The Lambda Variant in Argentina: Analyzing the Evolution and Spread of SARS-CoV-2 Lineage C.37.

The second wave of COVID-19 occurred in South America in early 2021 and was mainly driven by Gamma and Lambda variants. In this study, we aimed to describe the emergence and local genomic diversity of the SARS-CoV-2 Lambda variant in Argentina, from its initial entry into the country until its detection ceased. Molecular surveillance was conducted on 9356 samples from Argentina between October 2020 and April 2022, and sequencing, phylogenetic, and phylogeographic analyses were performed. Our findings revealed that the Lambda variant was first detected in Argentina in January 2021 and steadily increased in frequency until it peaked in April 2021, with continued detection throughout the year. Phylodynamic analyses showed that at least 18 introductions of the Lambda variant into the country occurred, with nine of them having evidence of onward local transmission. The spatial--temporal reconstruction showed that Argentine clades were associated with Lambda sequences from Latin America and suggested an initial diversification in the Metropolitan Area of Buenos Aires before spreading to other regions in Argentina. Genetic analyses of genome sequences allowed us to describe the mutational patterns of the Argentine Lambda sequences and detect the emergence of rare mutations in an immunocompromised patient. Our study highlights the importance of genomic surveillance in identifying the introduction and geographical distribution of the SARS-CoV-2 Lambda variant, as well as in monitoring the emergence of mutations that could be involved in the evolutionary leaps that characterize variants of concern.

Omicron Waves in Argentina: Dynamics of SARS-CoV-2 Lineages BA.1, BA.2 and the Emerging BA.2.12.1 and BA.4/BA.5.

The COVID-19 pandemic has lately been driven by Omicron. This work aimed to study the dynamics of SARS-CoV-2 Omicron lineages during the third and fourth waves of COVID-19 in Argentina. Molecular surveillance was performed on 3431 samples from Argentina, between EW44/2021 and EW31/2022. Sequencing, phylogenetic and phylodynamic analyses were performed. A differential dynamic between the Omicron waves was found. The third wave was associated with lineage BA.1, characterized by a high number of cases, very fast displacement of Delta, doubling times of 3.3 days and a low level of lineage diversity and clustering. In contrast, the fourth wave was longer but associated with a lower number of cases, initially caused by BA.2, and later by BA.4/BA.5, with doubling times of about 10 days. Several BA.2 and BA.4/BA.5 sublineages and introductions were detected, although very few clusters with a constrained geographical distribution were observed, suggesting limited transmission chains. The differential dynamic could be due to waning immunity and an increase in population gatherings in the BA.1 wave, and a boosted population (for vaccination or recent prior immunity for BA.1 infection) in the wave caused by BA2/BA.4/BA.5, which may have limited the establishment of the new lineages.

High prevalence of hepatitis A and E viruses in environmental and clinical samples from West Argentina.

Environmental surveillance of water sources is important to monitoring viral hepatitis transmission in clinical settings. This study investigated the circulation of hepatitis A (HAV) and E (HEV) viruses in sewage and clinical samples from Argentina. Between 2016 and 2017, 80 raw sewage samples and 86 clinical samples (stool and serum) from suspected cases of hepatitis A and hepatitis E were obtained. HAV and HEV were tested by both real-time and nested PCR. Positive samples were sequenced for genotype determination and phylogenetic analysis. Overall, HAV was recovered in 39% of sewage samples and 61.1% of clinical samples. HEV was detected in 22.5% of sewage samples and 15.9% of clinical samples. HAV was found more frequently in sewage during the winter and in clinical samples in spring; HEV was more prevalent in sewage during summer and in clinical samples in autumn. All HAV isolates belonged to genotype IA and HEV isolates belonged to genotype 3, the most prevalent genotypes in South America. High prevalence of HAV and HEV in environmental and clinical samples in Mendoza, Argentina was observed. These findings reinforce the importance of environmental surveillance and implementation of health strategies to control the spread of HAV and HEV in developing countries.

