Design, simulation, and fabrication of an ingestible capsule with gastric balloon for obesity treatment.

The treatment of obesity based only on lifestyle changes has been shown ineffectiveness in a long-term period. The development of more definitive and non-invasive therapies has been the subject of study. In this paper, a magnetically driven ingestible capsule with the capacity to inflate a gastric balloon is devised, simulated, and fabricated. The balloon is inflated to a volume of 150 ml using an acid-base reaction between citric acid and potassium bicarbonate. Finite element method simulations were performed to study the interaction between the permanent external magnet and the ingestible capsule and confirm the magnetic activation mechanism. A fabrication process was proposed to manufacture a polydimethylsiloxane (PDMS) balloon in a simple, functional, and reproducible way. The two layers and 1:8 ratio balloons are the most cost-effective without compromising their mechanical properties. The capsule body parts manufactured by a three-dimensional (3D) printing process - Digital Light Processing (DLP) showed high accuracy and excellent resolution. This study demonstrated that the proposed ingestible capsule would successfully inflate the gastric balloon to treat obesity.

Prooxidant activity of norbixin in model of acute gastric ulcer induced by ethanol in rats.

Free radicals and oxidative stress play a central role in gastric injuries caused by ethanol (EtOH). Antioxidant strategies to counteract EtOH toxicity are highly desirable. Norbixin (NBIX) is a carotenoid with antioxidant potential largely used in the food industry. This study evaluated the NBIX effects in a model of gastric ulcer induced by EtOH in rats. Male Wistar rats received NBIX doses of 0, 10, and 25 mg/kg by gavage 1 h after EtOH administration (0 or 75% solution, 1 mL/200 g of animal). The animals were euthanized 1 h after the NBIX administration, and their stomachs were removed for macroscopic and histopathological analyses, quantification of nonprotein sulfhydryl (NPSH) groups, lipid peroxidation (LPO) levels, and catalase (CAT) activity determination. NBIX increased LPO in gastric mucosa and caused CAT inhibition and NPSH depletion in EtOH-treated animals. Results showed that NBIX did not protect gastric tissue against EtOH damage, and this could be associated to a prooxidant effect.

Effect of Vernonia cognata on oxidative damage induced by ethanol in rats.

Free radicals production and oxidative stress play a central role in injuries caused by ethanol (EtOH) on gastric mucosal. Thus, strategies to counteract EtOH toxicity are highly desirable. This study was aimed at evaluating whether Vernonia cognata extract would reduce EtOH effects in rats. Rats received Vernonia cognata extract (0, 1 and 2 g/kg bw, by gavage) 1 hour after EtOH had been administered (0 or 70%, 0.5 mL/100 g bw, by gavage) and were killed 1 hour after Vernonia cognata extract administration. The stomach was removed for macroscopic and histopathological evaluation, as well as, oxidative stress markers such as lipoperoxidation (LPO) and non-protein thiol groups (NPSH) levels and catalase (CAT) activity. EtOH acute exposure increased LPO and decreased NPSH levels and CAT activity along with macroscopic and microscopic lesions in gastric tissue, confirming the involvement of oxidative stress in EtOH toxicity. Vernonia cognata extract attenuated oxidative and histopathological features induced by EtOH at all evaluated doses. Moreover, both studied doses of Vernonia cognata extract caused an increase in NPSH levels per se. However, only the dose of 2 g/kg reverted all macroscopic changes caused by EtOH toxicity. The protective effect of the extract could be attributed to antioxidant molecules present in the extract, such as flavonoids and phenolic acids, which were quantified by high performance liquid chromatography (HPLC). Thus, an antioxidant effect of the extract leads to a protection on gastric tissue. Our results indicate that Vernonia cognata hydroethanolic extract could have a beneficial role against EtOH toxicity by preventing oxidative stress and gastric tissue injury.

Outbreaks of human-herpes virus 6 (HHV-6) infection in day-care centers in Belém, Pará, Brazil.

