Norovirus outbreaks in a nursery school in Buenos Aires, Argentina.

Norovirus (NoV) is the leading cause of outbreaks of acute gastroenteritis worldwide. These are non-enveloped viruses that are classified into 10 genogroups, of which genogroup I (GI), II (GII), IV (GIV), VIII (GVIII), and IX (GIX) are the ones that infect humans. Two outbreaks (A and B) of acute gastroenteritis that occurred in a nursery school are described. The first outbreak (A) occurred in November 2018, and the second (B) in February 2020. The detection of viral and bacterial pathogens was performed to study both outbreaks. Additionally, an epidemiological investigation of the outbreaks was conducted. In the analyzed fecal and vomit samples from both children and adults in the nursery school, NoV GII.4 [P16] Sydney 2012 and NoV GI.3 [P13] were detected in outbreaks A and B, respectively. Since the study of acute gastroenteritis outbreaks is underestimated in Argentina, it is necessary to design prevention, study, and control protocols, as well as to improve the outbreak notification system in our country.

Association between detection rate of norovirus GII and climatic factors in the Northwest Amazon region.

Worldwide, approximately one fifth of all cases of diarrhea are associated with norovirus, mainly in children, with a defined seasonality in temperate climates, but seasonal dynamics are less known in tropical climates. The objective was to investigate the impact of external clinical, epidemiological, and climatic factors on norovirus detection rates in samples from children under 5 years of age from Roraima, the Amazon region of Brazil. A total of 941 samples were included. According to climatic factors, we observed correlations between external climatic factors and weekly positivity rates, where temperature (P = 0.002), relative humidity (P = 0.0005), absolute humidity (P < 0.0001) and wind speed had the strongest effect (P = 0.0006). The Brazilian Amazon region presents a typical and favorable scenario for the persistence, expansion, and distribution of viral gastroenteritis. Importance: This study is important as it will serve as a basis for studies carried out in Brazil and Latin American countries on the epidemiological importance, seasonality, climate change, antigenic diversity, among other factors in the circulation of gastroenteric virus.

Analysis of viral diversity in dogs with acute gastroenteritis from Brazilian Amazon.

Viral gastroenteritis is commonly reported in dogs and involves a great diversity of enteric viruses. In this research, viral diversity was investigated in dogs with diarrhea in Northern Brazil using shotgun metagenomics. Furthermore, the presence of norovirus (NoV) was investigated in 282 stool/rectal swabs of young/adult dogs with or without diarrhea from two public kennels, based on one-step reverse transcription polymerase chain reaction (RT-PCR) for genogroup VI and VII (GVI and GVII) and real-time RT-PCR for GI, GII, and GIV. Thirty-one viral families were identified, including bacteriophages. Phylogenetic analyses showed twelve complete or nearly complete genomes belonging to the species of Protoparvovirus carnivoran1, Mamastrovirus 5, Aichivirus A2, Alphacoronavirus 1, and Chipapillomavirus 1. This is the first description of the intestinal virome of dogs in Northern Brazil and the first detection of canine norovirus GVII in the country. These results are important for helping to understand the viral groups that circulate in the canine population.

Molecular Characterization of Enteric Viruses Causing Acute Gastroenteritis among Children under 5 Years Old in Distrito Central, Honduras.

INTRODUCTION: Diarrheal diseases constitute a significant public health problem in terms of mortality and morbidity. In Honduras and around the world, RVs have consistently emerged as the single most important etiologic agent in acute childhood diarrhea. However, other viruses, such as NoVs and HAstVs, have also been shown to be responsible for viral gastroenteritis. Unfortunately, the country has limited information concerning the etiologic role of these viral agents in acute gastroenteritis. This study investigated the frequency, genotypes, and epidemiological characteristics of RV-A, NoVs, and HAstVs among children under 5 years old in Distrito Central, Honduras. METHODS: Stool samples and their corresponding epidemiological data were collected from children with acute gastroenteritis in three healthcare centers in Distrito Central. All samples were screened by immunoassays for RV-A and HAstVs. RV-A-positive samples were molecularly characterized by RT-PCR and genotyping assays. RT-PCR was also applied to confirm HAstVs positivity and to detect NoVs, followed by nucleotide sequencing to assign their genotypes. RESULTS: Our results show that at least one viral agent was detected in 31% of the children. The frequency of RV-A, NoVs, and HAstVs was 14%, 13%, and 5%, respectively. The most frequent RV-A genotype was G2P[4], occurring in 93% of cases. 92.3% of NoVs-positive samples belonged to genogroup II, with GII.4 and GII.16 being the most common. HAstVs were clustered into three genotypes: HAstV-1, HAstV-2, and HAstV-8. Only one sample showed coinfection with NoVs and HAstVs. CONCLUSION: This comprehensive molecular and epidemiological characterization of enteric viruses demonstrates the vast diversity of these agents and describes for the first time NoVs and HAstVs as causative agents of acute childhood gastroenteritis in Distrito Central, Honduras. This suggests that further in-depth studies of the pediatric population are necessary to develop and implement effective preventive and control measures in the country.

