EHEC O111:H8 strain and norovirus GII.4 Sydney [P16] causing an outbreak in a daycare center, Brazil, 2019.

BACKGROUND: This study describes the investigation of an outbreak of diarrhea, hemorrhagic colitis (HC), and hemolytic uremic syndrome (HUS) at a daycare center in southeastern Brazil, involving fourteen children, six staff members, six family members, and one nurse. All bacterial and viral pathogens detected were genetically characterized. RESULTS: Two isolates of a strain of enterohemorrhagic Escherichia coli (EHEC) serotype O111:H8 were recovered, one implicated in a case of HUS and the other in a case of uncomplicated diarrhea. These isolates had a clonal relationship of 94% and carried the stx2a and eae virulence genes and the OI-122 pathogenicity island. The EHEC strain was determined to be a single-locus variant of sequence type (ST) 327. EHEC isolates were resistant to ofloxacin, doxycycline, tetracycline, ampicillin, and trimethoprim-sulfamethoxazole and intermediately resistant to levofloxacin and ciprofloxacin. Rotavirus was not detected in any samples, and norovirus was detected in 46.7% (14/30) of the stool samples, three of which were from asymptomatic staff members. The noroviruses were classified as the recombinant GII.4 Sydney [P16] by gene sequencing. CONCLUSION: In this outbreak, it was possible to identify an uncommon stx2a + EHEC O111:H8 strain, and the most recent pandemic norovirus strain GII.4 Sydney [P16]. Our findings reinforce the need for surveillance and diagnosis of multiple enteric pathogens by public health authorities, especially during outbreaks.

Etiology of acute gastroenteritis among children less than 5 years of age in Bucaramanga, Colombia: A case-control study.

BACKGROUND: Acute gastroenteritis (AGE) is a major cause of morbidity and mortality in children aged less than 5 years in low- and middle-income countries where limited access to potable water, poor sanitation, deficient hygiene, and food product contamination are prevalent. Research on the changing etiology of AGE and associated risk factors in Latin America, including Colombia, is essential to understand the epidemiology of these infections. The primary objectives of this study were to describe etiology of moderate to severe AGE in children less than 5 years of age from Bucaramanga, Colombia, a middle-income country in Latin American, and to identify the presence of emerging E. coli pathotypes. METHODOLOGY/PRINCIPAL FINDINGS: This was a prospective, matched for age, case-control study to assess the etiology of moderate to severe AGE in children less than 5 years of age in Bucaramanga, Colombia, South America. We tested for 24 pathogens using locally available diagnostic testing, including stool culture, polymerase chain reaction, microscopy and enzyme-linked immunoassay. Adjusted attributable fractions were calculated to assess the association between AGE and each pathogen in this study population. The study included 861 participants, 431 cases and 430 controls. Enteric pathogens were detected in 71% of cases and in 54% of controls (p = <0.001). Co-infection was identified in 28% of cases and in 14% of controls (p = <0.001). The adjusted attributable fraction showed that Norovirus GII explained 14% (95% CI: 10-18%) of AGE, followed by rotavirus 9.3% (6.4-12%), adenovirus 3% (1-4%), astrovirus 2.9% (0.6-5%), enterotoxigenic Escherichia coli (ETEC) 2.4% (0.4-4%), Cryptosporidium sp. 2% (0.5-4%), Campylobacter sp. 2% (0.2-4%), and Salmonella sp.1.9% (0.3 to 3.5%). Except for Cryptosporidium, all parasite infections were not associated with AGE. Three emergent diarrheagenic E. coli pathotypes were identified in cases (0.7%), including an enteroaggregative/enterotoxigenic E.coli (EAEC/ETEC), an enteroaggregative/enteropathogenic E.coli (EAEC/EPEC), and an emergent enteroinvasive E. coli with a rare O96:H19. No deaths were reported among cases or controls. CONCLUSIONS/SIGNIFICANCE: Norovirus and rotavirus explained the major proportion of moderate to severe AGE in this study. Higher proportion of infection in cases, in the form of single infections or co-infections, showed association with AGE. Three novel E. coli pathotypes were identified among cases in this geographic region.

Molecular epidemiology and temporal evolution of norovirus associated with acute gastroenteritis in Amazonas state, Brazil.

