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1.
Increased transport and trade as well as climate shifts play an important role in the introduction, establishment and spread of new pathogens. Arguably, the introduction of bluetongue virus (BTV) serotype 8 in Benelux, Germany and France in 2006 is such an example. After its establishment in receptive local vector and host populations the continued spread of such a disease in a suitable environment will mainly depend on movement of infected vectors and animals. In this paper we explore how wind models can contribute to explain the spread of BTV in a temperate eco-climatic setting. Based on previous work in Greece and Bulgaria filtered wind density maps were computed using data from the European Centre for Medium-Range Weather Forecasts (ECMWF). Six hourly forward wind trajectories were computed at pressure levels of 850hPa for each infected farm as from the recorded onset of symptoms. The trajectories were filtered to remove wind events that do not contribute to possible spread of the vector. The suitable wind events were rastered and aggregated on a weekly basis to obtain weekly wind density maps. Next to this, cumulated wind density maps were also calculated to assess the overall impact of wind dispersal of vectors. A strong positive correlation was established between wind density data and the horizontal asymmetrical spread pattern of the 2006 BTV8 epidemic. It was shown that short (<5km), medium (5-31km) and long (>31km) distance spread had a different impact on disease spread. Computed wind densities were linked to the medium/long-distance spread whilst short range spread was mainly driven by active Culicoides flight. Whilst previous work in the Mediterranean basin showed that wind driven spread of Culicoides over sea occurred over distances of up to 700km, this phenomenon was not observed over land. Long-distance spread over land followed a hopping pattern, i.e. with intermediary stops and establishment of local virus circulation clusters at distances of 35-85km. Despite suitable wind densities, no long range spread was recorded over distances of 300-400km. Factors preventing spread Eastwards to the UK and Northwards to Denmark during the 2006 epidemic are discussed. Towards the east both elevation and terrain roughness, causing air turbulences and drop down of Culicoides, were major factors restricting spread. It is concluded that the proposed approach opens new avenues for understanding the spread of vector-borne viruses in Europe. Future developments should take into consideration both physical and biological factors affecting spread.  相似文献   

2.
Culicoides were captured at a BTV-infected dairy near Gulpen in the province of Limburg (south-east Netherlands) between 14 September and 4 October 2006. Onderstepoort-type blacklight traps were used to sample Culicoides both inside and outside a partially open shed housing 11 cattle. A total of 28 light trap collections were made at the shed and yielded:
• 9371 Culicoides representing 11 species; >90% comprised five potential vectors of BTV and in order of abundance were Culicoides obsoletus and Culicoides scoticus (of the Obsoletus Complex), Culicoides dewulfi, Culicoides pulicaris and Culicoides chiopterus; Culicoides imicola, the principal Mediterranean (and African) vector of BTV, was absent.
• 2339 Culicoides representing seven species were captured inside (endophily) the cattle shed; >95% comprised the Obsoletus Complex and C. dewulfi. Conversely, the Pulicaris Complex, represented by five species and including C. pulicaris, showed strong exophily with >97% captured outside the shed.
• 7032 Culicoides were captured outside the shed, approximately threefold more than inside. This trend was reversed on an overcast day, when eightfold more Culicoides were captured inside; this indicates that when the light intensity outdoors is low Culicoides will attack (i) earlier in the day while cattle are still at pasture, and (ii) might follow cattle into the sheds in the late afternoon leading to elevated numbers of biting midges being trapped inside the shed during the subsequent hours of darkness.
• Culicoides were captured inside the shed on all 14 sampling nights. On occasion up to 33% were freshly blood fed indicating they had avidly attacked the cattle inside (endophagy); because half the cattle had seroconverted to BTV, and because no cattle were left outdoors at night, the data indicate that (i) the housing of animals in partially open buildings does not interrupt the transmission of BTV, and/or (ii) BTV is being transmitted while cattle are grazing outdoors during the day.
• The capture of partially engorged midges inside the shed shows they are being disturbed while feeding; this may lead to cattle being attacked repeatedly, and if these attacks include older parous BTV-infected Culicoides, may enhance virus dissemination (particularly in sheds where cattle stand close together).
• Endo- and exophagy by potential vector Culicoides – coupled to increased adult longevity and multiple feeding events in single (potentially) infected midges – would ensure an R0 of >1, resulting in the continued maintenance and spread of BTV within local vertebrate populations.
• Four light trap collections made additionally in a mature deciduous forest 70 m from the shed yielded a high proportion (48%) of gravid females amongst which 10% had incompletely digested blackened blood meals in their abdomens; the absence of this age category in Culicoides captured at the sheds indicates that all Culicoides, after engorgement, exit the buildings to undergo oogenesis elsewhere.
In Europe, the blacklight trap is used widely for the nocturnal monitoring of Culicoides; a drawback to this approach is that this trap cannot be used to sample midges that are active during the day. Because diurnal biting in vector Culicoides may constitute a significant and underestimated component of BTV transmission a novel capture methodology will be required in future and is discussed briefly.  相似文献   

