Pappaioanou M, Schwabe C W, Sard D M
Am J Trop Med Hyg. 1977 Jul;26(4):732-42. doi: 10.4269/ajtmh.1977.26.732.
Echinococcus granulosus infection was being acquired in the contiguous United States by Virginia sharecroppers and small-holders by the turn of the century. The last recorded human infection from that general area was diagnosed in 1947. By 1920 human infections were also being acquired in the lower Mississippi valley. Apparently, infection in both of these areas was maintained chiefly in swine. By 1940 a third transmission area definitely existed in the Central Valley of California, with its reservoir intermediate host sheep. Seemingly, infection has been disseminated from these California foci into Utah and more recently into northern New Mexico and Arizona. Human populations now at unusual risk in the western United States are transhumant sheep ranchers, including Basque-Americans in California, Mormons in central Utah, and Navajo and Zuni Indians in New Mexico and Arizona. Conditions highly favorable to E. granulosus transmission, intensification and spread now exist throughout relatively large areas of the American West.
到世纪之交时，弗吉尼亚州的佃农和小农场主在美国毗邻地区感染了细粒棘球绦虫。该地区最后一次有记录的人类感染病例于1947年被确诊。到1920年，密西西比河下游流域也出现了人类感染病例。显然，这两个地区的感染主要在猪群中传播。到1940年，加利福尼亚中央谷地明确成为第三个传播区域，其保虫中间宿主为绵羊。似乎感染已从加利福尼亚的这些疫源地传播到犹他州，最近又传播到新墨西哥州北部和亚利桑那州。美国西部目前面临异常风险的人群是游牧牧羊民，包括加利福尼亚州的巴斯克裔美国人、犹他州中部的摩门教徒以及新墨西哥州和亚利桑那州的纳瓦霍族和祖尼族印第安人。现在，美国西部相对大片地区存在着非常有利于细粒棘球绦虫传播、增殖和扩散的条件。