Evaluation of Extraction Methods to Detect Noroviruses in Ready-to-Eat Raw Milk Minas Artisanal Cheese.

This study aimed to assess two homogenization methods to recover norovirus from Minas artisanal cheese (MAC) made with raw bovine milk obtained from four microregions of the Minas Gerais state, Brazil, with different ripening times and geographical and abiotic characteristics. For this purpose, 33 fiscal samples were artificially contaminated with norovirus GI and GII, and Mengovirus (MgV), used as an internal process control (IPC). TRIzol® reagent and Proteinase K homogenization methods were evaluated for all samples were then subjected to RNA extraction using viral magnetic beads and RT-qPCR Taqman® for viral detection/quantification. Proteinase K method showed better efficiency results for both norovirus GI and GII, with means recovery efficiency of 45.7% (95% CI 34.3-57.2%) and 41.4% (95% CI 29.1-53.6%), respectively, when compared to TRIzol method (16.6% GI, 95% CI 8.4-24.9%, and 12.3% GII, 95% CI 7.0-17.6%). The limits of detection for norovirus GI and GII for this method were 101GC/g and 103GC/g, respectively, independent of cheese origin. MgV was detected and revealed in 100% success rate in all types of cheese, with mean recovery efficiency of 25.6% for Proteinase K, and 3.8% for the TRIzol method. According to cheese origin, Triangulo Mineiro MAC had the highest mean recovery rates for the three viral targets surveyed (89% GI, 87% GII, and 51% MgV), while Serro MAC showed the lowest rates (p < 0.001). Those results indicate that the proteinase K adapted method is suitable for norovirus GI and GII detection in MAC and corroborated MgV as an applicable IPC to be used during the process.

Norovirus in children under 2 years of age: an epidemiological study in Panama during the COVID-19 pandemic.

Introduction: Norovirus infection is a common cause of acute gastroenteritis (AGE). Surveillance activities are important to aid investigation into effective norovirus control strategies, including vaccination. Here, we report ancillary findings related to the incidence, prevalence, and etiology of AGE caused by norovirus in Panama after adjustment of study methodology to comply with national coronavirus disease 2019 (COVID-19) mandates. Methods: In January 2020, children aged <2 years began enrolling into an epidemiological study in Panama to estimate the burden of norovirus in preparation for evaluating upcoming prevention strategies. This included an observational, longitudinal, community-based AGE surveillance study and a hospital-based AGE surveillance study. For the longitudinal study, healthy children aged 5-18 months were enrolled from January 6 through March 23, 2020, with a follow-up of approximately 6 months. The last participant was contacted on September 23, 2020. For the hospital-based study, starting on January 21, 2020, children aged <2 years who were admitted to the Hospital del Niño Dr. José Renán Esquivel in Panama City due to AGE were evaluated. The last sample was collected on September 29, 2020. Collected stool samples were tested for norovirus as well as astrovirus, sapovirus, and various enteropathogens. Unfortunately, this study was disrupted by the subsequent implementation of disease transmission control procedures for the COVID-19 pandemic, and the study methodology was revised to comply with COVID-19 mandates. Results: In the longitudinal surveillance cohort [N = 400 (Chiriquí, n = 239; Panama, n = 161)], a total of 185 AGE episodes were documented (Chiriquí, n = 85; Panama, n = 100) resulting in an overall AGE incidence of 11.6 (95% CI: 9.99-13.4) episodes per 100 child-months. The norovirus-related AGE incidence was 0.3 (95% CI: 0.10-0.73) episodes per 100 child-months (5/185 AGE episodes) and the prevalence of norovirus was 4.6% (13/282 stool samples collected). In the hospital-based surveillance cohort, at least one pathogen was detected in 50% of samples (44/88 stool samples collected) and norovirus prevalence was 6.8% (6/88 stool samples collected). Discussion: This report demonstrates how the occurrence of the COVID-19 pandemic hindered the conduct of clinical trials. However, this also created unique research opportunities to investigate the potential impact of pandemic control measures on the etiology of infectious diarrheal disease.