3.
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4.
In August 2006, bluetongue virus (BTV) was detected in the Netherlands, Belgium, western Germany, Luxembourg and northern France for the first time. Consequently, a longitudinal entomological study was conducted in the affected region of northern France (Ardennes) throughout the autumn of 2006. Data on the spatio-temporal distribution of Culicoides (Diptera: Ceratopogonidae) associated with livestock were collected and an attempt was made to identify the vector(s) involved in BTV transmission by means of virus detection in wild-caught biting midges. Weekly sampling using standardized Onderstepoort-type blacklight traps were performed simultaneously both outdoors and indoors in one BTV-free and three BTV-affected farms between September and December 2006.Culicoides were sorted according to farm, location (outdoors vs. indoors), time point (in weeks), species and physiological stage. BTV detection was conducted by RT-PCR on monospecific pools of non-bloodfed parous female Culicoides.The principal results showed: (i) the absence of the Mediterranean vector, C. imicola, (ii) the relatively low abundance of C. dewulfi and C. pulicaris, (iii) the widespread occurrence and abundance of C. obsoletus/C. scoticus with longevity and behaviour compatible with BTV transmission, and (iv) all Culicoides pools tested for BTV were negative.In France, the very low levels of BTV-8 circulation were probably due to the limited introduction of the virus from affected neighbouring countries, and not due to the absence of local vector populations. A key finding has been the substantiation, for the first time, that Culicoides, and particularly the potential vectors C. obsoletus/C. scoticus and C. dewulfi, can be active at night inside livestock buildings and not only outside, as originally believed.The endophagic tendencies of members of the Obsoletus group are discussed in light of the prolonged period of BTV transmission during the autumn of 2006 and the risk of BTV overwintering and resurgence in the spring of 2007. Overall, there is an urgent need to improve our knowledge on the ecology of local Culicoides species before any clear, effective and reliable recommendations can be provided to the veterinary authorities in terms of prevention and control.  相似文献   

5.
The collection of biting midges was taking place some months before the first bluetongue outbreak in Belgium in August 2006. The Walloon Agricultural Research Centre had been monitoring aphid populations at two sites annually in Belgium (Gembloux and Libramont), using two stationary ‘12-m’ Rothamsted suction traps. For the Gembloux trap, collections of insects captured daily from 11 May 2006 onwards were already available at the time of the outbreak. An examination of these samples revealed the presence of Culicoides, some species of which are considered as potential vectors of the bluetongue virus (BTV). The trapping was therefore extended beyond the normal aphid activity period and the Culicoides captured were identified to species level. From 11 May to 31 December 2006, the Gembloux trap caught 664 Culicoides specimens belonging to 19 species comprising known BTV-vectors. The second trap, at Libramont, was reactivated from 12 September to 13 October and caught 97 specimens belonging to nine species, all of which had been found at the Gembloux site. Among the 19 species identified, four were new to Belgian fauna: Culicoides achrayi, C. deltus, C. lupicaris and C. newsteadi. This paper examines the overall phenology and the physiological status of Culicoides in 2006 before and during the bluetongue epidemic. It discusses the potential of the Rothamsted suction trap to monitor Culicoides.  相似文献   

