The efficacy of licensed rotavirus vaccines has only been shown against certain rotavirus group A (RV-A) types. It is critical to understand the burden of rotavirus gastroenteritis (RVGE) and its prevalent types to assess the potential impact of these vaccines in Latin America and the Caribbean (LA&C). We performed a systematic review and meta-analyses of all the available evidence reported from 1990 to 2009 on the burden of rotavirus disease and strains circulating in LA&C. Eligible studies--185 country-level reports, 174 951 faecal samples--were selected from MEDLINE, Cochrane Library, EMBASE, LILACS, regional Ministries of Health, PAHO, regional proceedings, doctoral theses, reference lists of included studies and consulting experts. Arc-sine transformations and DerSimonian-Laird random-effects model were used for meta-analyses. The proportion of gastroenteritis cases due to rotavirus was 24.3% (95%CI 22.3-26.4) and the incidence of RVGE was 170 per 1000 children-years (95%CI 130-210). We estimated a global annual mortality for 22 countries of 88.2 (95%CI 79.3-97.1) deaths per 100 000 under 5 years (47 000 deaths).The most common G type detected was G1 (34.2%), followed by G9 (14.6%), and G2 (14.4%). The most common P types detected were P (56.2%), P (22.1%) and P 5.4%, and the most prevalent P-G type associations were PG1 17.9%, PG2 9.1% and PG9 8.8%. In the last 10 years, G9 circulation increased remarkably and G5 almost disappeared. More recently, G12 appeared and PG2 re-emerged. To our knowledge, this is the first meta-analysis of rotavirus infection and burden of disease in LA&C.
Rotaviruses are dynamic pathogens that have been shown to infect multiple species. In 2006, two G4P rotavirus strains with porcine characteristics were detected in Santa Fe, Argentina. To further characterize and determine the origin of these strains, nearly the full length of their genome was sequenced. While most of the genome segments were from porcine origin, the two strains grouped in different phylogenetic clusters in five out of the 11 genes, suggesting two independent interspecies transmission events. This study expands our knowledge of G4 rotavirus and reinforces the use of complete genome analyses as a key tool for diversity and evolution mechanicisms.
Eight outbreaks of acute gastroenteritis occurred in Argentina in 2004 were tested for the presence of Calicivirus, Rotavirus and Astrovirus as possible causative agents. Caliciviruses were found in 39 out of the 100 tested samples, followed by six Astrovirus-positive samples and two Rotavirus-positive samples. Thirty-seven out of the 39 Calicivirus-positive samples were typed as Norovirus while the remaining two were typed as Sapovirus. Sequence and phylogenetic analyses of 13 Norovirus-positive samples revealed the presence of strains from the genogroups GI, GII, and GIV. Six Norovirus strains were grouped with the GIV-1 strains, three with the GIIb strains, two with the Farmington Hill-cluster (GII-4) strains, and the remaining two with the GI strains. To our knowledge, this study constitutes the first report of molecular epidemiology of human Caliciviruses associated to gastroenteritis outbreaks in Argentina and the circulation of GIIb and GIV-1 strains in South-America.
Norovirus is a major cause of acute gastroenteritis worldwide. Over 30 different genotypes, mostly from genogroup I (GI) and II (GII), have been shown to infect humans. Despite three decades of genome sequencing, our understanding of the role of genomic diversification across continents and time is incomplete. To close the spatiotemporal gap of genomic information of human noroviruses, we conducted a large-scale genome-wide analyses that included the nearly full-length sequencing of 281 archival viruses circulating since the 1970s in over 10 countries from four continents, with a major emphasis on norovirus genotypes that are currently underrepresented in public genome databases. We provided new genome information for 24 distinct genotypes, including the oldest genome information from 12 norovirus genotypes. Analyses of this new genomic information, together with those publicly available, showed that (i) noroviruses evolve at similar rates across genomic regions and genotypes; (ii) emerging viruses evolved from transiently-circulating intermediate viruses; (iii) diversifying selection on the VP1 protein was recorded in genotypes with multiple variants; (iv) non-structural proteins showed a similar branching on their phylogenetic trees; and (v) contrary to the current understanding, there are restrictions on the ability to recombine different genomic regions, which results in co-circulating populations of viruses evolving independently in human communities. This study provides a comprehensive genetic analysis of diverse norovirus genotypes and the role of non-structural proteins on viral diversification, shedding new light on the mechanisms of norovirus evolution and transmission.
During the surveillance of rotavirus strains that were circulating in Argentinean children from 2000 to 2004, seven rotaviruses were detected bearing the genotype combination G9P. The molecular characterization of the VP7 and NSP4 genes and the RNA migration patterns support the hypothesis that rotaviruses G9 could have been reintroduced into Argentina as a novel G9P strain, rather than represent VP7 gene reassortants from G9P strains that had been circulating previously in this country.
Argentina incorporated rotavirus massive vaccination in 2015. No specific strategy has been designed to accurately measure the impact of this recent introduction on the diarrhoeal disease burden in our country. We assessed post-vaccine introduction data (all-cause acute diarrhoea and rotavirus laboratory-confirmed cases, and genotype distribution), compared with pre-vaccination period in children under 5 years of age in Argentina. Cross-sectional ecologic analysis was conducted with data from the Argentine Surveillance Health System. Endemic channel and global and seasonal incidence rates of pre- and post-vaccination periods were calculated and further compared. Conventional binary genotypification on rotavirus-positive samples was also performed. In post-vaccination period, a global decrease of 20.8% in the rate of all-cause acute diarrhoea cases was found. The endemic channel showed that declination was more significant in the autumn/winter season. Rotavirus laboratory-confirmed cases showed 61.7% of reduction and the weekly distribution analyses indicated a significant flattening of the expected seasonal peak. G2P was the most prevalent circulating genotype (57.2%). This study represents the first assessment of diarrhoeal disease burden since rotavirus massive vaccination strategy was implemented in Argentina. This introduction represented a successful intervention due to the significant decrease in all-cause acute diarrhoea cases and rotavirus laboratory-confirmed cases.
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