High prevalence of hepatitis A and E viruses in environmental and clinical samples from West Argentina

ABSTRACT Environmental surveillance of water sources is important to monitoring viral hepatitis transmission in clinical settings. This study investigated the circulation of hepatitis A (HAV) and E (HEV) viruses in sewage and clinical samples from Argentina. Between 2016 and 2017, 80 raw sewage samples and 86 clinical samples (stool and serum) from suspected cases of hepatitis A and hepatitis E were obtained. HAV and HEV were tested by both real-time and nested PCR. Positive samples were sequenced for genotype determination and phylogenetic analysis. Overall, HAV was recovered in 39% of sewage samples and 61.1% of clinical samples. HEV was detected in 22.5% of sewage samples and 15.9% of clinical samples. HAV was found more frequently in sewage during the winter and in clinical samples in spring; HEV was more prevalent in sewage during summer and in clinical samples in autumn. All HAV isolates belonged to genotype IA and HEV isolates belonged to genotype 3, the most prevalent genotypes in South America. High prevalence of HAV and HEV in environmental and clinical samples in Mendoza, Argentina was observed. These findings reinforce the importance of environmental surveillance and implementation of health strategies to control the spread of HAV and HEV in developing countries.

Epidemiology of hepatitis B and C virus infection in Central West Argentina.

Little information is available regarding the prevalence of viral hepatitis in Central West Argentina. This study aims to give new information regarding HBV and HCV prevalence, genotypes, and risk factors in Central West Argentina and the suitability of dried blood spot (DBS) sampling for HBV and HCV screening. METHODS: A total of 622 individuals were included; the mean age was 36.6 ± 14.3 years and 55.4% were females. HBV and HCV markers were detected using serological and molecular analysis, and risk factors were evaluated using statistical analysis. RESULTS: Using serum samples, the HBsAg prevalence was 1.8%, the rate of HBV exposure (anti-HBc positivity) was 5.3%, and the rate of HBV immunity was 34.9%. HBV DNA was found in four out of 11 HBsAg+ samples, and the viruses in three of these samples were classified as genotypes A1, A2 and F2a. Multivariate analysis showed that anti-HBs positivity was associated with the level of schooling and history of HBV vaccination. The anti-HCV prevalence was 2.6%, and HCV RNA was found in 11 samples, seven of which contained viruses of genotypes 1a (n = 2), 1b (n = 3) and 2 (n = 2). The sensitivity of the DBS assay for HBsAg, anti-HBc, and anti-HCV was 100%, 66.6%, and 75%, respectively, and the specificity was above 98% for all markers when compared to serum. CONCLUSION: A low rate of HBV immunity was observed, demonstrating the importance of HBV vaccination. High HCV prevalence was found, and HCV 1b was closely related to other Argentinian isolates. Finally, the performance of DBS testing in this population needs more optimization to increase its sensitivity and specificity.

High prevalence of a variety of autoantibodies in a population of hepatitis C virus-infected individuals.

Hepatitis C virus (HCV) infection has been related to self-reactivity, extrahepatic manifestations and autoimmune diseases. The main goals of this work were to study the prevalence of autoantibodies and their relationship with viral titers and biochemical markers of hepatic damage in patients infected with HCV. Autoantibodies (ANA, AMA, SMA, APC, LKM, DNAds, ANCA, ATG and RF) were determined in 73 individuals with chronic HCV infection and 44 healthy volunteers. The presence of these antibodies was related to demographic variables, viral titers and biochemical parameters. A high prevalence of autoantibodies, particularly for RF, that was associated with female gender was observed in HCV-infected patients. In addition, SMA, ANA and ATG showed increased frequencies in HCV infection. Interestingly, the concurrent detection of SMA and more than one autoantibody was associated with high gGT levels. Notably, concurrent higher gGT, HCV and SMA levels were observed in male patients as compared to their female counterparts. These results indicate a relationship between HCV infection and the concurrent detection of various autoantibodies in the absence of symptoms of autoimmune diseases. They also suggest a link among the presence of a variety of autoantibodies simultaneously with SMA, increased gGT levels and HCV titers in a population of male patients.