Ozone and photodynamic inactivation of norovirus surrogate bacteriophage MS2 in fresh Brazilian berries and surfaces.

This study assessed the efficacy of ozone (bubble diffusion in water; 6.25 ppm) and photodynamic inactivation (PDT) using curcumin (75 µM) as photosensitizer (LED emission 430-470 nm; 33.6 mW/cm2 irradiance; 16.1, 20.2, and 24.2 J/cm2 light dose) against the Norovirus surrogate bacteriophage MS2 in Brazilian berries (black mulberry and pitanga) and surfaces (glass and stainless steel). Contaminated berries and surfaces were immersed in ozonized water or exposed to PDT-curcumin for different time intervals. Transmission electron microscopy was used to assess the effects of the treatments on MS2 viral particles. The MS2 inactivation by ozone and PDT-curcumin varied with the fruit and the surface tested. Ozone reduced the MS2 titer up to 3.6 log PFU/g in black mulberry and 4.1 log PFU/g in pitanga. On surfaces, the MS2 reduction by ozone reached 3.6 and 4.8 log PFU/cm2 on glass and stainless steel, respectively. PDT-curcumin reduced the MS2 3.2 and 4.8 log PFU/g in black mulberry and pitanga and 2.7 and 3.3 log PFU/cm2 on glass and stainless steel, respectively. MS2 particles were disintegrated by exposure of MS2 to ozone and PDT-curcumin on pitanga. Results can contribute to establishing effective practices for controlling NoV in fruits and surfaces, estimated based on MS2 bacteriophage behavior.

Transmission Patterns of Norovirus From Infected Children to Household Members in León, Nicaragua.

Norovirus is a common and highly transmissible gastrointestinal pathogen. Among 34 Nicaraguan households with a norovirus-infected child, 48% experienced norovirus transmission within 1 week, infecting 18% of household members; GII norovirus was more commonly transmitted than GI. Pediatric norovirus vaccines could prevent both index cases and transmission to close contacts.

Epidemiological and molecular surveillance of norovirus in the Brazilian Amazon: description of recombinant genotypes and improvement of evolutionary analysis

ABSTRACT Noroviruses are highly infectious, genetically diverse viruses. Global outbreaks occur frequently, making molecular surveillance important for infection monitoring. This cross-sectional descriptive study aimed to monitor cases of norovirus gastroenteritis in the Brazilian Amazon. Fecal samples were tested by immunoenzymatic assay, RT-PCR and genetic sequencing for the ORF1/ORF2 and protease regions. Bayesian inference with a molecular clock was employed to construct the phylogeny. The norovirus prevalence was 25.8%, with a higher positivity rate among children aged 0-24 months. Genogroup GII accounted for 98.1% of the sequenced samples, while GI accounted for 1.9% of them. The GII.P16/GII.4 genotype was the most prevalent, with an evolution rate of 2.87x10−3 and TMRCA estimated in 2012. This study demonstrates that norovirus is a primary causative agent of gastroenteritis and provides data on viral genetic diversity that may facilitate infection surveillance and vaccine development.

Acute gastroenteritis outbreak associated with multiple and rare norovirus genotypes after storm events in Santa Catarina, Brazil.

Norovirus is a major cause of acute diarrheal disease (ADD) outbreaks worldwide. In the present study, we investigated an ADD outbreak caused by norovirus in several municipalities of Santa Catarina state during the summer season, southern Brazil in 2023. As of the 10th epidemiological week of 2023, approximately 87 000 ADD cases were reported, with the capital, Florianópolis, recording the highest number of cases throughout the weeks. By using RT-qPCR and sequencing, we detected 10 different genotypes, from both genogroups (G) I and II. Some rare genotypes were also identified. Additionally, rotavirus and human adenovirus were sporadically detected among the ADD cases. Several features of the outbreak suggest that sewage-contaminated water could played a role in the surge of ADD cases. Storm events in Santa Catarina state that preceded the outbreak likely increased the discharge of contaminated wastewater and stormwater into water bodies, such as rivers and beaches during a high touristic season in the state. Climate change-induced extreme weather events, including intensified rainfall and frequent floods, can disturb healthcare and sanitation systems. Implementing public policies for effective sanitation, particularly during peak times, is crucial to maintain environmental equilibrium and counter marine pollution.

