Epidemiology of bluetongue virus serotype 8 outbreaks in the Netherlands in 2006     

Elbers A  Backx A  van der Spek A  Ekker M  Leijs P  Steijn K  van Langen H  van Rijn P 《Tijdschrift voor diergeneeskunde》2008,133(6):222-229

In August 2006 a major epidemic of Bluetongue (BT) occurred in north-western Europe, affecting The Netherlands, Belgium, Germany, Luxemburg, and the north of France. It was caused by Br virus serotype 8 (BTV-8), a serotype previously unknown to the EU. Although clinical disease is usually restricted to sheep, this virus also caused clinical disease in a small proportion of cattle. The last clinical outbreak of BT in The Netherlands occurred mid-December 2006. The delay between observation of the first clinical signs by the owner and reporting of a clinically suspect BT situation to the veterinary authorities was approximately 2 weeks. BTV-8-associated clinical signs were more prominent in sheep than in cattle, and the relative frequency of specific clinical signs was different in cattle and sheep. Morbidity and mortality rates were significantly higher among sheep than among cattle, and a higher proportion of cattle than sheep recovered from clinical disease.  相似文献   

Comparison of flow cytometry and immunofluorescence microscopy for the detection of Giardia duodenalis in bovine fecal samples.     

Fabienne D Uehlinger  Herman W Barkema  Ryan M O'Handley  Monique Parenteau  Lorna J Parrington  John A Vanleeuwen  Brent R Dixon 《Journal of veterinary diagnostic investigation》2008,20(2):178-185

The performance of flow cytometry (FC) was compared with immunofluorescence microscopy (IM) for detection of Giardia duodenalis in bovine feces. Samples from 36 adult dairy cows and 208 dairy calves were collected. Flow cytometry test characteristics were calculated using continuous, ordinal, and dichotomized results. Spearman correlation coefficients comparing the results of the 2 tests were 0.47 and 0.68 for cows and calves, respectively. Using IM as indicative of presence or absence of G. duodenalis cysts in each sample, likelihood ratios of FC results with 0, 1, and > or = 2 gated events indicated that samples with 1 gated event were likely to be positive in the cows but not in the calves. Immunofluorescence microscopy detected G. duodenalis in 69.7% and 48.1% of cows and calves, respectively. When dichotomizing the FC results at a cut-off point of 1 or 2 gated events, 46.3% and 19.9% of the cow and 51.9% and 35.1% of the calf samples, respectively, were classified as G. duodenalis-positive. Relative to IM, the sensitivity in the cows was 0.59 and 0.28, respectively, and 0.76 and 0.64, respectively, in the calves. At a cut-off point of 1, 65.7% and 73.1% of the cow and calf samples, respectively, were correctly classified in FC, and at a cut-off point of 2, 49.3% and 78.4% were correctly classified in the cows and calves, respectively. Flow cytometry was less sensitive than IM. Possible reasons and research needed to improve FC for G. duodenalis detection are discussed.  相似文献   

挪威春季产卵的大西洋鲱仔稚鱼年孵化量的估算方法     

梁兴明  Herman　Bjφrke 《中国水产科学》1999,6(2):46-51

１９８６～１９９０年间,挪威卑尔根海洋研究所每年都对挪威西海岸春季产卵的大西洋鲱仔稚鱼的分布区进行一次综合性调查,每年在大西洋鲱的孵化期,都在Ｓｕｎｎｍｒｅ近岸和Ｂｕａｇｒｕｎｎｅｎ的两个小区重复取样（通常每周２次）,并用覆盖整个孵化区的综合调查所得的资料计算出仔稚鱼日孵化量,用两个小区所得的资料作孵化曲线,从而得出在孵化期内仔稚鱼孵化量占年总孵化量的百分比。１９８６～１９９０年间仔稚鱼年孵化量分别是１．７×１０１２、３．９×１０１２、３５．４×１０１２、７２．８×１０１２和９９．１×１０１２尾。  相似文献   

Reducing Drosophila suzukii emergence through inter‐species competition          下载免费PDF全文

