Virological and Epidemiological Features of Norovirus Infections in Brazil, 2017-2018.

Noroviruses are considered an important cause of acute gastroenteritis (AGE) across all age groups. Here, we investigated the incidence of norovirus, genotypes circulation, and norovirus shedding in AGE stool samples from outpatients in Brazil. During a two-year period, 1546 AGE stool samples from ten Brazilian states were analyzed by RT-qPCR to detect and quantify GI and GII noroviruses. Positive samples were genotyped by dual sequencing using the ORF1/2 junction region. Overall, we detected norovirus in 32.1% of samples, with a massive predominance of GII viruses (89.1%). We also observed a significant difference between the median viral load of norovirus GI (3.4×105 GC/g of stool) and GII (1.9×107 GC/g). The most affected age group was children aged between 6 and 24 m old, and norovirus infection was detected throughout the year without marked seasonality. Phylogenetic analysis of partial RdRp and VP1 regions identified six and 11 genotype combinations of GI and GII, respectively. GII.4 Sydney[P16] was by far the predominant genotype (47.6%), followed by GII.2[P16], GII.4 Sydney[P31], and GII.6[P7]. We detected, for the first time in Brazil, the intergenogroup recombinant genotype GIX.1[GII.P15]. Our study contributes to the knowledge of norovirus genotypes circulation at the national level, reinforcing the importance of molecular surveillance programs for future vaccine designs.

Human Norovirus Proteins: Implications in the Replicative Cycle, Pathogenesis, and the Host Immune Response.

Human noroviruses (HuNoVs) are the cause of more than 95% of epidemic non-bacterial gastroenteritis worldwide, with some lethal cases. These viral agents affect people of all ages. However, young children and older adults are the highest-risk groups, being affected with the greatest rate of hospitalizations and morbidity cases. HuNoV structural proteins, especially VP1, have been studied extensively. In contrast, the functions of the non-structural proteins of the virus have been undescribed in depth. Studies on HuNoV non-structural proteins have mostly been made by expressing them individually in in vitro cultures, providing insights of their functions and the role that they play in HuNoV replication and pathogenesis. This review examines exhaustively the functions of both HuNoV structural and non-structural proteins and their possible role within the viral replicative cycle and the pathogenesis of the virus. It also highlights recent findings regarding the host's innate and adaptive immune responses against HuNoV, which are of great relevance for diagnostics and vaccine development so as to prevent infections caused by these fastidious viruses.

Viral uptake and stability in Crassostrea gigas oysters during depuration, storage and steaming.

More stable than bacteria in environmental samples, enteric viruses are generally related to outbreaks of gastroenteritis caused by the consumption of contaminated oysters. This study evaluated: i) the dynamic processes of enteric viral models bioaccumulation by Crassostrea gigas oysters artificially contaminated; ii) the stability of these viruses in oysters in controlled temperature conditions and iii) the effect of UV light in inactivating these viruses in depurated oysters. Plaque assay (PA) was used to assess the infectivity of both viral models. Cell culture coupled with RT-qPCR (ICC-RT-qPCR) was used to measure infectious adenovirus type 2 (HAdV-2) genomes and qPCR to measure genome copies of murine norovirus (MNV-1). The virus uptake through bioaccumulation behave differently: HAdV-2 reached its peak of uptake faster than MNV-1. Both viruses showed high stability in oysters when maintained under 4 °C, but were completely inactivated in steamed oysters. The HAdV-2 was completely inactivated after 12 h of depuration with UV light and after 24 h without UV light. After 72 h of depuration, MNV-1 was still detected in both tanks, probably due to the stronger interaction of this virus with the oyster's tissues. This study demonstrated the importance of a secure depuration time in ensuring a clean and safe product, and that the steaming process is the safest way to prepare oysters for consumption.

