| Objective According to the description and analysis of epidemiological characteristics of measles and immunity in people in border areas of Yunnan province in2013, it was realized the disposition of measles in different groups of peolpe^regions and periods as well as immunity in people. It was also acknowledged the type and relevance with representative strains of genes of measles virus strains in Yunnan province by monitoring molecular biology of measles in border areas. The research provide a scientific basis on the measures of prevention and control of measles. And had important practical significance of the implementation of elimination of measles.Methods Describe epidemiological characteristics of measles and immunity in people in border areas of Yunnan province in2013by method of descriptive epidemiology. By the method of experimental epidemiology, it was used Vero/SLAM cells (nephrocyte of African green monkeys transfected by lymphatic signal activation factor) to perform isolation and culture of measles virus. It was confirmed cases and identification of isolated virus, extracted the virus nucleic acid directly and performed RT-PCR and gene sequencing by the method of reverse transcription-polymerase chain reaction (RT-PCR).The data entry of research of descriptive epidemiology is in help of software Epidata3.0. After type-in we educe Excel then organize data. Software SPSS17.0is used to analyse data. Compare data of experimental epidemiology researches and450nucleotide sequences at the terminal of N Gene carboxyl in WHO representative.strains. Perform gene sequence affinity analysis by software MEGA5.1, then make Genetic affinity evolutionary tree.Results Epidemiological characteristics of measles in border areas of Yunnan province in2013:(1) The total reported number of confirmed measles cases was141(including laboratory diagnosis and clinical diagnosis).(2) Age distribution:The incidence of the highest percentage of age group was in20to49years old which had83cases reported(58.86%,83/141), followed by children aged0to1.5years old which had39cases reported (27.66%,39/141);From the aspects of morbidity by ages, there was the highest incidence between group of ages from0to1, which was68.56/100,000(34/49592).(3) Sex ratio for men and women was0.94. However, sex ratio for men and women in group from1years old was3.0.(4) Among occupational groups, farmers have reported52cases (37%), scattered children have reported48cases (34%), number of reported cases among other occupations was small.(5) Epidemiological characteristics:the occurring of disease had obvious seasonal characteristic. Spring and summer are the high-occurrence seasons of measles from border area. The number of reported cases was115, accounted for81.56%of all cases in a year. Outbreaks and sporadic occurance of measles all had seasonal characteristic. Besides Ruili, Longchuan and Menglian, measles all showed its occurance. High-risk area was mainly in Mang city,15.66/100,000(62/395913)> Linxiang District,7.67/100,000(25/325945)、Simao District,6.07/100,000(18/296540) and Menghai County,4.84/100,000(18/296540), which was higher than the morbidity in Yunnan province (3.04/100,000).(6) The history of immune:among measles cases, only23cases (16.31%) had exact history of immune."0" dose of measles had70cases (49.65%), unknown immune dose had48cases (34.04%). Number of cases according to ages:<8months,18cases、≥18years old,88cases, accounted for75.18%(106/141), who was beyond the range of current immunization strategy;31cases between8months and6years old, who was of the right age to inoculate. Number of cases which had a history of vaccination was13(41.94%),"0" dose of measles had16cases (51.61%), unknown immune dose had2cases (6.45%).(7) Measles vaccination:the reported vaccination rate of measles in border area of Yunnan province in2013was more than98%.Monitoring of measles and its genetic characteristics in the border area of Yunnan province in2013:(1) Isolation of measles virus:393samples were collected. After vaccinating samples into Vero/SLAM cells,19samples had CPE, including13urine specimen, isolation rate was6.84%,6throat swabs samples, isolation rate was2.96%. Extract nucleic acid from measles samples which do not isolated to viral strain,30strains were achieved.(2) RT-PCR result:After purification of PCR products, test according to2%AGE(agarose gel electrophoresis), there was an obvious positive belt at700bp.(3) Genotype distribution:analyze and test the gene sequences of19isolated virus strains and30strains of viral nucleic acid, there were3types ofgenotype. H1genotype was spread over5border area in Yunnan province, that wasNanmo county, Mengsai province, Laos and Kutkai, Burma. D9genotype was spreadover3counties and Longlin, Baoshan and Mengre、Mujie、Guigai, Burma borderingon Dehong and Burma; Genotype A derives from Mang city, Dehong.(4) Affinityanalysis on genes:perform gene affinity analysis on virus isolates and viral nucleicacid by softeare MEGA5.1. The result showed that12strains were gene subtype H1afrom genotype H1-(24.49%),36strains were genotype D9(73.47%),1strain wasgenotype A (vaccine strain191Shanghai, China,2.04%).(5) Compare the36D9genotype strains with WHO D9genotype:divided them into5groups(set a group forrepresentative strains). Nucleotide homology of each group was96.0%～99.5%,amino acid homology was95.2%～99.3%. Clusterl and Cluster2only containedBurma strains, Cluster3and Cluster4was formed by local isolated strains of Yunnanand Burma.(6) Compared12strains of H1a subtype with WHO H1a subtype andHlb subtype representative strains:divided them into4groups(set a group forrepresentative strains). Nucleotide homology of each group was97.1%～99.1%,amino acid homology was95.8%～99.3%. Custerl only contained1Burma strains,Cluster2was formed by local isolated strains of Yunnan and Laos.(7) Monitoring ofD9genotype measles outbreaks:from May to August,2013,3measles outbreaks wereoccurred in Fengping, Mong city, Dehong. Involving22cases, number of cases wasbetween2to13; The3outbreaks were involved13natural villages(agency), dotoutbreaks were occurred in3villages (Xiangzhang village, Laoguang village,Mangsai village). Collected etiology samples, then isolated3strains of live virus andtested5strains of the virus nucleic acid. The8strains were all isolated and tested D9Genotype strains in one outbreak.(8) Compared1strain of A subtype with WHO Asubtype strain:Nucleotide homology of each group was99.1%, amino acid homologywas99.3%.Conclusion The incidence of the highest percentage of age group was in20to49years old (58.86%), followed by children aged0to1.5years old (27.66%) in borderarea of Yunnan.From the aspects of morbidity by ages, there was the highest incidencebetween group of ages from0to1, which was68.56/100,000. A high morbidity in farmers (36.88%) and scattered children (34.04%), total number was100cases(70.92%); Winter and spring were the seasons with high incidence of measles. High-incidence area was located in4border area:Dehong (Mang city), Lincang(Linxiang District),Puer(Simao District) and Xishuangbanna (Menghai). The morbidity of4areas were higher than morbidity of Yunnan(3.04/100,000); Only23cases (16.31%) had exact history of immune. Among people who was of the right age to inoculate, people with exact immune history accounted for15cases (41.94%),"0" dose of measles had16cases (51.61%). The reported vaccination rate of measles in13border areas of Yunnan province in2013was more than98%. The cycle of the measles virus of H1and D9genotype was existed in area bordering on Yunnan and Burma. D9genotype was imported from Myanmar,it was the dominate genotype on Dehong now, and this genotype had mutual communication among area bordering on Dehong and Burma; H1genotype had mutual communication among area bordering on Yunnan and Laos. Genotype A was the similar strains of191vaccine strains of Shanghai, China. |
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