Seven-year follow-up of the immune response after one or 2 doses of inactivated hepatitis A vaccine given at 1 year of age in the Mendoza Province of Argentina.

This monocenter, descriptive, prospective, non-interventional study evaluated the long-term immune responses following routine vaccination with one or 2 doses of a licensed inactivated hepatitis A (HA) vaccine (Avaxim® 80U Pediatric) at age 11-23 months in a cohort of children from Mendoza, Argentina. Antibodies to hepatitis A virus (anti-HAV) were quantified annually up to Y5, and at Y7. Children whose titer decreased to below the seroprotection threshold (defined as an anti-HAV antibody concentration of ≥ 10 mIU/mL in a microparticle enzyme immunoassay up to Y5, or ≥ 3 mIU/mL in an electrochemiluminescence immunoassay at Y7) received a routine booster dose of the same HA vaccine. This report summarizes the data at 7 year after the first vaccination. Of 546 participants initially included, 264 participants remained at Y7 and provided blood samples. Of these, 204 having received one HA primary dose as a toddler were still seroprotected at Y7; titers for a further 7 also having received one HA dose as a toddler fell to below the seroprotection threshold and they therefore received a booster; all 53 having received 2 HA doses as a toddler and still present at Y7 remained seroprotected at Y7. One or 2 primary doses of this HA vaccine in toddlers result in very good persistence of anti-HAV up to 7 year post-first vaccination.

Updating the knowledge of hepatitis E: new variants and higher prevalence of anti-HEV in Argentina.

INTRODUCTION: Hepatitis E is a disease of global distribution, with significant morbidity and mortality, whose scope and burden continue to emerge in low endemic countries. MATERIAL AND METHODS: In 2012, we studied the prevalence of anti-HEV antibodies in 202 adult serum samples. We also analyzed samples from 143 patients with acute non-A-C hepatitis from January 2011 to December 2013. Acute HEV infections were diagnosed with anti-HEV IgM and/or HEV RNA. HEV RNA was also investigated in 94 swine fecal samples. HEV RNA was sequenced and characterized. RESULTS: We found higher values of prevalence than those previously reported in the 1990s. The overall prevalence of anti-HEV IgG antibodies was 15.4%. The prevalence was 10.6% in the 123 adults voluntarily screened on World Hepatitis Day 2012 in Buenos Aires city and 14.8, 16.7 and 35.7% respectively in the smaller groups of healthcare workers, blood donors and HIV-positive patients from different regions of the country. Nine acute HEV infections were diagnosed in the three years analyzed. We characterized new human variants of subgenotype 3a and 3i. New subgenotype 3i variants were found in swine from two distant provinces closely related to the human ones. CONCLUSIONS: These results enlarge the knowledge of HEV and contribute with new information. However, higher values of prevalence found in small groups need to be confirmed in larger studies. Many aspects of the spectrum of the disease and the reservoirs and routes of transmission are still unknown and thus deserve additional research.

Persistence of immunity from 1 year of age after one or two doses of hepatitis A vaccine given to children in Argentina.