A total of 730 children aged less than 7 years, attending 8 day-care centers (DCCs) in Belém, Brazil were followed-up from January to December 1997 to investigate the occurrence of human-herpes virus 6 (HHV-6) infection in these institutional settings. Between October and December 1997 there have been outbreaks of a febrile- and -exanthematous disease, affecting at least 15-20% of children in each of the DCCs. Both serum- and- plasma samples were obtained from 401 (55%) of the 730 participating children for the detection of HHV-6 antibodies by enzyme-linked immunosorbent assay (ELISA), and viral DNA amplification through the nested-PCR. Recent HHV-6 infection was diagnosed in 63.8% (256/401) of them, as defined by the presence of both IgM and IgG-specific antibodies (IgM+/IgG+); of these, 114 (44.5%) were symptomatic and 142 (55.5%) had no symptoms (p = 0.03). A subgroup of 123 (30.7%) children were found to be IgM-/IgG+, whereas the remaining 22 (5.5%) children had neither IgM nor IgG HHV-6- antibodies (IgM-/IgG-). Of the 118 children reacting strongly IgM-positive (> or = 30 PANBIO units), 26 (22.0%) were found to harbour the HHV-6 DNA, as demonstrated by nested-PCR. Taken the ELISA-IgM- and- nested PCR-positive results together, HHV-6 infection was shown to have occurred in 5 of the 8 DCCs under follow-up. Serological evidence of recent infections by Epstein-Barr virus (EBV) and parvovirus B19 were identified in 2.0% (8/401) and 1. 5% (6/401) of the children, respectively. Our data provide strong evidence that HHV-6 is a common cause of outbreaks of febrile/exanthematous diseases among children attending DCCs in the Belém area.

Inmunogenicidad, inocuidad y eficacia de una vacuna tetravalente obtenida por recombinación genética de rotavirus aislados de monos rhesus y seres humanos en Belém, Brasil / Immunogenicity, safety and efficacy of tetravalent rhesus-human, reassortant rotavirus vaccine in Belém, Brazil

Se evaluó la inocuidad, inmunogenicidad y eficacia de una vacuna tetravalente obtenida por recombinación genética de rotavirus aislados de monos rhesus y seres humanos (RRV-TV) (4 x 104 unidades formadoras de placas por dosis) en un ensayo prospectivo, aleatorio, a doble ciego y controlado con placebo que se efectuó con 540 lactantes brasileños. Se administraron dosis de vacuna o de placebo a la edad de 1, 3 y 5 meses. No se observaron diferencias significativas en la frecuencia de diarrea o vómito en los bebés de ninguno de los dos grupos después de administrar la dosis correspondiente. De 2 a 3% de los vacunados tuvieron fiebre baja los días tercero a quinto después de recibir la primera dosis, pero no después de las dosis segunda o tercera. Se observó una respuesta de anticuerpos del tipo IgA al rotavirus aislado de monos rhesus (RRV) en 58% de los vacunados y en 33% de quienes recibieron placebo. La respuesta de anticuerpos neutralizantes a cada serotipo no pasó de 20% cuando se determinó con la prueba de reducción de focos de fluorescencia, pero fue superior a 40% al medirse con la prueba de neutralización a base de reducción de placas. Se presentaron 91 casos de diarrea causada por rotavirus entre los niños que recibieron las tres dosis (de vacuna o de placebo) durante un seguimiento de 2 años, 36 de ellos en los niños vacunados. La eficacia general de la vacuna fue de 8% (P = 0,005) contra toda clase de diarrea y de 35% (P = 0,03) contra la diarrea causada por rotavirus. La protección durante el primer año de seguimiento, cuando predominó el rotavirus G del serotipo 1, fue de 57% (P = 0,008), pero se redujo a 12% en el segundo año. Se obtuvieron resultados similares al restringir el análisis a episodios en que el rotavirus fue el único agente patógeno identificado. Se observó en la vacuna una mayor tendencia a proteger contra casos de enfermedad con un promedio de seis o más deposiciones diarias. Estos resultados son lo suficientemente...

A tetravalent rhesus-human reassortant rotavirus (RRV-TV) vaccine (4 x 104 plaque-forming units/dose) was evaluated for safety, immunogenicity and efficacy in a prospective, randomized, double-blind, placebo-controlled trial involving 540 Brazilian infants. Doses of vaccine or placebo were given at ages, 1, 3 and 5 months. No significant differences were noted in the occurrence of diarrhoea or vomiting in vaccine and placebo recipients following each dose. Low-grade fever occurred on days 3­5 in 2­3% of vaccinees after the first dose, but not after the second or third doses of vaccine. An IgA antibody response to rhesus rotavirus (RRV) occurred in 58% of vaccinees and 33% of placebo recipients. Neutralizing antibody responses to individual serotypes did not exceed 20% when measured by fluorescent focus reduction, but exceeded 40% when assayed by plaque reduction neutralization. There were 91 cases of rotavirus diarrhoea among the 3-dose (vaccine or placebo) recipients during two years of follow-up, 36 of them among children given the vaccine. Overall vaccine efficacy was 8% (P = 0.005) against any diarrhoea and 35% (P = 0.03) against any rotavirus diarrhoea. Protection during the first year of follow-up, when G serotype 1 rotavirus predominated, was 57% (P = 0.008), but fell to 12% in the second year. Similar results were obtained when analysis was restricted to episodes in which rotavirus was the only identified pathogen. There was a tendency for enhanced protection by vaccine against illness associated with an average of 6 or more stools per day. These results are sufficiently encouraging to warrant further studies of this vaccine in developing countries using a higher dosage in an attempt to improve its immunogenicity and efficacy.

