Rodríguez-Vivas R I, Rivas A L, Chowell G, Fragoso S H, Rosario C R, García Z, Smith S D, Williams J J, Schwager S J
Universidad Autónoma de Yucatán, Facultad de Medicina Veterinaria y Zootecnia, Mérida, Yucatán, Mexico.
Vet Parasitol. 2007 May 15;146(1-2):158-69. doi: 10.1016/j.vetpar.2007.01.016. Epub 2007 Mar 8.
The ability of Boophilus microplus strains to be susceptible (-) or resistant (+) to amidines (Am), synthetic pyrethroids (SP), and/or organo-phosphates (OP) (or acaricide profiles) was investigated in 217 southeastern Mexican cattle ranches (located in the states of Yucatán, Quintana Roo, and Tabasco). Three questions were asked: (1) whether acaricide profiles varied at random and, if not, which one(s) explained more (or less) cases than expected, (2) whether the spatial distribution of acaricide profiles was randomly or non-randomly distributed, and (3) whether acaricide profiles were associated with farm-related covariates (frequency of annual treatments, herd size, and farm size). Three acaricide profiles explained 73.6% of the data, representing at least twice as many cases as expected (P<0.001): (1) Am-SP-, (2) Am+SP+, and (3) (among ranches that dispensed acaricides > or = 6 times/year) Am-OP+SP+. Because ticks collected in Yucatán ranches tended to be susceptible to Am, those of Quintana Roo ranches displayed, predominantly, resistance to OP/SP, and Tabasco ticks tended to be resistant to Am (all with P < or = 0.05), acaricide profiles appeared to be non-randomly disseminated over space. Across states, two farm-related covariates were associated with resistance (P < or = 0.02): (1) high annual frequency of acaricide treatments, and (2) large farm size. Findings supported the hypothesis that spatial acaricide profiles followed neither random nor homogeneous data distributions, being partially explained by agent- and/or farm-specific factors. Some profiles could not be explained by these factors. Further spatially explicit studies (addressing host-related factors) are recommended.
在墨西哥东南部的217个养牛场（位于尤卡坦州、金塔纳罗奥州和塔巴斯科州），对微小牛蜱菌株对脒类（Am）、合成拟除虫菊酯（SP）和/或有机磷（OP）（或杀螨剂谱）的易感性（-）或抗性（+）进行了研究。提出了三个问题：（1）杀螨剂谱是否随机变化，如果不是，哪种谱解释的病例数比预期多（或少），（2）杀螨剂谱的空间分布是随机分布还是非随机分布，以及（3）杀螨剂谱是否与农场相关协变量（年度处理频率、畜群规模和农场规模）相关。三种杀螨剂谱解释了73.6%的数据，代表的病例数至少是预期的两倍（P<0.001）：（1）Am-SP-，（2）Am+SP+，以及（3）（在每年施用杀螨剂≥6次的牧场中）Am-OP+SP+。由于在尤卡坦州牧场采集的蜱往往对Am敏感，金塔纳罗奥州牧场的蜱主要对OP/SP有抗性，而塔巴斯科州的蜱往往对Am有抗性（所有P≤0.05），杀螨剂谱似乎在空间上是非随机分布的。在各州中，两个与农场相关的协变量与抗性相关（P≤0.02）：（1）杀螨剂处理的高年度频率，以及（2）大农场规模。研究结果支持了这样的假设，即空间杀螨剂谱既不遵循随机数据分布也不遵循均匀数据分布，部分原因是由药剂和/或农场特定因素造成的。有些谱无法用这些因素来解释。建议进一步开展考虑宿主相关因素的空间明确研究。
