Epidemiological Study On Viral Diarrhea Among Infants

Background:Acute gastroenteritis is not only one of the most common diseases among infants,but also one of the highest morbidity and mortality around the world.Enteroviruses are the most important pathogen of infantile diarrhea. Improving public health conditions is not reducing effectively the incidence of viral diarrhea,at the same time, we lack clinical specific drug, so the long-term systematic surveillance is very necessary. The development and application of vaccines is the effective way to prevent and control the viral diarrhea.Objective:To study and compare the epidemiologic characteristics of viral diarrhea by investigating the popular conditions in children under 5 years old in Lanzhou and Nanjing.And accumulate materials for the prevention.control and clinical diagnosis of viral diarrhea among infants in the two district.Methods:We collected 290 stool specimens from diarrheic children under 5 years old in the first hospital of Lanzhou University from July 2009 to June 2010 and 302 from diarrheic children under 5 years old in Nanjing Children's Hospital of Nanjing Medical University. Then we detected the rotavirus antigen by ELISA and typed the rotavirus-positive specimens by nested PCR. And we detected HuCV and AstV by RT-PCR, detected AdV by PCR. Then we detected HuCV-positive specimens,AstV-positive specimens and AdV-positive specimens by sequence based typing.Results:At least one of the four viral agents was found in 60% of the diarrheic specimens in Lanzhou and Nanjing.11 samples of mixed infection were detected in Lanzhou and 22 samples in Nanjing. October to the following February were the high-frequency period in the two districts and the high-frequency time of different pathogens had slight mismatches. They mainly threatened the infants who were under 2 years old.The positive rate of RV of the 290 specimens in Lanzhou was 39.31%,and the G serotyping results of RV were that G1 was 5.3%,G2 was 14.9%, G3 was 62.2%,G9 was 9.7% and the untyping was 7.9%.The typing results of P genotype were that P[4]-type was 26.3%, P[8] was 56.1%, each of P[4]+P[6] and P[6] was 0.9% and the untyping was 15.8%.The positive rate of HuCV was 11.38%,and 22 samples were NV,11 samples were SV.The positive rate of AstV was 4.83%.Among which,13 samples were AstV1 type and one was AstV4.The positive of AdV was 10.69% and 16 samples were AdV41,13 were AdV40.each of AdV 12 and AdV31 was one. In Nanjing the positive rate of RV was 37.42%. Of which the G serotyping results were that G1 was 6.2%,G2 was 10.6%,G3 was 68.1%,G9 was 1.8%,G2+G3 was 1.8%and the untyping was 11.5%.The typing results of P genotype were that P[4] was 22.1%,P[8] was 65.5% and the untyping was 12.4%.The positive rate of HuCV was 23.5%.67 samples were NV and 4 were SV among them. The positive rate of AstV was 3.97% and they were all AstV1.The positive rate of AdV was 2.65%.Each of AdV41,AdV3,AdV5,AdV6 and AdV7 was one sample, and 3 were AdV 12.Conclusion:The results indicated that the pathogens of viral diarrhea among infants in Lanzhou and Nanjing were complex.The Viral Pathogens played an important role in infant diarrhea in Lanzhou and Nanjing.Group A RV was the most principal pathogen and followed by HuCV,AdV and AstV.The main epidemic strain of RV was G3P[8] and the main epidemic strains of AstV and HuCV were the same in the two district. Group F(40 type,41 type) was the main epidemic strain of AdV in Lanzhou,but Group A(12type) was the main strain in Nanjing.