美国1999-2009年西尼罗病毒感染流行的回顾

西尼罗病毒(West Nile virus,WNV)是一种蚊传虫媒病毒,1937年从非洲乌干达西尼罗地区一名发热土著妇女血液标本中分离并得名[1].此后在非洲、欧洲和亚洲中东地区的一些国家出现WNV感染病例,表现以发热为主的临床症状,为自愈性疾病[2].但是1999年该病毒首次在美国流行,仅1个月时间报道数十例WNV感染所引发的病毒性脑炎[3].随后WNV感染在美国的分布范围逐渐扩大并迅速扩散到美国大陆全境,至今已经有数万人染病并致上千人死亡[4].     

West Nile virus isolation from equines in Argentina, 2006

West Nile virus (WNV) was isolated from the brains of 3 horses that died from encephalitis in February 2006. The horses were from different farms in central Argentina and had not traveled outside the country. This is the first isolation of WNV in South America.     

Alexander the Great and West Nile virus encephalitis

Alexander the Great died in Babylon in 323 BC. His death at age 32 followed a 2-week febrile illness. Speculated causes of death have included poisoning; assassination, and a number of infectious diseases. One incident, mentioned by Plutarch but not considered by previous investigators, may shed light on the cause of Alexander's death. The incident, which occurred as he entered Babylon, involved a flock of ravens exhibiting unusual behavior and subsequently dying at his feet. The inexplicable behavior of ravens is reminiscent of avian illness and death weeks before the first human cases of West Nile virus infection were identified in the United States. We posit that Alexander may have died of West Nile virus encephalitis.     

Ecological factors associated with West Nile virus transmission, northeastern United States

Since 1999, West Nile virus (WNV) disease has affected the northeastern United States. To describe the spatial epidemiology and identify risk factors for disease incidence, we analyzed 8 years (1999-2006) of county-based human WNV disease surveillance data. Among the 56.6 million residents in 8 northeastern states sharing primary enzootic vectors, we found 977 cases. We controlled for population density and potential bias from surveillance and spatial proximity. Analyses demonstrated significant spatial spreading from 1999 through 2004 (p<0.01, r2 = 0.16). A significant trend was apparent among increasingly urban counties; county quartiles with the least (<38%) forest cover had 4.4-fold greater odds (95% confidence interval [CI] 1.4-13.2, p = 0.01) of having above-median disease incidence (>0.75 cases/100,000 residents) than counties with the most (>70%) forest cover. These results quantify urbanization as a risk factor for WNV disease incidence and are consistent with knowledge of vector species in this area.     

新疆伊犁地区动物脑组织西尼罗病毒E基因片段的检测

目的了解新疆伊犁地区动物中西尼罗病毒（West Nile virus,WNV）感染现状,为我国WNV的防治提供资料。方法采用一步法实时荧光定量反转录-聚合酶链反应（RT-PCR）,对采自新疆伊犁地区的70头驴和100只牧羊犬的脑组织进行WNV包膜蛋白（E）基因片段检测。结果 70头驴和100只牧羊犬脑组织标本的西尼罗病毒包膜蛋白基因片段检测有2例可疑阳性,但经3%凝胶电泳法再次验证后排除。故所有待检样本WNV包膜蛋白基因检测均为阴性。结论我国新疆伊犁地区的驴和牧羊犬脑组织中未检测到WNV的感染。     

West Nile virus infections projected from blood donor screening data, United States, 2003

National blood donor screening for West Nile virus (WNV) RNA using minipool nucleic acid amplification testing (MP-NAT) was implemented in the United States in July 2003. We compiled national NAT yield data and performed WNV immunoglobulin M (IgM) testing in 1 WNV-epidemic region (North Dakota). State-specific MP-NAT yield, antibody seroprevalence, and the average time RNA is detectable by MP-NAT were used to estimate incident infections in 2003. WNV donor screening yielded 944 confirmed viremic donors. MP-NAT yield peaked in August with >0.5% of donations positive for WNV RNA in 4 states. Peak IgM seroprevalence for North Dakota was 5.2% in late September. The average time viremia is detectable by MP-NAT was 6.9 days (95% confidence interval [CI] 3.0-10.7). An estimated 735,000 (95% CI 322,000-1,147,000) infections occurred in 2003, with 256 (95% CI 112-401) infections per neuroinvasive case. In addition to preventing transfusion-transmitted WNV infection, donor screening can serve as a tool to monitor seasonal incidence in the general population.     

Enhancing West Nile virus surveillance, United States

We provide a method for constructing a county-level West Nile virus risk map to serve as an early warning system for human cases. We also demonstrate that mosquito surveillance is a more accurate predictor of human risk than monitoring dead and infected wild birds.     