6.
This study described the first report of BTV-16 in Croatia. Serological evidence occurred in cattle at the end of September and continued during October and November 2004. All positive animals were in the Dubrovnik-Neretva County, a region located in the southernmost part of Croatia. BTV-16 infection was also detected in goats and sheep. Apart from few cases reported in Greece between 1999 and 2000, BTV-16 has never been reported in the Balkanic peninsula before. The BTV strain was isolated from cattle blood samples and typed as BTV-16. When the S5 was sequenced, it showed 100% homology with the BTV-16 vaccine isolate produced by Ondersterpoort Biological Product (SA) and used in Italy during the 2004 BT vaccination campaign. On the other hand no complete homology was found when the same RNA segment sequence was compared with that of the homologous Italian field isolate. As no evidence of livestock movements from Italy was demonstrated, an eolic transmission of the infection through infected Culicoides was hypothesised. According to the local meteostations, in several occasions, during the 2004 summer months, the west–east breeze blew with a speed above 50 km/h from Italy towards the Dubrovnik County. It is concluded that the BTV-16 which infected Croatian livestock was similar to the homologous OBP vaccine isolate and it is likely that it was introduced from Italy into the Southern regions of Croatia through infected Culicoides carried by the wind.  相似文献   

7.
This laboratory study investigates the sub-adult developmental cycle of field collected Culicoides (Avaritia) imicola Kieffer (Diptera; Ceratopogonidae). The period required from blood-feeding field-collected females to the production of progeny adults occupied 34–56 days at 20 °C, 15–21 days at 25 °C and 11–16 days at 28 °C, demonstrating clear temperature dependence. When reared at 28 °C, C. imicola demonstrated higher variability in fecundity (between 2.4 and 20.6 eggs/female) and lower hatching rates (50.0–62.2%), although larval survival rates to pupation were low at all temperatures (20–30%). Similarly, the mean emergence rate from pupae was the highest at lower temperatures. These results highlight the difficulty in establishing and maintaining a laboratory colony of this species from field-collected material and results are discussed in reference to future research directions that may aid this process.  相似文献   

8.
After bluetongue (BT) appeared in northern Europe in August 2006 entomological studies were implemented in all five affected Member States (MSs) to establish which species of Culicoides had acted as vectors. The findings can be summarised as follows: (i) C. imicola the principal southern European/African vector of BTV has not penetrated into northern Europe, (ii) three pools of C. obsoletus/C. scoticus and one of C. dewulfi assayed RT-PCR-positive to BTV-8, (iii) in support of these results it was found that both potential vectors had also high parity rates (approximately 40%) indicating increased longevity favouring BTV virogenesis and transmission, (iv) furthermore, C. obsoletus/C. scoticus and C. dewulfi occurred also widely and abundantly on sheep and cattle holdings across the entire affected region, (v) and during the latter part of the season showed strong endophily readily entering livestock buildings in significant numbers to bite the animals inside (endophagy), (vi) which demonstrates that housing at best offers only limited protection to livestock from Culicoides attacks, (vii) in contrast the potential vector C. pulicaris sensu stricto was restricted geographically, was captured rarely, had a low parity rate (10%) and was exophilic indicating it played no role in the outbreak of BT, (viii) the incrimination of C. dewulfi as a novel vector is significant because it breeds in cattle and horse dung this close association raising its vectorial potential, but (ix) problems with its taxonomy (and that of the Obsoletus and Pulicaris species complexes) illustrates the need for morphological and molecular techniques to become more fully integrated to ensure progress in the accurate identification of vector Culicoides, (x) midge densities (as adjudged by light traps) were generally low indicating northern European Culicoides to have a high vector potential and/or that significant numbers of midges are going undetected because they are biting (and transmitting BTV) during the day when light traps are not effective, and (xi) the sporadic capture of Culicoides in the winter of 2007 invites re-examination of the current definition of a vector-free period. The re-emergence of BT over a wide front in 2007 raises anew questions as to precisely how the virus overwinters and asks also that we scrutinise our monitoring systems in terms of their sensitivity and early warning capability.  相似文献   

