关键词: 牛, 动物, 日本血吸虫, 感染度, 虫卵回收率

Abstract: In order to carry out quantitative epidemiological survey of animal schistosomiasis, a sensitive egg-counting method was studied both in the laboratory and in the field.Fecal material was filtered by a copper gauze (60 meshes/inch) into a nylon-tissue bag with 2 layers, 150 and 260 meshes/inch respectively. Thin smears were made from the residue in the bag.The mean recovery rate of mature schistosome eggs by previously adding 100 eggs to 5g of feces from noninfected cattle was 67.5%, ranging from 53 to 81%.To compare the egg-concentration thin smear method mentioned above,with egg-concentration thick smear method after hyalinization, various numbers of eggs, namely, 25, 50 and 100, were added to 5g of feces. The mean recovery rates of fecal eggs were 57.6%, 57.6% and 69.1% respectively, for the thin smear method and 3.2%, 13.8% and 19.5% for the thick smear method. The coefficients of variability in the former were from 12.9% to 17.4% and in the latter, from 30.7% to 98.8%.The total number of schistosome eggs per 5g of feces found in 34 egg-positive cattle in the field were 434 and 178 by the thin smear method and the thick smear method, respectively.A correlation analysis performed on the numbers of detected eggs in a total volume of fecal sediment and from half a volume of fecal sediment multiplied by two, showed a correlation coeffecient of 0.98 (P0.01), indicating that half a volume of fecal sediment may be used instead of a whole volume. The value of EPG, X, can be calculated from 5g of feces by applying the following formula:X(EPG)=total number of eggs in 6 slides × 2/5The adjustment value to estimate the true value of EPG from the detected one is Y= 1.1 + 1.4X.The results indicated that the egg-concentration thin smear method was significently better than the thick smear method in terms of sensitivity and reliability, so the former was considered to be useful in field epidemiological survey for animal schistosomiasis.