Norovírus no município de São Paulo, 2010-2016: estudo transversal sobre a principal causa de gastroenterite infantil / Norovirus en el Municipio de São Paulo, Brasil, 2010-2016: estudio transversal sobre la principal causa de gastroenteritis infantil / Norovirus in São Paulo city, Brazil, 2010-2016: a cross-sectional study of the leading cause of gastroenteritis in children

Objetivo: descrever casos de doença diarreica aguda por norovírus em crianças menores de 5 anos do município de São Paulo, Brasil. Métodos: estudo transversal com dados provenientes da Vigilância Epidemiológica das Gastroenterites Causadas por Rotavírus; foi definido como caso o paciente internado em unidade sentinela por doença diarreica aguda e identificação laboratorial do norovírus como agente etiológico, entre os anos de 2010 e 2016. Resultados: durante o período estudado, a proporção de casos de norovírus em menores de 5 anos de idade ultrapassou a proporção de casos de rotavírus, agente considerado predominante na infância; o norovírus foi associado a 28,4% do total de casos notificados, ocorrendo o ano todo, principalmente nos meses mais quentes. Conclusão: norovírus foi o principal agente etiológico identificado em crianças menores de 5 anos com doença diarreica aguda no município de São Paulo.

Objetivo: describir casos de enfermedad diarreica aguda por Norovirus en niños menores de 5 años provenientes del Municipio de São Paulo, Brasil. Métodos: Estudio transversal con datos de la Vigilancia Epidemiológica de las Gastroenteritis causadas por Rotavirus. Se definió como caso el paciente internado en unidad centinela por enfermedad diarreica aguda e identificación de laboratorio del Norovirus como agente etiológico entre los años de 2010 y 2016. Resultados: Durante el período estudiado, la proporción de casos de Norovirus en menores de 5 años superó la proporción de casos de Rotavirus, agente considerado predominante en la infancia. El Norovirus fue asociado al 28,4% del total de los casos notificados, ocurriendo todo el año, principalmente en los meses más cálidos. Conclusión: el Norovirus fue el principal agente etiológico identificado en niños menores de 5 años con enfermedad diarreica aguda en el Municipio de São Paulo.

Objective: to describe cases of acute diarrheal disease caused by norovirus in children under 5 years old in São Paulo city, Brazil. Methods: this was a cross-sectional study using data from Epidemiological Surveillance of Gastroenteritis due to Rotavirus; cases were defined as patients hospitalized in a sentinel unit because of acute diarrheal disease and laboratory identification of norovirus as the etiological agent between 2010 and 2016. Results: during the study period, the proportion of norovirus cases in children under 5 years old exceeded the proportion of Rotavirus, an agent considered predominant in childhood; norovirus was associated with 28.4% of total reported cases, occurring all year round, especially in warmer months. Conclusion: norovirus was the leading etiological agent identified in children under 5 years old with acute diarrheal disease in São Paulo city.

Asymptomatic norovirus infection associated with swimming at a tropical beach: A prospective cohort study.

BACKGROUND: Swimming in fecally-contaminated waterbodies can result in gastrointestinal infections. However, the pathogenic microorganisms responsible are not well understood because sporadic cases of illness are not reported completely, exposure information is often not collected, and epidemiology studies rely on self-reported symptoms. Noroviruses are considered a likely cause because they are found in high densities in sewage, resistant to wastewater treatment and survive in the environment. In this study, saliva samples were collected from subjects at a beach in Puerto Rico and tested for evidence of norovirus-specific IgG responses as an indicator of incident norovirus infection. METHODS: Saliva samples were collected from 1298 participants using an oral swab. Samples were collected on the day of the beach visit (S1); after 10-12 days (S2); and after three weeks (S3). Saliva was tested for IgG responses to GI.1 and GII.4 noroviruses using a microsphere based multiplex salivary immunoassay. Immunoconversion was defined as a four-fold increase in median fluorescence intensity (MFI) from S1 to S2 with the S3 sample at least three times above the S1 MFI. RESULTS: Thirty-four subjects (2.6%) immunoconverted to GI.1 or GII.4 norovirus. Swimmers who immersed their head in water had a higher rate of immunoconversion (3.4%), compared to either non-swimmers (0.0%, p = 0.003) or waders and non-swimmers combined (0.4%, Odds Ratio: 5.07, 95% Confidence Interval:1.48-17.00). Immunoconversion was not associated with gastrointestinal symptoms. CONCLUSIONS: This is the first study to demonstrate an association between swimming at a beach impacted by fecal contamination and asymptomatic norovirus infection. The findings implicate recreational water as potentially important transmission pathway for norovirus infection.