BACKGROUND: Globally, Norovirus (NoV) is considered the most common cause of diarrheal episodes across all age groups. Despite its wide genetic diversity, the GII.4 strain is the most predominant and has been associated with epidemics worldwide. In this study, we characterized sporadic cases of diarrhea from NoV-positive children, during a five-year period (2010-2014). METHODS: A total of 250 NoV-positive samples identified by an enzyme immunoassay (EIA) were subjected to RT-PCR and partial nucleotide sequencing for polymerase and capsid genes. Phylogenetic analysis was performed to identify NoV genotypes using the binary classification. In addition, sequences from the P2 subdomain (capsid) gene of GII-4 variants were characterized by evolutionary analyses, using the MCMC method implemented in the BEAST package. A 3D structure was built using protein modeling. RESULTS: Phylogenetic analysis demonstrated a predominance of genotype GII.4 (52.4% - 99/189), variants New Orleans_2009 and Sydney_2012 followed by GII.P7/GII.6 with 6.3% (12/189). Amino acid analyses of the GII.4 strains showed several important amino acid changes. A higher evolutionary rate was found, 7.7 × 10- 3 in the Sydney variant and 6.3 × 10- 3 in the New Orleans. Based in evolutionary analysis the time to the most recent common ancestor (TMRCA) has been calculated as estimates of the population divergence time. Thus, TMRCA for New Orleans and Sydney variant were 2008.7 and 2010.7, respectively. Also, we observed a lineage of transition between New Orleans and Sydney. CONCLUSION: This study describes the different strains of norovirus isolated from Amazonas state in Brazil during a five-year period. Considering that NoV are capable of changing their antigenic epitopes rapidly, a continuous surveillance is important to monitor the occurrence and changes of the NoV in the community through epidemiological studies. These results contribute to the understanding of NoV molecular epidemiology and its evolutionary dynamics in Amazonas state, Brazil.

Incidence and Clinical Profile of Norovirus Disease in Guatemala, 2008-2013.

Background: Acute gastroenteritis (AGE) is a leading infectious cause of morbidity worldwide, particularly among children in developing countries. With the decline of rotavirus disease rates following introduction of rotavirus vaccines, the relative importance of norovirus will likely increase. Our objectives in this study were to determine the incidence and clinical profile of norovirus disease in Guatemala. Methods: We analyzed data from a population-based surveillance study conducted in Guatemala from 2008 through 2013. Demographic information, clinical data, and stool samples were collected from patients who presented with AGE (≥3 liquid stools within 24 hours that initiated 7 days before presentation). Estimated incidence of hospitalized, outpatient, and total community norovirus disease was calculated using surveillance data and household surveys of healthcare use. Results: We included 999 AGE hospitalizations and 3189 AGE outpatient visits at facilities, of which 164 (16%) and 370 (12%), respectively, were positive for norovirus. Severity of norovirus was milder than of rotavirus. Community incidence of norovirus ranged from 2068 to 4954 per 100000 person-years (py) in children aged<5 years. Children aged <5 years also had higher incidence of norovirus-associated hospitalization (51-105 per 100000 py) compared with patients aged ≥5 years (0-1.6 per 100000 py and 49-80 per 100000 py, respectively). Conclusions: This study highlights the burden of norovirus disease in Guatemala, especially among young children. These data can help prioritize development of control strategies, including the potential use of vaccines, and provide a baseline to evaluate the impact of such interventions.

Caliciviruses in hospitalized children, São Luís, Maranhão, 1997-1999: detection of norovirus GII.12

Gastroenteritis is one of the most common diseases during childhood, with norovirus (NoV) and sapovirus (SaV) being two of its main causes. This study reports for the first time the incidence of these viruses in hospitalized children with and without gastroenteritis in São Luís, Maranhão. A total of 136 fecal samples were tested by enzyme immunoassays (EIA) for the detection of NoV and by reverse transcription-polymerase chain reaction (RT-PCR) for detection of both NoV and SaV. Positive samples for both agents were subjected to sequencing. The overall frequency of NoV as detected by EIA and RT-PCR was 17.6% (24/136) and 32.6% (15/46), respectively in diarrheic patients and 10.0% (9/90) in non-diarrheic patients (p 0.01). Of the diarrheic patients, 17% had fever, vomiting and anorexia, and 13% developed fever, vomiting and abdominal pain. Of the 24 NoV-positive samples, 50% (12/24) were sequenced and classified as genotypes GII.3 (n = 1), GII.4 (6), GII.5 (1), GII.7 (2), GII.12 (1) and GII.16 (1). SaV frequency was 9.8% (11/112), with 22.6% (7/31) in diarrheic patients and 4.9% (4/81) in nondiarrheic (p = 0.04) ones. In diarrheic cases, 27.3% had fever, vomiting and anorexia, whereas 18.2% had fever, anorexia and abdominal pain. One SaV-positive sample was sequenced and classified as GII.1. These results show a high genetic diversity of NoV and higher prevalence of NoV compared to SaV. Our data highlight the importance of NoV and SaV as enteropathogens in São Luís, Maranhão.(AU)

Etiology of childhood diarrhea after rotavirus vaccine introduction: a prospective, population-based study in Nicaragua.

