The relationships between host factors, virus strain, viral load, and illness severity in respiratory syncytial virus (RSV)-induced bronchiolitis are poorly defined. These relationships were evaluated prospectively in 81 previously healthy infants hospitalized with RSV bronchiolitis. Disease severity was determined by the respiratory rate, the duration of hospitalization, and whether patients during their hospitalization required pediatric intensive care unit admission or mechanical ventilation. RSV typing into subgroup A and B was obtained by RT-PCR-hybridization assay. The nasopharyngeal RSV viral loads were measured by real-time quantitative RT-PCR. Disease severity correlated significantly with the presence of risk factor (estimated gestational age < 37 weeks and/or birth weight < 2,500 g) and with chronologic age

Global rotavirus surveillance has led to the detection of many unusual human rotavirus (HRV) genotypes. During 1996-2004 surveillance within the African Rotavirus Network (ARN), six P[8],G8 and two P[6],G8 human rotavirus strains were identified. Gene fragments (RT-PCR amplicons) of all 11-gene segments of these G8 strains were sequenced in order to elucidate their genetic and evolutionary relationships. Phylogenetic and sequence analyses of each gene segment revealed high similarities (88-100% nt and 91-100% aa) for all segments except for gene 4 encoding VP4 proteins P[8] and P[6]. For most strains, almost all of the genes of the ARN strains other than neutralizing antigens are related to typical human strains of Wa genogroup. The VP7, NSP2, and NSP5 genes were closely related to cognate genes of animal strains (83-99% and 97-99% aa identity). This study suggests that the ARN G8 strains might have arisen through VP7 or VP4 gene reassortment events since most of the other gene segments resemble those of common human rotaviruses. However, VP7, NSP2 (likely), and NSP5 (likely) genes are derived potentially from animals consistent with a zoonotic introduction. Although these findings help elucidate rotavirus evolution, sequence studies of cognate animal rotavirus genes are needed to conclusively determine the specific origin of those genes relative to both human and animal rotavirus strains.

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Viral diarrhea remains a major cause of childhood morbidity and mortality worldwide. In Tunisia, no comprehensive studies of all viral agents related to diarrhea in children have yet been conducted. The present study was performed to investigate the role of enteric viruses in acute diarrhea in the country. Six hundred thirty-eight stool samples were collected from children under 5 years of age seeking medical care for acute diarrhea between October 2003 and September 2005 in hospitals from the Eastern-Center Tunisia. All samples were tested for rotavirus, astrovirus, and adenovirus using commercial antigen enzyme immunoassays (EIAs). Positive samples for rotavirus and astrovirus were confirmed by an "in-house" reverse transcriptase-polymerase chain reaction (RT-PCR). Samples positive for adenovirus antigen were subjected to further EIA screening for species F enteric adenovirus types 40 and 41. At least one viral agent was found in 30% of the specimens. The frequency of rotavirus, astrovirus, and adenovirus was 20%, 7%, and 6%, respectively. Of the stool samples containing adenovirus, 57% (20/35) were found to be positive for species F adenovirus types 40/41. Dual infections were found in 9% (17/191) of the positive samples. Enteric viruses appear to play an important role in pediatric diarrhea in Tunisia. The introduction of affordable viral diagnosis in pediatric hospitals will improve patient care by reducing the unnecessary use of antibiotics.