A Comparison of Pathogen Detection and Risk Factors among Symptomatic Children with Gastroenteritis Compared with Asymptomatic Children in the Post-rotavirus Vaccine Era.

OBJECTIVE: To describe demographics, pathogen distribution/seasonality, and risk factors in children seeking care for acute gastroenteritis (AGE) at a midwestern US emergency department during 5 postrotavirus vaccine years (2011-2016), and further, to compare the same data with matched healthy controls (HC). STUDY DESIGN: AGE and HC participants <11 years old enrolled in the New Vaccine Surveillance Network study between December 2011 to June 2016 were included. AGE was defined as ≥3 diarrhea episodes or ≥1 vomiting episode. Each HC's age was similar to an AGE participant's age. Pathogens were analyzed for seasonality effects. Participant risk factors for AGE illness and pathogen detections were compared between HC and a matched subset of AGE cases. RESULTS: One or more organisms was detected in 1159 of 2503 children (46.3%) with AGE compared with 99 of 537 HC (17.3%). Norovirus was detected most frequently among AGE (n = 568 [22.7%]) and second-most frequently in HC (n = 39 [6.8%]). Rotavirus was the second most frequently detected pathogen among AGE (n = 196 [7.8%]). Children with AGE were significantly more likely to have reported a sick contact compared with HC, both outside the home (15.6% vs 1.4%; P < .001) and inside the home (18.6% vs 2.1%; P < .001). Daycare attendance was higher among children with AGE (41.4%) compared with HC (29.5%; P < .001). The Clostridium difficile detection rate was slightly higher among HC (7.0%) than AGE (5.3%). CONCLUSIONS: Norovirus was the most prevalent pathogen among children with AGE. Norovirus was detected in some HC, suggesting potential asymptomatic shedding among HC. The proportion of AGE participants with a sick contact was approximately 10 times greater than that of HC.

Detection of rotavirus and norovirus among children with acute gastroenteritis in Merida and Chihuahua cities, Mexico.

INTRODUCTION: Infantile acute gastroenteritis (AGE) is a leading cause of morbidity and mortality, particularly in developing countries. The most frequent etiological agents of viral gastroenteritis in children are adenovirus, astrovirus, rotavirus, and norovirus, the last two, leading causes. Thus, the aim of this study was to identify the presence of these two viruses in children with AGE, from two cities located in the Southeast and the Northwest regions of México. METHODOLOGY: HuNoVs were detected and characterized by RT-PCR and sequencing, while RVs were detected by RNA electrophoresis. RESULTS: The presence of RV and HuNoV was evaluated in 81 stool samples; 37 were collected between April and July 2013 from patients with acute diarrhea in Merida, and 44 were collected between January and June 2017 in Chihuahua, who attended health services. Despite vaccination, RV resulted in the predominant viruses detected, with 30.8% (25/81) positivity, while HuNoV infection was present in 8.6% (7/81) of the stool samples; GII strains were identified circulating in the Southeast, while GI strains were identified in the Northwest. Moreover, co-infections with both viruses were detected at a prevalence rate of 2.4% (2/81). CONCLUSIONS: The circulation of RV and HuNoV in the country is continuous and should be constantly monitored due to their impact on public health.

Immunogenicity and tolerability of a bivalent virus-like particle norovirus vaccine candidate in children from 6 months up to 4 years of age: A phase 2 randomized, double-blind trial.

