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

Rotavirus is the most common cause of severe diarrhea in children worldwide, and vaccines currently being field-tested could be available for childhood immunization in several years. To assess the rotavirus disease burden in Argentina and the value of future national surveillance for the disease, we reviewed available data on rotavirus detections reported by published and unpublished studies conducted in nine Argentine cities and by a multicenter study. Data from these studies indicated that rotavirus was detected in 20% of 5,226 specimens (within a range of 6% to 54% for different studies) from children hospitalized for diarrhea and in 9% of 6,587 specimens (within a range of 5% to 22% for different studies) from children who were outpatients, members of mixed populations (hospitalized patients 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. Attempted serotyping of 294 rotavirus-positive specimens for G-protein by three laboratories was successful in 230 cases (78%); the resulting data indicated that serotype G1 was the most common (being present in 60% of the successfully serotyped specimens), followed by G2 (in 20%), G4 (in 14%), and G3 (in 5%). Based on national data for Argentina, we estimate that in 1991 there were roughly 84,500 rotavirus-associated outpatient visits (1 for every 8 births) and 21,000 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 assess the cost-effectiveness of a rotavirus vaccine program, and to indicate what methods might best be used to monitor such a program's impact.

[Detection of non-A rotavirus in Tucumán]. / Detección de rotavirus no-A en Tucumán.

A case of infectious gastroenteritis (GEI) caused by a non-A Rotavirus (RV) in the province of Tucumán is reported. Fecal sample analysis for group A RV by enzyme immunoassay (ELISA) gave a negative result. Polyacrylamide gel electrophoresis (PAGE) of the viral RNA showed a genomic pattern coincident with that described by Pedley for RV belonging to group C. To our knowledge, this is the first communication on the detection of non-A RV as an etiological agent of human GEI in Argentina.

Detección de rotavirus no-A en Tucumán. / [Detection of non-A rotavirus in Tucumán]

A case of infectious gastroenteritis (GEI) caused by a non-A Rotavirus (RV) in the province of Tucumán is reported. Fecal sample analysis for group A RV by enzyme immunoassay (ELISA) gave a negative result. Polyacrylamide gel electrophoresis (PAGE) of the viral RNA showed a genomic pattern coincident with that described by Pedley for RV belonging to group C. To our knowledge, this is the first communication on the detection of non-A RV as an etiological agent of human GEI in Argentina.

[Electrophoretic types of rotavirus RNA during a 4-yr study of gastroenteritis in Tucumán]. / Electroferotipos del ARN de rotavirus durante cuatro años de estudio de gastroenteritis en Tucumán.

Between May 1986 and November 1989 a total of 796 faecal samples obtained from children with symptoms of acute diarrhea were analyzed. Rotavirus (RV) was detected in 166 cases by polyacrylamide gel electrophoresis of the viral RNA (PAGE) (Fig. 1). This technique allowed us to identify 19 different electropherotypes (EPT) eleven with a long pattern and 8 with a short one (Fig. 2). Two EPT's were dominant during this study; one detected in 1986 only and the other one in 1987, 1988 and 1989. During the last months of 1989 a new EPT was detected. The 8 EPT's with short patterns were the causative organisms of an outbreak during the cold season of 1987 (Table 2). These results show that the rotaviral infection is endemic in the province of Tucumán, as well as its prevalence during the winter season (Table 1).

Electroferotipos del ARN de rotavirus durante cuatro años de estudio de gastroenteritis en Tucumán. / [Electrophoretic types of rotavirus RNA during a 4-yr study of gastroenteritis in Tucumán]

Between May 1986 and November 1989 a total of 796 faecal samples obtained from children with symptoms of acute diarrhea were analyzed. Rotavirus (RV) was detected in 166 cases by polyacrylamide gel electrophoresis of the viral RNA (PAGE) (Fig. 1). This technique allowed us to identify 19 different electropherotypes (EPT) eleven with a long pattern and 8 with a short one (Fig. 2). Two EPTs were dominant during this study; one detected in 1986 only and the other one in 1987, 1988 and 1989. During the last months of 1989 a new EPT was detected. The 8 EPTs with short patterns were the causative organisms of an outbreak during the cold season of 1987 (Table 2). These results show that the rotaviral infection is endemic in the province of Tucumán, as well as its prevalence during the winter season (Table 1).

[Enzyme immunoassay for rotavirus using nylon as the solid phase]. / Enzimoinmunoanálisis para rotavirus con nylon como fase sólida.

An enzyme-linked immunoassay (EIA) to detect Rotavirus in stools is described. Antibodies prepared in rabbits were immobilized on small nylon cubes as capture phase and enzyme conjugated antibodies were used to reveal the reaction. The conjugate was prepared with horseradish peroxidase by the Nakane periodate oxidation method. The solid phase consisted of 3 mm nylon cubes (66 CNL Du-cilo) previously submitted to partial acid hydrolysis to liberate amino-reactive groups. Glutaraldehyde was employed to couple the capturing antibody to the solid phase resulting in a covalent linkage between the gamma-globulin and the nylon. Phenylenediamine in citrate buffer pH 5.0 with 0.5% hydrogen peroxide was used as revealing substrate. EIA was performed as follows: stools watery extracts were incubated 1 h at 37 degrees C with antibody-treated nylon cubes, and then with enzyme conjugate, rinsed with distilled water and substrate-added. Samples developing colour, with optical density of at least 0.350 at 492 nm, were considered positive. The method showed good correlation with a commercial kit.

Enzimoinmunoanálisis para rotavirus con nylon como fase sólida. / [Enzyme immunoassay for rotavirus using nylon as the solid phase]

An enzyme-linked immunoassay (EIA) to detect Rotavirus in stools is described. Antibodies prepared in rabbits were immobilized on small nylon cubes as capture phase and enzyme conjugated antibodies were used to reveal the reaction. The conjugate was prepared with horseradish peroxidase by the Nakane periodate oxidation method. The solid phase consisted of 3 mm nylon cubes (66 CNL Du-cilo) previously submitted to partial acid hydrolysis to liberate amino-reactive groups. Glutaraldehyde was employed to couple the capturing antibody to the solid phase resulting in a covalent linkage between the gamma-globulin and the nylon. Phenylenediamine in citrate buffer pH 5.0 with 0.5

hydrogen peroxide was used as revealing substrate. EIA was performed as follows: stools watery extracts were incubated 1 h at 37 degrees C with antibody-treated nylon cubes, and then with enzyme conjugate, rinsed with distilled water and substrate-added. Samples developing colour, with optical density of at least 0.350 at 492 nm, were considered positive. The method showed good correlation with a commercial kit.