Catala S S, Gorla D E, Basombrio M A
Centro de Investigaciones Entomologicas, Universidad de Cordoba, Argentina.
Am J Trop Med Hyg. 1992 Jul;47(1):20-6. doi: 10.4269/ajtmh.1992.47.20.
The dynamics of vectorial transmission of Trypanosoma cruzi and the level of host (guinea pigs) protection after immunization with attenuated parasites (TCC strain) was studied under natural climatic conditions in an endemic region of northern Argentina. The experimental design included two guinea pig corrals isolated by mosquito netting. One (controls) had 17 healthy and susceptible adult guinea pigs. The other had 19 guinea pigs immunized with attenuated T. cruzi TCC strain. Each corral was colonized in April 1988 with equal-sized populations of Triatoma infestans naturally infected by T. cruzi. To evaluate relevant variables in the natural transmission of Chagas' disease, corrals were sampled in both winter and late spring to assess vector populations, and to carry out parasitologic studies on both vertebrate and invertebrate hosts. In both corrals, vector density decreased in winter and reached a maximum in the hot season. The vector infection rate was very high (greater than 50%) throughout the experiment. Vector infectivity increased with temperature and vector age, but did not differ between the experimental and control corrals. The vector-host contact rate showed a close relationship with temperature, although a very high vector density decreased this rate, even with high ambient temperatures. Initial infections by T. cruzi occurred among guinea pigs only during the hot season. Vectorial transmission risk was estimated from the total number of bug bites per day, the proportion of infected bugs, and the daily incidence in the guinea pig population. During the hot season, this risk was 6.84 x 10(-4) in the control group and 1.82 x 10(-4) in the immunized group.
在阿根廷北部一个地方病流行区的自然气候条件下，研究了克氏锥虫的媒介传播动态以及用减毒寄生虫（TCC 株）免疫后宿主（豚鼠）的保护水平。实验设计包括两个用蚊帐隔离的豚鼠围栏。一个围栏（对照组）有 17 只健康且易感的成年豚鼠。另一个围栏有 19 只经减毒克氏锥虫 TCC 株免疫的豚鼠。1988 年 4 月，每个围栏都引入了等量的自然感染克氏锥虫的侵扰锥蝽种群。为了评估恰加斯病自然传播中的相关变量，在冬季和晚春对围栏进行采样，以评估媒介种群数量，并对脊椎动物和无脊椎动物宿主进行寄生虫学研究。在两个围栏中，媒介密度在冬季下降，在炎热季节达到最高值。在整个实验过程中，媒介感染率非常高（大于 50%）。媒介感染力随温度和媒介年龄增加，但在实验组和对照组之间没有差异。媒介与宿主的接触率与温度密切相关，尽管媒介密度非常高会降低该接触率，即使在环境温度较高时也是如此。克氏锥虫的初始感染仅在炎热季节发生在豚鼠中。通过每天臭虫叮咬总数、感染臭虫的比例以及豚鼠种群中的每日发病率来估计媒介传播风险。在炎热季节，对照组的这种风险为 6.84×10⁻⁴，免疫组为 1.82×10⁻⁴。
