Actual transmission modes of pathogenic Entamoeba histolytica and Cryptosporidium

近年来，利用新的遗传学技术建立了溶组织内阿米巴和隐孢子虫的新分类。这促使我们重新审视两种真正致病的寄生虫的传播模式。我们对菲律宾和尼泊尔的两个物种进行了流行病学调查，这些感染很常见。得到的结果是1.结果表明，所有调查区域内均存在溶组织内阿米巴（Entamoeba histolytica）和非致病性内阿米巴（Edispar），但溶组织内阿米巴所占比例较低。H.不同地区带菌率在10%~ 30%之间.高流行率的囊带菌者被认为是在一个人口密集的房子条件，表明人与人之间的直接接触是传播的第一个危险因素。无症状E. H.和E. d见于年轻一代（5-20岁）的男女，而严重的症状性感染（肝脓肿）仅见于男性成年人（20-60岁）.血清学阳性病例为E. H.在青年群体中也是最高的，表明E. H.感染通常是短暂的。5.隐孢子虫的感染方式与E. A、从血清阳性模式判断。未发现隐孢子虫无症状卵囊携带者。蛔虫和贾第鞭毛虫的感染方式似乎与大肠杆菌不同。H.研究结果表明，改善供水系统和厕所等有序控制方法可以有效地控制隐孢子虫的发生。不能有效降低E. H.和隐孢子虫

Recently, new taxonomic classification of Entamoeba histolytica and Cryptosporidium have been established using new genetic technology. This drove us to reexamine the transmission mode of really pathogenic species of two parasites. We conducted epidemiological surveys of two species in the Philippines and Nepal where these infections are commonly seen. Obtained results are1. Pathogenic species ( Entamoeba histolytica ) and non-pahtogenic species ( Edispar) coexisted in all the area examined, but the proportion of E. h. in all cyst carriers was varied from 10 % to 30 % in different localities.2. High prevalence of cyst-carriers was seen in a densely populated house condition, indicating direct contact between persons is the first risk-factor for transmission.3. The peak ofasymptomatic cyst-carriers of E. h. and E. d was seen in young generation ( 5-20 years ) of both sexes, whereas severe symptomatic infections ( liver abscess ) were exclusively found in male adults ( 20-60 years ).4. Seropositive cases to E. h. were also highest in young population, indicating E. h. infections are commonly short.5. The mode of Cryptosporidium infection seems to be similar to E. A, judging from the sero-positive pattern.6. Asymptomatic oocyst-carriers of Cryptosporidium were not found.7. The mode of infection ofAscaris lumbricoides and Giardia lamblia seems to be different from that of E. h. and Cryptosporidium.Our results indicated that ordinal control methods such as improvement of the water-supply system and toilets may. not be effective for reduction of E. h. and Cryptosporidium.