The Experience of Testing for Coronavirus Disease (COVID-19) at a Single Diagnostic Center in Paraguay before the Introduction of Vaccination.

Soon after the declaration of the COVID-19 pandemic, the Institute for Health Sciences Research (IICS) of the National University of Asunción, Paraguay became a testing laboratory (COVID-Lab) for SARS-CoV-2. The COVID-Lab testing performance was assessed from 1 April 2020 to 12 May 2021. The effect of the pandemic on the IICS and how the COVID-Lab contributed to the academic and research activities of the institute were also assessed. IICS researchers and staff adjusted their work schedules to support the COVID-Lab. Of the 13,082 nasopharyngeal/oropharyngeal swabs processed, 2704 (20.7%) tested positive for SARS-CoV-2 by RT-PCR. Of the individuals testing positive, 55.4% were female and 48.3% were aged 21-40 years. Challenges faced by the COVID-Lab were unstable reagent access and insufficient staff; shifting obligations regarding research, academic instruction, and grantsmanship; and the continuous demands from the public for information on COVID-19. The IICS provided essential testing and reported on the progress of the pandemic. IICS researchers gained better laboratory equipment and expertise in molecular SARS-CoV-2 testing but struggled to manage their conflicting educational and additional research obligations during the pandemic, which affected their productivity. Therefore, policies protecting the time and resources of the faculty and staff engaged in pandemic-related work or research are necessary components of healthcare emergency preparedness.

Genome-wide analyses of human noroviruses provide insights on evolutionary dynamics and evidence of coexisting viral populations evolving under recombination constraints.

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.

Chagas disease: national survey of seroprevalence in children under five years of age conducted in 2008

BACKGROUND Since the early 1990s, programs to control Chagas disease in South America have focused on eradicating domiciliary Triatoma infestans, the main vector. Seroprevalence studies of the chagasic infection are included as part of the vector control programs; they are essential to assess the impact of vector control measures and to monitor the prevention of vector transmission. OBJECTIVE To assess the interruption of domiciliary vector transmission of Chagas disease by T. infestans in Paraguay by evaluating the current state of transmission in rural areas. METHODS A survey of seroprevalence of Chagas disease was carried out in a representative sample group of Paraguayans aged one to five years living in rural areas of Paraguay in 2008. Blood samples collected on filter paper from 12,776 children were tested using an enzyme-linked immunosorbent assay. Children whose serology was positive or undetermined (n = 41) were recalled to donate a whole blood sample for retesting. Their homes were inspected for current triatomine infestation. Blood samples from their respective mothers were also collected and tested to check possible transmission of the disease by a congenital route. FINDINGS A seroprevalence rate of 0.24% for Trypanosoma cruzi infection was detected in children under five years of age among the country’s rural population. Our findings indicate that T. cruzi was transmitted to these children vertically. The total number of infected children, aged one to five years living in these departments, was estimated at 1,691 cases with an annual incidence of congenital transmission of 338 cases per year. MAIN CONCLUSION We determined the impact of vector control in the transmission of T. cruzi, following uninterrupted vector control measures employed since 1999 in contiguous T. infestans-endemic areas of Paraguay, and this allowed us to estimate the degree of risk of congenital transmission in the country.

Chagas disease: national survey of seroprevalence in children under five years of age conducted in 2008.

BACKGROUND: Since the early 1990s, programs to control Chagas disease in South America have focused on eradicating domiciliary Triatoma infestans, the main vector. Seroprevalence studies of the chagasic infection are included as part of the vector control programs; they are essential to assess the impact of vector control measures and to monitor the prevention of vector transmission. OBJECTIVE: To assess the interruption of domiciliary vector transmission of Chagas disease by T. infestans in Paraguay by evaluating the current state of transmission in rural areas. METHODS: A survey of seroprevalence of Chagas disease was carried out in a representative sample group of Paraguayans aged one to five years living in rural areas of Paraguay in 2008. Blood samples collected on filter paper from 12,776 children were tested using an enzyme-linked immunosorbent assay. Children whose serology was positive or undetermined (n = 41) were recalled to donate a whole blood sample for retesting. Their homes were inspected for current triatomine infestation. Blood samples from their respective mothers were also collected and tested to check possible transmission of the disease by a congenital route. FINDINGS: A seroprevalence rate of 0.24% for Trypanosoma cruzi infection was detected in children under five years of age among the country's rural population. Our findings indicate that T. cruzi was transmitted to these children vertically. The total number of infected children, aged one to five years living in these departments, was estimated at 1,691 cases with an annual incidence of congenital transmission of 338 cases per year. MAIN CONCLUSION: We determined the impact of vector control in the transmission of T. cruzi, following uninterrupted vector control measures employed since 1999 in contiguous T. infestans-endemic areas of Paraguay, and this allowed us to estimate the degree of risk of congenital transmission in the country.

