Research of Virus Pathogen of Cases with Viral Encephalitis and Unknown Fever in Yunnan Province
|Course||Epidemiology and Biostatistics,|
|Keywords||Viral Encephalitis Unknown Fever Viral Pathogen Arbovirus Enterovirus Respiratory Virus Yunnan Province|
ObjectivesYunnan province is a region that vast, relatively complex natural condition and distinct vertical climate. There exits some kinds of arboviruses and related arboviral infectious diseases, and some kinds of host of arboviral infectious diseases and vector mosquitoes. For a long time, there was an epidemic region of Japanese encephalitis (JE) and other arboviral diseases which were mosquitoes-borne infectious diseases in China, and whom incidence rate were high. And viral encephalitis and unknown fever cases existed in every summer and autumn in every regions in Yunnan, that got some difficulties to medical institutions and CDCs for diagnosing, preventing and controlling of these diseases. Yunnan is adjacent with Laos, Myanmar and Vietnam, where exist high incidences of arboviral diseases, and is bordering Guizhou province and Sichuan province where exist high incidence rate of JE. So there exist may exist several imported arbovi ruses in Yunnan. In the peak of mosquito breeding (summer and autumn), there existed viral encephalitis and unknown fever patients, who were diagnosed as arbovirus infections, and could not made clear diagnoses depending on medical departments in local. With the rapid development of economic and social, there will have more movement of people and goods that will lead imported arbovi ruses, and even will lead to outbreak of related arboviral diseases that may lead to great negative impact on public health in local. So that carrying out the research of viral pathogen of viral encephalitis and unknown fever in Yunnan to clear distribution of viral pathogen will have very important public health significance.There exist some kinds of pathogens The study carries out the research of viral serological research of viral encephalitis and unknown fever patients in 5 regions in Yunnan province in China, will clear infectious status and distributional character of arbovi ruses and others common viruses (including related viral diseases) and will offer scientific basis of monitoring, detection and prevention of viral encephalitis and unknown fever patients in Yunnan.MethodsCarried out surveillance to viral encephalitis and unknown fever cases in Xishuangbanna prefecture, Dehong prefecture、Dali prefecture、Baoshan city and Zhaotong city. And collected serum and cerebrospinal fluid (CSF) specimens from viral encephalitis and unknown fever patients in 5 regions in Yunnan. Carried out epidemiology survey and clinical data collection. Made Excel tables of background of patients and their specimens. Tested IgM and IgG antibodies to 16 species of viruses of all specimens by using serological methods of enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence assay (IFA). Analyzed the results by epidemiological and viral etiological methods according to the results of antibodies detections and others data.ResultsThe research detected total 79.5%(594/747) of patients were positive IgM antibodies to 10 species of viruses in 747 patients, which were Japanese encephalitis virus (JEV), Banna virus (BAV), Dengue virus (DENV) 1/4, Ross river virus (RRV), Barmah forest virus (BFV), Herpes simplex virus (HSV) 1/2, Mumps virus (MuV), Entero cytopathic human orphan virus (ECHOV), Coxsackie virus (COXV), and Measles virus (MV). In which including 357 patients (47.8%) were positive IgM antibodies to 5 species of arboviruses and 153 patients (32.8%) were positive IgM antibodies to 5 species of common viruses (Table 1.1).Notes: DH, Dehong region; BN, Xishuangbanna region; DL, Dali region; BS, Baoshan region; ZT, Zhaotong region; ELISA, enzyme-linked immunosorbent assay; IgM, immunoglobin M; JEV, Japanese Encephalitis virus; BAV, Banna virus; DENV, Dengue virus; RRV, Ross River virus; BFV, Barmah Forest virus; LNV, Liaoning virus; TAHV, Tahyna virus; SINV, Sindbis virus; SEADNV, Seadomavirus; YNOBV, Yunnan Orbivirus; COXV, Coxsackievirus; ECHOV, Echo virus; HSV, Herpes Simplex virus; MuV, Mumps