BACKGROUND: This study was done to determine the immunogenicity of a single dose of hepatitis A vaccine in children, providing needed clinical data on the flexibility of booster administration. METHODS: Participants had received one dose of inactivated hepatitis A vaccine (Avaxim™ 80 U Pediatric) at 12-23 months of age or two doses of the same vaccine at 12 and 18 months of age prior to enrolment. Anti-hepatitis A antibody concentrations were measured at the first, second, and third year after vaccination. Suspected cases of hepatitis A in participant families were assessed and family socioeconomic data were collected. RESULTS: A series of 546 participants were enrolled. Of 467 (85.5%) participants completing 3 years of follow-up, 365 had received a single vaccine dose and 94 had received two vaccine doses. Seropositivity (anti-HAV ≥ 10 mIU/mL) at 3 years was 99.7% after one dose and 100% after two doses. At one year, geometric mean concentrations were higher after two doses (1433.9 mIU/mL, 95% confidence interval [CI] 1108-1855) than one (209.7 mIU/mL, 95% CI 190.6-230.6). Geometric mean concentrations decreased in both groups during the study, but remained well above 10 mIU/mL through the third year. The geometric mean of 3-year to one-year anti-hepatitis A concentration ratios was 0.74 (95% CI 0.70-0.79) following one dose and 0.57 (95% CI 0.47-0.70) following two doses. The greatest decrease in geometric mean concentrations occurred during the third year, ie, 21.2% in the one-dose group and 40.8% in the two-dose group. Six participants became seronegative during follow-up and responded strongly to a booster dose. Anti-hepatitis A concentrations increased in 135 children (34.9%) in the second year and 50 (13.7%) in the third year; none lived in a family with a case of hepatitis A. Three confirmed cases of hepatitis A occurred in family members. Participants belonged to a middle-income, urban/suburban population with good sanitation facilities and water supplies. CONCLUSION: A single dose of hepatitis A vaccine at 12-23 months of age resulted in hepatitis A seropositivity in all but one vaccinee after 3 years. Increased anti-hepatitis A serum concentrations suggested exposure to wild-type hepatitis A virus in this middle-class socioeconomic environment. Continuing surveillance is required to confirm the effectiveness of a single-dose hepatitis A vaccination; however, the results of the first three years are encouraging.

Infección Respiratoria Aguda por metapneumovirus humano en Ushuaia, Argentina: descripción del primer caso / Acute lower respiratory infection by human metapneumovirus in Ushuaia, Argentina: description of the first patient

RESUMEN Hacia fines del año 2003, en la ciudad de Ushuaia resultó llamativa la cantidad de niños internados con cuadros respiratorios graves y estudios virológicos negativos. Sobre la base de publicaciones acerca de la circulación de un nuevo virus respiratorio, metapneumovirus humano, se decidió investigar su presencia en tres muestras respiratorias de niños internados con infección respiratoria aguda en el Hospital Regional de Ushuaia. Los aspirados nasofaríngeos, previamente negativos para los virus respiratorios comunes por la técnica de inmunofluorescencia, fueron estudiados mediante la técnica de transcripción inversa y amplificación genómica por reacción en cadena de la polimerasa para metapneumovirus humano. Una de las muestras resultó positiva para metapneumovirus humano. En ninguno de los pacientes se detectaron anticuerpos de clase IgM para Chlamydia spp y Mycoplasma pneumoniae, por la técnica de inmunofluorescencia. La descripción del presente caso enfatiza la necesidad de ampliar el espectro diagnóstico en niños internados que resulten negativos para los virus respiratorios más comunes.

Infección Respiratoria Aguda por metapneumovirus humano en Ushuaia, Argentina: descripción del primer caso / Acute lower respiratory infection by human metapneumovirus in Ushuaia, Argentina: description of the first patient

RESUMEN Hacia fines del año 2003, en la ciudad de Ushuaia resultó llamativa la cantidad de niños internados con cuadros respiratorios graves y estudios virológicos negativos. Sobre la base de publicaciones acerca de la circulación de un nuevo virus respiratorio, metapneumovirus humano, se decidió investigar su presencia en tres muestras respiratorias de niños internados con infección respiratoria aguda en el Hospital Regional de Ushuaia. Los aspirados nasofaríngeos, previamente negativos para los virus respiratorios comunes por la técnica de inmunofluorescencia, fueron estudiados mediante la técnica de transcripción inversa y amplificación genómica por reacción en cadena de la polimerasa para metapneumovirus humano. Una de las muestras resultó positiva para metapneumovirus humano. En ninguno de los pacientes se detectaron anticuerpos de clase IgM para Chlamydia spp y Mycoplasma pneumoniae, por la técnica de inmunofluorescencia. La descripción del presente caso enfatiza la necesidad de ampliar el espectro diagnóstico en niños internados que resulten negativos para los virus respiratorios más comunes. (AU)

Prevalence and characterization of astroviruses in Argentinean children with acute gastroenteritis.

