The Study Of Characteristics Of Dengue Molecular Epidemiology And Prevention And Control Strategies In Guangdong Province

Background and objectiveDengue fever(DF)is an acute infectious disease caused by dengue virus(DENV)which is transmitted by mosquitoes,mainly Aedes aegypti or ae.albopictus.Dengue may cause rash,fever,joint or muscle pain,nausea,vomiting,poor appetite and other various degrees of symptoms.Severe dengue,including dengue hemorrhagic fever and dengue shock syndrome,may even cause death.It has now been widely spread in more than 120 countries worldwide,including China.Since the first epidemic of dengue in China broke out in Foshan city,Guangdong Province,in 1978,local transmission of dengue has mainly occurred in a few southern provinces of China such as Hainan,Guangdong,Guangxi and Fujian,but the distribution of cases has gradually expanded to the north over the years.Guangdong province is a high-risk area of dengue epidemics among those provinces,which has accumulated over 720,000 cases in the past epidemics.Dengue has brought heavy burden to the economy and people’s physical and mental health in Guangdong Province.It has become a major public health problem in Guangdong province that needs to be paid close attention to.This study has described the overall epidemiological characteristics of dengue in Guangdong province in recent 4 decades(1978-2017)based on the collected epidemiological data,and has revealed the differences between Guangdong province and the other endemic areas of dengue.Then the strategies of molecular epidemiological study have been applied to compare the E gene between DENV which epidemic in Guangdong Province in recent 4 decades(1978-2017)and DENV which are endemic in other areas around the world,to understand the overall characteristics of evolution of DENV in Guangdong,and confirm the pattern of dengue outbreaks in Guangdong.And we have discussed the reforming of dengue prevention and control policies in Guangdong Province during the past four decades(1987-2017),to provide scientific clues for precise prevention and control,and also a reference for other new epidemic or risk areas.Methods1.Described the overall prevalence of dengue in Guangdong Province and revealed the characteristics of dengue outbreaks in Guangdong Province.2.Time series molecular evolution analysis was performed between DENV sequences of local cases in Guangdong and representative reference sequences in the database to describe the evolutionary characteristics.3.Discussed the periodic reforming of dengue prevention and control policies in Guangdong province from 1978 to 2017,and got some experience from those policies.Results1.Dengue mainly occurs during a period from July to November in Guangdong from 1978 to 2017,and the highest risk period is from August to September,presenting a clear seasonal epidemic characteristic.The patients are mostly young and middle-aged people.Dengue cases in Guangdong province rarely result in severe illness or death.There were 503 dengue deaths from 1978 to 2017.2.Four types of DENV(DENV 1-4)were all detected in Guangdong province from 1978 to 2017.DENV1 was the dominant epidemic type of dengue outbreaks in the past 40 years,but DENV 2 showed an increasing trend after 2010,while DENV3 was rarely transmitted locally.DENV4 has only been detected in imported cases.However,the third branch of the Malaysia-Indonesia-Singapore branch of DENV 1 genotype I may be a localized branch,which requires further monitoring.3.The periodic updates of the guidelines for dengue prevention and control issued by Guangdong Health authorities in 1979,1987 and 2015 have provided Guangdong with accurate and effective prevention and control strategies.Conclusions1.The characteristics of dengue epidemics in Guangdong are different from those in dengue endemic areas during 1978-2017.The most typical characteristics of the dengue epidemics in Guangdong are localized transmission caused by imported cases.Dengue fever has not been localized as a vector-borne disease in Guangdong Province.2.DENV1 and 2 are the major epidemic serotypes in Guangdong province from 1978 to 2017.Most of locally detected viruses were imported from other countries,with the only possible local branch occurring in the third cluster of DENV1 genotype I.Imported cases and their associated transmission remain the main sources of DENV in Guangdong Province.3.Early detection,case management,and precise control measures remain important methods to control localized transmission of dengue in Guangdong Province.Case and vector surveillance still needs to be strengthened to prevent risks.