Hudson P J, Norman R, Laurenson M K, Newborn D, Gaunt M, Jones L, Reid H, Gould E, Bowers R, Dobson A
Department of Biological and Molecular Sciences, University of Stirling, UK.
Parasitology. 1995;111 Suppl:S49-58. doi: 10.1017/s0031182000075818.
The population dynamics of tick-borne disease agents and in particular the mechanisms which influence their persistence are examined with reference to the flavivirus that causes louping-ill in red grouse and sheep. Pockets of infection cause heavy mortality and the infection probably persists as a consequence of immigration of susceptible hosts. Seroprevalence is positively associated with temporal variations in vectors per host, although variation between areas is associated with the abundance of mountain hares. The presence of alternative tick hosts, particularly large mammals, provides additional hosts for increasing tick abundance. Grouse alone can not support the vectors and the pathogen but both can persist when a non-viraemic mammalian host supports the tick population and a sufficiently high number of nymphs bite grouse. These alternative hosts may also amplify virus through non-viraemic transmission by the process of co-feeding, although the relative significance of this has yet to be determined. Another possible route of infection is through the ingestion of vectors when feeding or preening. Trans-ovarial transmission is a potentially important mechanism for virus persistence but has not been recorded with louping-ill and Ixodes ricinus. The influence of non-viraemic hosts, both in the multiplication of vectors and the amplification of virus through non-viraemic transmission are considered significant for virus persistence.
本文参照在红松鸡和绵羊中引发跳跃病的黄病毒，研究了蜱传疾病病原体的种群动态，尤其是影响其持续存在的机制。感染区域会导致大量死亡，而感染可能因易感宿主的迁入而持续存在。血清阳性率与每只宿主身上蜱虫数量的时间变化呈正相关，尽管不同区域之间的差异与山地野兔的数量有关。替代蜱宿主的存在，尤其是大型哺乳动物，为蜱虫数量的增加提供了额外宿主。仅松鸡无法维持蜱虫和病原体的生存，但当一个非病毒血症的哺乳动物宿主维持蜱虫种群，且足够数量的若虫叮咬松鸡时，两者都能持续存在。这些替代宿主也可能通过共进食过程中的非病毒血症传播来扩增病毒，尽管其相对重要性尚未确定。另一种可能的感染途径是在进食或梳理羽毛时摄入蜱虫。经卵传播是病毒持续存在的一个潜在重要机制，但跳跃病和蓖麻硬蜱尚未有相关记录。非病毒血症宿主在蜱虫繁殖以及通过非病毒血症传播扩增病毒方面的影响，被认为对病毒的持续存在具有重要意义。
