Persistent gastroenteritis in children infected with astrovirus: association with serotype-3 strains

The relationship between cases of persistent diarrhoea and the levels and type of human astrovirus was investigated. The potential correlation between human astrovirus excretion levels and the occurrence of protracted gastroenteritis was elucidated after quantifying astroviruses in faecal samples by a competitive RT-PCR. This assay was developed employing an internal RNA standard constructed for this purpose and showed a threshold of positivity of 3.4 x 10(4) genomes per gram of faeces. By this procedure, the levels of astrovirus, belonging to serotypes 1, 2, 3, 4, and 8, in faecal samples could be ascertained to range from 3.4 x 10(8) to 1 x 10(13) per gram of faeces. The mean viral titre in the serotype 3-containing faeces was higher than in any of the other serotype-containing samples. In children with no background disease, persistent gastroenteritis cases were detected in 8.5% of the astrovirus infections, and 37.5% of those were associated with astrovirus type 3 infection. In addition, 42.9% of astrovirus 3 isolates were implicated with persistent cases, some of them lasting for 3 months. Other type 3 isolates, detected in the faeces in very large numbers, caused severe gastroenteritis.