Epidemiological and molecular analysis of human norovirus infections in Taiwan during 2011 and 2012

Abstract

BackgroundThe human norovirus (NV) circulates worldwide and is a major cause of epidemics, which have increased in Taiwan since 2002. NV in acute gastroenteritis (AGE) and non-acute gastroenteritis (asymptomatic) patients, including children and adults, have not been previously examined in Taiwan; therefore, we examined the epidemiology and phylogeny of NV in AGE and asymptomatic patients of all ages.Methods253 stool samples were collected from August 2011 to July 2012 (including 155 AGE and 98 asymptomatic samples in Taiwan) and analyzed using reverse transcription-polymerase chain reaction (RT-PCR) for NV. Primers targeting the RNA-polymerase gene were used for RT-PCR to allow DNA sequencing of Taiwan NV strains and phylogenetic analyses.ResultsNV was detected in 24 (9.5%) of 253 stool specimens using RT-PCR. NV was isolated from all age groups (1 to 86 y) and those NV-positive samples were major identified from inpatients (79.2%, 19/24). Statistical analysis showed that the NV infectious rate of AGE patients was statistically significant (P < 0.05) for age, season and water type, respectively. Phylogenetic analyses of the RdRp region sequence showed that 24 NV isolates belonged to Genogroup II Genotype 4 (GII.4). They were closely related to the epidemic strain in Taiwan in 2006, the GII.4-2006b pandemic strain in 2006, and the GII.4-New Orleans strain in 2010.ConclusionThis study is the first to examine NV in sporadic AGE and asymptomatic patients in Taiwan. Furthermore, epidemic strains of isolated GII.4 were predominant in Taiwan during 2011 and 2012.

Epidemiology of norovirus infections among diarrhea outpatients in a diarrhea surveillance system in Shanghai, China: a cross-sectional study

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“…Other than previous studies, which concluded that young children and elderly people were more vulnerable than other age groups [ 10 , 24 ], our study discovered that the highest detection rate was found in the youth group (19-44y) (25.97%), and the lowest in the children group (13.30%), with the elderly group in the middle (23.50%), whereas in a logistic model, the age distribution of NoV(+) patients could not be proved to be different from NoV(−) patients. Age distribution differences were found to be significant in NoV(+) vs RV(+) and NoV(+) vs bacteria(+) comparisons, which are stated below.…”

“…Some studies recognized diarrhea, vomiting and fever as the most common symptoms of norovirus-affected patients [ 13 , 24 - 26 ]. Although in this study it was proved that norovirus was distinguished by diarrhea (automatically included), nausea, and vomiting among diarrhea patients, fever was less commonly seen in NoV(+) patients when compared with NoV(−) ones.…”

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“…In contrast, fever, dehydration and frequency of stool output per day were lower in norovirus patients compared to patients with other bacterial pathogens. Some of these findings were inconsistent with those reported from other studies [Rahman et al, ; Nahar et al, ; Tang et al, ; Xue et al, ].…”

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“…In 2012, we encountered a major outbreak of acute gastroenteritis associated with NV of a subgenogroup (GII.4, Sydney strain) in Taiwan [14] . The conventional RT-PCR method targeting the RdRp gene was applied for the rapid detection of NV in faecal samples during this outbreak [11] .…”