| Hydatid disease,also known as Echinococcosis,is an important zoonotic parasitic disease caused by the larval stage of Echinococcus spp.,which is one of the seventeen neglected tropical diseases identified by the World Health Organization.The Three-River Source Region is one of the most severely prevalent regions of Echinococcus spp.in the Qinghai-Tibet Plateau,where there are three species of Echinococcus,including Echinococcus multilocularis,Echinococcus granulosus and Echinococcus shiquicus.The metacestode larval stage of E.multilocularis and E.granulosus causes Alveolar Echinococcosis(AE)and Cystic Echinococcosis(CE)in humans and other intermediate hosts,respectively.Whether E.shiquicus infecting humans is unknown.The definitive hosts of Echinococcus spp.are generally canines such as foxes,dogs and wolves,and the intermediate hosts include small mammals such as cattle,sheep,voles,pikas,and humans.When the faeces are excreted from the definitive hosts,and Echinococcus spp.eggs will be excreted together with the faeces,then the soil and water sources will be contaminated with the eggs,which will pose a severe threat to health of intermediate hosts.In order to explore contamination of Echinococcus spp.eggs in water sources,soil samples and faeces of canines in the Three Rivers Source Region,to find out the environment factors of eggs infection and the degree of risk of background status,the risk assessment system is established for guiding humans and animals related epidemic prevention work.Three types of PCR molecular detection methods are established suitable for detection of three Echinococcus spp.in different levels of laboratories.The epidemiological investigation on contamination of Echinococcus spp.eggs in the water,soil and fecal samples in the Three Rivers Source Region.The positive rates of each type of source samples from different sampling sites are comprehensively analyzed,the possible scenes of the risk of eggs infection are determined,the probability of each influence factors and the weight coefficient of each environment factors are also determined,the risk of Echinococcus spp.eggs infection is also evaluated.The main conclusions are as follows:(1)Three PCR molecular methods for detection of Echinococcus spp.are established in this study,including multiplex PCR method(m PCR),multiplex recombinase-aid amplification(m RAA),and multiplex fluorescence real-time quantitative PCR detection method(mq PCR),the sensitivity of m PCR is 1000 copies/μL,the sensitivity of m RAA is 200copies/μL and the sensitivity of mq PCR is 10 copies/μL;all three methods can specifically detect the corresponding Echinococcus spp.The artificially simulated field samples are detected by using the above-established detection methods,the detection rate is 100%,and the coincidence rate among the three methods is 100%.(2)The epidemiological investigation on contamination of Echinococcus spp.eggs in canine faeces,water sources and soil samples in the Three Rivers Source Region by using the most sensitive fluorescence real-time quantitative PCR detection method.The results show that there are three species of Echinococcus spp.detected in the samples,and there is no mixed infection;the total prevalence of Echinococcus spp.in fecal samples is 7.13%(45/631),and the infection rate of Echinococcus spp.in dogs is 6.08%(18/296),and the infection rate of Echinococcus spp.in foxes is 8.06%(27/335);the total contamination rate of Echinococcus spp.eggs in soil samples is 2.51%(10/398);the total contamination rate of Echinococcus spp.eggs in water samples is 3.67%(11/300).(3)The epidemiological data of Echinococcus spp.is comprehensively analyzed,the possible scenes of the risk of eggs infection are determined,the risk probability of infection is calculated as 0.199,and the risk level is probably not infected.The possible occurrence scenes of the degree of hazard influence factors are determined,the risk probability of infection is calculated as 0.158,the severity level of the hazard is relatively small.Finally,it was determined that the risk of Echinococcus spp.eggs infection in the Three Rivers Source Region is low risk.The risk of transmission of Echinococcus spp.eggs carried by various sources samples is analyzed,which will provide relevant information and decision-making basis for the prevention and control of hydatid disease in the Three Rivers Source Region.There is a prompting effect on the risk of infection in production and life activities,animal husbandry and tourism in this region,and there is also an important practical significance in carrying out risk assessment. |
PDF Full Text Request