Emergence and continuous evolution of genotype 1E rubella viruses in China.

In China, rubella vaccination was introduced into the national immunization program in 2008, and a rubella epidemic occurred in the same year. In order to know whether changes in the genotypic distribution of rubella viruses have occurred in the postvaccination era, we investigate in detail the epidemiological profile of rubella in China and estimate the evolutionary rate, molecular clock phylogeny, and demographic history of the predominant rubella virus genotypes circulating in China using Bayesian Markov chain Monte Carlo phylodynamic analyses. 1E was found to be the predominant rubella virus genotype since its initial isolation in China in 2001, and no genotypic shift has occurred since then. The results suggest that the global 1E genotype may have diverged in 1995 and that it has evolved at a mutation rate of 1.65 × 10(-3) per site per year. The Chinese 1E rubella virus isolates were grouped into either cluster 1 or cluster 2, which likely originated in 1997 and 2006, respectively. Cluster 1 viruses were found in all provinces examined in this study and had a mutation rate of 1.90 × 10(-3) per site per year. The effective number of infections remained constant until 2007, and along with the introduction of rubella vaccine into the national immunization program, although the circulation of cluster 1 viruses has not been interrupted, some viral lineages have disappeared, and the epidemic started a decline that led to a decrease in the effective population size. Cluster 2 viruses were found only in Hainan Province, likely because of importation.

Rubella virus genotypes in the People's Republic of China between 1979 and 2007: a shift in endemic viruses during the 2001 Rubella Epidemic.

The incidence of rubella cases in China from 1991 to 2007 was reviewed, and the nucleotide sequences from 123 rubella viruses collected during 1999 to 2007 and 4 viral sequences previously reported from 1979 to 1984 were phylogenetically analyzed. Rubella vaccination was not included in national immunization programs in China before 2007. Changes in endemic viruses were compared with incidences of rubella epidemics. The results showed that rubella epidemics occur approximately every 6 to 8 years (1993/1994, 2001, and 2007), and a shift of disease burden to susceptible young adults was observed. The Chinese rubella virus sequences were categorized into 5 of the 13 rubella virus genotypes, 1a, 1E, 1F, 2A, and 2B; cocirculations of these different genotypes were found in China. In Anhui province, a shift in the predominant genotype from 1F and 2B to 1E coincided with the 2001 rubella epidemic. This shift may have occurred throughout China during 2001 to 2007. This study investigated the genotype distribution of rubella viruses in China over a 28-year period to establish an important genetic baseline in China during its prevaccination era.

[Evaluation on the effect of implementation regarding the measles surveillance system in Hainan province].

OBJECTIVE: To evaluate the development and operation on measles surveillance system. METHODS: To formulate surveillance program, and then establish surveillance system on measles in Hainan province before the case surveillance was conducted. Descriptive epidemiological method was used to analyze the measles cases reported through the notifiable diseases epidemic situation report system and measles surveillance system during 2004 - 2008 in Hainan province. RESULTS: From 2004 to 2008, through surveillance system, 3040 suspected measles cases were reported which was 96.00% higher than that from the notifiable diseases epidemic situation report system. When the measles surveillance system was first established in 2004, the number of cases reported by the surveillance system was less than that from the epidemic report system, however, the sensitivity of the surveillance system had been increasing since 2005. In 2008, the number of suspected cases reported by surveillance system was 19.12 times more than from the epidemic report system. The proportion of confirmed cases in the total suspected cases was decreasing annually, from 90.34% to 4.48%, along with the increase of the sample collection rate, from 22.73% to 99.12%. The proportion of laboratory confirmed cases in the total confirmed cases increased from 7.55% to 86.97%. With suspected cases, the IgM antibody positive rate on measles and rubella were 31.57% and 34.52%, respectively. In Hainan, the epidemic pattern of measles had been sporadic, except for 2006 as there occurred several outbreaks in that year. The of disease incidence had an obvious seasonal peaks, from March to June. Measles mainly attacked children under 15 years of age, accounted for 86.68% of the age group. Children with no immunity or unknown immune history accounted for 85.67%. CONCLUSION: The sensitivity of surveillance system had been increasing annually since it was developed and the incidence had been dropping to its lowest level. These achievements had built a solid foundation for the eventual elimination of measles.