Bethan Shaw  Philip Brain  Herman Wijnen  Michelle T Fountain 《Pest management science》2018,74(6):1466-1471

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Differential Sensitivity of Genetically Related Potato Cultivars to Treatments Designed to Alter Apical Dominance,Tuber Set and Size Distribution     

Derek J. Herman  Lisa O. Knowles  N. Richard Knowles 《American Journal of Potato Research》2016,93(4):331-349

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Temporal evolution of collar lesions associated with ash dieback and the occurrence of Armillaria in Belgian forests          下载免费PDF全文

A. Chandelier  F. Gerarts  G. San Martin  M. Herman  L. Delahaye 《Forest Pathology》2016,46(4):289-297

Ash dieback, caused by the fungus Hymenoscyphus fraxineus, has been observed in Europe for several years. In Belgium, the disease was first reported in 2010. Besides crown defoliation and dieback, collar lesions have sometimes been reported. To evaluate the prevalence and the progression of collar lesions and crown defoliation in ash dieback‐affected stands of various ages, a survey was conducted in 2013 and 2014 on 268 ash trees (Fraxinus excelsior) originating from 17 Walloon forest stands. The results showed that the proportion of trees with collar lesions greatly increased between June 2013 and September 2014 and that there appeared to be no significant link between a tree's diameter‐at‐breast height (DBH) and collar lesion occurrence. The mean percentage of defoliation increased in each forest stand across time, with observations conducted in September 2013 and 2014 showing a positive correlation with the mean percentage of trees with collar lesions. Molecular tests were carried out on 103 additional trees originating from 12 of the 17 stands to evaluate the occurrence of H. fraxineus and Armillaria spp. at the collar level. Most of the trees (98%) were infected by H. fraxineus. In contrast, only 41% of the samples were infected with Armillaria spp., most commonly A. gallica and A. cepistipes. This study discusses the role of Armillaria spp. and the rapid increase in the number of trees with collar lesions within the context of the evolution of ash dieback in Europe.  相似文献   

Non-crop plants used as hosts by Drosophila suzukii in Europe     

Marc Kenis  Lorenzo Tonina  René Eschen  Bart van der Sluis  Manuel Sancassani  Nicola Mori  Tim Haye  Herman Helsen 《Journal of pest science》2016,89(3):735-748

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Can differences in soil community composition after peat meadow restoration lead to different decomposition and mineralization rates?     

Jerry van Dijk  Wim A.M. Didden  Frans Kuenen  Herman A. Verhoef 《Soil biology & biochemistry》2009,41(8):1717-6164

Reducing decomposition and mineralization of organic matter by increasing groundwater levels is a common approach to reduce plant nutrient availability in many peat meadow restoration projects. The soil community is the main driver of these processes, but how community composition is affected by peat meadow restoration is largely unknown. Furthermore, it is unclear whether restoration induced changes could lead to altered decomposition and mineralization rates. We determined soil community composition in restored peat meadows with different groundwater levels and soil pH. This composition was subsequently used in food web model calculations of C and N mineralization rates to assess whether differences in soil community composition may have contributed to differences in decomposition and mineralization rates observed between these meadows.Community composition of micro-organisms, Collembola and Enchytraeidae differed considerably between meadows and were correlated with differences in groundwater levels and soil pH. Collembolan and enchytraeid species from wet and neutral environments were more abundant at meadows with higher groundwater levels. Lower fungal to bacterial PLFA ratios and higher numbers of protozoa indicated an increased importance of the bacterial part of the food web at meadows with higher groundwater levels. Food web model calculations suggested that the observed changes in community composition would lead to higher rates of C and N mineralization at meadows with high groundwater levels. Results from modeling were consistent with field measurements of C mineralization, but not with measurements of N mineralization.We conclude that understanding changes in soil community composition in response to specific restoration measures may help us to better understand ecosystem responses to wetland restoration schemes, especially regarding soil biogeochemical processes.  相似文献   

