DETECTION OF ECHINOCOCCUS-MULTILOCULARIS IN THE DEFINITIVE HOST - COPRODIAGNOSIS BY PCR AS AN ALTERNATIVE TO NECROPSY

Recently, extensions of the range of Echinococcus multilocularis in Eu rope and North America and drastic increases in fox populations in Eur ope put an increasing proportion of the human population at risk of al veolar echinococcosis, To obtain data on the local infection pressure, studies of the prevalence of the parasite in the animals that transmi t the parasite, foxes, dogs, and cats, are urgently required. Such inv estigations, however, have been hampered by the need for necropsy of t he host animal to specifically diagnose infection with the parasite. I n this study, a nested PCR and an improved method for DNA extraction w ere developed to allow the sensitive and specific diagnosis of E. mult ilocularis infections directly from diluted fecal samples from foxes, The target sequence for amplification is part of the E. multilocularis mitochondrial 12S rRNA gene. The specificity of the method was 100% w hen it was tested against 18 isolates (metacestodes and adult worms) o f 11 cestode species, including E, granulosus. The sensitivity of the method was evaluated by adding egg suspensions and individual eggs to samples of diluted feces from uninfected foxes, The presence of one eg g was sufficient to give a specific signal, To confirm the PCR results , an internal probe which hybridized only with E. multilocularis ampli fication products but not with the DNA of other cestodes was construct ed. In order to investigate the applicability of this method for epide miological studies, 250 wild foxes from a area in southern Germany whe re echinococcosis is highly endemic were examined by both necropsy and PCR of rectal contents. The sensitivity correlated with the parasites ' number and stage of maturity. It ranged from 100% (>1,000 gravid nor ms) to 70% (<10 nongravid worms), On the basis of positive PCR results for 165 foxes, the sensitivity of the traditional and widely used nec ropsy method was found to be not higher than 76%, We therefore present this PCR system as an alternative method for the routine diagnosis of E. multilocularis is in carnivores.