Understanding the origin of seasonal epidemics of mycoplasmal conjunctivitis
Understanding the origin of seasonal epidemics of mycoplasmal conjunctivitis
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DOI：
10.1111/j.1365-2656.2012.01986.x
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发表时间：
2012-09-01
影响因子：
4.8
通讯作者：
Schat, Karel A.
中科院分区：
文献类型：
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作者：
Dhondt, Andre A.;States, Sarah L.;Schat, Karel A.
1.许多寄主系统表现出规律性的季节振荡。2.家雀支原体结膜炎患病率的季节变化就是这种振荡的一个例子。3.鸡毒支原体幼虫的年脉搏增加了易感人群的数量，成群行为的季节性变化增加了传播率，对再次感染的抵抗力随着时间的推移逐渐丧失，足以模拟观察到的疾病流行的季节性变化。然而，需要进行实验来测试潜在的机制。4.我们在大型鸟类养殖场进行了为期18个月的小群鸟类实验，以检验两个假设。5.为了检验第一个假设，即幼稚的幼虫涌入一组康复的成年人足以导致疫情爆发，我们在11只从早期感染中恢复的成年人中增加了8只幼虫。总共有三个重复的青少年感染了病毒，但只是在一些成年人复发之后。6.为了验证第二个假设，即将鸡败血杆菌重新引入以前接触过但完全康复的多年龄组家雀会导致新的疫情爆发，我们在第二年3月为每组接种了两只鸟。与当时在野外发生的情况相反，重新引入鸡败血杆菌后，疾病流行率迅速增加。7.我们的结论是，没有症状、康复的成虫可以引发流行病，并将鸡毒支原体传播给幼年的家雀，即使在一年中支原体结膜炎在自由生活的鸟类中很少的时候，重新引入鸡毒杆菌也足以引起新的疫情。因此，日期对于解释结膜炎的季节性变化似乎没有幼虫的存在或鸡毒杆菌的引入那么重要。8.疫情的季节性很可能与鸟类活动和行为的季节性变化密切相关。
1. Many hostpathogen systems show regular seasonal oscillations. 2. Seasonal variation in mycoplasmal conjunctivitis prevalence in house finches is an example of such oscillations. 3. An annual pulse of Mycoplasma gallisepticum-naive juveniles increasing the number of susceptibles, seasonal changes in flocking behaviour increasing transmission rate and a gradual loss of resistance to reinfection with time are sufficient to model the observed seasonal variation in disease prevalence. Nevertheless, experiments are needed to test the underlying mechanisms. 4. We carried out an 18-month experiment with small groups of birds in large aviaries to test two hypotheses. 5. To test the first hypothesis that an influx of naive juveniles in a group of recovered adults is sufficient to cause an outbreak, we added eight juveniles to a group of 11 adults that had recovered from an earlier infection. In all, three replicates juveniles became infected, but only after some of the adults relapsed. 6. To test the second hypothesis that reintroduction of M.gallisepticum into a multiage group of previously exposed but fully recovered house finches causes a new outbreak, we inoculated two birds in each group in March of the 2nd year. Contrary to what happens in the wild at that time disease prevalence increased rapidly after reintroduction of M.gallisepticum. 7. We conclude that asymptomatic, recovered adults can initiate an epidemic and transmit M.gallisepticum to naive house finches and that the reintroduction of M.gallisepticum is sufficient to cause a new outbreak, even at a time of the year when mycoplasmal conjunctivitis is low in free-living birds. Date, as such, seems to be less important to explain seasonal variation in conjunctivitis than the presence of naive juveniles or the introduction on M.gallisepticum. 8. Seasonality in outbreaks is most likely tightly linked to seasonal variation in bird movements and behaviour.