Isolation and identification of a distinct strain of Culex Flavivirus from mosquitoes collected in Mainland China.

BACKGROUND: Culexflavivirus (CxFV) is an insect specific virus that has been isolated from Culexpipiens, Culexquinquefasciatus, Culextritaeniorhynchus and other Culex mosquitoes. It is a novel flavivirus isolated in Asia, North America, Central America and Africa. Phylogenetic analysis indicates that, based on the envelope gene (E gene) sequence, the worldwide CxFV strains can be divided into two genotypes. RESULT: A virus (SDDM06-11) was isolated from Culexpipiens collected in Shandong Province, China in 2006. The strain caused cytopathic effect (CPE) in Aedesalbopictus (C6/36) cells by 3 days post-infection and immunofluorescence assay (IFA) showed a reaction with Japanese encephalitis virus (JEV) polyclonal antibodies. Phylogenetic analysis of the E gene sequence showed CxFV formed two genotypes with the SDDM06-11 strain assigned to genotype 1. Analysis of the E gene nucleotide homology showed the virus possessed characteristic amino acids at specific sites. The nucleotide homology of the open reading frame (ORF) was 94.8%-95.1% between SDDM06-11 and isolates from Japan, Iowa and Texas, and 90.2%-90.5% between SDDM06-11 and isolates from Uganda and Mexico. CONCLUSION: In this paper we report the first isolation and identification of an isolate of CxFV in mainland China. Phylogenetic analysis indicates the isolate belongs to genotype 1. Our findings provide insight into the occurrence of CxFV in Culex mosquito populations and its distribution on a global scale.

Active case-based surveillance for measles in China: lessons learned from Shandong and Henan provinces.

To identify issues relevant to nationwide implementation, a project was conducted during 1999-2001 to support and evaluate the development of a case-based measles surveillance system (MSS) in Shandong and Henan provinces, China. The performance of MSS surveillance and the descriptive characteristics of reported measles cases and outbreaks were analyzed. Of the 5782 suspected cases in 2001, 85% were investigated and 66% had serologic results. In all, 39% of cases were confirmed, 36% were compatible, and 25% were discarded; 81% of outbreaks identified involved <15 cases. In all, 15% of cases were temporary (floating) residents. The MSS was useful in monitoring the impact of measles control activities. Standardized laboratory quality-assurance activities and indicators should be developed while the system is still in the early stages of implementation.