We conducted a dose-finding phase 2 study of the HilleVax bivalent virus-like particle (VLP) vaccine candidate (HIL-214) in two cohorts of children, 6-≤12 months and 1-≤4 years of age (N = 120 per cohort), in Panama and Colombia (ClinicalTrials.gov, identifier NCT02153112). On Day 1, children randomized to one of the four equal groups received intramuscular injections of four different HIL-214 formulations containing 15/15, 15/50, 50/50, or 50/150 µg of GI.1/GII.4c genotype VLPs and 0.5 mg Al(OH)3. On Day 29, half the children in each group received a second vaccination (N = 60), while the other half received saline placebo injections to maintain the blind. VLP-specific ELISA Pan-Ig and histo-blood group binding antigen-blocking antibodies (HBGA) were measured on Days 1, 29, 57 and 210. On Day 29, after one dose, there were large Pan-Ig and HBGA responses in both age cohorts with some indication of dose-dependence, and higher geometric mean titers (GMT) in the older children. A further increase in titers was observed 28 days after a second dose in the 6-≤12-month-old groups, but less so in the 1-≤4-year-old groups; GMTs at Day 57 were broadly similar across doses and in both age groups. GMTs of Pan-Ig and HBGA persisted above baseline up to Day 210. All formulations were well tolerated with mostly mild-to-moderate transient solicited adverse events reported by parents/guardians, and no vaccine-related serious adverse events occurred. Further development of HIL-214 is warranted to protect the most susceptible young children against norovirus.

Immunoinformatics-guided design of a multi-valent vaccine against Rotavirus and Norovirus (ChRNV22).

Rotavirus (RV) and Norovirus (NV) are the main viral etiologic agents of acute gastroenteritis (AG), a serious pediatric condition associated with significant death rates and long-term complications. Anti-RV vaccination has been proved efficient in the reduction of severe AG worldwide, however, the available vaccines are all attenuated and have suboptimal efficiencies in developing countries, where AG leads to substantial disease burden. On the other hand, no NV vaccine has been licensed so far. Therefore, we used immunoinformatics tools to develop a multi-epitope vaccine (ChRNV22) to prevent severe AG by RV and NV. Epitopes were predicted against 17 prevalent genotypes of four structural proteins (NV's VP1, RV's VP4, VP6 and VP7), and then assembled in a chimeric protein, with two small adjuvant sequences (tetanus toxin P2 epitope and a conserved sequence of RV's enterotoxin, NSP4). Simulations of the immune response and interactions with immune receptors indicated the immunogenic properties of ChRNV22, including a Th1-biased response. In silico search for putative host-homologous, allergenic and toxic regions also indicated the vaccine safety. In summary, we developed a multi-epitope vaccine against different NV and RV genotypes that seems promising for the prevention of severe AG, which will be further assessed by in vivo tests.

Household Surveillance for Norovirus Gastroenteritis in a Nicaraguan Birth Cohort: A Nested Case-Control Analysis of Norovirus Risk Factors.

Norovirus causes a large proportion of pediatric acute gastroenteritis (AGE) worldwide, and no vaccines are currently available. To inform public health measures against norovirus gastroenteritis, we assessed risk factors in a case-control study nested in a birth cohort study in Nicaragua. Between June 2017 and January 2022, we followed children weekly for AGE episodes, and collected stool specimens from symptomatic children. Risk factors for AGE were collected during routine weekly visits. Norovirus was detected in stools using real-time reverse transcriptase polymerase chain reaction and positive specimens were genotyped using Sanger sequencing. We included 40 norovirus-positive AGE children matched 1:2 to controls and conducted bivariate and multivariable analyses of norovirus AGE risk factors. Among typeable norovirus infections, GII.4 were more severe than non-GII.4 (four/twenty-one vs. one/nine) and accounted for all emergency visits and hospitalizations. Adjusted conditional logistic regression found that female sex and higher length-for-age Z score were protective against norovirus AGE; a dirt floor in the home, sharing cups or bottles, and recent contact with someone with AGE symptoms were associated with norovirus AGE, though estimates were highly imprecise. Reducing contact with symptomatic persons and with saliva or other bodily fluids on cups or floors could reduce infant norovirus incidence.

Molecular characterization of norovirus and sapovirus detected in animals and humans in Costa Rica: Zoo-anthropozoonotic potential of human norovirus GII.4.

