for ETEC subunit vaccine development.

A Survey of Escherichia coli and Salmonella in the Hyporheic Zone of a Subtropical Stream: Their Bacteriological, Physicochemical and Environmental Relationships

The Hyporheic Zone is among the most important interstitial freshwater habitats, but the relationship between biotic and abiotic factors in this zone remains under-explored. Enterobacteria were expected to be present, but no specific studies had ever confirmed this prediction. The aim of this study was, therefore, to evaluate the total coliforms, Escherichia coli and Salmonella spp. in hyporheic water and to determine the relationship of the physical, chemical and environmental factors at different depths in a rainforest stream. To this end, thirty-six water samples were collected at three depths in sites located in the first, second and third orders in diverse substrates. The total coliforms, Escherichia coli and Salmonella sp. were evaluated in terms of their CFU/ml. In the interstitial samples, coliforms were detected in 100% of the samples. The total coliform counts had higher values at intermediate depths, while E. coli and Salmonella spp. instead had higher values at intermediate and large depths, often reaching or exceeding the values of the surface samples. Our results revealed that Salmonella spp. and the coliforms have different microhabitat preferences. Salmonella spp. and coliform species prefer deposition areas, such as lateral sides of pools, curves and bars, but they have a tendency to distribute into different depths, likely due to temperature differences. Salmonella spp. prefer compact substrata, with fewer fluids passing through and with upwelling areas with lower oxygen inflow. The coliform species showed the opposite preference. Our results suggest that bacterial variation is related to environmental factors and physical-chemical parameters within the HZ and may play a key role in the microbial diversity and distribution in these ecosystems.

Draft Whole-Genome Sequences of 10 Enterotoxigenic Escherichia coli Serogroup O6 Strains

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children under the age of 5 years and in adults living in developing countries, as well as in travelers to these countries. In this announcement, we release the draft whole-genome sequences of 10 ETEC serogroup O6 strains.

Cost-effectiveness of norovirus vaccination in children in Peru

BACKGROUND

With candidate norovirus (NV) vaccines in a rapid phase of development, assessment of the potential economic value of vaccine implementation will be necessary to aid health officials in vaccine implementation decisions. To date, no evaluations have been performed to evaluate the benefit of adopting NV vaccines for use in the childhood immunization programs of low- and middle-income countries.

METHODS

We used a Markov decision model to evaluate the cost-effectiveness of adding a two-dose NV vaccine to Peru's routine childhood immunization schedule using two recent estimates of NV incidence, one for a peri-urban region and one for a jungle region of the country.

RESULTS

Using the peri-urban NV incidence estimate, the annual cost of vaccination would be $13.0 million, offset by $2.6 million in treatment savings. Overall, this would result in 473 total DALYs averted; 526,245 diarrhea cases averted;153,735 outpatient visits averted; and 414 hospitalizations averted between birth and the fifth year of life. The incremental cost-effectiveness ratio would be $21,415 per DALY averted; $19.86 per diarrhea case; $68.23 per outpatient visit; and $26,298 per hospitalization. Using the higher jungle NV incidence rates provided a lower cost per DALY of $10,135. The incremental cost per DALY with per-urban NV incidence is greater than three times the 2012 GDP per capita of Peru but the estimate drops below this threshold using the incidence from the jungle setting. In addition to the impact of incidence, sensitivity analysis showed that vaccine price and efficacy play a strong role in determining the level of cost-effectiveness.

CONCLUSIONS

The introduction of a NV vaccine would prevent many healthcare outcomes in the Peru and potentially be cost-effective in scenarios with high NV incidence. The vaccine cost-effectiveness model could also be applied to the evaluation of NV vaccine cost-effectiveness in other countries. In resource-poor settings, where NV incidence rates are expected to be higher.

Global burden of childhood diarrhea and interventions

PURPOSE OF REVIEW

Diarrhea is a leading cause of morbidity and mortality among children under 5 years in low-income and middle-income countries. Over the past 2 decades under-five mortality has decreased substantially, but reductions have been uneven and unsatisfactory in resource-poor regions.

