de Freitas Carolina Maria Vianna, Leite Romário Cerqueira, Bastianetto Eduardo, da Cunha Arildo Pinto, de Paiva Belo Ana Cristina Passos
Laboratório de Ectoparasitoses, Escola de Veterinária-EV, Universidade Federal de Minas Gerais-UFMG, Av. Antônio Carlos 6627, CEP 30161-970 Belo Horizonte-MG, Brazil.
Rev Bras Parasitol Vet. 2009 Dec;18 Suppl 1:40-2. doi: 10.4322/rbpv.018e1007.
The present study aimed to evaluate the occurrence of immune resistance in dogs successively infested with Amblyomma cajennense nymphs. Five animals were submitted to four consecutive infestations with A. cajennense nymphs, at fourteen-day intervals. For each infestation, 50 nymphs were used per animal and data on the parasitic and non-parasitic periods were recorded. The average recovering rate of engorged nymphs in the successive infestations were 52.0, 29.2, 9.6 and 12.8%, respectively, with a significant reduction (p<0.05) of this parameter from the second infestation onwards. The modal drop-off day of engorged nymphs was Day 4 of parasitism in all infestations. The average mortality rates of nymphs seen on the first, second, third and fourth infestations were 3.6, 3.2, 2.0 and 2.8%, respectively, with no significant differences among them (p<0.05). In addition, no significant differences were seen among the ecdysis rates for specimens recovered from successive parasitic challenges. The study results suggest that the acquired resistance of infested dogs had a negative effect on recovery rate of A. cajennense nymphs; however, it did not affect the other biological parameters evaluated.
本研究旨在评估先后感染卡延花蜱若虫的犬只中免疫抗性的发生情况。五只动物每隔14天连续接受四次卡延花蜱若虫的感染。每次感染时，每只动物使用50只若虫，并记录寄生期和非寄生期的数据。连续感染中饱血若虫的平均回收率分别为52.0%、29.2%、9.6%和12.8%，从第二次感染开始该参数显著降低（p<0.05）。所有感染中饱血若虫的模式脱落日均为寄生后第4天。第一次、第二次、第三次和第四次感染时观察到的若虫平均死亡率分别为3.6%、3.2%、2.0%和2.8%，它们之间无显著差异（p>0.05）。此外，从连续寄生挑战中回收的标本的蜕皮率之间没有显著差异。研究结果表明，受感染犬只获得的抗性对卡延花蜱若虫的回收率有负面影响；然而，它并未影响所评估的其他生物学参数。