Prevalence of human herpesvirus 6 antibody in the population of Belém, Pará, northern Brazil.

A total of 497 serum samples obtained from residents of 2 neighbourhoods (Terra-Firme and Guamá) in Belém, Pará, Brazil was tested for the presence of antibody to human herpesvirus 6 (HHV6), using an indirect immunofluorescence assay. The overall seroprevalence was 90%, with seropositivity rates ranging from 75% to 100% in the different age groups and sexes. There was a significant difference between the antibody prevalences in Terra-Firme and Guamá, 94% and 87%, respectively (P = 0.01). The geometric mean titres (GMT) of antibody to HHV6 declined from the first (< or = 2 years) to the sixth (31-40 years) age groups, and slightly increased (GMT > 50) among individuals older than 40 years.

Immunogenicity, safety and efficacy of tetravalent rhesus-human, reassortant rotavirus vaccine in Belém, Brazil.

A tetravalent rhesus-human reassortant rotavirus (RRV-TV) vaccine (4 x 10(4) plaque-forming units/dose) was evaluated for safety, immunogenicity and efficacy in a prospective, randomized, double-blind, placebo-controlled trial involving 540 Brazilian infants. Doses of vaccine or placebo were given at ages 1, 3 and 5 months. No significant differences were noted in the occurrence of diarrhoea or vomiting in vaccine and placebo recipients following each dose. Low-grade fever occurred on days 3-5 in 2-3% of vaccinees after the first dose, but not after the second or third doses of vaccine. An IgA antibody response to rhesus rotavirus (RRV) occurred in 58% of vaccinees and 33% of placebo recipients. Neutralizing antibody responses to individual serotypes did not exceed 20% when measured by fluorescent focus reduction, but exceeded 40% when assayed by plaque reduction neutralization. There were 91 cases of rotavirus diarrhoea among the 3-dose (vaccine or placebo) recipients during two years of follow-up, 36 of them among children given the vaccine. Overall vaccine efficacy was 8% (P = 0.005) against any diarrhoea and 35% (P = 0.03) against any rotavirus diarrhoea. Protection during the first year of follow-up, when G serotype 1 rotavirus predominated, was 57% (P = 0.008), but fell to 12% in the second year. Similar results were obtained when analysis was restricted to episodes in which rotavirus was the only identified pathogen. There was a tendency for enhanced protection by vaccine against illness associated with an average of 6 or more stools per day. These results are sufficiently encouraging to warrant further studies of this vaccine in developing countries using a higher dosage in an attempt to improve its immunogenicity and efficacy.

Association of human herpesvirus 6 infection with exanthem subitum in Belem, Brazil

Infeccao recente por hipervirus humano tipo 6 (HHV-6) foi detectada em casos de exantema subito envolvendo quatro criancas com idades de 10 a 24 meses, no periodo compreendido entre abril e agosto de 1994, em Belem, Brasil. Utilizando-se a tecnica da imunofluorecencia indireta, aumentos significativos (de pelo menos oito vezes) foram observadas nas concentracoes de anticorpos das amostras de soro, da fase aguda para as da convalescente, com oito titulos variando de <1:10 / 1:80 a < 1:10 / 1:640 (pacientes 3 e 2, respectivamente). Todas as criancas apresentaram febre alta (acima de 39ºC) por tres dias, seguida de exantema maculo-papular generalizado. O exame fisico realizado nas criancas revelou concomitancia de adenomegalia cervical e amigdalite em dois desses individuos.

Association of human herpesvirus 6 infection with exanthem subitum in Belem, Brazil.