Background: Noroviruses (NoV) and sapoviruses (SaV) are major causes of acute viral gastroenteritis in humans worldwide, as well as gastrointestinal infections in animals. However, it has not been determined whether these viruses are zoonotic pathogens. Aim: In this study, we investigated the presence of NoV and SaV in stool samples from dogs, pigs, cows, and humans to determine some aspects of the molecular epidemiology and the genetic relationship of several strains present in these species. Methods: Polymerase chain reaction and sequencing of NoV and SaV strains present in stool samples from humans and dogs with diarrhea, pigs, and cattle with and without diarrhea were carried out during fragmented periods from 2002 to 2012. Results: Of all samples analyzed, 11.6% (123/1,061) of the samples were positive for NoV and 0.88% (9/1,023) were positive for SaV. The phylogenetic analysis confirmed 16 human strains of NoV (HuNoV) belonging to HuNoV G?/GII.P2 (1), GII.4/GII.P4 (5), G?/GII.P4 (9), and GII.6/GII.P6 (1) and allowed us to verify and assign three strains of human SaV to genotypes GI.2 (1) and GII.5 (2). In dogs, eight strains of NoV [HuNoV G?/GII.P4 (4) and canine G?/GVI.P1 (4)] and two strains of canine SaV were determined. In pigs, six strains were assigned to HuNoV G?/GII.P4 and four strains to porcine SaV were assigned to genogroup GIII (2), GVIII (1), and GXI (1). In bovines, five strains were characterized as HuNoV G?/GII.P4. Conclusions: This study showed that NoV and SaV prototype strains have been present in humans and dogs in Costa Rica. Additionally, it revealed that the zoonotic potential of SaV is very limited, while the zoonotic implications for HuNoV GII.4 are stronger due to the simultaneous circulation of strains related to HuNoV GII.4 in four species, which suggests a zoo-anthropozoonosis.

Norovirus Epidemiology and Genotype Circulation during the COVID-19 Pandemic in Brazil, 2019-2022.

Norovirus stands out as a leading cause of acute gastroenteritis (AGE) worldwide, affecting all age groups. In the present study, we investigated fecal samples from medically attended AGE patients received from nine Brazilian states, from 2019 to 2022, including the COVID-19 pandemic period. Norovirus GI and GII were detected and quantified using RT-qPCR, and norovirus-positive samples underwent genotyping through sequencing the ORF1/2 junction region. During the four-year period, norovirus prevalence was 37.2%, varying from 20.1% in 2020 to 55.4% in 2021. GII genotypes dominated, being detected in 92.9% of samples. GII-infected patients had significantly higher viral concentrations compared to GI-infected patients (median of 3.8 × 107 GC/g and 6.7 × 105 GC/g, respectively); and patients aged >12-24 months showed a higher median viral load (8 × 107 GC/g) compared to other age groups. Norovirus sequencing revealed 20 genotypes by phylogenetic analysis of RdRp and VP1 partial regions. GII.4 Sydney[P16] was the dominant genotype (57.3%), especially in 2019 and 2021, followed by GII.2[P16] (14.8%) and GII.6[P7] (6.3%). The intergenogroup recombinant genotype, GIX.1[GII.P15], was detected in five samples. Our study is the first to explore norovirus epidemiology and genotype distribution in Brazil during COVID-19, and contributes to understanding the epidemiological dynamics of norovirus and highlighting the importance of continuing to follow norovirus surveillance programs in Brazil.

Detection and Molecular Characterization of Enteric Viruses in Bivalve Mollusks Collected in Arraial do Cabo, Rio de Janeiro, Brazil.

Viral bivalve contamination is a recognized food safety hazard. Therefore, this study investigated the detection rates, seasonality, quantification, and genetic diversity of enteric viruses in bivalve samples (mussels and oysters). We collected 97 shellfish samples between March 2018 and February 2020. The screening of samples by qPCR or RT-qPCR revealed the detection of norovirus (42.3%), rotavirus A (RVA; 16.5%), human adenovirus (HAdV; 24.7%), and human bocavirus (HBoV; 13.4%). There was no detection of hepatitis A virus. In total, 58.8% of shellfish samples tested positive for one or more viruses, with 42.1% of positive samples contaminated with two or more viruses. Norovirus showed the highest median viral load (3.3 × 106 GC/g), followed by HAdV (median of 3.5 × 104 GC/g), RVA (median of 1.5 × 103 GC/g), and HBoV (median of 1.3 × 103 GC/g). Phylogenetic analysis revealed that norovirus strains belonged to genotype GII.12[P16], RVA to genotype I2, HAdV to types -C2, -C5, and -F40, and HBoV to genotypes -1 and -2. Our results demonstrate the viral contamination of bivalves, emphasizing the need for virological monitoring programs to ensure the quality and safety of shellfish for human consumption and as a valuable surveillance tool to monitor emerging viruses and novel variants.

Norovirus Infection in Young Nicaraguan Children Induces Durable and Genotype-Specific Antibody Immunity.

