Platt Kenneth B, Tucker Brad J, Halbur Patrick G, Blitvich Bradley J, Fabiosa Flor G, Mullin Kathleen, Parikh Grishma R, Kitikoon Pravina, Bartholomay Lyric C, Rowley Wayne A
Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50014, USA.
Vector Borne Zoonotic Dis. 2008 Apr;8(2):225-33. doi: 10.1089/vbz.2007.0182.
The West Nile virus (WNV) viremia and shedding profiles of 11 adult fox squirrels (Sciurus niger) infected by needle inoculation or mosquito bite were characterized. Daily mean titers (95% confidence intervals) for all squirrels on days 1 through 6 postexposure (p.e.) were: 10(1.7 (1.32.1)), 10(4.4 (4.04.8)), 10(5.3 (5.05.6)), 10(4.4 (3.94.9)), 10(2.7 (2.03.4)), and 10(1.1 (0.52.1)) plaque-forming units (PFU)/mL. The highest WNV serum titers of individual squirrels infected by needle inoculation or mosquito bite ranged from 10(4.5) to 10(6.1) and from 10(5.1) to 10(5.3) PFU/mL, respectively. Nine (82%) squirrels, including all 4 squirrels infected by mosquito bite, had WNV serum titers > or =10(5.1) PFU/mL that persisted on average for 1.6 +/- 0.3 days. Infection and dissemination rates of Culex pipiens (L.) that fed on squirrels with serum titers of 10(4.4 +/- 0.1) PFU/mL were 56% and 13%, respectively. Both of these rates increased to over 80% when fed on squirrels with a mean WNV titer of 10(5.5 +/- 0.1) PFU/mL. Infection and dissemination also occurred in Aedes triseriatus (Say) but at a much lower rate. WNV was isolated from the oral and rectal cavities of all squirrels and from urine that was opportunistically collected from 5 squirrels. The largest quantity of WNV recovered from swabs of the oral cavity and urine was 10(3.1) PFU. The longest periods after exposure that WNV was isolated from the oral cavity and urine from a squirrel were 22 and 17 days p.e., respectively. WNV RNA was also detected in kidney tissue in 1 squirrel 29 days p.e., suggesting that fox squirrels can be persistently infected. Collectively these observations provide further evidence that squirrels can contribute to the natural history and epidemiology of WNV, especially in peridomestic environments.
对11只通过针刺接种或蚊虫叮咬感染西尼罗河病毒（WNV）的成年狐松鼠（东部灰松鼠）的病毒血症和排毒情况进行了特征描述。暴露后（p.e.）第1至6天所有松鼠的每日平均滴度（95%置信区间）为：10（1.7（1.3 - 2.1））、10（4.4（4.0 - 4.8））、10（5.3（5.0 - 5.6））、10（4.4（3.9 - 4.9））、10（2.7（2.0 - 3.4））和10（1.1（0.5 - 2.1））空斑形成单位（PFU）/毫升。通过针刺接种或蚊虫叮咬感染的单个松鼠的最高WNV血清滴度分别为10（4.5）至10（6.1）和10（5.1）至10（5.3）PFU/毫升。9只（82%）松鼠，包括所有4只通过蚊虫叮咬感染的松鼠，WNV血清滴度≥10（5.1）PFU/毫升，平均持续1.6±0.3天。以血清滴度为10（4.4±0.1）PFU/毫升的松鼠为食的致倦库蚊（L.）的感染率和传播率分别为56%和13%。当以平均WNV滴度为10（5.5±0.1）PFU/毫升的松鼠为食时，这两个率均增加到80%以上。三带喙库蚊（Say）也发生了感染和传播，但发生率要低得多。WNV从所有松鼠的口腔和直肠腔以及从5只松鼠机会性收集的尿液中分离出来。从口腔拭子和尿液中回收的WNV最大量为10（3.1）PFU。从松鼠口腔和尿液中分离出WNV的暴露后最长时间分别为22天和17天。在暴露后29天，在1只松鼠的肾脏组织中也检测到WNV RNA，这表明狐松鼠可能会被持续感染。总体而言，这些观察结果提供了进一步的证据，表明松鼠可能对WNV的自然史和流行病学有影响，尤其是在家庭周边环境中。