RECENT FINDINGS

There are known interventions which can prevent diarrhea or manage children who suffer from it. Interventions with proven effectiveness at the prevention level include water, sanitation, and hygiene interventions, breastfeeding, complementary feeding, vitamin A and zinc supplementation, and vaccines for diarrhea (rotavirus and cholera). Oral rehydration solution, zinc treatment, continued feeding, and antibiotic treatment for certain strains of diarrhea (cholera, Shigella, and cryptosporidiosis) are effective strategies for treatment of diarrhea. The recent Lancet series using the 'Lives Saved' tool suggested that if these identified interventions were scaled up to a global coverage to at least 80%, and immunizations to at least 90%; almost all deaths due to diarrhea could be averted.

SUMMARY

The current childhood mortality burden highlights the need of a focused global diarrhea action plan. The findings suggest that with proper packaging of interventions and delivery platforms, the burden of childhood diarrhea can be reduced to a greater extent. All that is required is greater attention and steps toward right direction.

A comparative study of bacterial and parasitic intestinal infections in India

BACKGROUND

Infectious diarrhea causes a major health problem in developing countries with significant morbidity and mortality. Very often, rehydration therapy alone does not suffice, mandating the use of antimicrobial agents. However, rapidly decreasing antimicrobial susceptibility is complicating the matters.

MATERIALS AND METHODS

The study aimed to determine the prevalent bacterial and parasitic agents of diarrhea in India. A cross-sectional study was done at Maulana Azad Medical College and associated Lok Nayak Hospital, New Delhi, during 2012-14. Stool samples were received from patients of all age groups and processed for bacteriological and parasitological identification by microscopy, bacterial culture, biochemical identification, serotyping and antimicrobial susceptibility tests. The study also aimed to identify the recent papers (after year 2000) reporting aetiology of infectious diarrhea in India involving the general population as a whole and compare them with present findings.

RESULTS

Out of 6527 samples, 581 (8.90%) were positive for bacterial pathogens. A total of 280 samples (of 3823 under-five year children) were positive for diarrheagenic Escherichia coli. Other organisms like Vibrio cholera were found in 159 (2.44%) cases, Shigella spp. in 126 (1.93%), Salmonella Typhi in 7 (0.11%), Salmonella Typhimurium in 6 (0.10%), Aeromonas hydrophila in 3 (0.05%) cases. Levels of resistance to nalidixic acid, amoxicillin and ciprofloxacin were alarmingly high. Third generation cephalosporins were seen to be moderately active except against E. coli. Parasites were identified in 312 (4.78%) cases. Giardia intestinalis, Ascaris lumbricoides and Entamoeba histolytica were identified in 2.27%, 1.15% and 0.64% cases respectively.

CONCLUSION

Analysis of recent nationwide studies revealed V. cholerae was the most common bacterial/parasitic agent of diarrhea across all populations, being followed by diarrheagenic E. coli and Giardia intestinalis. Periodic laboratory monitoring of antimicrobial susceptibility pattern is essential, as is formulation of effective antibiotic use policy.

Virulence factors and mechanisms of antimicrobial resistance in Shigella strains from periurban areas of Lima (Peru)

The study was aimed to describe the serotype, mechanisms of antimicrobial resistance, and virulence determinants in Shigella spp. isolated from Peruvian children. Eighty three Shigella spp. were serogrouped and serotyped being established the antibiotic susceptibility. The presence of 12 virulence factors (VF) and integrase 1 and 2, along with commonly found antibiotic resistance genes was established by PCR. S. flexneri was the most relevant serogroup (55 isolates, 66%), with serotype 2a most frequently detected (27 of 55, 49%), followed by S. boydii and S. sonnei at 12 isolates each (14%) and S. dysenteriae (four isolates, 5%). Fifty isolates (60%) were multi-drug resistant (MDR) including 100% of S. sonnei and 64% of S. flexneri. Resistance levels were high to trimethoprim-sulfamethoxazole (86%), tetracycline (74%), ampicillin (67%), and chloramphenicol (65%). Six isolates showed decreased azithromycin susceptibility. No isolate was resistant to nalidixic acid, ciprofloxacin, nitrofurantoin, or ceftriaxone. The most frequent resistance genes were sul2 (95%), tet(B) (92%), cat (80%), dfrA1 (47%), blaOXA-1like (40%), with intl1 and intl2 detected in 51 and 52% of the isolates, respectively. Thirty-one different VF profiles were observed, being the ipaH (100%), sen (77%), virA and icsA (75%) genes the most frequently found. Differences in the prevalence of VF were observed between species with S. flexneri isolates, particularly serotype 2a, possessing high numbers of VF. In conclusion, this study highlights the high heterogeneity of Shigella VF and resistance genes, and prevalence of MDR organisms within this geographic region.