Cost-effectiveness of West Nile virus vaccination

West Nile virus (WNV) was first detected in the Western Hemisphere in 1999 in New York City. From 1999 through 2004, >16,600 cases of WNV-related illnesses were reported in the United States, of which >7,000 were neuroinvasive disease and >600 were fatal. Several approaches are under way to develop a human vaccine. Through simulations and sensitivity analysis that incorporated uncertainties regarding future transmission patterns of WNV and costs of health outcomes, we estimated that the range of values for the cost per case of WNV illness prevented by vaccination was US 20,000 dollars-59,000 dollars(mean 36,000 dollars). Cost-effectiveness was most sensitive to changes in the risk for infection, probability of symptomatic illness, and vaccination cost. Analysis indicated that universal vaccination against WNV disease would be unlikely to result in societal monetary savings unless disease incidence increases substantially over what has been seen in the past 6 years.     

天津市蚊虫西尼罗病毒携带调查

目的了解天津市蚊虫携带西尼罗病毒（WNV）情况。方法以灯诱法进行蚊虫采集,采用荧光定量PCR检测方法对WNV进行检测。结果天津市有候鸟栖息的湖泊、洼地周边主要蚊种为淡色库蚊（占93．68％）,同时存在凶小库蚊和三带喙库蚊。对1091只蚊虫进行西尼罗病毒检测,结果均为阴性。结论本次调查未发现蚊虫携带WNV,为预防和控制WNV传人及可能发生的流行,有必要开展对媒介蚊虫及WNV的长期监测。     

病毒性脑炎患者外周血和脑脊液西尼罗病毒E基因的检测

西尼罗病毒(WNV)是单股正链RNA病毒,属于黄病毒科黄病毒属,其传播媒介和储存宿主是蚊虫[1].人感染WNV会出现感冒样症状,部分患者为脑膜脑炎、坏死性脑干炎等神经系统症状[2,3].本研究对重庆地区不明病因的78例病毒性脑炎(VE)患者血液和脑脊液进行wNV E基因片段检测.     

江西省1995～1999年肾综合征出血热流行病学分析

肾综合征出血热 (ＨＦＲＳ)是一种广泛流行于世界各大洲的自然疫源性疾病 ,我国为重疫区 ,江西省又是该病发病较高疫区。为深入研究出血热的流行规律 ,掌握流行动态及发病趋势 ,为制定防治策略提供科学依据 ,现将江西省 1995～1999年ＨＦＲＳ的流行特征分析如下。1.流行特征 :(1)发病情况 :江西省 1995～ 1999年ＨＦＲＳ 5年发病总数为 894 9例 ,发病率为 4 .4 6 / 10万 ,病死数为 70例 ,病死率为 0 .79%。发病数及死亡数均以 1996年最低 ,分别为 14 38例和 12例 ,而发病数最高为 1998年 ,为 2 0 91例 ,病死数则以1995、1997两年最高 ,均为 …     

Experimental infection of cats and dogs with West Nile virus

Domestic dogs and cats were infected by mosquito bite and evaluated as hosts for West Nile virus (WNV). Viremia of low magnitude and short duration developed in four dogs but they did not display signs of disease. Four cats became viremic, with peak titers ranging from 10(3.0) to 10(4.0) PFU/mL. Three of the cats showed mild, non-neurologic signs of disease. WNV was not isolated from saliva of either dogs or cats during the period of viremia. An additional group of four cats were exposed to WNV orally, through ingestion of infected mice. Two cats consumed an infected mouse on three consecutive days, and two cats ate a single infected mouse. Viremia developed in all of these cats with a magnitude and duration similar to that seen in cats infected by mosquito bite, but none of the four showed clinical signs. These results suggest that dogs and cats are readily infected by WNV. The high efficiency of oral transmission observed with cats suggests that infected prey animals may serve as an important source of infection to carnivores. Neither species is likely to function as an epidemiologically important amplifying host, although the peak viremia observed in cats may be high enough to infect mosquitoes at low efficiency.     

Corvidae feather pulp and West Nile virus detection

We evaluated cloacal swab, vascular pulp of flight feather, and kidney and spleen pool samples from carcasses of members of the family Corvidae as sources of West Nile virus (WNV). The cloacal swab, kidney and spleen pool, and feather pulp were the source of WNV in 38%, 43%, and 77%, respectively, of the carcasses.     

Epidemiological history and phylogeography of West Nile virus lineage 2

West Nile virus (WNV) was first isolated in Uganda. In Europe WNV was sporadically detected until 1996, since then the virus has been regularly isolated from birds and mosquitoes and caused several outbreaks in horses and humans. Phylogenetic analysis showed two main different WNV lineages. The lineage 1 is widespread and segregates into different subclades (1a–c). WNV-1a includes numerous strains from Africa, America, and Eurasia. The spatio-temporal history of WNV-1a in Europe was recently described, identifying two main routes of dispersion, one in Eastern and the second in Western Europe. The West Nile lineage 2 (WNV-2) is mainly present in sub-Saharan Africa but has been recently emerged in Eastern and Western European countries. In this study we reconstruct the phylogeny of WNV-2 on a spatio-temporal scale in order to estimate the time of origin and patterns of geographical dispersal of the different isolates, particularly in Europe. Phylogeography findings obtained from E and NS5 gene analyses suggest that there were at least two separate introductions of WNV-2 from the African continent dated back approximately to the year 1999 (Central Europe) and 2000 (Russia), respectively. The epidemiological implications and clinical consequences of lineage 1 and 2 cocirculation deserve further investigations.