BACKGROUND: Nicaragua was the first developing nation to implement routine immunization with the pentavalent rotavirus vaccine (RV5). In this RV5-immunized population, understanding infectious etiologies of childhood diarrhea is necessary to direct diarrhea treatment and prevention efforts. METHODS: We followed a population-based sample of children <5 years in León, Nicaragua for diarrhea episodes through household visits. Information was obtained on RV5 history and sociodemographics. Stool samples collected during diarrhea episodes and among healthy children underwent laboratory analysis for viral, bacterial and parasitic enteropathogens. Detection frequency and incidence of each enteropathogen was calculated. RESULTS: The 826 children in the cohort experienced 677 diarrhea episodes during 607.5 child-years of exposure time (1.1 episodes per child-year). At least 1 enteropathogen was detected among 61.1% of the 337 diarrheal stools collected. The most common enteropathogens among diarrheal stools were: norovirus (20.4%), sapovirus (16.6%), enteropathogenic Escherichia coli (11.3%), Entamoeba histolytica/dispar (8.3%), Giardia lamblia (8.0%) and enterotoxigenic E. coli (7.7%), with rotavirus detected among 5.3% of diarrheal stools. Enteropathogenic Escherichia coli and enterotoxigenic E. coli were frequently detected among stools from healthy children. Among children with diarrhea, norovirus was more commonly detected among younger children (< 2 years) and G. lamblia was more commonly detected among older children (2-4 years). The mean age of rotavirus detection was 34.6 months. CONCLUSIONS: In this Central American community after RV5 introduction, rotavirus was not commonly detected among children with diarrhea. Prevention and appropriate management of norovirus and sapovirus should be considered to further reduce the burden of diarrheal disease.

Outbreak of gastrointestinal illness during Operation New Horizons in Pisco, Peru, July 2012.

In July 2012, the U.S. Naval Medical Research Unit No. 6 investigated an outbreak of gastrointestinal illness characterized by diarrhea among U.S. service members participating in Operation New Horizons in Pisco, Peru. Overall, there were 25 cases of self-reported diarrheal illness among 101 respondents to a questionnaire (attack rate: 24.8%). Personnel who consumed food that was prepared at the two hotels where they were lodged were more likely to report diarrhea than those who did not eat at the hotels (40.9% [9/22] versus 20.3% [16/79]; RR=2.1; p=.047). The difference in diarrhea attack rates between lodgers at the two hotels was not statistically significant. Known or putative pathogens were identified in 72.7 percent (8/11) of samples tested: Blastocystis hominis, Shigella sonnei, diffusely adherent Escherichia coli, and norovirus genotypes I and II. The investigation's findings suggested a food-borne etiology from hotel kitchens. Among all personnel, hand-washing hygiene was reinforced; however, food sources were not restricted.

Calicivirus and Giardia lamblia are associated with diarrhea in human immunodeficiency virus-seropositive patients from southeast Brazil.

To study enteropathogens, 100 fecal samples were collected from a Brazilian human immunodeficiency virus (HIV)-seropositive population, with or without diarrhea. Giardia lamblia and calicivirus were significantly associated with diarrhea as were severe immunosuppression and the presence of at least one enteropathogen. No sample was positive for rotavirus and only one asymptomatic individual carried the astrovirus. We concluded that there is a great diversity of pathogens and opportunistic infections in the studied population, with a high prevalence of mixed colonization/infection. Our findings pave the way for future molecular studies related to the expression of virulence factors and to the possibility of pathogen-pathogen interactions, especially between G. lamblia and calicivirus. These findings are relevant to the improvement of therapies and controlling diarrhea in the HIV-seropositive population.

Calicivirus infection in human immunodeficiency virus seropositive children and adults.

BACKGROUND: The importance of enteric viral infections in HIV-related diarrhea is uncertain. Human caliciviruses have emerged as a leading cause of acute diarrhea worldwide. OBJECTIVES: To evaluate the importance of calicivirus infections in HIV-related diarrhea. Study design 151 fecal samples collected from children and adults infected with HIV, with and without diarrhea, were examined. In addition, 89 fecal samples from non HIV-infected children and adults were also tested. Samples were analyzed by RT-PCR using primer sets specific to Norovirus genogroup I or genogroup II as well as primers designed to react with both Noroviruses and Sapovirus genus. RESULTS: Viruses were detected with equal frequencies in stools from HIV infected and non-infected adults (12%). However, specimens from HIV infected children were more likely than those of HIV-negative children to have caliciviruses (51% versus 24%, P<0.05). Viral infections were not significantly associated with diarrhea neither in children nor in adults, regardless of HIV status. Viruses genetically related to the common Lordsdale virus (Norovirus genogroup II) and London/92 virus (Sapovirus) clusters were detected circulating among children. CONCLUSIONS: These results suggest that caliciviruses may be an important opportunistic pathogen in children infected with HIV.