Determination of a Viral Load Threshold To Distinguish Symptomatic versus Asymptomatic Rotavirus Infection in a High-Disease-Burden African Population

We evaluated quantitative real-time PCR to establish the diagnosis of rotavirus gastroenteritis in a high-disease-burden population in Malawi using enzyme immunoassay as the gold standard diagnostic test. In 146 children with acute gastroenteritis and 65 asymptomatic children, we defined a cutoff point in the threshold cycle value (26.7) that predicts rotavirus-attributable gastroenteritis in this population. These data will inform the evaluation of direct and indirect rotavirus vaccine effects in Africa.

The RpoE Stress Response Pathway Mediates Reduction of the Virulence of Enteropathogenic Escherichia coli by Zinc

Zinc supplements are an effective clinical treatment for infantile diarrheal disease caused by enteric pathogens. Previous studies demonstrated that zinc acts on enteropathogenic Escherichia coli (EPEC) bacteria directly to suppress several virulence-related genes at a concentration that can be achieved by oral delivery of dietary zinc supplements. Our in vitro studies showed that a micromolar concentration of zinc induced the envelope stress response and suppressed virulence in EPEC, providing a possible mechanistic explanation for zinc's therapeutic action. In this report, we investigated the molecular and physiological changes in EPEC induced by zinc. We found that micromolar concentrations of zinc reduced the bacterial growth rate without affecting viability. We observed increased membrane permeability caused by zinc. Zinc upregulated the RpoE-dependent envelope stress response pathway and suppressed EPEC virulence gene expression. RpoE alone was sufficient to inhibit virulence factor expression and to attenuate attaching and effacing lesion formation on human host cells. By mutational analysis we demonstrate that the DNA-binding motif of RpoE is necessary for suppression of the LEE1, but not the LEE4, operon. Predictably, inhibition of the RpoE-mediated envelope stress response in combination with micromolar concentrations of zinc reduced EPEC viability. In conclusion, zinc induces the RpoE and stress response pathways in EPEC, and the alternate sigma factor RpoE downregulates EPEC LEE and non-LEE virulence genes by multiple mechanisms.

Enteric bacterial pathogens in children with diarrhea in Niger: diversity and antimicrobial resistance

Background

Although rotavirus is the leading cause of severe diarrhea among children in sub-Saharan Africa, better knowledge of circulating enteric pathogenic bacteria and their antimicrobial resistance is crucial for prevention and treatment strategies.

Methodology/Principal Findings

As a part of rotavirus gastroenteritis surveillance in Maradi, Niger, we performed stool culture on a sub-population of children under 5 with moderate-to-severe diarrhea between April 2010 and March 2012. Campylobacter, Shigella and Salmonella were sought with conventional culture and biochemical methods. Shigella and Salmonella were serotyped by slide agglutination. Enteropathogenic Escherichia coli (EPEC) were screened by slide agglutination with EPEC O-typing antisera and confirmed by detection of virulence genes. Antimicrobial susceptibility was determined by disk diffusion. We enrolled 4020 children, including 230 with bloody diarrhea. At least one pathogenic bacterium was found in 28.0% of children with watery diarrhea and 42.2% with bloody diarrhea. Mixed infections were found in 10.3% of children. EPEC, Salmonella and Campylobacter spp. were similarly frequent in children with watery diarrhea (11.1%, 9.2% and 11.4% respectively) and Shigella spp. were the most frequent among children with bloody diarrhea (22.1%). The most frequent Shigella serogroup was S. flexneri (69/122, 56.5%). The most frequent Salmonella serotypes were Typhimurimum (71/355, 20.0%), Enteritidis (56/355, 15.8%) and Corvallis (46/355, 13.0%). The majority of putative EPEC isolates was confirmed to be EPEC (90/111, 81.1%). More than half of all Enterobacteriaceae were resistant to amoxicillin and co-trimoxazole. Around 13% (46/360) Salmonella exhibited an extended-spectrum beta-lactamase phenotype.