9.
The Netherlands has enjoyed a relatively free state of vector-borne diseases of economic importance for more than one century. Emerging infectious diseases may change this situation, threatening the health of humans, domestic livestock and wildlife. In order to be prepared for the potential outbreak of vector-borne diseases, a study was undertaken to investigate the distribution and seasonal dynamics of candidate vectors of infectious diseases with emphasis on bluetongue vectors (Culicoides spp.). The study focused primarily on the relationship between characteristic ecosystems suitable for bluetongue vectors and climate, as well as on the phenology and population dynamics of these vectors.Twelve locations were selected, distributed over four distinct habitats: a wetland area, three riverine systems, four peat land areas and four livestock farms. Culicoides populations were sampled continuously using CO2-baited counterflow traps from July 2005 until August 2006, with an interruption from November 2005 to March 2006. All vectors were identified to species level. Meteorological and environmental data were collected at each location.Culicoides species were found in all four different habitat types studied. Wetland areas and peat bogs were rich in Culicoides spp. The taxonomic groups Culicoides obsoletus (Meigen) and Culicoides pulicaris (Linnaeus) were strongly associated with farms. Eighty-eight percent of all Culicoides consisted of the taxon C. obsoletus/Culicoides scoticus. On the livestock farms, 3% of Culicoides existed of the alleged bluetongue vector Culicoides dewulfi Goetghebuer. Culicoides impunctatus Goetghebuer was strongly associated with wetland and peat bog. Many Culicoides species were found until late in the phenological season and their activity was strongly associated with climate throughout the year. High annual variations in population dynamics were observed within the same study areas, which were probably caused by annual variations in environmental conditions.The study demonstrates that candidate vectors of bluetongue virus are present in natural and livestock-farm habitats in the Netherlands, distributed widely across the country. Under favourable climatic conditions, following virus introduction, bluetongue can spread among livestock (cattle, sheep and goats), depending on the nature of the viral serotype. The question now arises whether the virus can survive the winter conditions in north-western Europe and whether measures can be taken that effectively halt further spread of the disease.  相似文献   

10.
Culicoides species (Diptera: Ceratopogonidae) belonging to the Obsoletus and Pulicaris groups are considered to be the main vectors of bluetongue virus (BTV) in non Mediterranean Europe. Selected terrestrial microhabitats (n = 17) on a farm in northern Spain were sampled repeatedly over a year-long period and characterized for use by Culicoides species for immature development. Concurrent use of CDC light traps showed the presence of 37 species and 66,575 specimens of adult Culicoides. A total of 28 species and 11,396 individuals emerged from laboratory-maintained soil samples. Culicoides obsoletus and Culicoides scoticus (pooled as Obsoletus complex) were particularly abundant (comprising 58.6% and 74.5% of the total collections in light traps and emergence traps respectively). Potential key vectors of animal viruses (such as BTV) were found in two main terrestrial types of microhabitats. In the case of C. obsoletus, different types of manure (old and composted manure, manure mixed with organic matter, and fresh manure) produced most of the specimens. In contrast, larvae of C. scoticus and Culicoides lupicaris were associated with soil substantially comprised of rotting leaf litter that included the parasitic plant Lathraea clandestina. Several species, Culicoides festivipennis, Culicoides punctatus and Culicoides brunnicans, were very common in mud at pond margins. Indeed, pond microhabitats and runoff below barn rooflines supported the greatest species richness. In the pond habitat, 49.4% of Culicoides specimens emerged from mud at the water edge, as opposed to 50 cm above (32.4%) and 1 meter above waterline (18%). Similar species richness, but statistically significant differences in abundance, were observed among the four pond microhabitats. Overall, the majority of the specimens were found in the upper layer (0–3 cm), except in manure, where they preferred deeper layers (>6 cm). Maximum peaks of abundance occurred in both light traps and soil samples in summer months, whereas increased captures in autumn were noticed only in light traps. Both trapping systems failed to collect adult Culicoides midges in the coldest months of December, January and February. The literature on immature habitats of species suspected in BTV transmission in Europe, the Pulicaris group and particularly the Obsoletus group, is briefly reviewed.  相似文献   

