本研究旨在調查台北市夏季棄犬感染心絲蟲之情形,利用全血直接濕抹片法檢測幼絲蟲,酵素免疫分析法(ELISA)偵測心絲蟲抗原及實際剖檢心臟檢查心絲蟲之成蟲,並比較檢測心絲蟲方法之準確率。供試150隻棄犬(公犬90隻,母犬60隻)中,經全血直接濕抹片法及心臟剖檢得陽性帶蟲者共80隻,感染率為53.3%。其中公犬之感染率為57.8%,母犬為46.7 %。陽性犬隻中每10μL血液含幼絲蟲數由1隻至551隻不等,心臟含成蟲數由1隻至73隻不等。本研究採用美國IDEXX Lab公司所提供之Snap^(TM)犬心絲蟲抗原診斷劑,經ELISA檢測呈陽性反應之68隻犬中,由心臟剖檢或血檢,可見有心絲蟲的成蟲或幼絲蟲之存在,其準確率為100 %。但有12隻犬經ELISA檢測呈偽陰性,即ELISA呈陰性反應,但心臟剖檢或血檢卻有少數心絲蟲之存在,所以本試劑具有85%之檢測率。如利用全血直接濕抹片法,只檢出43隻犬血液中有幼絲蟲之存在,檢測率為53.8%,由此可知全血直接濕抹片法檢出心絲蟲之感染,其效果不佳。
This study was conducted primarily to investigate the incidence of pound dogs infested by heartworm in Taipei city in summer 1994; secondly, to compare the direct wet smear test, ELISA, and autopsy of the heart to find out the accuracies of these three methods. The number of positive results to both blood test and autopsy was 80 among 150 pound dogs (90 male, 60 female). The total percentage of the infection was 53.3%, 57.8% in male individuals, 46.7% in female. The number of microfilaria found in 10 μ L of blood and of adult worms found in the heart of individuals with positive result was, respectively, from 1 to 551 and from 1 to 73. In this study we used the Snap^(TM) Canine Heartworm Antigen Test Kit manufactured by lDEXX Lab Company, U.S.A. Because 68 individuals found positive to ELISA were also found infected by microfilaria or adult worms, the accuracy of the Snap^(TM) ELISA Kit was 100%. 12 individuals found negative to ELISA were actually pseudonegative, because some heartworm or microfilaria could be found in their heart or blood. Consequently, the sensitive percentage of the Snap^(TM) ELISA Kit is 85%. In 43 cases we have detected microfilaria in the blood using the direct wet smear test, so the accuracy percentage of this method was 53.8%. It was thus shown that the ability of direct wet smear test to detect heartworm is not so good as ELISA's.