Conclusions

This study provides updated information on enteric bacteria diversity and antibiotic resistance in the Sahel region, where such data are scarce. Whether they are or not the causative agent of diarrhea, bacterial infections and their antibiotic resistance profiles should be closely monitored in countries like Niger where childhood malnutrition pre-disposes to severe and invasive infections.

Gastrointestinal infections and diarrheal disease in Ghanaian infants and children: an outpatient case-control study

Introduction

Diarrheal diseases are among the most frequent causes of morbidity and mortality in children worldwide, especially in resource-poor areas. This case-control study assessed the associations between gastrointestinal infections and diarrhea in children from rural Ghana.

Methods

Stool samples were collected from 548 children with diarrhea and from 686 without gastrointestinal symptoms visiting a hospital from 2007–2008. Samples were analyzed by microscopy and molecular methods.

Results

The organisms most frequently detected in symptomatic cases were Giardia lamblia, Shigella spp./ enteroinvasive Escherichia coli (EIEC), and Campylobacter jejuni. Infections with rotavirus (adjusted odds ratio [aOR] = 8.4; 95% confidence interval [CI]: 4.3–16.6), C. parvum/hominis (aOR = 2.7; 95% CI: 1.4–5.2) and norovirus (aOR = 2.0; 95%CI: 1.3–3.0) showed the strongest association with diarrhea. The highest attributable fractions (AF) for diarrhea were estimated for rotavirus (AF = 14.3%; 95% CI: 10.9–17.5%), Shigella spp./EIEC (AF = 10.5%; 95% CI: 3.5–17.1%), and norovirus (AF = 8.2%; 95% CI 3.2–12.9%). Co-infections occurred frequently and most infections presented themselves independently of other infections. However, infections with E. dispar, C. jejuni, and norovirus were observed more often in the presence of G. lamblia.

Conclusions

Diarrheal diseases in children from a rural area in sub-Saharan Africa are mainly due to infections with rotavirus, Shigella spp./EIEC, and norovirus. These associations are strongly age-dependent, which should be considered when diagnosing causes of diarrhea. The presented results are informative for both clinicians treating gastrointestinal infections as well as public health experts designing control programs against diarrheal diseases.

Gastrointestinal infections are frequent in many low-income countries. However, their role in diarrheal diseases is still under discussion. Many epidemiological studies focus on individuals with diarrheal symptoms only, ignoring the fact that infections may progress asymptomatically as well. In order to identify infectious agents associated with diarrhea it is imperative to consider cases without symptoms as a control group. We conducted a case-control study, including 548 children with diarrhea and 651 children without gastrointestinal symptoms in order to untangle the role of gastrointestinal infections in diarrheal disease. As shown in other studies infections with rotavirus, Shigella spp./EIEC and norovirus are responsible for the main diarrhea burden. Co-infections are frequently observed in our study group and some organisms occur more frequently in the presence of a second one. Especially Giardia lamblia, which is not associated with diarrhea, is more often observed along with Campylobacter jejuni and norovirus, which are responsible for a high number of diarrheal episodes. This may be of particular interest since G. lamblia is, with a frequency of 40% within the study group, the most prevalent organism observed. Furthermore, the high number of co-infections challenged the identification of causative pathogens since diagnosing a particular isolate may not rule out the effect of another potentially infectious agent in diarrheal disease. We observed a strong effect of age on the course of an infection, which may guide clinicians when diagnosing causes of diarrhea.

The burden of norovirus disease in children in the European Union

BACKGROUND

Noroviruses (NoVs) are the leading cause of acute gastroenteritis across all age groups. Because a vaccine is in clinical development, burden of disease data are required to guide the eventual introduction of this vaccine. In this study, we estimate the burden of NoV disease in children less than 5 years of age in the European Union (EU).