Among viral agents causing gastroenteritis, human astroviruses (HAstVs) take second or third place, after rotaviruses and caliciviruses, as the most frequent cause of illness. The aims of this study were to determine the prevalence of HAstV infection and to characterize the circulating HAstV strains in children with diarrhea under 3 years of age treated between 1995 and 1998 at out- or in-patient facilities of the children's hospital in Mendoza, Argentina. Reverse transcription-polymerase chain reaction (RT-PCR) and enzyme immunoassay (EIA) were used to detect HAstVs in stool specimens. Positive specimens were tested further by EIA and/or sequenced to type detected HAstV strains. HAstVs were detected in 40 (3.7%) of 1,070 samples that were rotavirus and calicivirus-negative: 14 (3.5%) of 402 from outpatients and 26 (3.9%) of 668 from inpatients. HAstV infection tended to be more severe in children during their first year of life: 18 (4.7%) of 383 HAstV-positive children 0-11 months old were hospitalized versus 8 (2.8%) of 285 children 1 year of age or older (P = 0.29). Type 1 (HAstV-1) was the most common type (41%), followed by HAstV-4 (25%), HAstV-2 (13%), HAstV-3 (13%), and HAstV-5 (8%). In this first epidemiological study of HAstV infection in this region, we confirmed HAstV to be a cause of severe gastroenteritis in children, more often among children younger than 12 months of age. HastV-4 caused 25% of HastV infections in Mendoza, although it has been detected commonly elsewhere. Distinct genetic lineages were apparent but their epidemiological significance remains to be demonstrated.

Sequence diversity of human caliciviruses recovered from children with diarrhea in Mendoza, Argentina, 1995-1998.

Human caliciviruses were detected by EIA and/or RT-PCR in stool specimens from children with diarrhea treated at out- or in-patient facilities between 1995 and 1998 in Mendoza, Argentina. Mexico virus-like strains detected by primers NV36/51 were transiently prevalent in 1995/1996. Significantly more human caliciviruses were detected when primers were designed from contemporaneously circulating strains. Nucleotide sequences of a highly conserved region in the RNA polymerase gene of 10 selected human caliciviruses were determined. Eight strains were Norwalk-like viruses and two strains were Sapporo-like viruses. Seven of the eight Norwalk-like viruses also were positive by the recombinant Mexico virus antigen EIA. The seven Mexico virus EIA-positive strains revealed two patterns in the RNA polymerase sequences: two strains were closest to Mexico virus and the other five strains were closest to Lordsdale virus. One of the five "Lordsdale" viruses was found to be a naturally occurring recombinant between the Mexico virus and Lordsdale human calicivirus genetic clusters [Jiang et al., (1999b) Archives of Virology 144:2377-2387]. The Mexico virus EIA-negative strain had 73-77% nucleotide identity with the closest related Norwalk-like viruses, indicating it might belong to a new genetic cluster of the Norwalk-like virus genus. The two Sapporo-like viruses were distinct genetically; one belonged to the Houston/90 or Parkville cluster and the other to a new cluster. Some strains appeared to have short periods of prevalence and locally adapted primer pairs significantly increased detection rates. The finding of high diversity of circulating strains, including recombinant strains and strains with previously unrecognized genetic identities, highlights a need for studies of human caliciviruses in these children and other populations.

En anticipación de una vacuna antirrotavirus: revisión de estudios epidemiológicos sobre la diarrea por rotavirus en la Argentina / Anticipating rotavirus vaccines: review of epidemiologic studies of rotavirus diarrhea in Argentina