11.
The method of segregating nulliparous and parous females of Culicoides spp. based on the presence of burgundy-red pigment inside the abdominal wall of parous Culicoides midges, is used worldwide. Out of 320 females of Culicoides imicola trapped by emergence traps, set over an artificial breeding site for 10 and 24 days, 73 (22.8%) showed a red-pigmentation despite the fact that they were nulliparous. This finding indicated that 23% of the “parous” females that are examined for the presence of arboviruses and other pathogens or for age-grading purposes, are actually old nulliparous females, which had no chance of acquiring pathogens. This bias in parous rate distorts upward the calculation of vectorial capacity.  相似文献   

12.
Using data from bluetongue (BT) outbreaks caused by viral serotype 4 (BTV-4) in Spain during 2004–2005, a predictive model for BTV-4 occurrence in peninsular Spain was developed. An autologistic regression model was employed to estimate the relationships between BTV-4 presence and bioclimatic-related and host-availability-related variables. In addition, the observed abundances of the main potential Culicoides vectors during 2004–2005, namely Culicoides imicola, Culicoides obsoletus group, and species of the Culicoides pulicaris group, were compared between BTV-4 presence/absence areas predicted by the model.BTV-4 occurrence was mainly explained by bioclimatic variables, although a consideration of host-availability variables led to improved fit of the model. The area of BTV-4 presence predicted by the model largely resembled the core distribution area of C. imicola, and this species was the most abundant Culicoides spp. in predicted BTV-4 presence areas. The results suggest that the spatial expansion of BTV-4 took place only as far as those areas in which C. imicola populations efficiently transmitted the virus.  相似文献   

13.
The outbreak of bluetongue (BT) in northern Europe 2006 initiated the monitoring of vectors, biting midges of the genus Culicoides in Sweden. In order to determine the diversity, distribution and seasonal dynamics of Culicoides, weekly collections were made during 2008 and during March-December 2009 using the Ondestepoort Veterinary Institute black light trap. Twenty sampling sites were selected in 12 provinces. In total of 30,704 Culicoides were collected in 2008 and 32,252 in 2009. The most abundant species were the potential vectors of BTV Culicoides obsoletus/C. scoticus that comprised of 77% of the total catches. Other biting midges collected were Culicoides impunctatus (9%), Culicoides grisescens (3%), Culicoides punctatus (2%), Culicoides chiopterus (2%) and Culicoides pulicaris (2%). Culicoides obsoletus/C. scoticus were most abundant during May-June and August-September. The majority of the species were active from March to November in 2008 and April to October in 2009. Species considered as potential vectors of bluetongue virus (BTV) occurred as far north as latitude 65°N (Kalix).  相似文献   

14.
Bovine cysticercosis is a zoonosis that is mainly of socioeconomic and public health importance. A survey of this disease was carried out in Northern Turkana District, Kenya to estimate the prevalence through both serology and meat inspection, to determine the prevalence of the adult tapeworm in the human definitive host, and to determine risk factors for cattle seropositivity. This information is of public health importance and will be of use in assessing economic losses due to downgrading, refrigeration or condemnation of infested carcasses.The study area was stratified into the three livestock grazing regions of Oropoi to the south, Lokichoggio–Mogilla centrally and Kibish in the north for the purposes of the serological and questionnaire (n = 53 herd owners) data. Five adakaars (grazing units) were selected and 34, 63, 49, 75 and 571 cattle serum samples obtained from these. The slaughter slabs of Lokichoggio and Kakuma were visited and 188 serum samples were obtained from slaughter cattle and compared to results of meat inspection. Human stool samples were collected in each of the three grazing areas and 66, 97 and 78 samples were obtained.The seroprevalence of cysticercosis in cattle was estimated at 16.7% (95% CI 13–20.9%) using a secretory–excretory antigen detection ELISA. There was poor agreement between meat inspection and serology (k = 0.025; p = 0.2797). The prevalence of taeniosis was estimated as 2.5% (95% CI 0.8–5.6%) by microscopy.A backwards elimination logistic regression analysis indicated that the grazing unit (Adakaar), the deworming history of household members and the distance (>2 km) of grazing fields from the homestead were significant explanatory variables for cattle being found to be positive on serology. An intra-cluster correlation coefficient (ICC) of 0.07 (0.02–0.12); p < 0.0001 was calculated for bovine cysticercosis in this area.  相似文献   

