| Objectives Human Parechoviruse (HPeV) are assumed to be common infec-tious agents, but their epidemiologic and pathogenic properties are not well known. By establishing rapid detection and typing assay from different specimens, the aim of the present study was to assess the prevalence and molecular epidemiology of HPeV infections in children in Shanghai, as well as investigate whether the presence of virus correlated with symptoms of infection. This study will provide data and evidence for prevention and therapy of HPeV infections.Methods 1. From 1 January 2008 to 31 December 2010, a total of 450 rota-virus negative stool specimens were collected from diarrhea children<5 years old who were hospitalized at Children's Hospital, Fudan University, Shanghai, China. A total of 78 stools from healthy controls were also collected during the same period. HPeV was detected by nested reverse transcripted PCR (RT-PCR), and then directly genotyped by sequencing a nested RT-PCR product. Phylogenetic analysis of the nucleotides of VP3/VP1 partial gene was conducted with MEGA4.1. All the data were analyzed by SPSS 17.0 statistical software.2. A total of 1225 enterovi-rus-negative specimens including 674 cerebrospinal fluid (CSF),550 blood samples and one ascitic fluid sample from 1112 hospitalized children<14 years of age ob-tained in the year of 2008-2010 were screened for HPeV by the same nested RT-PCR assay. The age of patients ranged from 1 day to 14 year. We also collected 99 blood samples from healthy children as controls.Results Molecular epidemiology of HPeV infections in children was as fol-lowing. Of the 450 rotavirus negative samples tested for HPeV,221 (49.1%) were positive. Yearly prevalence of HPeV infection in diarrhea children was 57.3% (86/150) in 2008,52.7% (79/150) in 2009 and 37.3% (56/150) in 2010. The prevalence of HPeV infections had no statistical difference between boys and girls (48.1% vs 50.9%, OR=0.9; 95%CI,0.6-1.3). HPeV infections could be seen in children of all age groups, especially in children under two years old. The median age of infected child-ren was 3 months. HPeV infections were detected all around the year. During the years of 2008 and 2009, HPeV infections peaked in August with prevalence of 91.7% (11/12) and 84.2%(16/19) respectively. December (84.6%,11/13) was another peak-ing month in 2009 and seasonal distribution was not obvious in the year of 2010. Among the 179 successfully genotyped samples, HPeV1 (92.2%,165/179) was found to be the most prevalent type followed by HPeV4 (2.2%,4/179) and HPeV8 (2.2%, 4/179). The other three HPeV types were HPeV2 (0.6%,1/179), HPeV3 (0.6%,1/179) and HPeV 5 (1.1%,2/179). HPeVl and HPeV8 were seen in 2008. Four genotypes including HPeV1,4,5 and 6 were found in 2009. In the year of 2010 HPeV1,3,6 and 8 were identified. The positive rate in healthy controls group was 52.6% (41/78) and HPeV1 was the only genotype. The prevalence of HPeV infections had no statistical difference between diarrhea group and control group (49.1% vs 52.6%; OR=0.87, 95%CI:0.52-1.45).HPeV infections involoved in the development of central nervous sys-tem-associated disease and sepsis were as follows. HPeV was detected in 96 samples, including 36 CSF samples,60 blood samples and 1 ascitic fluid sample from 92 (8.3%,92/1112) of the children. The prevalence of HPeV infections had no statistical difference between boys and girls (8.6% vs.7.7%, OR=1.1,95% CI:0.7-1.8). HPeV infetions were found in all age group children, ranging from 5 days to 13 years old. The median age of infected children was 3 years old. In the year of 2008, HPeV in-fections were only found in infants less than 1 year old. However, HPeV infections can be detected in all age groups of children during the years of 2009 and 2010. The highest frequency of HPeV infections was seen in children less than 3 months old (18.2%,12/66) in 2009. In the year of 2010, although the frequency of HPeV infec-tions was high in young infants (9.9%,8/81)< 3 month of age, it was lower than that found in children of 6 to 14 years old (14.9%,21/141). Yearly prevalence of HPeV in CSF and blood varied remarkably:1.3% (2/153) in 2008,8.2% (27/328) in 2009 and 10.0% (63/631) in 2010. HPeV infections were observed only in December of 2008. HPeV was detected mainly in autumn and winter, with the peak in December (18.8%, 9/48) in the year of 2009. In 2010, HPeV could be found throughout the year with the highest prevalence in January (24.2%,8/33). Of all the positive samples,49 were genotyped successfully.48 positive samples were HPeVl, and the other one was found to be HPeV 3 which was detected in 2010. The majority of the infected child-ren were born at term except two.34 patients were admitted to an intensive care unit. 86 children were diagnosed with central nervous system infections, of which 38 was diagnosed to be encephalitis,32 to be meningitis,10 to be meningoencephalitis and the other 6 to be encephalomyelitis.33 of the children showed signs of sepsis illness, 14 of which have severe sepsis illness.2 of patients had been in coma,1 was brain death and 3 were dead because of the illness. No HPeV infections were found in blood of healthy control group.Conclusion HPeV infections were very common in intestines of children. HPeV1 was the most prevalent and pathogenic genotype in Shanghai, China during the year of 2008-2010. HPeV infection was a significant cause of central nervous infections and sepsis in children. We suggested HPeV screening should be enrolled in the routine virus testing in specimens obtained from children.
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