En todo el mundo, los rotavirus son la causa más común de diarrea grave en los niños pequeños y actualmente se están ensayando sobre el terreno vacunas que posiblemente permitan inmunizar a la población infantil dentro de varios años. Con el fin de estimar la carga de enfermedad por rotavirus en la Argentina y la utilidad de establecer en el país un sistema de vigilancia de la enfermedad, se revisaron datos sobre la detección de estos virus, según estudios publicados y otros inéditos de nueve ciudades argentinas y uno multicéntrico. Los informes revisados indican que se detectaron rotavirus en 20 por cien de 5.226 especímenes (con un recorrido de 6 a 54 por ciento entre estudios) tomados de niños hospitalizados por diarrea y en 9 por ciento de 6.587 especímenes (recorrido de 5 a 22 por ciento entre estudios) tomados de pacientes ambulatorios, miembros de poblaciones mixtas (niños hospitalizados y ambulatorios) y sujetos de encuestas comunitarias. Los datos hospitalarios muestran que, si bien los virus se detectaron durante todo el año, en los meses de invierno (mayo a julio) hubo un pico de intensidad cuando hasta la mitad de los niños con diarrea dieron resultados positivos a los rotavirus. En tres laboratorios se logró serotipificar para la proteína G 230 de 294 especímenes positivos (78 por ciento); los resultados indican que el serotipo G1 fue el más común (presente en 60 por cien de los especímenes serotipificados) seguido del G2 (en 20 por cien), G4 (en 14 por cien) y G3 (en 5 por cien). Sobre la base de los datos obtenidos en el país, se estimó que en 1991 en la Argentina hubo aproximadamente 84.500 visitas de pacientes ambulatorios (1 de cada 8 nacimientos) y 21000 hospitalizaciones de 4 días en promedio (1 de cada 31 nacimientos) asociadas con rotavirus, que en conjunto costaron unos US$ 27.7 millones. Estos datos preliminares muestran que la carga de enfermedad por rotavirus en los niños argentinos es muy pesada y podría disminuirse con una vacuna segura y efectiva. Además se necesita ampliar la vigilancia para mejorar el conocimiento de la epidemiología y de la distribución de las cepas de rotavirus en el país, calcular más exactamente la eficacia en función del costo de un programa de vacunación antirrotavirus y determinar los mejores métodos de monitorear sus efectos

En anticipación de una vacuna antirrotavirus: revisión de estudios epidemiológicos sobre la diarrea por rotavirus en la Argentina / Anticipating rotavirus vaccines: review of epidemiologic studies of rotavirus diarrhea in Argentina

En todo el mundo, los rotavirus son la causa más común de diarrea grave en los niños pequeños y actualmente se están ensayando sobre el terreno vacunas que posiblemente permitan inmunizar a la población infantil dentro de varios años. Con el fin de estimar la carga de enfermedad por rotavirus en la Argentina y la utilidad de establecer en el país un sistema de vigilancia de la enfermedad, se revisaron datos sobre la detección de estos virus, según estudios publicados y otros inéditos de nueve ciudades argentinas y uno multicéntrico. Los informes revisados indican que se detectaron rotavirus en 20 por cien de 5.226 especímenes (con un recorrido de 6 a 54 por ciento entre estudios) tomados de niños hospitalizados por diarrea y en 9 por ciento de 6.587 especímenes (recorrido de 5 a 22 por ciento entre estudios) tomados de pacientes ambulatorios, miembros de poblaciones mixtas (niños hospitalizados y ambulatorios) y sujetos de encuestas comunitarias. Los datos hospitalarios muestran que, si bien los virus se detectaron durante todo el año, en los meses de invierno (mayo a julio) hubo un pico de intensidad cuando hasta la mitad de los niños con diarrea dieron resultados positivos a los rotavirus. En tres laboratorios se logró serotipificar para la proteína G 230 de 294 especímenes positivos (78 por ciento); los resultados indican que el serotipo G1 fue el más común (presente en 60 por cien de los especímenes serotipificados) seguido del G2 (en 20 por cien), G4 (en 14 por cien) y G3 (en 5 por cien). Sobre la base de los datos obtenidos en el país, se estimó que en 1991 en la Argentina hubo aproximadamente 84.500 visitas de pacientes ambulatorios (1 de cada 8 nacimientos) y 21000 hospitalizaciones de 4 días en promedio (1 de cada 31 nacimientos) asociadas con rotavirus, que en conjunto costaron unos US$ 27.7 millones. Estos datos preliminares muestran que la carga de enfermedad por rotavirus en los niños argentinos es muy pesada y podría disminuirse con una vacuna segura y efectiva. Además se necesita ampliar la vigilancia para mejorar el conocimiento de la epidemiología y de la distribución de las cepas de rotavirus en el país, calcular más exactamente la eficacia en función del costo de un programa de vacunación antirrotavirus y determinar los mejores métodos de monitorear sus efectos