Norovirus vaccines under development.

Noroviruses (NoVs) are one of the leading causes of acute gastroenteritis, including both outbreaks and endemic infections. The development of preventive strategies, including vaccines, for the most susceptible groups (children <5years of age, the elderly and individuals suffering crowding, such as military personnel and travelers) is desirable. However, NoV vaccine development has faced many difficulties, including genetic/antigenic diversity, limited knowledge on NoV immunology and viral cycle, lack of a permissive cell line for cultivation and lack of a widely available and successful animal model. Vaccine candidates rely on inoculation of virus-like particles (VLPs) formed by the main capsid protein VP1, subviral particles made from the protruding domain of VP1 (P-particles) or viral vectors with a NoV capsid gene insert produced by bioengineering technologies. Polivalent vaccines including multiple NoV genotypes and/or other viruses acquired by the enteric route have been developed. A VLP vaccine candidate has reached phase II clinical trials and several others are in pre-clinical stages of development. In this article we discuss the main challenges facing the development of a NoV vaccine and the current status of prevailing candidates.

Change in physical and chemical characteristics related to the binomial time-temperature used in sous pasteurization see Tambaqui (Colossoma macropomum) / Variação das características físico-químicas relacionadas ao binômio tempo-temperatura utilizado na pasteurização de sous vide de tambaqui (Colossoma macropomum)

The goal of this study was to evaluate sous vide fish and assess the influence of time and temperature on the pasteurization process through quality parameters. The raw material (tambaqui fillets) and the sous vide underwent physical, physicochemical, and microbiological analyses. A sauce was prepared containing soy sauce, water, horseradish and garlic flakes. The product's pasteurization parameters of time and temperature were defined according to a 22 central composite rotatable design (CCRD), and the dependent variables were water holding capacity (WHC) and instrumental texture aiming at obtaining high WHC values for the product to maintain the desired juiciness. The microbiological analysis required by legislation have indicated that the fish fillets and sous vide were within de standard. The values of total coliforms found in the samples (fillets and sous vide) analyzed were below the critical level of 10² CFU/g. The counts of sulphite-reducing clostridia and psychrotrophic and mesophilic bacteria on plates in the samples were <1x10 CFU/g. In conclusion, temperature was the most important factor in the pasteurization process, significantly contributing to the quality of the final product. The mathematical models proposed were considered predictive for each response.

O objetivo deste estudo foi avaliar a influência do tempo e da temperatura no processo de pasteurização do sous vide de peixe por meio dos parâmetros de qualidade. Foram realizadas análises físicas, físico-químicas e microbiológicas na matéria-prima (filé de tambaqui) e no sous vide. Foi preparado um molho contendo molho de soja, água, raiz forte e flocos de alho. Parâmetros de pasteurização do produto (tempo x temperatura) foram definidos de acordo com um projeto de 2x2 rotativo composto central (DRCC), e as variáveis dependentes foram capacidade de retenção de água (CRA) e textura instrumental, visando à obtenção de altos valores de CRA para que o produto obtivesse a suculência desejada. As análises microbiológicas exigidas na legislação indicaram que a matéria-prima e o sous vide encontravam-se dentro dos padrões estabelecidos. Os valores de coliformes totais encontrados nas amostras (filés e sous vide) analisadas foram inferiores ao nível crítico de 10² UFC/g. As contagens de clostrídios sulfitorredutores e bactérias psicrotróficas e mesófilas em placas nas amostras foram <1x10 UFC/g. Concluiu-se que a temperatura foi o fator mais importante no processo de pasteurização, contribuindo de forma significativa para a qualidade do produto final. Os modelos matemáticos propostos foram preditivos para cada resposta.

