旋毛虫幼虫在大鼠与小鼠肌肉分布及囊包内幼虫数量的观察

Observations on the distribution of Trichinella spiralis in muscles of rats and mice and its number in capsule

目的观察不同剂量旋毛虫感染大鼠与小鼠后幼虫在肌肉内的分布及囊包内的幼虫数量。方法将30只昆明小鼠和30只SD大鼠均随机分为轻、中、重度感染组(每组10只),分别按每g克体重1、5、20条肌幼虫经口感染。感染后42d剖杀,取不同部位肌肉称重后压片镜检,观察不同部位每克肌肉虫荷(larvaepergram,lpg)及囊包内幼虫数量。结果大鼠在轻度感染时以咬肌虫荷最高,中、重度感染时分别以膈肌和舌肌虫荷最高;小鼠在轻度感染时以咬肌虫荷最高,中、重度感染时均以膈肌虫荷最高。在大鼠肌肉8028个囊包中,含1、2、3条幼虫的囊包分别占97.91%、1.95%及0.14%;在小鼠肌肉7559个囊包中,含1、2、3条幼虫的囊包分别占97.33%、2.54%及0.13%。小鼠肌肉多幼虫(2～3条)囊包的检出率明显高于大鼠(χ2=5.644,P<0.05)。多幼虫囊包的检出率在大鼠和小鼠均随感染剂量的增加而升高(χ2大鼠=42.656,P<0.05;χ2小鼠=45.713,P<0.05);在含3条幼虫囊包的肌肉,重度感染的大鼠和小鼠肌肉分别占81.82%(9/11)与100%(10/10)。未发现含有4条及4条以上幼虫的囊包。结论对鼠类旋毛虫感染的流行病学调查时应首选咬肌进行病原学检查,其次为膈肌或舌肌;进行肌肉活检或肉类检疫时发现含3条幼虫的囊包提示为重度感染。

In order to observe the distribution of T. spiralis larvae in muscles of rats and mice and its number in capsule, 30 male Kunming mice and 30 male Sprague Dawley （SD） rats were randomly divided into 3 groups （10 animals for each group） ： i. e. light, moderate and heavy infection groups. Each group was orally inoculated with 1, 5 or 20 T. spiralis muscle larvae per gram of body weight, respectively. All infected animals were slaughtered at 42 days post infection. The muscles were compressed between two slides to examine under microscope for the larval burden （larvae per gram, lpg） and the number in capsule （nurse cell）. In rats with light infection, the larval burden in masseter muscle was the highest; in rats with moderate and heavy infection, the muscles contained the highest larval burden was diaphragmatic and lingual muscle, respectively. In mice with light infection, the larval burden in masseter muscle was also the highest; In both groups of mice with moderate and heavy infection, the larval burden in diaphragms was the highest. The frequency of capsules contained 1, 2 and 3 larvae among 8028 capsules in infected rat muscles was 97.91%, 1.95% and 0.14%, respectively. Out of 7559 capsules in infected mouse muscles, the capsules contained 1, 2 and 3 larvae accounted for 97.33%, 2.54% and 0.13%, respectively. The detection rate of capsules contained multiple （2-3） larvae in infeeted mouse muscles was obviously higher than that in infected rat muscles （X^2=5.644,P〈0.05）. The detection rate of capsules contained multiple larvae in rats and mice has the elevating trend with the increase of infective dose（X^2rat=42.656, P〈0.05; X^2mouse=45. 713,P〈0.05）. The muscles of rats and mice with heavy infection accounted for 81.82% （9/11）and 100%（10/10）of the muscles contained the capsules with 3 larvae. The capsules contained more than 4 larvae （4 or more） were not observed. These results indicate that when the epidemiological investigation on murine Trichinella infection was carried out, masseter muscles are preferred for pathogen examination, the next is diaphragm or masseter muscles; the detection of the capsules contained 3 larvae during muscle biopsy or meat quarantine suggests the presence of heavy Trichinella infection.