Recent human herpesvirus 6 (HHV-6) infection was detected in cases of exanthem subitum (ES) involving four children, aged 10 to 24 months, between April and August 1994, in Belém, Brazil. By using the indirect immunofluorescence antibody assay (IFA), significant increases (at least eight times) in antibody concentrations were noted from the acute to the convalescent serum samples, with titers ranging from < 1:10/1:80 to < 1:10/1:640 (patients 3 and 2, respectively). All children had high fever (over 39 degrees C) for three days, followed by generalized, maculo-papular skin rash. A physical examination of the children also revealed concomitant, cervical lymph node swelling and tonsillar pharyngitis in two of them.

[Prospective study of rotavirus infections in Belém, Pará, Brazil: clinical and epidemiological features]. / Estudo prospectivo das infecções por rotavírus em Belém, Pará, Brasil: uma abordagem clínico-epidemiológica.

A prospective study of acute diarrhoeal diseases was carried out from April 1990 to September 1992 with the purpose of assessing the immunogenicity, safety and efficacy of a Rhesus-human reassortant rotavirus ("RRV-TV") vaccine, involving 540 children living in Belém, Pará, Brazil. As half of the children received placebo, this trial provided the opportunity of broadening the knowledge on both clinical and epidemiological aspects of rotavirus infection in the Amazon region. There were 2,789 diarrhoeal episodes during the above mentioned period, of which 86 (3.1%) associated with rotavirus; serotype 1 was the more prevalent, accounting for 67.9% of serotyped strains. Rates of 5.9 and 0.2 episodes of diarrhoea per child/year were noted for all cases and the rotavirus-related ones, respectively. This agent was the only pathogen found in 70.9% of the 86 rotavirus-related episodes of acute diarrhoea, whereas the most frequent associations involved Giardia intestinalis and enteropathogenic Escherichia coli, accounting for 7.0% and 11.6% of mixed infections,respectively. The monthly rates of rotavirus-related episodes of diarrhoea ranged from 0.8% to 9.6%, reaching the highest peaks during the dry months of the year. Means of clinical severity scores of 9.4 and 5.3 were recorded for the rotavirus-related episodes of diarrhoea and those of other aetiology, respectively.

Prevalence of human herpesvirus 6 antibody among isolated Amazonian Amerindian communities in Brazil.

Human herpesvirus 6 (HHV6) antibody was detected by the anticomplement immunofluorescence test in 65 of 592 serum samples (10.9%) obtained from Amerindians belonging to 4 remote communities inhabiting the Amazon Region of Brazil. Seropositivity rates ranged from 5.4% in the Oyampí to 14.9% in the Tucano. Among the Mekranoiti and Tiriyo, the seroprevalence rates were 12.5% and 11.8%, respectively. In children aged 0-10 years, the prevalences of HHV6 antibody ranged from 5.2% to 24.2%, among the Oyampí and Mekranoiti tribes, respectively. In the 11-20 and > 20 years old age groups, percentages of positivity ranged, in the former group, from 9.5% to 17.5% in the Oyampí and Tucano, respectively and, in the latter group, from 1.3% in the Oyampí to 14.8% in the Tucano. The prevalences of HHV6 antibody decreased regularly through the first 3 age-groups in the Mekranoiti and Tiriyo. In addition, frequencies of seropositivity were consistently higher in males than in females in the Mekranoiti (P < 0.05), Oyampí and Tiriyo tribes.

Neutralizing antibody immune response in children with primary and secondary rotavirus infections.

We have characterized the neutralizing antibody immune response to six human rotavirus serotypes (G1 to G4, G8, and G9) in Brazilian children with primary and secondary rotavirus infections and correlated the response with the G serotype of the infecting rotavirus strain. Twenty-five children were studied: 17 had a single rotavirus infection, 4 were reinfected once, and 4 experienced three infections. Two of the reinfections were by non-group A rotaviruses. Among the 25 primary infections, we observed homotypic as well as heterotypic responses; the serotype G1 viruses, which accounted for 13 of these infections, induced mostly a homotypic response, while infections by serotype G2 and G4 viruses induced, in addition to the homotypic, a heterotypic response directed primarily to serotype G1. Two of the primary infections induced heterotypic antibodies to 69M, a serotype G8 virus that by RNA electrophoresis analysis was found not to circulate in the population during the time of the study. The specificity of the neutralizing antibody immune response induced by a virus of a given serotype was the same in primary as well as secondary infections. These results indicate that the heterotypic immune response induced in a primary rotavirus infection is an intrinsic property of the virus strain, and although there seem to be general patterns of serotype-specific seroconversion, these may vary from serotype to serotype and from strain to strain within a serotype.