Whole-genome analyses reveals the animal origin of a rotavirus G4P[6] detected in a child with severe diarrhea.

Group A rotaviruses are a major cause of severe gastroenteritis in children worldwide. Currently, two rotavirus vaccines are being used in vaccination programs, and one of the factors involved in lower vaccine efficacy is the mismatch among the circulating strains and the vaccine strains. Thus, the emergence of animal strains in the human population could affect the efficacy of vaccination programs. Here we report the presence of a G4P[6] strain in a Paraguayan child presenting acute gastroenteritis in 2009. Genomic analyses revealed that the strain presents a porcine-like genome (G4-P[6]-I1-R1-C1-M1-A8-N1-T7-E1-H1), suggesting a direct animal-to-human transmission. Continuous surveillance of rotaviruses in humans and animals will help us to better understand rotavirus epidemiology and evolution.

Predominance of rotavirus G2P[4] and emergence of G12P[9] strains in Asunción, Paraguay, 2006-2007.

Rotavirus is the most common cause of severe diarrhea in children worldwide. Monitoring the diversity of rotavirus strains is of great importance for current and future vaccination programs. To determine the diversity of rotavirus circulating in Asuncion, Paraguay, between 2006 and 2007, we carried out a molecular characterization of rotaviruses detected in children <5 years old and adults (>18 years old). We found that the most common circulating strain was G2P[4] (69/143), followed by G9P[8] (37/143). The temporal distribution of strains showed that, in children, G2P[4] was predominant in 2006, and that G2P[4] and G9P[8] were co-predominant in 2007, whereas in adults, G2P[4] was predominant in both years. Additionally, one G9P[6] and three G12P[9] strains were found in adult samples, making this the first report of these strains circulating in Paraguay. Sequence analysis of the G12P[9] strains suggests across-border migration of this strain within the southern cone of America.

Diversity of group A rotavirus strains circulating in Paraguay from 2002 to 2005: detection of an atypical G1 in South America.

BACKGROUND: Group A rotaviruses are the main cause of severe gastroenteritis in children worldwide. OBJECTIVES: To survey human rotavirus strains circulating in Paraguay. STUDY DESIGN: One hundred ninety-six rotavirus-positive fecal samples collected from children up to 5 years old, from 2002 to 2005, were characterized. RESULTS: The most common G genotype detected was G9 (36.2%), followed by G1 (34.2%), G2 (11.7%) and G4 (8.7%). Changes in the G genotype frequency were observed from year to year. The G4 genotype was predominant in 2002; G1 in 2003; and G9 from 2004 to 2005. Sequence and phylogenetic analysis of the VP7 gene from Paraguayan G1 strains suggested that the high frequency of G1 in 2003 could be due to the introduction of an atypical sub-lineage. In addition, there were amino acid changes in the variable/antigenic regions of the VP7 gene from G4 and G9 strains detected in different years. CONCLUSIONS: This study further indicates that antigenic pressure can drive the evolution of rotaviruses, and also suggests that a vaccine that protects against the most prevalent strains and its variants, will be necessary to elicit a protective immune response against the range of rotavirus types currently circulating in Paraguay.

Rotavirus infection in the Paraguayan population from 2004 to 2005: high incidence of rotavirus strains with short electropherotype in children and adults.

BACKGROUND: Rotavirus is considered the main viral cause of acute gastroenteritis in children in both developed and developing countries. The aim of the present study was to continue the surveillance of rotavirus in the Paraguayan population in anticipation of a rotavirus vaccination in children. MATERIAL/METHODS: Fecal samples from infants (< or =5 years of age) and adults with diarrhea (912 and 801 samples, respectively) were collected in Paraguay during 2004-2005. Rotavirus incidence was screened by PAGE and genotyping was performed by reverse transcription (RT)-PCR. RESULTS: Rotavirus incidence was 23.8% and 19.4% for children and adults, respectively. The rotavirus incidence was higher in the coolest and driest months of the year. Five different group A rotavirus electropherotypes were detected. Rotaviruses with a long electropherotype were the most frequently detected in children in 2004 and 2005. However, in 2005 (after six years of absence in Paraguay) rotaviruses with a short electropherotype were detected at high frequency in both children and adults. Of these, 14 samples were genotyped (11 from children and 3 from adults) and all of them showed the G2P[4] type. CONCLUSIONS: This study reinforces the importance of continuous survey of rotavirus infection, extended to all age groups, in order to increase our knowledge about the complexity of rotavirus epidemiology.