There are significant challenges to the development of a pediatric norovirus vaccine, mainly due to the antigenic diversity among strains infecting young children. Characterizing human norovirus serotypes and understanding norovirus immunity in naïve children would provide key information for designing rational vaccine platforms. In this study, 26 Nicaraguan children experiencing their first norovirus acute gastroenteritis (AGE) episode during the first 18 months of life were investigated. We used a surrogate neutralization assay that measured antibodies blocking the binding of 13 different norovirus virus-like particles (VLPs) to histo-blood group antigens (HBGAs) in pre- and post-infection sera. To assess for asymptomatic norovirus infections, stools from asymptomatic children were collected monthly, screened for norovirus by RT-qPCR and genotyped by sequencing. Seroconversion of an HBGA-blocking antibody matched the infecting genotype in 25 (96%) of the 26 children. A subset of 13 (50%) and 4 (15%) of the 26 children experienced monotypic GII and GI seroconversion, respectively, strongly suggesting a type-specific response in naïve children, and 9 (35%) showed multitypic seroconversion. The most frequent pairing in multitypic seroconversion (8/12) were GII.4 Sydney and GII.12 noroviruses, both co-circulating at the time. Blocking antibody titers to these two genotypes did not correlate with each other, suggesting multiple exposure rather than cross-reactivity between genotypes. In addition, GII titers remained consistent for at least 19 months post-infection, demonstrating durable immunity. In conclusion, the first natural norovirus gastroenteritis episodes in these young children were dominated by a limited number of genotypes and induced responses of antibodies blocking binding of norovirus VLPs in a genotype-specific manner, suggesting that an effective pediatric norovirus vaccine likely needs to be multivalent and include globally dominant genotypes. The duration of protection from natural infections provides optimism for pediatric norovirus vaccines administered early in life.

Eventos de precipitación extrema aumentan la circulación de patógenos infecciosos: detección de rotavirus, norovirus, astrovirus, adenovirus entérico y micobacterias no tuberculosas en agua de las inundaciones en Asunción, Paraguay, año 2014

Las precipitaciones extremas representan uno de los eventos naturales climáticos más importantes y pueden originar inundaciones devastadoras. De junio a agosto del 2014 se registró una de las más graves inundaciones en la historia de la ciudad de Asunción. Ocasionó un incremento considerable del nivel del río Paraguay y el desplazamiento de 300.000 personas a campamentos provisionales. Debido a que el contacto directo con el agua de inundación, el consumo de agua contaminada y la congregación de los afectados en refugios provisorios son factores de riesgo para enfermedades infecciosas, el objetivo de este estudio fue la implementación de una metodología estandarizada para la concentración y detección de virus entéricos y micobacterias no tuberculosas, por PCR en tiempo real y PCR-asociada al análisis de restricción enzimática (PRA), en muestras de agua de inundaciones y el reporte de los patógenos detectados en las zonas afectadas de Asunción y en la Bahía del Río Paraguay. La metodología propuesta demostró poseer buena sensibilidad y se registró la presencia de rotavirus, norovirus (genogrupos I y II), astrovirus, adenovirus entéricos y micobacterias no tuberculosas en 50% (N=4/8) de las muestras de los barrios Sajonia, San Jerónimo y Ricardo Brugada, Chacarita. Además, reportamos datos secundarios de casos de enfermedades infecciosas, registrados en los servicios de salud de los barrios afectados durante el periodo de inundación.

Extreme rainfall represents one of the most important natural climatic events and can cause devastating floods. From June to August 2014, one of the most serious floods in the history of the city of Asunción was recorded. It caused a considerable increase in the level of the Paraguay River and the displacement of 300,000 people to temporary camps. Since direct contact with flood water, consumption of contaminated water and the congregation of those affected in temporary shelters are risk factors for infectious diseases, the objective of this study was the implementation of a standardized methodology for the concentration and detection of enteric viruses and non-tuberculous mycobacteria, by real-time PCR and PCR-associated enzyme restriction analysis (PRA), in samples of flood water and the report of the pathogens detected in the affected areas of Asunción and in the Bay of the Paraguay River. The proposed methodology proved to have good sensitivity and the presence of rotavirus, norovirus (genogroups I and II), astrovirus, enteric adenovirus and non-tuberculous mycobacteria was recorded in 50% (N=4/8) of the samples from the Sajonia, San Jeronimo and Ricardo Brugada, Chacarita neighborhoods. In addition, we report secondary data on cases of infectious diseases, registered in the health services of the affected neighborhoods during the flood period.