Anticipating rotavirus vaccines: review of epidemiologic studies of rotavirus diarrhea in Argentina

Rotavirus is the most common cause of severe diarrhea in children worlwide, and vaccines currently being field-tested could be available for childhood immunization in several years. To asses the rotavirus disease in Argentina and the value of future national surveillance for the disease, we reviewed data on rotavirus detections reported by published an unpublished studies conducted in nine Argentine cities and by a multicenter study. Data from these studies indicated that rotavirus was detected in 20 por cent of 5226 specimens (within a range of 6 por cent to 54 por cent for different studies) from children hospitalized for diarrhea and in 9 por cent of 6587 spcimens (within a range of 5 por cent to 22 por cent for different studies) from children who were outpatients, members of mixed populations (hospitalized patiens and outpatients), or survey subjects in community-based studies. The hospital data showed that while rotavirus was detected throughout the year, a peak occurred during the winter months (May-July), when up to half of the children with diarrhea were found positive for rotavirus. Attemped serotyping of 294 rotavirus-positive speciments for G-protein by three laboratories was successful in 230 cases (78 por cent); the resulting data indicated that serotype G1 was the most common (being present in 60 por cent of the successfully serotyped specimens), followed by G2 (in 20 por cent), G4 (in 14 por cent), and G3 (in 5 por cent). Based on national data for Argentina, we estimate that in 1991 there were roughly 84500 rotavirus-associated outpatient visits (1 for every 8 births) and 21000 hospitalizations averaging 4 days in length (1 for every 31 births), all of which entailed direct medical costs estimated at US$ 27.7 million. These preliminary data show that the rotavirus disease burden in Argentine children is extensive and could be decreased by a safe and effective vaccine. Further surveillance is needed to improve our understanding of the epidemiology and distribution of rotavirus strains in Argentina, to more accurately asses the cost-effectiveness of a rotavirus vaccine program, and to indicate what methods might best be used to monitor such a program's impact

Anticipating rotavirus vaccines: review of epidemiologic studies of rotavirus diarrhea in Argentina

Rotavirus is the most common cause of severe diarrhea in children worlwide, and vaccines currently being field-tested could be available for childhood immunization in several years. To asses the rotavirus disease in Argentina and the value of future national surveillance for the disease, we reviewed data on rotavirus detections reported by published an unpublished studies conducted in nine Argentine cities and by a multicenter study. Data from these studies indicated that rotavirus was detected in 20 por cent of 5226 specimens (within a range of 6 por cent to 54 por cent for different studies) from children hospitalized for diarrhea and in 9 por cent of 6587 spcimens (within a range of 5 por cent to 22 por cent for different studies) from children who were outpatients, members of mixed populations (hospitalized patiens and outpatients), or survey subjects in community-based studies. The hospital data showed that while rotavirus was detected throughout the year, a peak occurred during the winter months (May-July), when up to half of the children with diarrhea were found positive for rotavirus. Attemped serotyping of 294 rotavirus-positive speciments for G-protein by three laboratories was successful in 230 cases (78 por cent); the resulting data indicated that serotype G1 was the most common (being present in 60 por cent of the successfully serotyped specimens), followed by G2 (in 20 por cent), G4 (in 14 por cent), and G3 (in 5 por cent). Based on national data for Argentina, we estimate that in 1991 there were roughly 84500 rotavirus-associated outpatient visits (1 for every 8 births) and 21000 hospitalizations averaging 4 days in length (1 for every 31 births), all of which entailed direct medical costs estimated at US$ 27.7 million. These preliminary data show that the rotavirus disease burden in Argentine children is extensive and could be decreased by a safe and effective vaccine. Further surveillance is needed to improve our understanding of the epidemiology and distribution of rotavirus strains in Argentina, to more accurately asses the cost-effectiveness of a rotavirus vaccine program, and to indicate what methods might best be used to monitor such a program's impact