Observation on virus shedding periods of enterovirus-71 and coxsackievirus A 16 monitored by nucleic acids determination in stool samples of children with hand, foot and mouth disease

Abstract

To observe the duration of enterovirus-71 (EV71) and coxsackievirus A 16 (CoxA16) viral shedding in stool samples of children with hand, foot and mouth disease (HFMD) infected with EV71 and CoxA16 and to explore the relationship between the duration of intestinal virus shedding and the severity of illness of children with HFMD. Totally 113 laboratory-confirmed cases of children with HFMD infected with EV71 and CoxA16 were followed up. The stool samples were collected with the interval of 4 to7 days and the viral nucleic acids were detected by fluorescent PCR until the stool viral nucleic acids of infected children turned to be negative. The cases in EV71 group were further divided into "ordinary EV71 group" and "severe EV71 group" according to the severity of the illness. The positive rates of viral nucleic acid and the differences of distribution among different groups were analyzed by Kaplan-Meier survival analysis during the follow-up period. The 113 cases of infected children were grouped as follows: 65 cases of EV71 positive children, 44 cases of CoxA16 positive children, 4 cases of EV71/CoxA16 mixed infection. The median duration of the stool viral nucleic acids turning to negative was 26 (18.25-32.50) days in EV71 group and 27 (14.50-33.75) days in CoxA16 group (Z = 1.51, P > 0.05). At 1, 4, 6 and 10 weeks, the positive rates of stool viral nucleic acid of children with HFMD in EV71 group were 100%, 48.1%, 17.2% and 0 respectively. At 1, 4 and 6 weeks, the positive rates of stool viral nucleic acid of children with HFMD in CoxA16 group were 95.5%, 53.8% and 0 respectively (χ(2) = 0.18, P > 0.05). At 1, 4 and 6 weeks, the positive rates of stool viral nucleic acid of children with HFMD in ordinary EV71 group were 100%, 23.5% and 0 respectively, while at 1, 4, 6 and 10 weeks, the positive rates of stool viral nucleic acid of children with HFMD in severe EV71 group were 100%, 62.4%, 26.0% and 0 respectively (χ(2) = 5.689, P < 0.05). The duration of enterovirus shedding in stool samples of children with HFMD lasted for a long period. The maximum duration of EV71 and CoxA16 in stool of children with HFMD was 10 weeks and 6 weeks, respectively. The duration of intestinal virus shedding of children with HFMD infected with EV71 was related with the severity of the illness.