RESUMO
BACKGROUND: Rotavirus is an important cause of dehydrating diarrhea in young children throughout the world. Knowledge about frequency of reinfections, development of immunity to the virus and the possible protective effect of breast milk is important, in particular in relation to possible strategies for immunization. METHODS: A prospective study of rotavirus infections in a cohort of 235 infants followed from birth until 2 years of age was performed in León, Nicaragua. Fecal and serum specimens were collected at specified times, and stools were also obtained during episodes of diarrhea. Fecal specimens were screened by rotavirus antigen detection and serum and colostral specimens were analyzed by isotype-specific rotavirus antibody enzyme-linked immunosorbent assay. RESULTS: As judged by anti-rotavirus IgA antibody seroconversion and/or demonstration of rotavirus antigen in fecal specimens, > 50% of the babies had evidence of past rotavirus infection by the age of 2 months. The total incidence of rotavirus infections, including many reinfections, was 0.7 infection/child-year, of which only 17% were associated with diarrhea. The time from birth to the first demonstration of rotavirus in stool samples correlated significantly with the concentration of anti-rotavirus IgA antibodies in colostrum. There was also a tendency toward a relationship between long duration of breast-feeding and asymptomatic infection. CONCLUSIONS: Rotavirus infections are acquired very early in infants in León, Nicaragua, and reinfections are common. Most infections are asymptomatic. Breast milk appears to confer partial protection against rotavirus infection, probably mediated by specific IgA antibodies. To be effective rotavirus vaccination would probably have to be given at a very early age to infants in developing countries.
Assuntos
Infecções por Rotavirus/imunologia , Anticorpos Antivirais/sangue , Pré-Escolar , Fezes/virologia , Feminino , Humanos , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Lactente , Recém-Nascido , Masculino , Estudos Prospectivos , Recidiva , Rotavirus/classificação , Infecções por Rotavirus/prevenção & controle , VacinaçãoRESUMO
A cross-sectional survey of the seroprevalence of hepatitis A virus (HAV), B (HBV), C (HCV), and E (HEV) antibodies in a healthy population in Leon, Nicaragua was conducted and associated with demographic data. The overall prevalence of antibodies to HAV was 94.6%, to HBV 6.5% and to HEV between 4.6% and 8.0%, whereas none of 399 tested subjects showed confirmed seropositivity to HCV. A high HAV seropositivity rate (72.7%) was observed even in the lowest age groups tested (2-4 years of age). In contrast, HBV and HEV seropositivity was observed mainly in adults, the seroprevalence in > 40-year-old individuals being 15.4% and 17.6%, respectively. The overall mean hepatitis B surface antigen carrier rate was estimated to be 0.9%, and in individuals more than 20 years of age, 2.0%. The prevalence of anti-HAV as well as anti-HEV was significantly higher in people having their water supply outside rather than inside the house. Furthermore anti-HAV seroprevalence correlated with lack of access to a flush toilet. Hepatitis B virus seropositivity was more frequent in people living in a crowded environment than in those living with few household members. These findings indicate that hepatitis A is a childhood infection in Nicaragua and that the spread of the infection is facilitated by poor socioeconomic conditions. In contrast, HBV infection is relatively infrequent in the country and HCV seems to be very uncommon. Hepatitis E virus infection may occur in all age groups and is apparently associated with water-borne transmission.
Assuntos
Hepatite A/imunologia , Anticorpos Anti-Hepatite/sangue , Hepatite B/imunologia , Hepatite C/imunologia , Hepatite E/imunologia , Adolescente , Adulto , Criança , Pré-Escolar , Estudos Transversais , Feminino , Hepatite A/sangue , Hepatite A/epidemiologia , Hepatite B/sangue , Hepatite B/epidemiologia , Hepatite C/sangue , Hepatite C/epidemiologia , Hepatite E/sangue , Hepatite E/epidemiologia , Humanos , Masculino , Nicarágua/epidemiologia , PrevalênciaRESUMO
Nasopharyngeal specimens from 42 children less than one-year old hospitalized with bronchiolitis or pneumonia in El Salvador were analyzed for the presence of subgroup-specific respiratory syncytial virus (RSV) antigens by the indirect immunofluorescence technique. The antigen RSV-A was demonstrated in 28 children, RSV-B in three, and in one child subgroup, specificity could not be determined. The male:female ratio in the RSV-infected children was 1.9:1. The most severe disease, requiring intensive care, was observed in two infants with RSV-B infection. Determination of serum IgG, IgA, and IgM antibodies in acute and convalescent sera showed that none of the tests alone had sufficient sensitivity for routine diagnostic purposes, although, in combination, they provided a correct diagnosis in 86% of the RSV-infected children. A seroprevalence study of IgG, IgA, and IgM antibodies in 206 healthy children showed that a primary RSV infection is usually acquired during the first year of life in El Salvador. These results also indicated that reinfections with RSV frequently occur during the first 3-4 years of life and suggest that the occurrence of serum RSV IgA antibodies may be a marker of reinfection.
Assuntos
Bronquiolite Viral/virologia , Pneumonia Viral/virologia , Infecções por Vírus Respiratório Sincicial/epidemiologia , Fatores Etários , Anticorpos Antivirais/sangue , Antígenos Virais/análise , Pré-Escolar , El Salvador/epidemiologia , Ensaio de Imunoadsorção Enzimática , Feminino , Imunofluorescência , Humanos , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Lactente , Recém-Nascido , Masculino , Nasofaringe/virologia , Prevalência , Vírus Sincicial Respiratório Humano/imunologia , Vírus Sincicial Respiratório Humano/isolamento & purificaçãoRESUMO
Eosinophil cationic protein (ECP) was assayed in nasopharyngeal secretion (NPS) and serum from 42 infants, hospitalized with acute lower respiratory infection, in El Salvador and the results analyzed in relation to etiology of the infection. ECP concentrations were high in NPS, at an average 50 times higher than those found in serum. Exceedingly high levels of ECP (> 1000 micrograms/L) were found more frequently in wheezing than in non-wheezing children (30% vs 7%) and, accordingly, were more commonly found in children hospitalized with bronchiolitis than in those with pneumonia. Excessive levels were significantly more common in girls than in boys. Of the 42 cases, 28 were found to be caused by respiratory syncytial virus (RSV) subgroup A, and 3 by RSV-B, by means of detection of RSV antigen in nasopharyngeal cells. ECP serum levels were moderately elevated during the acute phase of the respiratory infection and increased slightly but significantly, in cases with RSV antigen-positive bronchiolitis, but not in those with pneumonia. The ECP levels in NPS from patients in Sweden who, by antigen detection in NPS cells, were diagnosed as either RSV or para-influenza 3 infection or none of these, were similar. These results indicate that elevation of ECP in NPS is associated with acute lower respiratory infection in general, but particularly pronounced in cases of bronchiolitis. Elevation of ECP is not an exclusive consequence of RSV infection, but may occur to an equal extent in infections caused by other agents.(ABSTRACT TRUNCATED AT 250 WORDS)