RESUMO
The degree of viremia with human herpesvirus-6 was evaluated in 176 blood samples from 89 infants with exanthem subitum and viremia, and compared with the severity of clinical features and complications of the disease. Fever persisted for 3 to 4 days in 73% of infants and for more than 5 days in 22%, followed by a rubella- or measles-like rash. The viremia was observed between the first day of fever (day 0) and day 4 of the disease. The number of infected cells per 10 million mononuclear cells was 3.45 +/- 1.00 (log10, mean +/- SD) on days 0 to 2, 3.30 +/- 1.14 on day 3, and 3.09 +/- 2.05 on day 4 of the disease. The number of infected cells on days 3 to 4 in infants with a febrile period longer than 4 days and free virus in plasma was significantly greater than that in infants with a febrile period of less than 3 days and without free virus in plasma. The amount of virus in blood on days 0 to 2 did not relate to the duration of fever, and that on days 0 to 4 did not relate to the presence or absence of diarrhea, bulging fontanelle, or bronchopneumonia. These findings suggest that the magnitude of the virus replication in infants with exanthem subitum is reflected in the severity of the disease.
Assuntos
Exantema Súbito/microbiologia , Infecções por Herpesviridae/microbiologia , Herpesvirus Humano 6/isolamento & purificação , Viremia/microbiologia , Exantema Súbito/complicações , Feminino , Infecções por Herpesviridae/complicações , Humanos , Lactente , Masculino , Índice de Gravidade de Doença , Viremia/complicaçõesAssuntos
Exantema Súbito/diagnóstico , Infecções por Herpesviridae/diagnóstico , Exantema Súbito/complicações , Febre/etiologia , Herpesviridae/isolamento & purificação , Herpesviridae/ultraestrutura , Infecções por Herpesviridae/complicações , Humanos , Lactente , Leucócitos Mononucleares/microbiologia , Leucócitos Mononucleares/patologia , MasculinoRESUMO
Mononuclear cell-associated viremia caused by human herpesvirus type 6 was detected in 39 (66%) of 59 blood samples from 38 children with exanthem subitum between day 0 and day 7 of the disease. The rate of virus isolation from mononuclear cells was 100% (26/26) on days 0 to 2 (just before appearance of skin rash), 82% (9/11) on day 3, 20% (2/10) on day 4, 7% (2/12) on days 5 to 7, and 0% (0/37) on day 8 and thereafter. The cell-free virus was detected in blood in 10 (21%) of 47 blood samples during the same period. The antibody activity to the virus, evaluated by a newly developed neutralization assay, was first detected on day 3 of the disease with a positive rate of 18% (2/11). It became 60% (6/10) on day 4, 75% (9/12) on days 5 to 7, and 100% on day 8 and thereafter. Thus the disappearance of the virus from blood was associated with the induction of specific immunity to the virus.