15.
A new field survey monitoring the spatial distribution of Dermacentor (D.) reticulatus (Fabricius, 1794) tick in Slovakia was carried out in 2005–2008 in order to record changes in its distribution when compared to former studies. Last surveys on the geographical distribution were conducted in 1950s and 1970s and the presence of D. reticulatus was determined along the rivers in the south-east (Latorica) as well as in the south-west (Morava, Dunaj) Slovakia. In the present survey new areas with D. reticulatus occurrence were detected, providing evidence that this tick species has extended its range in the surroundings of its former habitats but also by at least 200 km further North and by 300 m of elevation into higher altitudes. D. reticulatus is known to transmit Babesia spp. causing babesiosis in cattle and dogs. Expansion of D. reticulatus range is therefore likely to bring a spread of babesiosis, which can be severe or fatal especially for dogs.  相似文献   

16.
The objective of the study was to estimate the range of influence between cattle herds with positive Salmonella Dublin herd status. Herd status was a binary outcome of high/low antibody levels to Salmonella Dublin in bulk-tank milk and blood samples collected from all cattle herds in Denmark for surveillance purposes. Two methods were used. Initially, a spatial generalised linear mixed model was developed with an exponential correlation function to estimate the range of influence simultaneously with the effect of potential risk factors. An iteratively reweighted generalised least squares procedure was used as a second method for verifying the range of influence estimates. With this iterative procedure, deviance residuals were calculated based on a generalised linear model and the range of influence was estimated based on the residuals using an exponential semivariogram. The range of influence was estimated for six different regions in Denmark using both methods. The analyses were performed on data collected during 1 year after initiation of the Salmonella Dublin surveillance program providing herd classifications for the 4th year-quarter of 2003 and 2 years later for the 4th year-quarter of 2005. The prevalence of dairy herds with a positive Salmonella Dublin herd classification status in this period had decreased from 22.1 to 17.0%. In non-dairy herds, the prevalence was nearly unchanged during the same period (3.4 and 3.7% in 4th quarter of 2003 and 2005, respectively). For all cattle herds, the range of influence was 2.3–6.4 km in 2003 and 1.5–8.3 km in 2005. There seemed to be no association between the range of influence and the density of herds in the different regions.  相似文献   

17.
The aim of this study was to determine the herd prevalence of veal and dairy herds and to identify risk factors for VTEC O157 positive veal herds. The study was based on monitoring data from November 1996 through July 2005 of 1051 dairy herds and 930 veal herds. The herd level prevalence (95% CI) was 8.0% (6.4–9.6) for dairy herds and 12.6% (10.5–14.7) for veal herds. Within the population of veal herds, a prevalence of 39.8% (33.9–45.6) was found for pink veal herds (n = 269) and 1.5% (0.7–2.8) for white veal herds (n = 661).Multivariable logistic regression showed that the type of veal (pink vs. white; OR = 21.6; 95% CI: 10.4–45.0), ventilation (mechanical vs. natural; OR = 0.4; 95% CI: 0.2–0.8), time between arrival in the herd and sampling (3–5 months vs. 0–2 months: OR = 2.33; 95% CI: 1.1–5.1, ≥6 months vs. 0–2 months: OR = 4.11; CI: 1.9–8.9), other feed than the 7 most common (yes vs. no; OR = 2.1; 95% CI: 1.2–3.7) and at least one dog present in the stable (yes vs. no; OR = 2.6; 95% CI: 1.5–4.6) were significantly (P < 0.05) associated with the presence of VTEC O157. The large difference in the VTEC O157 prevalences for pink veal and white veal production might have been caused by a very different management of these type of herds. However, this could not be studied with the data collected.  相似文献   