Change in physical and chemical characteristics related to the binomial time-temperature used in sous pasteurization see Tambaqui (Colossoma macropomum) / Variação das características físico-químicas relacionadas ao binômio tempo-temperatura utilizado na pasteurização de sous vide de tambaqui (Colossoma macropomum)

The goal of this study was to evaluate sous vide fish and assess the influence of time and temperature on the pasteurization process through quality parameters. The raw material (tambaqui fillets) and the sous vide underwent physical, physicochemical, and microbiological analyses. A sauce was prepared containing soy sauce, water, horseradish and garlic flakes. The product's pasteurization parameters of time and temperature were defined according to a 22 central composite rotatable design (CCRD), and the dependent variables were water holding capacity (WHC) and instrumental texture aiming at obtaining high WHC values for the product to maintain the desired juiciness. The microbiological analysis required by legislation have indicated that the fish fillets and sous vide were within de standard. The values of total coliforms found in the samples (fillets and sous vide) analyzed were below the critical level of 10² CFU/g. The counts of sulphite-reducing clostridia and psychrotrophic and mesophilic bacteria on plates in the samples were <1x10 CFU/g. In conclusion, temperature was the most important factor in the pasteurization process, significantly contributing to the quality of the final product. The mathematical models proposed were considered predictive for each response.(AU)

O objetivo deste estudo foi avaliar a influência do tempo e da temperatura no processo de pasteurização do sous vide de peixe por meio dos parâmetros de qualidade. Foram realizadas análises físicas, físico-químicas e microbiológicas na matéria-prima (filé de tambaqui) e no sous vide. Foi preparado um molho contendo molho de soja, água, raiz forte e flocos de alho. Parâmetros de pasteurização do produto (tempo x temperatura) foram definidos de acordo com um projeto de 2x2 rotativo composto central (DRCC), e as variáveis dependentes foram capacidade de retenção de água (CRA) e textura instrumental, visando à obtenção de altos valores de CRA para que o produto obtivesse a suculência desejada. As análises microbiológicas exigidas na legislação indicaram que a matéria-prima e o sous vide encontravam-se dentro dos padrões estabelecidos. Os valores de coliformes totais encontrados nas amostras (filés e sous vide) analisadas foram inferiores ao nível crítico de 10² UFC/g. As contagens de clostrídios sulfitorredutores e bactérias psicrotróficas e mesófilas em placas nas amostras foram <1x10 UFC/g. Concluiu-se que a temperatura foi o fator mais importante no processo de pasteurização, contribuindo de forma significativa para a qualidade do produto final. Os modelos matemáticos propostos foram preditivos para cada resposta.(AU)

Llama nanoantibodies with therapeutic potential against human norovirus diarrhea.

Noroviruses are a major cause of acute gastroenteritis, but no vaccines or therapeutic drugs are available. Llama-derived single chain antibody fragments (also called VHH) are small, recombinant monoclonal antibodies of 15 kDa with several advantages over conventional antibodies. The aim of this study was to generate recombinant monoclonal VHH specific for the two major norovirus (NoV) genogroups (GI and GII) in order to investigate their potential as immunotherapy for the treatment of NoV diarrhea. To accomplish this objective, two llamas were immunized with either GI.1 (Norwalk-1968) or GII.4 (MD2004) VLPs. After immunization, peripheral blood lymphocytes were collected and used to generate two VHH libraries. Using phage display technology, 10 VHH clones specific for GI.1, and 8 specific for GII.4 were selected for further characterization. All VHH recognized conformational epitopes in the P domain of the immunizing VP1 capsid protein, with the exception of one GII.4 VHH that recognized a linear P domain epitope. The GI.1 VHHs were highly specific for the immunizing GI.1 genotype, with only one VHH cross-reacting with GI.3 genotype. The GII.4 VHHs reacted with the immunizing GII.4 strain and showed a varying reactivity profile among different GII genotypes. One VHH specific for GI.1 and three specific for GII.4 could block the binding of homologous VLPs to synthetic HBGA carbohydrates, saliva, and pig gastric mucin, and in addition, could inhibit the hemagglutination of red blood cells by homologous VLPs. The ability of Nov-specific VHHs to perform well in these surrogate neutralization assays supports their further development as immunotherapy for NoV treatment and immunoprophylaxis.

Norovirus prevalence in 'pathogen negative' gastroenteritis in children from periurban areas in Lima, Peru.