METHODS

We carried out a literature search using PubMed to identify studies providing incidence or prevalence data for NoV disease in the EU. We applied the pooled average NoV incidence and prevalence rates to the EU population less than 5 years of age to obtain the annual number of NoV illnesses, medical visits, hospitalizations and deaths occurring in the EU among children younger than 5 years.

RESULTS

Data from 12 studies were included. We estimate that NoV infection may cause up to 5.7 million illnesses in the community, 800,000 medical visits, 53,000 hospitalizations and 102 deaths every year in children younger than 5 years in the EU.

CONCLUSION

The burden of NoV disease in children in the EU is substantial, and will grow in relative importance as rotavirus (RV) vaccines are rolled out in the EU. This burden of disease is comparable with the burden of RV disease in the EU before RV vaccine introduction. More country-specific studies are needed to better assess this burden and guide the potential introduction of a vaccine against NoV at the national level.

Diarrheagenic Escherichia coli phylogroups are associated with antibiotic resistance and duration of diarrheal episode

Conventionally, in Escherichia coli, phylogenetic groups A and B1 are associated with commensal strains while B2 and D are associated with extraintestinal strains. The aim of this study was to evaluate diarrheagenic (DEC) and commensal E. coli phylogeny and its association with antibiotic resistance and clinical characteristics of the diarrheal episode. Phylogenetic groups and antibiotic resistance of 369 E. coli strains (commensal strains and DEC from children with or without diarrhea) isolated from Peruvian children <1 year of age were determined by a Clermont triplex PCR and Kirby-Bauer method, respectively. The distribution of the 369 E. coli strains among the 4 phylogenetic groups was A (40%), D (31%), B1 (21%), and B2 (8%). DEC-control strains were more associated with group A while DEC-diarrhea strains were more associated with group D (P < 0.05). There was a tendency (P = 0.06) for higher proportion of persistent diarrhea (≥14 days) among severe groups (B2 and D) in comparison with nonsevere groups (A and B1). Strains belonging to group D presented significantly higher percentages of multidrug resistance than the rest of the groups (P > 0.01). In summary, DEC-diarrhea strains were more associated with group D than strains from healthy controls.

Structural analysis of a specialized type III secretion system peptidoglycan-cleaving enzyme

The Gram-negative bacterium enteropathogenic Escherichia coli uses a syringe-like type III secretion system (T3SS) to inject virulence or "effector" proteins into the cytoplasm of host intestinal epithelial cells. To assemble, the T3SS must traverse both bacterial membranes, as well as the peptidoglycan layer. Peptidoglycan is made of repeating N-acetylmuramic acid and N-acetylglucosamine disaccharides cross-linked by pentapeptides to form a tight mesh barrier. Assembly of many macromolecular machines requires a dedicated peptidoglycan lytic enzyme (PG-lytic enzyme) to locally clear peptidoglycan. Here we have solved the first structure of a T3SS-associated PG-lytic enzyme, EtgA from enteropathogenic E. coli. Unexpectedly, the active site of EtgA has features in common with both lytic transglycosylases and hen egg white lysozyme. Most notably, the β-hairpin region resembles that of lysozyme and contains an aspartate that aligns with lysozyme Asp-52 (a residue critical for catalysis), a conservation not observed in other previously characterized lytic transglycosylase families to which the conserved T3SS enzymes had been presumed to belong. Mutation of the EtgA catalytic glutamate, Glu-42, conserved across lytic transglycosylases and hen egg white lysozyme, and this differentiating aspartate diminishes type III secretion in vivo, supporting its essential role in clearing the peptidoglycan for T3SS assembly. Finally, we show that EtgA forms a 1:1 complex with the building block of the polymerized T3SS inner rod component, EscI, and that this interaction enhances PG-lytic activity of EtgA in vitro, collectively providing the necessary strict localization and regulation of the lytic activity to prevent overall cell lysis.

Deconstructing the differences: a comparison of GBD 2010 and CHERG's approach to estimating the mortality burden of diarrhea, pneumonia, and their etiologies

Background

Pneumonia and diarrhea are leading causes of death for children under five (U5). It is challenging to estimate the total number of deaths and cause-specific mortality fractions. Two major efforts, one led by the Institute for Health Metrics and Evaluation (IHME) and the other led by the World Health Organization (WHO)/Child Health Epidemiology Reference Group (CHERG) created estimates for the burden of disease due to these two syndromes, yet their estimates differed greatly for 2010.

