The survival of human enteric viruses on several porous (paper and cotton cloth) and nonporous (aluminum, china, glazed tile, latex, and polystyrene) environmental surfaces has been evaluated. Viruses persisted for extended periods on several types of materials commonly found in institutions and domestic environments. The stability of the viruses was generally influenced by environmental factors such as relative humidity (RH), temperature, and the type of surface contaminated. Overall, hepatitis A virus (HAV) and human rotavirus (HRV) were more resistant to inactivation than enteric adenovirus (ADV) and poliovirus (PV). The resistance to the desiccation step appears to be of major significance in determining the survival of a virus dried on fomites. ADV and PV showed a pronounced decrease in titer at this stage, whereas HAV and HRV displayed little decay at the desiccation step. HAV and HRV persistence was not affected by the presence of fecal material. On nonporous surfaces, PV and ADV persisted better in the presence of feces. However, on porous fomites the presence of fecal material had a negative influence on the survival of PV and ADV. Except for HRV, greater virus survival was observed at 40 than at 20°C. PV and HAV survival was enhanced at high RH; the survival of the latter was enhanced at least for nonporous materials. When dried on porous materials, HRV also exhibited greater persistence at high RH. The survival of ADV was not affected by RH. The validity of using bacteriophages of Bacteroides fragilis as indicators of human viruses dried on fomites was evaluated. B. fragilis phages persisted consistently longer than PV and ADV and sometimes survived as long as HAV and HRV.

The presence of rotavirus strains in sewage samples from Cairo, Egypt (November 1998 to October 1999), and Barcelona, Spain (November 1998 to December 2002), was investigated by using a generic molecular detection method based on amplification of a VP6 gene fragment. Overall, 85.7 and 66.9% of the sewage samples from Cairo and Barcelona, respectively, were positive. Positive samples were characterized further, and VP7 and VP4 genotypes were determined. Although 30% of the positive samples from Cairo were G untypeable, the distribution of G types in the positive samples was 69.6% G1, 13% G3, 8.7% G4, and 8.7% G9. The percentage of untypeable samples was much higher for the Barcelona samples (56.5%), and the distribution in the positive samples was 56.4% G1, 31.5% G3, 6% G9, 4% G2, and 2% G5. When the P types were examined, 26.7% of the positive samples from Cairo were untypeable, and the distribution of types in the positive samples was 53. Group A rotaviruses are the leading cause of infantile diarrhea worldwide (24) and are associated with more than 600,000 deaths annually, mainly in developing countries (15). Rotavirus strains may be serotyped on the basis of two outer capsid proteins that are the targets of neutralizing antibodies produced following natural infection; these are glycoprotein VP7, which determines G serotypes, and the protease-sensitive protein VP4, which determines P types (24). Fourteen rotavirus G serotypes, including 10 serotypes that infect humans, have been identified (11). A good correlation between G serotypes and genotypes has been demonstrated (16), and a new genotype of bovine origin has been recognized (30). The correlation is less clear for VP4, since while 13 P serotypes have been detected (11), at least 20 genotypes, including 8 genotypes that infect humans, have been characterized (11). Genotyping studies have indicated that four G-P combinations, P[8]G1, P[4]G2, P[8]G3, and P[8]G4, are common worldwide. Two emerging combinations, P[8]G9 and P[6]G9, are becoming common (1,2,12,15,23). The distribution of rotavirus types may vary between distinct geographic and socioeconomic regions of the world or even between years in a given community. Since the rotavirus serotypes (genotypes) circulating in a given region have a direct influence on the predicted efficiency of a potential vaccine for the region, an examination of the G and P type distribution is necessary.The aim of the present work was to ascertain the G and P type distributions in two different urban areas, Greater Cairo in Egypt from November 1998 to October 1999 and Barcelona in Spain from October 1998 to December 2002, by using sewage samples as the virus sources. Different concentration procedures were used in Cairo and Barcelona. In the first case, viruses from 3 liters of sewage were concentrated in 75 ml of 50 mM glycine buffer with 3% beef extract (Oxoid) by adsorption-elution to negatively charged nitrocellulose membranes (Schleicher and Schuell) (31) and were reconcentrated by organic flocculation in 1 ml of 0.14 N...

No abstract

The persistence of human astroviruses dried on representative porous (paper) and nonporous (china) surfaces was investigated. Long-term astrovirus survival on fomites was monitored by an integrated cell culture-reverse transcription-PCR procedure. Viruses were applied to inanimate surfaces in the presence and absence of fecal material, and their survival was assayed at 4 and 20°C with high relative humidity. Astroviruses exhibited a notable persistence when dried on porous and nonporous materials, particularly at low temperature. Short-term survival of astroviruses on fomites was compared to that of other enteric viruses significant for health, such as rotavirus, adenovirus, poliovirus, and hepatitis A virus. Overall, astroviruses persisted better than poliovirus and adenovirus, although they exhibited a shorter survival than rotavirus and hepatitis A virus. Astroviruses show a high level of persistence at the desiccation step, which is of major significance in determining the chance of subsequent virus survival dried on fomites. Astroviruses are able to survive on inert surfaces long enough to suggest that fomites may play a relevant role in the secondary transmission of astrovirus diarrhea.

A method based on infection of CaCo-2 cultured cell monolayers (CC) and reverse transcription-PCR (RT-PCR) was developed for the specific detection of infectious astrovirus. The procedure was validated by titrating poliovirus stocks in parallel in CaCo-2 cells by determining the most probable number of cytopathogenic units and by cell culture and subsequent RT-PCR (CC-RT-PCR). CC-RT-PCR was then employed to measure the persistence of astrovirus suspended in dechlorinated tap water. After 60 days, the decay of astrovirus infectivity was 2 log units at 4 ؎ 1°C and 3.2 log units at 20 ؎ 1°C, while after 90 days, the titer reduction was 3.3 and 5 log units at 4 ؎ 1°C and 20 ؎ 1°C, respectively. Astrovirus decay in the presence of free chlorine (FC) was monitored by CC-RT-PCR. Residual infectivity was found after 2 h in the presence of 1 mg of FC/liter. Under these conditions, astrovirus shows a log titer reduction (LTR) of 4, while 0.5 mg of FC/liter induced an LTR of 2.4. The possibility of acquiring data on the survival of fastidious viruses in the environment opens new perspectives on the epidemiology of some significant infections transmitted by the fecal-oral route.