Norovirus was detected in 17.4% of 224 diarrhoeal samples from children younger than 24 months of age in Lima, in whom all common pathogens had been excluded (pathogen negative). Norovirus was identified more frequently in children older than 12 months of age than in younger children (34% vs 8%, P<0.001). Among norovirus-positive samples, genogroup II was the predominant group (92%). Compared with rotavirus, norovirus episodes tended to be of shorter duration and less severe. The role of norovirus as a cause of diarrhoea and the ascertainment of its severity in developing countries needs further confirmation by future epidemiological studies.

Norovirus: an overview.

Although noroviruses (NoVs) were the first viral agents linked to gastrointestinal disease, for a long time they have been considered secondary cause of gastroenteritis, second to rotaviruses as etiologic agents. The development of molecular techniques in diagnosing NoV provided a clearer insight into the epidemiological impact of these viruses, which are currently recognized not only as the leading cause of non-bacterial gastroenteritis outbreaks, but also as a major cause of sporadic gastroenteritis in both children and adults. This review focuses on the required knowledge to understand their morphology, genetics, transmission, pathogenesis, and control. Since no vaccine is available, prevention of NoV infection relies mainly on strict community and personal hygiene measures.

Norovírus: uma visão geral / Norovirus: an overview

Os norovírus (NoV) foram os primeiros agentes virais ligados à doença gastrointestinal, entretanto, eles foram, por muito tempo, considerados como causa secundária de gastroenterite, após os rotavírus. O desenvolvimento de técnicas moleculares voltadas ao diagnóstico dos NoV forneceu dados mais claros sobre o impacto epidemiológico desses vírus, os quais são, atualmente, reconhecidos não apenas como principal causa de surtos de gastroenterite não bacteriana, mas também como causa importante de gastroenterite esporádica em crianças e adultos. Esta revisão enfoca os conhecimentos necessários para compreender a sua morfologia, genética, transmissão, patogênese e controle. Uma vez que não há vacina disponível, a prevenção da infecção por NoV depende principalmente de medidas de higiene da comunidade e pessoais.

Although noroviruses (NoVs) were the first viral agents linked to gastrointestinal disease, for a long time they have been considered secondary cause of gastroenteritis, second to rotaviruses as etiologic agents. The development of molecular techniques in diagnosing NoV provided a clearer insight into the epidemiological impact of these viruses, which are currently recognized not only as the leading cause of non-bacterial gastroenteritis outbreaks, but also as a major cause of sporadic gastroenteritis in both children and adults. This review focuses on the required knowledge to understand their morphology, genetics, transmission, pathogenesis, and control. Since no vaccine is available, prevention of NoV infection relies mainly on strict community and personal hygiene measures.

Concurrent outbreak of norovirus genotype I and enterotoxigenic Escherichia coli on a U.S. Navy ship following a visit to Lima, Peru.

An outbreak of norovirus (NoV) genotype I and Enterotoxigenic Escherichia coli (ETEC) occurred among US Navy Ship personnel following a visit to Lima, Peru, in June 2008. Visiting a specific area in Lima was significantly associated with illness. While ETEC and NoV are commonly recognized as causative agents of outbreaks, co-circulation of both pathogens has been rarely observed in shipboard outbreaks.

Asymptomatic norovirus infections in Nicaraguan children and its association with viral properties and histo-blood group antigens.

BACKGROUND: It has been previously reported that histo-blood group antigens (HBGAs) and particularly secretor status provides protection against symptomatic norovirus infection, but it remains unclear to what extent this includes asymptomatic infections in children. METHODS: To explore whether HBGAs or certain viral genotypes are associated with asymptomatic norovirus infections in a pediatric population in Nicaragua, we investigated 163 children ≤5 years of age, without a recent history of diarrhea (≤10 days). RESULTS: Asymptomatic norovirus infections were observed in 11.7% (19/163), with children ≤6 months of age being most frequently infected (16%). Of the 19 norovirus-positive children, 4 (21%) and 10 (53%) were infected with genogroups GI and GII, respectively, and 4 children (21%) were infected with viruses of both genogroups. Most children had ≥10 viral genomes per gram of feces. Nucleotide sequence analysis (15/19) revealed uncommon genotypes, such as, GII.7 (n = 5) and GII.2 (n = 3). An interesting observation was the low frequency of norovirus GII.4 strains among the asymptomatic children. AB blood type, Lewis a (Le) phenotype and nonsecretor genotype (sese) were not found among the asymptomatic children, but they occurred in population controls. CONCLUSIONS: Frequency of asymptomatic norovirus infections was similar to that observed in symptomatic children from Nicaragua. Norovirus GII.2 and GII.7 were frequently detected but the globally dominating GII.4 was infrequent. Host genetic factors previously observed to be associated with protection against symptomatic norovirus infection were not found in this study.

