Nationwide surveillance of West Nile virus targeting mosquitoes and dead birds from April 2004 through March 2007 in Japan.

We conducted nationwide West Nile virus (WNV) surveillance targeting mosquitoes and dead birds to reveal whether the virus and its potential vectors are present in Japan. A total of 12 766 mosquitoes and 230 dead birds were collected in April 2004-March 2005 (the 2004-2005 period), 10 755 mosquitoes and 267 dead birds in April 2005-March 2006 (the 2005-2006 period), and 8624 mosquitoes and 245 dead birds in April 2006-March 2007 (the 2006-2007 period). The species of most of the mosquitoes collected over the 3 years were Culex tritaeniorhynchus (47.82%) and Anopheles sinensis (28.49%), and other species included Aedes albopictus (6.75%), the Culex pipiens group (Cx. pipiens pallens and Cx. pipiens molestus: 5.37%), Aedes vexans nipponii (2.54%), Armigeres subalbatus (1.08%), and Aedes japonicus (0.95%). As for the dead birds, most were Passeriformes (456 specimens), which included several crow species, and the other orders included Anseriformes, Columbiformes and Ciconiiformes (78, 66 and 36 specimens, respectively). All the specimens tested negative for WNV RNA by reverse-transcriptase polymerase chain reaction (RT-PCR) in the 2004-2005 period and by real-time RT-PCR in the 2005-2006 and the 2006-2007 periods, respectively. Our surveillance provided no evidence for WNV in Japan as of the end of the surveillance period, but on the other hand, it revealed that several species of potential WNV vectors are distributed widely in Japan, which suggests that WNV in principle could be transmitted by the potential vectors if introduced. Thus, it is essential to take continued precautions against WNV introduction.

Risk factors for the introduction of avian influenza virus into commercial layer chicken farms during the outbreaks caused by a low-pathogenic H5N2 virus in Japan in 2005.

Avian influenza outbreaks caused by a low-pathogenic H5N2 virus occurred in Japan from June to December 2005. All 41 affected farms housed layer chickens. Therefore, we conducted a case-control study targeting all commercial layer chicken farms within the movement restriction areas in Ibaraki prefecture, where most outbreaks were detected, to investigate the risk factors for the introduction of avian influenza virus (AIV). Four variables were identified as risk factors associated with the introduction of AIV by multivariate logistic regression: 'introduction of end-of-lay chickens ' (odds ratio (OR) = 36.6), 'sharing of farm equipment among farms' (OR = 29.4), 'incomplete hygiene measures of farm visitors on shoes, clothes and hands' (OR = 7.0), and 'direct distance to the nearest case farm' (0-500 m, OR = 8.6; 500-1000 m, OR = 0.8; 1000-1500 m, OR = 20.1; referenced more than 1500 m). We fully believe that strict biosecurity measures should be applied against any incursion points so as not to introduce AIV into more farms.

Control of an outbreak of highly pathogenic avian influenza, caused by the virus sub-type H5N1, in Japan in 2004.

An outbreak of highly pathogenic avian influenza (HPAI), caused by the virus sub-type H5N1, occurred at four premises in three prefectures in Japan during January and March 2004. As a result, 274,654 poultry died or were slaughtered. This was the first outbreak of HPAI in Japan since 1925. (The earlier outbreak was caused by H7N7.) The disease was successfully eradicated within three-and-a-half months, following an eradication campaign that included depopulating the affected premises, implementing movement controls and intensive surveillance. Control measures were conducted in accordance with the National Manual of HPAI Control. However, during the eradication campaign, some key issues arose, such as delays in notification by the affected farmers. As a result of these experiences, the relevant laws and HPAI Control Manual have been appropriately revised.

Radical cyclization in heterocycle synthesis. 11.(1) A novel synthesis of alpha,beta-disubstituted gamma-lactones via sulfanyl radical addition-cyclization using hydroximates as a tether

A combination of sulfanyl radical addition-cyclization of dienes connected with hydroximates and subsequent conversion of the resulting cyclic hydroximate to the lactones provides a novel method for the construction of alpha,beta-disubstituted gamma-lactones. Upon treatment with thiophenol in the presence of AIBN, dienes connected with hydroximates smoothly underwent sulfanyl radical addition-cyclization to give cyclic cis- and trans-hydroximates. Hydrolysis of cyclic hydroximates gave the desired cis- and trans-lactones in high yield. This method was successfully applied to the practical synthesis of (+/-)-oxo-parabenzlactone.