Abstract
Measles morbidity and mortality decreased significantly after measles vaccine was introduced into China in 1965. From 1995 to 2004, average annual measles incidence decreased to 5.6 cases per 100,000 population following the establishment of a national two-dose regimen. Molecular characterization of wild-type measles viruses demonstrated that genotype H1 was endemic and widely distributed throughout the country in China during 1995-2004. A total of 124,865 cases and 55 deaths were reported from the National Notifiable Diseases Reporting System (NNDRS) in 2005, which represented a 69.05% increase compared with 2004. Over 16,000 serum samples obtained from 914 measles outbreaks and the measles IgM positive rate was 81%. 213 wild-type measles viruses were isolated from 18 of 31 provinces in China during 2005, and all of the isolates belonged to genotype H1. The ranges of the nucleotide sequence and predicted amino acid sequence homologies of the 213 genotype H1 strains were 93.4%-100% and 90.0%-100%, respectively. H1-associated cases and outbreaks caused the measles resurgence in China in 2005. H1 genotype has the most inner variation within genotype, it could be divided into 2 clusters, and cluster 1 viruses were predominant in China throughout 2005.
Highlights
Countries in the Western Pacific Region of the World Health Organization (WHO) have identified 2012 as the target year to eliminate measles [1]
Thirty-seven percent of the cases were in the "floating populations", which are defined as persons who do not have a permanent residence card for the place in which they reside, and the proportion was over 50% in some developed provinces and big cities
This study reported that the measles resurgence was caused by co-criculationg of cluster1 and cluster2 subgenotypes measles virus in China, 2005
Summary
Countries in the Western Pacific Region of the World Health Organization (WHO) have identified 2012 as the target year to eliminate measles [1]. Measles continues to be a leading cause of childhood morbidity and mortality in developing countries and an outbreak threat in the majority of countries, despite the availability of an effective vaccine for 40 years [2,3]. Approximately 20% of measles cases occurred in infants under 12 months in 2005. The peak of incidence of measles occurred in the early spring. Molecular epidemiologic studies can help to measure the transmission pathways of MeV and to clarify epidemiological links during outbreaks. Virological surveillance can help to measure the success of measles vaccination programs by documenting the interruption of transmission of the endemic viral genotype(s) [7,8]
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