[Outbreak of classical fever of dengue caused by serotype 2 in Araguaiana, Tocantins, Brazil]. / Epidemia de febre clássica de dengue causada pelo sorotipo 2 em Araguaina, Tocantins, Brasil.

We report the first outbreak of dengue fever caused by dengue 2 (DEN 2) in Araguaina, Tocantins State. Four hundred people of 74 families, living at S. João, Araguaina Sul and Neblina districts were questioned and then bled, in order to obtain sera to test for anti-dengue antibodies. If a person was sick, a small quantity of blood was collected for virus isolation. The main clinical picture of disease was characterized by fever, headache, myalgias, arthralgias and skin rash. Were obtained 1,105 (56 females and 45 males of Culex quinquefasciatus and 567 females and 437 males of Aedes aegypti) mosquitoes from larvae collected in Araguaina. The females of Aedes aegypti obtained from larvae were allowed to feed on 8 febrile patients. The diagnosis of infection was made by both virus isolation into Aedes albopictus (C6/36) cells, and serology, by Hemagglutination-inhibition (HI) and IgM capture ELISA (MAC ELISA). No virus was isolated from mosquitoes. Although five strains of DEN 2 were obtained from humans, and another 111 infections were diagnosed serologically (IgM positive). The positivity rate of the samples was 27.75% (111 of 400), while that of the families was 66.2% (45 of 72), where at least one member of the each family was infected. It was also detected 26.1% of asymptomatic infections. All age groups were affected. Therefore, the infection was more frequent in females (33.5%) than males (23.8%).(ABSTRACT TRUNCATED AT 250 WORDS)

The correct sequence of the porcine group C/Cowden rotavirus major inner capsid protein shows close homology with human isolates from Brazil and the U.K.

Amino acid sequence alignments between the human group C/Bristol and the published porcine group C/Cowden VP6 proteins have revealed a region of extreme sequence divergence. We have been unable to confirm the nucleotide sequence of the Cowden VP6 gene corresponding to this region of divergence. Direct sequencing of a PCR-amplified cDNA pool has revealed a frame shift, and three nucleotide changes, within the published sequence of the porcine (Cowden) VP6 gene. The corrected sequence of the porcine protein revealed a closer homology with VP6 from the Bristol strain and two new human group C rotavirus isolates. Atypical rotaviruses have been detected in the feces of children living in Belém, Brazil, and Preston, U.K. Direct sequencing of PCR-amplified cDNA corresponding to the VP6 gene of one isolate from each location confirmed the presence of a group C rotavirus. The complete nucleotide sequences of the VP6 genes from the group C/Belém and C/Preston rotaviruses contained an open reading frame of 1185 nucleotides (395 amino acids; deduced M(r) 44,669 Da). The Belém VP6 gene demonstrated 97.9% nucleotide homology with the human group C/Bristol VP6 gene and 83.4% nucleotide homology (91.6% deduced amino acid homology) with the corrected porcine group C/Cowden sequence. The Preston VP6 gene demonstrated 99.6% nucleotide homology with the human group C/Bristol VP6 gene and 84.0% nucleotide homology (91.6% deduced amino acid homology) with the corrected porcine group C/Cowden sequence. Remarkably, the deduced amino acid sequence of the Brazilian strain was identical to that of the U.K. isolates.

Prevalence of human parvovirus (B19) and rubella virus infections in urban and remote rural areas in northern Brazil.

Sera from inhabitants of Belém, Pará (542 sera), Brazil and of members of 3 Brazilian tribes--Tiriyo/Alto Paru (near Surinam) (212 sera), Xicrin (128 sera), and Mekranoiti (121 sera)--of different age and sex groups were tested for the presence of specific antibody against human parvovirus (B19) (RIA) and rubella virus (latex agglutination test). Parvovirus (B19) IgG was found in 42.6% of the population sample from Belém but in only 4.7 to 10.7% of the members of the tribes. Rubella virus antibody was found in 72.7% of the sera from Belém but approaching a prevalence of 85-90% in age groups above 20 years. In the tribes rubella virus antibody was detected in 36.9 to 72.6% of all sera. There were remarkable sex differences of antibody prevalence in several age groups of the population from Belém and of the tribal populations. About a quarter of the skin rashes in Belém that were not attributable to infections with rubella, measles, or arboviruses were caused by recent B19 infections.

