Etiological spectrum of clinically diagnosed Japanese encephalitis cases reported in Guizhou Province, China, in 2006.

The proportion of laboratory-confirmed Japanese encephalitis (JE) virus (JEV) infections was compared to the number of JE cases reported on the basis of seasonality and the clinical symptoms of hospitalized patients in Guizhou Province, China, between April and November 2006. Of the 1,837 patients with reported JE, 1,382 patients in nine prefectures were investigated. JE was confirmed in 1,210 of 1,382 (87.6%) patients by a JEV-specific immunoglobulin M (IgM) antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA), heminested reverse transcriptase PCR, and virus isolation. Two strains of JEV belonging to genotype 1 were isolated. Other viral pathogens responsible for encephalitis, including echovirus, mumps virus, herpes simplex virus, and cytomegalovirus, were identified in 67 of 172 (38.9%) JE-negative cases. On the basis of the distribution of the laboratory-confirmed JE cases from different hospitals according to the Chinese administrative division, which included hospitals at the provincial, city, county, and township levels, county hospitals detected the highest number of JE cases (81.8%), whereas township hospitals detected the smallest number of JE cases (1.4%). Provincial and city hospitals had the highest and lowest rates of accuracy of providing a clinical diagnosis of JE, as confirmed by laboratory testing (91.8% and 76.7%, respectively). This study demonstrates that laboratory confirmation improves the accuracy of diagnosis of JE and that an enhanced laboratory capacity is critical for JE surveillance as well as the identification of other pathogens that cause encephalitic syndromes with clinical symptoms similar to those caused by JEV infection.

First isolation of Banna virus in northwestern part of Yunnan province / 中华微生物学和免疫学杂志

Objective To identify the Banna viruses isolated in northwestern part of Yunnan prov-ince in order to make the difference clear between the isolates and other Banna viruses isolated in other parts of Yunnan. Methods Three isolates of Banna vires isolated in 2005 and 2006 were identified by morpholo-gy, RNA-PAGE profile and molecular biologic method. Nueleotide and amino acid sequences of segment 12 of the 3 isolates were sequenced and analyzed. Results Three Banna viruses were isolated from mosquitoes collected in northwestern part of Yunnan during 2005 and 2006. Electron microscopy study showed that they are spherical with a diameter of 70 nm, no envelope but two layers of eapsid. It was found that the genome of the 3 isolates composes of 12 segments presenting band profile of 6-6 in RNA-PAGE. Nueleotide acid se-quence analysis about segment 12 showed that the identity was 99% between the 3 new isolates, 98% and 90% between the 3 isolates and the strains isolated in other parts of Yunnan, China and Indonesia, respec-tively. Phylogenetie analysis based on segment 12 gene showed that 3 new isolates clnstered in the same branch with the viruses isolated in other parts of Yunnan. The same difference of amino acids was found between Banna viruses isolated in China and Indonesia strains in the analysis of segment 12. Conclusion Banna virus strains were firstly isolated from mosquitoes collected in northwestern part of Yunnan province. Nueleotide acid sequence analysis of the 3 new isolates showed higher identity with strains isolated in other parts of Yunnan.