Methods

This paper discusses three main drivers of the differences: data sources, data processing, and covariates used for modelling. The paper discusses differences in the model assumptions for etiology-specific estimates and presents recommendations for improving future models.

Results

IHME’s Global Burden of Disease (GBD) 2010 study estimated 6.8 million U5 deaths compared to 7.6 million U5 deaths from CHERG. The proportional differences between the pneumonia and diarrhea burden estimates from the two groups are much larger; GBD 2010 estimated 0.847 million and CHERG estimated 1.396 million due to pneumonia. Compared to CHERG, GBD 2010 used broader inclusion criteria for verbal autopsy and vital registration data. GBD 2010 and CHERG used different data processing procedures and therefore attributed the causes of neonatal death differently. The major difference in pneumonia etiologies modeling approach was the inclusion of observational study data; GBD 2010 included observational studies. CHERG relied on vaccine efficacy studies.

Discussion

Greater transparency in modeling methods and more timely access to data sources are needed. In October 2013, the Bill & Melinda Gates Foundation (BMGF) hosted an expert meeting to examine possible approaches for better estimation. The group recommended examining the impact of data by systematically excluding sources in their models. GBD 2.0 will use a counterfactual approach for estimating mortality from pathogens due to specific etiologies to overcome bias of the methods used in GBD 2010 going forward.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0728-4) contains supplementary material, which is available to authorized users.

Prevalence of Non-Nutritive Sucking Habits and Potential Influencing Factors among Children in Urban Communities in Nigeria

BACKGROUND

The use of non-nutritive sucking materials like pacifiers and fingers poses health challenges to children in resource-limited settings, where hygiene practices and provision of clean water are poor. This study was designed to determine the prevalence of non-nutritive sucking habits and its association with acute diarrhea in children aged 6-23 months in urban communities of Nigeria.

METHODS

In this cross-sectional study, 12 communities from 4 out of 12 geopolitical wards in Ibadan North Local Government Area and 427 mothers of children aged 6-24 months were randomly selected. A pre-tested, interviewer-administered questionnaire was used to obtain information on socio-demographic characteristics, recent history of diarrhea (3 months prior to visit) and use of non-nutritive sucking materials. Descriptive statistics, Chi-square, and logistic regression were used for data analysis at p = 0.05.

RESULTS

Mean age of the children was 13.9 ± 5.3 months and 50.6% were males. Prevalence of non-nutritive sucking was 45.2%. Prevalence of non-nutritive sucking was not significantly different between males (45.8%) and females (44.5%). The odds ratio of engaging in non-nutritive sucking increases by 6.0% with increasing age (OR = 1.06; 1.02; 1.10). More children who were not exclusively breastfed (53.5%) than exclusively breastfed (26.2%) were likely to engage in non-nutritive sucking (OR = 3.25; 95% CI = 2.07, 5.12). Acute diarrhea was more frequently reported in non-nutritive sucking group than the other (OR = 1.51; 95% CI = 1.03, 2.22).

CONCLUSION

Non-nutritive sucking was linked with failure to practice exclusive breastfeeding, worse with increasing age, and predisposes to acute diarrhea. Further studies are necessary to verify the nature of these associations.

Recommendations regarding the development of combined enterotoxigenic Eschericha coli and Shigella vaccines for infants

PATH hosted a workshop on October 14 and 15, 2013 in Washington, DC to solicit expert opinions on the potential merits and challenges of developing combined enterotoxigenic Escherichia coli (ETEC) and Shigella vaccine products to benefit children in developing countries. This article summarizes the key issues raised during the workshop and provides an analysis of the recommendations regarding the strategic, clinical and regulatory, and manufacturing considerations for the development of a combined enteric vaccine, which aim to guide future vaccine development efforts and donor investment strategies in this area. Notwithstanding the potential technical, legal, financial, and other constraints that would be faced in developing a combined ETEC/Shigella vaccine, it is clear that this is the preferred approach over standalone products. There are many advantages to a combined vaccine, such as the potential cost-effectiveness and easier logistics of introducing a combined vaccine instead of two standalone vaccines in low-resource, endemic countries.

