Gurtler R E, Cecere M C, Castanera M B, Canale D, Lauricella M A, Chuit R, Cohen J E, Segura E L
Departamento de Ciencias Biologicas, Universidad de Buenos Aires, Argentina.
Am J Trop Med Hyg. 1996 Jul;55(1):24-31.
The probability that an uninfected Triatoma infestans would become infected with Trypanosoma cruzi after a single feed on people or dogs seropositive for T. cruzi was estimated in Amama, a rural village in northwest Argentina where transmission had resurged four years earlier. The prevalence of seropositivity for T. cruzi was 34.2% among 225 people tested, and 65.1% among 83 dogs tested. Parasitemia was detected by xenodiagnosis in 29.3% of 41 seropositive persons and in 85.3% of 34 seropositive dogs. Parasitemia decreased with age more sharply in seropositive people than in seropositive dogs. Seropositive humans infected 2.6% (95% confidence interval = 1.6%-3.6%) of 963 third or fourth instar nymphs fed once on them, whereas dogs infected 48.7% (44.7%-52.7%) of 610 nymphs. The probability of bug infection increased significantly with instar and was positively related to molting success. The infectivity to bugs of seropositive dogs was 12 times higher than that of seropositive children, and 100 times higher than that of seropositive adults. The weighted probability of infection of an uninfected bug fed randomly on any dog (0.3082) was about 50 times higher than that of bugs fed on any human (0.0062). Such differences in relative infectivity, combined with the relative host-feeding preference of domiciliary Triatoma infestans for dogs, reinforces the important role of domestic dogs as a risk factor for the domestic transmission of T. cruzi.
在阿根廷西北部一个名为阿马马的乡村，恰加斯病传播在四年前已经复苏。在此，研究人员估计了未感染的克氏锥蝽在吸食克氏锥虫血清学阳性的人或狗一次后感染克氏锥虫的概率。在接受检测的225人中，克氏锥虫血清学阳性率为34.2%；在接受检测的83只狗中，阳性率为65.1%。通过异种接种诊断，在41名血清学阳性者中有29.3%检测到寄生虫血症，在34只血清学阳性狗中有85.3%检测到寄生虫血症。血清学阳性者中寄生虫血症随年龄下降的幅度比血清学阳性狗更明显。血清学阳性的人感染了963只吸食过他们一次的三龄或四龄若虫中的2.6%（95%置信区间 = 1.6% - 3.6%），而狗感染了610只若虫中的48.7%（44.7% - 52.7%）。臭虫感染的概率随龄期显著增加，并且与蜕皮成功率呈正相关。血清学阳性的狗对臭虫的感染性比血清学阳性的儿童高12倍，比血清学阳性的成年人高100倍。随机吸食任何一只狗的未感染臭虫的加权感染概率（0.3082）比吸食任何人的臭虫的概率（0.0062）高约50倍。这种相对感染性的差异，再加上家栖克氏锥蝽对狗的相对宿主取食偏好，强化了家犬作为克氏锥虫家庭传播风险因素的重要作用。
