Reisen W K, Milby M M, Presser S B, Hardy J L
Department of Biomedical and Environmental Health Sciences, School of Public Health, University of California, Berkely 94720.
J Med Entomol. 1992 Jul;29(4):582-98. doi: 10.1093/jmedent/29.4.582.
St. Louis encephalitis (SLE) virus has become established in the Los Angeles Basin of California, where it most likely is maintained by horizontal transmission among Culex tarsalis Coquillet and passerine birds in park-riparian habitat. Viral transmission also was detected at low levels in residential habitat by the infrequent seroconversion of sentinel chickens. SLE virus activity was documented in all months except March and April. Cx. tarsalis was incriminated as the primary vector, based on elevated field infection rates (0.17 infected females per 1,000 tested), population abundance concomitant in time and space with increased SLE virus activity, vector competence, and vectorial capacity. Culex stigmatosoma Dyar also may be important in the horizontal maintenance of SLE virus because this species was an efficient laboratory vector, fed frequently on passeriform birds, and had field infection rates (0.15 females per 1,000) comparable with Cx. tarsalis. However, difficulty in trapping adult females precluded the assessment of Cx. stigmatosoma because abundance may have been underestimated and comparatively few females were tested for virus. Although Cx. quinquefasciatus Say was the most abundant species in residential habitats (greater than 85% of total catch at CO2 traps) where it occasionally fed on humans (0.6% of total tested), this species was considered to be of secondary importance because field infection rates were low (0.03 females per 1,000) and few females became infected and transmitted SLE virus in laboratory vector competence experiments. Although Culex erythrothorax Dyar fed on humans in marsh habitat (5% of total tested), this species infrequently fed on birds (12%) and was refractory to SLE virus infection in vector competence experiments; therefore, it was not considered a vector of SLE virus. Future SLE virus surveillance and mosquito control programs should be directed toward Cx. tarsalis populations.
圣路易斯脑炎（SLE）病毒已在加利福尼亚州的洛杉矶盆地定殖，在那里它很可能通过在公园河岸栖息地的致倦库蚊和雀形目鸟类之间的水平传播得以维持。通过哨兵鸡偶尔的血清转化，在居民区栖息地也检测到了低水平的病毒传播。除了3月和4月外，所有月份都记录到了SLE病毒活动。基于较高的野外感染率（每1000只检测的雌蚊中有0.17只感染）、在时间和空间上与SLE病毒活动增加相伴的种群数量、媒介能力和传播能力，致倦库蚊被认定为主要传播媒介。骚扰库蚊也可能在SLE病毒的水平维持中起重要作用，因为该物种是一种高效的实验室传播媒介，经常吸食雀形目鸟类，并且野外感染率（每1000只中有0.15只雌蚊）与致倦库蚊相当。然而，诱捕成年雌蚊存在困难，这妨碍了对骚扰库蚊的评估，因为其数量可能被低估，且接受病毒检测的雌蚊相对较少。尽管致倦库蚊是居民区栖息地中数量最多的物种（在二氧化碳诱捕器捕获的总数中占比超过85%），它偶尔也吸食人类血液（占检测总数的0.6%），但该物种被认为次要，因为野外感染率较低（每1000只雌蚊中有0.03只），并且在实验室媒介能力实验中很少有雌蚊感染并传播SLE病毒。尽管红胸库蚊在沼泽栖息地吸食人类血液（占检测总数的5%），但该物种很少吸食鸟类血液（占12%），并且在媒介能力实验中对SLE病毒感染具有抗性；因此，它不被认为是SLE病毒的传播媒介。未来的SLE病毒监测和蚊虫控制计划应针对致倦库蚊种群。