Infecciones virales intestinales en pediatría / Intestinal viral infections in pediatrics

Los virus que causan diarrea en humanos generalmente muestran gran trofismo por las células epiteliales del intestino delgado. El mecanismo tradicionalmente aceptado es que estos agentes causan enfermedad destruyendo gran cantidad de entericitos maduros, (sea por lisis directa o induciendo la apoptosis) los que son reemplazados por células inmaduras provenientes de las criptas. Esto lleva a una absorción inadecuada de agua, electrolitos y nutrientes, con capacidad conservada de secretar cloro y agua. A diferencia de lo que ocurre frente a patógenos bacterianos invasores, la respuesta inflamatoria del huésped es leve y no contribuye significativamente en el mecanismo de la diarrea viral. Estudios posteriores han llevado a postular mecanismos adicionales, que no serían autoexcluyentes. Se ha descrito que algunas proteínas virales no estructurales actuarían como enterotoxina. Además, jugaría un rol la alteración de las uniones estrechas con aumento del flujo paracelular de agua y electrolitos, el aumento de la secreción intestinal mediada por neurotransmisores, y la microisquemia vellositaria. El impacto de la enteritis viral es mayor y la recuperación más lenta en niños previamente desnutridos. Se ha demostrado en animales de experimentación desnutridos un notorio retraso en la recuperación de la capacidad enzimática y absortiva de la mucosa intestinal frente a una enteritis viral, lo que refuerza la necesidad de una temprana y efectiva rehabilitación nutricional durante los episodios agudos de diarrea. Es ampliamente conocido que la lactancia materna, disminuye la incidencia y severidad de las diarreas virales en niños, los primeros meses de vida.

Viruses that cause diarrhea in humans generally show great tropism due to epithelial cells of the small intestine. The traditionally accepted mechanism is that these agents cause illness by destroying large number of mature enterocytes (via direct lysis or by inducing apoptosis), which are replaced by immature cells coming from the crypts. This leads to an inadequate absorption of water, electrolytes and nutritients with conserved chloride and water secretion. In contrast to invasive bacterial pathogens, the host infl amatory response is mild and it does not contribute significantly to the mechanism of viral diarrhea. Subsequent studies have leaded to postulate additional mechanisms that would not exclude each other. It has been described that some non-structural viral proteins may act as enterotoxin. In addition, the alteration of the tight junctions with an enhanced paracellular flow of water and electrolytes, the increase of neurotransmitter mediated intestinal secretion, and the micro-ischemia of villi would also play a role. The impact of viral enteritis is larger and the recovery slower in previously undernourished children. Studies carried out on undernourished experimentation animals have demonstrated a notorious delay in the recovery of the enzymaticand absorptive capacity of intestinal mucosa after viral enteritis, which reinforces the need for early and effective nutritional rehabilitation during episodes of acute diarrhea. It is well-known that the breastfeeding reduces the incidence and severity of viral diarrheas in children during the first months of life.

Enteritis virales en adultos inmunocompetentes, agentes clásicos y emergentes / Viral enteritis in immunocompetent adults: classic and emergent agents

