Detection and diversity of gastrointestinal viruses in wastewater from Caracas, Venezuela, 2021-2022.

Gastrointestinal viruses (GIV) are an important cause of childhood morbidity and mortality, particularly in developing countries. Their epidemiological impact in Venezuela during the COVID-19 pandemic remains unclear. GIV can also be detected in domestic sewage. Ninety-one wastewater samples from urban areas of Caracas collected over 12 months and concentrated by polyethylene-glycol-precipitation, were analyzed by multiplex reverse-transcription-PCR for rotavirus/calicivirus/astrovirus and enterovirus/klassevirus/cosavirus, and monoplex-PCR for adenovirus and Aichi virus. The overall frequency of virus detection was 46.2%, fluctuating over months, and peaking in the rainy season. Adenoviruses circulated throughout the year, especially type F41, and predominated (52.7%) over caliciviruses (29.1%) that peaked in the rainy months, rotaviruses (9.1%), cosaviruses (5.5%), astroviruses and enteroviruses (1.8%). Aichi-virus and klassevirus were absent. Rotavirus G9/G12, and P[4]/P[8]/P[14] predominated. The occurrence of GIV in wastewater reflects transmission within the population of Caracas and the persistence of a potential public health risk that needs to be adequately monitored.

Molecular characterization of human adenovirus causing infantile acute gastroenteritis in Venezuela before and after rotavirus vaccine implementation.

Human adenoviruses (HAdV) of species F are commonly involved in pediatric acute gastroenteritis (AGE). The real impact on Venezuelan health is unknown. To investigate the prevalence and molecular diversity of HAdV in Venezuela, 630 fecal samples collected from children with AGE in 3 cities, from 2001 to 2013, were tested by PCR. Species F and types F40/41 were identified by REA. HAdV was detected in 123 cases (19.5%), most from outpatient females under 24 months old. A progressive and substantial increase in the detection rate was observed over time, significantly higher in rotavirus vaccinated than unvaccinated children (28.4% vs. 9.5%, P = 0.00019). Phylogenetic analysis of 28 randomly selected genomes showed high similarity among HAdV-F40/41 and those worldwide. HAdV-F of type 41 prevailed (79.8%) and clustered into 2 intratypic major clades. The significant involvement of HAdV-F41 in AGE suggests the importance of actively monitoring viral agents other than rotavirus, especially after vaccine introduction.

HUMAN COSAVIRUS INFECTION IN HIV SUBJECTS WITH DIARRHOEA: PERSISTENT DETECTION ASSOCIATED WITH FATAL OUTCOME.

BACKGROUND: Human cosavirus (HCoSV) is a new member of the Picornaviridae family, geographically widespread among humans. It has been suggested as a causative agent of acute gastroenteritis, but its pathogenicity is not currently certain. In HIV-infected subjects, diarrhoea is one of the most frequent gastrointestinal manifestations, whose aetiology remains often unexplained. OBJECTIVES: To identify the cause of viral diarrhoea among HIV infected patients by molecular assays. STUDY DESIGN: A total of 143 stool samples from HIV subjects with and without diarrhoea, were screened for conventional enteric viruses (rotavirus, adenovirus, norovirus and astrovirus) by molecular assays. The presence of HCoSV genome was investigated by nested RT-PCR for the 5'UTR region. Positive samples were further characterized by sequencing and phylogenetic analysis. RESULTS: Enteric viruses were more frequently found in diarrhoea cases (9/82) than controls (0/61) (p=0.007). HCoSV was detected in five (3.5%) of the subjects affected by diarrhoea. Phylogenetic analysis revealed the predominance of the HCoSV species D. One patient suffered a persistent cosavirus infection with a same strain and after eight months he had a fatal outcome. No other pathogens could be detected. CONCLUSIONS: The results suggest a role of non-conventional enteric viruses, as HCoSV, as a potential opportunistic agent causing persistent infection and deterioration of the clinical conditions in HIV-infected patients. Screening procedures and monitoring including such viruses would be helpful in the clinical management of such patients.

Human rotavirus strains circulating in Venezuela after vaccine introduction: predominance of G2P[4] and reemergence of G1P[8].

BACKGROUND: Rotavirus (RV) is the most common cause of severe childhood diarrhea worldwide. Despite Venezuela was among the first developing countries to introduce RV vaccines into their national immunization schedules, RV is still contributing to the burden of diarrhea. Concerns exist about the selective pressure that RV vaccines could exert on the predominant types and/or emergence of new strains. RESULTS: To assess the impact of RV vaccines on the genotype distribution 1 year after the vaccination was implemented, a total of 912 fecal specimens, collected from children with acute gastroenteritis in Caracas from February 2007 to April 2008, were screened, of which 169 (18.5%) were confirmed to be RV positive by PAGE. Rotavirus-associated diarrhea occurred all year-round, although prevailed during the coolest and driest months among unvaccinated children under 24 months old. Of 165 RV strains genotyped for G (VP7) and P (VP4) by seminested multiplex RT-PCR, 77 (46.7%) were G2P[4] and 63 (38.2%) G1P[8]. G9P[8], G3P[8] and G2P[6] were found in a lower proportion (7.3%). Remarkable was also the detection of <5% of uncommon combinations (G8P[14], G8P[4], G1P[4] and G4P[4]) and 3.6% of mixed infections. A changing pattern of G/P-type distribution was observed during the season studied, with complete predominance of G2P[4] from February to June 2007 followed by its gradual decline and the reemergence of G1P[8], predominant since January 2008. Phylogenetic analysis of VP7 and VP4 genes revealed a high similarity among G2P[4] and global strains belonging to G2-II and P[4]-V lineages. The amino acid substitution 96D → N, related with reemergence of the G2 genotype elsewhere, was observed. The G1P[8] strains from Caracas were grouped into the lineages G1-I and P[8]-III, along with geographically remote G1P[8] rotaviruses, but they were rather distant from Rotarix® vaccine and pre-vaccine strains. Unique amino acid substitutions observed on neutralization domains of the VP7 sequence from Venezuelan post-vaccine G1P[8] could have conditioned their re-emergence and a more efficient dissemination into susceptible population. CONCLUSIONS: The results suggest that natural fluctuations of genotypes in combination with forces driving the genetic evolution could determine the spread of novel strains, whose long-term effect on the efficacy of available vaccines should be determined.