Incidencia das diarreias infantis agudas em um bairro periferico de Belem, Para: fase preparatoria de um futuro estudo de campo com uma vacina contra rotavirus / Incidence of the diarrhea infantile acute in one perifheric district of Belem, Para: preparatory phase of one future study of field with one vaccine against rotaviruses

No periodo de fevereiro a setembro de 1988 foram recruta-das e submetidas a acompanhamento sistematico, 78 criancas habitantes de um bairro periferico de Belem, Brasil. Observou-se que cinco (6,4%) desses individuos foram excluidos no decurso do estudo, uma ves que passaram a morar em outra areada cidade. Visitas domiciliares, duas vezes por semana, foram empreendidas por agentes de campo, sendo os cuidados medicos proporcionados por dois profissionaisde nosso grupo. Foram registrados 67 episodios de diarreia, obtendo-se especimesfecais para exames em 62 (92.5%) deles. Rotavirus foram detectados em 4 (6.4%) dos episodios analisados laboratorialmente, todos classificados como subgrupo II(perfil eletroforetico de ARN longo). De 60 especies fecais processados quanto apresenca de enteropatogenos bacterianos, logrou-se obter 7(11,7%) isolamentos deEscherichia coli enteropatogenicas, 3 (5,0%) de Sjigella sonnei e 1 (1,7%) deSalmonella grupo C1. Detectou-se, ainda, Campilobacter sp em 2 (4,9%) dos 41 es-pecimes fecais cultivados com o proposito especifico de detectar-se esse agente Cryptosporidium sp. foi observado em apenas 1 (2.7%) dos 37 especimes fecais analisados. A maior incidencia de diarreia, 24,5%, ocorreu em abril, enquanto que amenor, 9,3%, em marco. Das 78 criancas recrutadas, 52 (66.7%) apresentaram diarreia. A taxa de ataque clinico especifica por idade nao exibiu diferencas niti-das nos intervalos de 0 a 3 e 5 a 8 meses, porem, configurou-se um pico aos 4. Ataxa de diarreia cumulativa atingiu a cifra de 1,4 episodio por crianca, aos oi-to meses. As frequencias de vomitod (75%), febre (50%) e desidartacao (50%) revelaram-se superiores aos mesmos parametros avaliados no grupo de diarreias relacionadas a outros agentes etiologicos.

Naturally occurring serotype 2/subgroup II rotavirus reassortants in northern Brazil.

Nine serotype 2 human rotavirus strains were isolated in a community-based longitudinal study in Northern Brazil. Five of these strains had a 'long' RNA electrophoretic pattern and all five strains were determined to belong to subgroup II by ELISA assay, in contrast to properties common to serotype 2 human rotaviruses previously characterized. Hybridization studies of one of these unusual strains with 32P-labelled mRNAs derived from the prototype human strains Wa (serotype 1, subgroup II) and S2 (serotype 2, subgroup I) suggested that it was generated by a reassortment event in nature, in which a subgroup II, 'long' electropherotype rotavirus exchanged its serotype-specific gene and gene number 10 for the equivalent genes from a serotype 2, 'short' electropherotype virus.

Longitudinal study of rotavirus infections among children from Belém, Brazil.

From December 1982 to March 1986 a group of 80 children between 0 and 3 years old who lived in the peripheral area of Belém, Brazil, were followed up for episodes of diarrhoea. A total of 441 diarrhoeal episodes were recorded and 36 (8.2%) were associated with rotavirus. This agent was the only pathogen in 50% of rotavirus-related episodes of acute diarrhoea, and strains were characterized by analysis of RNA in polyacrylamide gels. Forty-one belonged to subgroup II (long pattern) and five to subgroup I. Reinfections by rotavirus were noted in 12 children involving either the same or different subgroups. Ten distinct electrophoretypes were detected in the study period and the predominant one had the '1N2L' profile. The cumulative age-specific attack rate for diarrhoea reached 2.8 by the end of the first year of life; a frequency of 2.3 episodes of diarrhoea per child per year was observed throughout the complete investigation. In comparing the age-specific attack rates for diarrhoea between breast-fed and bottle-fed children, a peak at 6 months of age was noted in the former, and at 1 month in the latter. A comparison by Fischer's exact test (P = 0.21) provided no evidence for protection against clinical rotavirus disease by maternal milk. By the same test, however (P = 0.021), we found significant evidence that early rotavirus infections were more likely to be asymptomatic and that infections after 4 months were more likely to be symptomatic. The clinical picture in children with rotavirus-related diarrhoea was more severe than in those suffering from acute diarrhoea due to another agent.