Objetivo: Revisar aspectos epidemiológicos y clínicos de las enteritis de etiología viral en pacientes adultos inmunocompetentes. Resumen: La diarrea aguda infecciosa (enteritis) es una patología relevante en todo el mundo y aún es responsable de una alta mortalidad en niños y elevada morbilidad en adultos. En pacientes adultos inmunocompetentes la etiología viral es frecuentemente subestimada aunque la mayoría de las enteritis agudas son causadas por virus. Los agentes virales más frecuentemente identificados son el Norovirus, Rotavirus, Astrovirus, y Adenovirus. Su principal vía de contagio es la ruta fecal-oral y el cuadro clínico suele ser en su gran mayoría leve y autolimitado, con manifestaciones clínicas similares e inespecíficas: diarrea acuosa, náuseas, vómitos y dolor abdominal. Adultos mayores y pacientes inmunosuprimidos pueden presentar cuadros más severos y prolongados. El tratamiento es fundamentalmente sintomático. La prevención se basa en tomar medidas sanitarias y limitar el contagio de persona a persona. Virus respiratorios emergentes como SARS e InfluenzaA-H1N1, con frecuencia comprometen el tracto gastrointestinal y en períodos de epidemia deben ser considerados en el diagnóstico diferencial de enteritis aguda.

Objective: To review epidemiological and clinical aspects of viral enteritis in immunocompetent adult patients. Abstract: Acute infectious diarrhea (enteritis) is a worldwide important disease and it still accounts for high mortality among children and high morbidity among adults. In immunocompetent adult patients the viral etiology is frequently underestimated, although the most common cause of acute enteritis is avirus. The mos frequently identified viral agents are Norovirus, Rotavirus, Astrovirus, and Adenovirus. The main mechanism of spread of the disease is fecal-oral transmission and the clinical setting is commonly mild and self-limited, with clinical manifestations that are similar and unspecific: aqueous diarrhea, nausea, vomiting and abdominal pain. Elderly and immunosupressed patients may show more severe and prolonged episodes. Treatment is mainly symptomatic. Prevention is based on taking sanitary measures and reducing person-to-person transmission. Emerging respiratory viruses as SARS and A-H1N1 influenza frequently compromise the gastrointestinal tract and during epidemic periods these viruses should be considered in differential diagnosis of acute enteritis.

Genetic susceptibility to symptomatic norovirus infection in Nicaragua.

Host genetic resistance to Norovirus (NoV) has been observed in challenge and outbreak studies in populations from Europe, Asia, and USA. In this study, we have investigated if histo-blood group antigens can predict susceptibility to diarrhea caused by NoV in Nicaragua, Central America, and if this can be reflected in antibody-prevalence and titer to NoV among individuals with different histo-blood group antigen phenotypes. Investigation of 28 individuals infected with NoV and 131 population controls revealed 6% of non-secretors in the population and nil non-secretors among patients infected with NoV, suggesting that non-secretors may be protected against NoV disease in Nicaragua. Surprisingly, 25% of the population was Lewis negative (Le(a-b-)). NoV infections with genogroup I (GI) and GII occurred irrespective of Lewis genotype, but none of the Lewis a positive (Le(a + b-)) were infected. The globally dominating GII.4 virus infected individuals of all blood groups except AB (n = 5), while the GI viruses (n = 4) infected only blood type O individuals. Furthermore, O blood types were susceptible to infections with GI.4, GII.4, GII.7, GII.17, and GII.18-Nica viruses, suggesting that secretors with blood type O are susceptible (OR = 1.52) and non-secretors resistant. The overall antibody-prevalence to NoV GII.3 VLP was 62% with the highest prevalence among blood type B carriers (70%) followed by A (68%) and O (62%). All four investigated individuals carrying blood type AB were antibody-negative. Among secretors, 63% were antibody-positive compared to 33% among non-secretors (P = 0.151). This study extends previous knowledge about the histo-blood group antigens role in NoV disease in a population with different genetic background than North American and European.

Norovirus infection among children with acute gastroenteritis in Recife, Brazil: disease severity is comparable to rotavirus gastroenteritis.

Norovirus has captured increasing attention as an agent of childhood diarrhoea. However, it is not known whether norovirus causes as severe diarrhoea as rotavirus, particularly among children in developing countries. In a 1-year study conducted between May 2004 and April 2005 in Recife, Brazil, norovirus was detected by ELISA in 34/233 (15%) diarrhoeal children less than 5 years of age. The severity of clinical illness, as indicated by the presence of dehydration, the requirement for hospitalization, and the duration of hospital stay, was similar between children with norovirus and rotavirus infection. These data underscore the importance of norovirus as a cause of severe diarrhoea in children.