virus.IgG-antibodies to BAV (BJ95-75 strain) were not detected. IgM-antibodies to 6 species viruses, which were Liaoning virus (LNV), Tahyna virus (TAHN), Sindbis virus (SINV), Yunnan orbi virus (YNOBV) (65 and 93 strain), Seadornavirus (SEADNV) (BAV-6 strain) were not detected.ConclusionsFrom March to November in 2008, serum and CSF specimens (total 853 specimens) in acute or convalescence phase were collected from 747 viral encephalitis and unknown fever patients of 2006～2008. The results showed 10 species arboviruses and common viruses were key pathogens of viral encephalitis and unknown fever patients in tropical and subtropical zones in 2008 in Yunnan, which were JEV、BAV、HSV、COXV、MuV、ECHOV、DENV、RRV、BFV and MV. In which JEV was the main pathogen; what was more, BAV was the secondary pathogen, their positive rates were 31.8%(148/466) and 14.4%(67/466) respective. And 24 JEV and BAV co-infectious patients were detected in 67 positive I gM-anti bodies to BAV patients. BAV was the secondary cause of unknown fever and viral encephalitis except JE, and Common viruses (ECHOV、COXV、HSV1/2 and MuV) were important cause.An outbreak of imported dengue cases in Ruili city was monitored, and 45 positive IgM-anti bodies to DENV1/4 patients were detected, in which most people were migrant workers. 153 patients were positive IgM-antibodies to 5 species common viruses,the age distribution of these 153 positive cases was between 1-78 years old, of the total positive cases 62.9%(96/153) were distributed between 0-20 years old and the male:female ratio was 0.59:1.IgM-antibodies to JEV、COXV、ECHOV、RRV and BFV were detected in cases of 2006～2007 in Xishuangbanna, Zhaotong and Dehong region.251 positive cases were detected in total.167 JE cases (59.4%) were the main positive cases,83 COXV and ECHOV infectious cases were the secondary positive cases. The results indicated JE was the most important viral encephalitis (VE), which was according with results of previous epidemiological research.DiscussionAmong 526 viral encephalitis cases,314 cases of positive IgM-antibodies to 4 species arboviruses were detected, and their total positive rate was 59.69%, that indicated arbovi ruses were the main pathogen among viral encephalitis cases in local. In which 268 cases of positive JEV-IgM were detected, that indicated JEV not only was the mai n pathogen i n arboviral encephal iti s cases but also was the most important pathogen in viral encephalitis in local.lgM-antibodies to DENV、BAV and RRV were detctded among viral encephalitis cases, that indicated these three species viruses could lead to encephalitises. And the positive rate of COXV、ECHOV、HSV and MuV were high among viral encephalitis cases, that indicated Enterovirus(COXV and ECHOV)、respiratory virus(MuV) and HSV were important pathogens of encephalitises, and COXV and ECHOV led to more important pathogenic significances.Among 221 unknown fever cases, there existed JEV. DENV, BAV. RRV and BFV infectious cases and total positive rate of these 5 species arboviruses was 56.56%(125 cases),that indicated arboviruses were main pathogen in unknown fever cases in local too. Enterovirus(COXV and ECHOV)、respiratory virus(MuV and MV) and HSV were important pathogens of unknown fever cases, in which HSV and MuV were more i mportant pathogens.In arboviral infectious cases,BAV might was important pathogen of viral encephalitis and unknown fever except JEV.The study prepared the detective methods of indirect EL ISA for detections of antibodies to BAV successfully; depended on these methods, speamens’ detections in the research were finished and offered the basis to viral surveillance in future.The study improved the research methods of viral pathogens to viral encephalitis and unknown fever cases. Great deals of data, which got from the study, offered reference material to further etiological and molecular-biological research, and accumulated initial value for carrying out further study to prevention and control of viral encephalitis and unknown fever patients. The results indicated that it was of great importance on public health to improve monitoring, detection and prevention of viral pathogens and related viral diseases in Yunnan.