Feline leukaemia. ABCD guidelines on prevention and management     

Hans Lutz  Diane Addie  Sándor Belák  Corine Boucraut-Baralon  Herman Egberink  Tadeusz Frymus  Tim Gruffydd-Jones  Katrin Hartmann  Margaret J. Hosie  Albert Lloret  Fulvio Marsilio  Maria Grazia Pennisi  Alan D. Radford  Etienne Thiry  Uwe Truyen  Marian C. Horzinek 《Journal of Feline Medicine and Surgery》2009,11(7):565-574

OverviewFeline leukaemia virus (FeLV) is a retrovirus that may induce depression of the immune system, anaemia and/or lymphoma. Over the past 25 years, the prevalence of FeLV infection has decreased considerably, thanks both to reliable tests for the identification of viraemic carriers and to effective vaccines.InfectionTransmission between cats occurs mainly through friendly contacts, but also through biting. In large groups of non-vaccinated cats, around 30–40% will develop persistent viraemia, 30–40% show transient viraemia and 20–30% seroconvert. Young kittens are especially susceptible to FeLV infection.Disease signsThe most common signs of persistent FeLV viraemia are immune suppression, anaemia and lymphoma. Less common signs are immune-mediated disease, chronic enteritis, reproductive disorders and peripheral neuropathies. Most persistently viraemic cats die within 2–3 years.DiagnosisIn low-prevalence areas there may be a risk of false-positive results; a doubtful positive test result in a healthy cat should therefore be confirmed, preferably by PCR for provirus. Asymptomatic FeLV-positive cats should be retested.Disease managementSupportive therapy and good nursing care are required. Secondary infections should be treated promptly. Cats infected with FeLV should remain indoors. Vaccination against common pathogens should be maintained. Inactivated vaccines are recommended. The virus does not survive for long outside the host.Vaccination recommendationsAll cats with an uncertain FeLV status should be tested prior to vaccination. All healthy cats at potential risk of exposure should be vaccinated against FeLV. Kittens should be vaccinated at 8–9 weeks of age, with a second vaccination at 12 weeks, followed by a booster 1 year later. The ABCD suggests that, in cats older than 3–4 years of age, a booster every 2–3 years suffices, in view of the significantly lower susceptibility of older cats.  相似文献   

Feline rabies. ABCD guidelines on prevention and management     

Tadeusz Frymus  Diane Addie  Sándor Belák  Corine Boucraut-Baralon  Herman Egberink  Tim Gruffydd-Jones  Katrin Hartmann  Margaret J. Hosie  Albert Lloret  Hans Lutz  Fulvio Marsilio  Maria Grazia Pennisi  Alan D. Radford  Etienne Thiry  Uwe Truyen  Marian C. Horzinek 《Journal of Feline Medicine and Surgery》2009,11(7):585-593

OverviewRabies virus belongs to the genus Lyssavirus, together with European bat lyssaviruses 1 and 2. In clinical practice, rabies virus is easily inactivated by detergent-based disinfectants.InfectionRabid animals are the only source of infection. Virus is shed in the saliva some days before the onset of clinical signs and transmitted through a bite or a scratch to the skin or mucous membranes. The average incubation period in cats is 2 months, but may vary from 2 weeks to several months, or even years.Disease signsAny unexplained aggressive behaviour or sudden behavioural change in cats must be considered suspicious. Two disease manifestations have been identified in cats: the furious and the dumb form. Death occurs after a clinical course of 1–10 days.DiagnosisA definitive rabies diagnosis is obtained by post-mortem laboratory investigation. However, serological tests are used for post-vaccinal control, especially in the context of international movements.Disease managementPost-exposure vaccination of cats depends on the national public health regulations, and is forbidden in many countries.Vaccination recommendationsA single rabies vaccination induces a long-lasting immunity. Kittens should be vaccinated at 12–16 weeks of age to avoid interference from maternally derived antibodies and revaccinated 1 year later. Although some vaccines protect against virulent rabies virus challenge for 3 years or more, national or local legislation may call for annual boosters.  相似文献