Studies On The Relationship Between Breteau Index,Mosquito And Oviposition Positive Index And Investigation Of Viruses In Aedes Albopictus

1 Background and PurposeAedes albopictus can transmit a variety of mosquito-borne diseases,such as dengue fever,Zika,Chikungunya fever.Monitoring the density of Ae.albopictus,establishing a population model of Ae.albopictus and pathogen detection can guide vector control effect and judge the risk of disease outbreak,which has important public health significance.2 MethodFrom August 2017 to July 2018,Breteau Index(BI)and Mosquito and oviposition positive index(MOI)were used for the abundance surveillance of Ae.albopictus in village XW and village NF,Baiyun District,Guangzhou.Another Adult-mosquito Density Index(ADI)was also obtained from December 2017.Our team also conducted a one-year,twice-monthly survey for Ae.albopictus abundance in XW village between July 2014 and June 2015.The dataset was also used for model validation.Meteorological data and monthly dengue cases in Baiyun District were collected.Based on references and meteorological data,an 8 stage-strctured Ae.albopictus population model would be established.As for viral metagenomics,different Ae.albopictus samples from 2 villages and 2 urban communities in Baiyun,Yuexiu and Tianhe Ditricts were pooled according to their areas and collected seasons.3 Results3.1 Field surveillance results of Ae.albopictusThe population dynamics of larvae and adult mosquitoes were affected by temperature and their overall trend was consistent in two villages,but the normalized BI was higher than the normalized abundance of adult mosquitoes in most months.From August to September 2017,BI and MOI indicated the same risk of level 3 for dengue fever.Due to the effect of vector control measures in October,the indicators for dengue risk in October and November were not consistent.From December to February the next year,BI represented a risk of level 1 to 3 for dengue fever,while MOI and ADI indicated no risk.In March,compared with BI which indicated a risk of level 3,MOI were 2.13 and 3.77,respectively,representing for no risk.ADI were 4 to 6 per man-hour,indicating a risk of level 1 and level 2,respectively.After April,the dengue risk level reflected by each indicator became to be consistent.3.2 population dynamics model of Ae.albopictusThere were two peaks in the simulated population of adult Ae.albopictus,namely from June to July and from September to October.However,the density of adult Ae.albopictus decreased in August when the temperature was generally high.The average absolute residuals between simulated relative abundance and standardized monitoring data ranged from 7.40%to 11.22%,and the Pearson correlation coefficient was 0.902-0.989.In a word,the population dynamics model fitted well with the field data.Based on the model,we built reference range of the corresponding relationship between BI and MOI,and compared with the field data,the overall coincidence rate was 83.33%(40/48)3.3 viral metagenomics of Ae.albopictusA total of 499 virus were annotated in four metagenomcal samples.The WV sample contained more viral genera included Alphacoronavirus,Rhadinovirus,Orthopoxvirus,Negevirus,Chlorovirus,Parechovirus and Prasinovirus.Besides,there were more Flavivirus,Phikzlikevirus and Lambdalikevirus in SV sample.We found more phage virus genera in WC sample,such as Yualikevirus,T4likevirus and Phikmvlikevirus.The results of cluster tree analysis and principal component analysis showed that the structure of virus community in urban and rural areas was similar,but there were differences between samples in different seasons4 Conclusion4.1 The risk of dengue fever indicated by BI is always higher than or equal to the risk indicated by MOI and ADI.Compared with BI,MOI and ADI are more sensitively in reflecting the activity of Ae.albopictus.4.2 In this paper,a population dynamics model of Ae.albopictus was established based on its ecological habits,temperature,daylight and rainfall,and was verified by field data,BI and MOI.4.3 This study showed that viral communities between urban and rural areras were similar,but there were differences between winter-spring and summer-autumn samples.