Presence of Shiga toxin 2e-producing Escherichia coli and atypical enteropathogenic E. coli in an asymptomatic child

Introduction:

Escherichia coli causes gastroenteritis in humans and animals.

Case presentation:

In this study, both Shiga toxin-producing E. coli (STEC) and atypical enteropathogenic E. coli (EPEC) strains were identified in a stool sample from a healthy child, and they were serotyped as Shiga toxin-producing E. coli (STEC) ONT : H19 and atypical enteropathogenic E. coli (EPEC) O37 : H45.

Conclusion:

This is the first report, to our knowledge, of a concomitant presence of diarrhoeagenic E. coli (DEC) strains in an asymptomatic child. None of the microorganisms was able to produce diarrhoea, maybe because they were transient bacteria or because of the good immune status of the child. Attention should be paid to this result and it could be of interest in vaccine prospects.

Aetiology, epidemiology and clinical characteristics of acute moderate-to-severe diarrhoea in children under 5 years of age hospitalized in a referral paediatric hospital in Rabat, Morocco

The objective of the study was to describe the aetiology, epidemiology and clinical characteristics of the principal causes of acute infectious diarrhoea requiring hospitalization among children under 5 years of age in Rabat, Morocco. A prospective study was conducted from March 2011 to March 2012, designed to describe the main pathogens causing diarrhoea in hospitalized children >2 months and less than 5 years of age. Among the 122 children included in the study, enteroaggregative Escherichia coli (EAEC) and rotavirus were the main aetiological causes of diarrhoea detected. Twelve (9.8 %) children were referred to an intensive care unit, while two, presenting infection by EAEC, and EAEC plus Shigella sonnei, developed a haemolytic uraemic syndrome. Additionally, six (4.9 %) deaths occurred, with EAEC being isolated in four of these cases. Diarrhoeagenic E. coli and rotavirus play a significant role as the two main causes of severe diarrhoea, while other pathogens, such as norovirus and parasites, seem to have a minimal contribution. Surveillance and prevention programmes to facilitate early recognition and improved management of potentially life-threatening diarrhoea episodes are needed.

Community based case-control study of rotavirus gastroenteritis among young children during 2008-2010 reveals vast genetic diversity and increased prevalence of G9 strains in Kolkata

BACKGROUND

Group A Rotaviruses are a major etiologic agent of gastroenteritis in infants and young children (<5 years) worldwide. Although rotavirus vaccines have been successfully administered in many countries, in India the introduction of rotavirus vaccine in national immunization program was approved in 2014. Since high disease burden and large number of genetic variants have been reported from low income countries including India, monitoring of rotavirus was initiated prior to implementation of the vaccine in the region.

METHODS

A total number of 3,582 stool samples were collected from an urban slum community in Kolkata, among which 1,568 samples were obtained from children of ≤ 5 years of age, with moderate to severe diarrhoea and 2,014 samples were collected from age-sex matched healthy neighbourhood controls. Rotavirus positive samples were typed by multiplex semi-nested PCR and nucleotide sequencing. Circulating strains were phylogenetically analyzed.

RESULTS

Among 1,568 children with diarrhoea, 395 (25.2%), and among 2,014 asymptomatic children, 42 (2%) were rotavirus positive. G1P[8] was identified as the most common strain (32%) followed by G9P[8] (16.9%), G2P[4] (13.5%) and G9P[4] (10.75%). G12 strains with combinations of P[4], P[6] and P[8] comprised 11.9% of total positive strains. The rest (<10%) were rare and uncommon strains like G1P[4], G1P[6], G2P[8] and animal-like strains G4P[6], G6P[14] and G11P[25]. The 42 rotavirus positive samples from asymptomatic children revealed common genotypes like G1, G2 and G9.

CONCLUSION

This community based case-control study showed increased predominance of genotype G9 in Kolkata. It also confirmed co-circulation of a large number of genetic variants in the community. Asymptomatic rotavirus positive children though low in number can also be a source of dispersal of infection in the community. This study provides background information to the policy makers for implementation of rotavirus vaccines in this region.