Epidemiological And Molecular Epidemiological Studies Of The Chinese Measles Virus In 2013

Measles which caused by Measles virus (MV) is a highly respiratory infectious disease that causes enormous morbidity and mortality among children in many parts of the world. The main symptoms of Measles is fever, respiratory tract catarrh symptom and systemic maculopapule. The incidence of measles has reduced greatly, since China established the national Expanded programme on immunization and began to implement a standard schedule for routine immunization in 1978.The measles incidence of China started to decrease since 2008, and reached an all-time low in 2012, by then the Region of the Americas of the World Health Organization (WHO) had sustained measles elimination status for more than a decade. In 2005, the Regional Committee for WHO's Western Pacific Region resolved to attempt to eliminate measles from the Western Pacific Region by 2012. and the elimination of measles in China is critical to achieving the goal of regional measles elimination. ObjectiveStudy the epidemiological characteristics of measles and the genotype characteristics of measles virus which Cause of measles epidemic in China mainland. analyze the three distribution of measles outbreaks and gene; Clear the high risk population and high-risk areas; discover the possible Wild-type viruses from abroad in time; Improve the database of gene and amino acid variations of wild-type measles viruses in china to provide scientific basis for preventing the spread of imported measles virus. MethodsAnalyze the data from Measles Surveillance System(MSS), The throat swabs and urine specimens were collected from the suspected imported measles patient to isolate virus by using Vero/SLAM cell line Fragment of 676 nucleotide acids of the carboxyl end of nucleoprotein gene were amplified with reverse transcription-polymerase chain reaction(RT-PCR), and then the PCR products were directly sequenced and analyzed. The phylogenetic tree was constructed based on 450 nucleotide acids of the carboxyl end of nucleoprotein gene, and homological analysis was performed on nucleotide acid level and amino acid level. ResultIn 2013, the incidence of measles was 2.05/100,000, with a total of 27,769 cases; The age-specific incidence was highest in infants aged<8 months which is 75.42/100,000; The male-to-female ratio for the measles cases is 1.5:1; The priority of cases id scattered children(68.2%); The provinces with the highest number of cases were, Qinghai, Guangdong, Hunan, Anhui and Xinjiang, in order; The seasonal peak incidence of measles was April and May.2325wild-type measles virus were isolated in 2013, among which 2217 were genotype H1a,47 were D9,45 were D8,13 were VAC and 3 were B3.The nucleotide sequence and amino acid homologies of 2217 Hla isolates were 92.9%?100% and 84.8%?100%, respectively. Comparing with China H1a genotype reference strain(Hunan, China93-7), the nucleotide sequence and amino acid homologies of 2217 2013 H1a isolates were 94.3%? 98.0% and 87.9% ?98.0%, respectively; The nucleotide sequence and amino acid homologies of 47 D9 isolates were 96.1%?100% and 96.6%?100%, respectively. Comparing with S-191 strain, the nucleotide sequence and amino acid homologies were 88.0%?92.3% and 80.0%? 90.1%, and comparing with WHO D9 genotype reference strain(MVi/Victoria.AUS/12.99/D9), the nucleotide sequence and amino acid homologies were 95.4%?100% and 94.5%?100%, respectively; The nucleotide sequence and amino acid homologies of 45 D8 isolates were 99.1%?100% and 98.0%?100%, respectively. Comparing with S-191 strain, the nucleotide sequence and amino acid homologieswere 88.0%?92.3% and80.0%?90.1%, and comparing with WHO D8 genotype reference strain(MVi/Manchester.GBR/30.94/D8), the nucleotide sequence and amino acid homologies were 97.3%?100%, both; The nucleotide sequence and amino acid homologies of 3 B3 isolates were 99.8%?100% and 100%, respectively. Comparing with S-191 strain, the nucleotide sequence and amino acid homologies were 88.0%?92.3% and 80.0%?90.1%, and comparing with WHO B3 genotype reference strain(MVi/New York.USA/0.94/B3,MVi/Ibadan.NGA/0.97/1/B3), the nucleotide sequence and amino acid homologies were 96.6%?100% and 95.2%?100%, respectively. ConclusionAlthough there is evidence of progress towards the elimination of measles from China, resurgence in 2013 indicated that many children were still not being vaccinated on time. Routine immunization must be strengthened and the remaining immunity gaps need to be identified and filled. Molecular characterization of wild-type measles viruses in China during 2013 demonstrated that genotype Hla was endemic and widely distributed throughout the country, while we find more and more wild-type measles viruses Imported from abroad, which indicate that the measles surveillance on the basis of the laboratory is pretty, which also indicate that the endemic measles virus will decrease, more and more wild-type measles viruses Imported from abroad will be found, and we should pay attention to it.