18.
In recent years the vector-borne diseases (VBD) are (re)-emerging and spreading across the world having a profound impact on human and veterinary health, ecology, socio-economics and disease management. Arguably the best-documented example of veterinary importance is the recent twofold invasion of bluetongue (BT) in Europe. Much attention has been devoted to derive presence-absence habitat distribution models and to model transmission through direct contact. Limited research has focused on the dynamic modelling of wind mediated BT spread. This paper shows the results of a stochastic predictive model used to assess the spread of bluetongue by vectors considering both wind-independent and wind-mediated movement of the vectors. The model was parameterised using epidemiological knowledge from the BTV8 epidemic in 2006/2007 and the BTV1 epidemic in 2008 in South-France. The model correctly reflects the total surface of the infected zone (overall accuracy=0.77; sensitivity=0.94; specificity=0.65) whilst slightly overestimating spatial case density. The model was used operationally in spring 2009 to predict further spread of BTV1. This allowed veterinary officers in Belgium to decide whether there was a risk of introduction of BTV1 from France into Belgium and thus, whether there was a need for vaccination. Given the far distance from the predicted infected zone to the Belgian border, it was decided not to vaccinate against BTV1 in 2009 in Belgium.  相似文献   

19.
The aim of the present study was to carry out molecular epidemiological investigation on enterotoxigenic Escherichia coli (ETEC) K99 and Salmonella spp. in diarrheic neonatal calves. Fecal samples were obtained from 220 diarrheic calves at 9 farms related to four governorates in central and northern Egypt. E. coli and Salmonella spp. isolates were examined for E. coli K99 and Salmonella spp. using PCR. ETEC K99 was recovered from 20 (10.36 %) out of 193 isolates, whereas Salmonella spp. was recovered from nine calves (4.09%).Multivariable logistic regression was used to evaluate the risk factors associated with both infections. ETEC K99 was significantly affected by age (P < 0.01; OR: 1.812; CI 95%: 0.566–1.769), colostrum feeding practice (P < 0.01; OR: 5.525; CI 95%: 2.025–15.076), rotavirus infection (P < 0.001; OR: 2.220; CI 95%: 0.273–1.251), vaccination of pregnant dams with combined vaccine against rotavirus, coronavirus and E. coli (K99) (P < 0.001; OR: 4.753; CI 95%: 2.124–10.641), and vitamin E and selenium administration to the pregnant dam (P < 0.01; OR: 3.933; CI 95%: 0.703–1.248).Infection with Salmonella spp. was found to be significantly affected by the animal age (P < 0.05; OR: 0.376; CI 95%: 0.511–1.369), Hygiene (P < 0.05; OR: 0.628; CI 95%: 1.729–5.612), and region (P < 0. 01; OR: 0.970; CI 95%: 0.841–1.624).The results of the present study indicate the importance of PCR as rapid, effective and reliable tool for screening of ETEC and Salmonella spp. when confronted with cases of undifferentiated calf diarrhea. Moreover, identification of the risk factors associated with the spreading of bacteria causing diarrhea may be helpful for construction of suitable methods for prevention and control.  相似文献   

20.
The spread of benzimidazole-resistant nematodes in dairy goat farms is of a great concern as probably more than 70% of the flocks are involved. As there are very few other anthelmintic options during the lactating period, we have evaluated the efficacy of copper oxide needles (CON, Copinox, Bayer, UK) in both experimental and natural infections in goats. The curative effect of CON (2–4 g) on existing worm burdens was assessed in goats experimentally infected with Teladorsagia circumcincta, Haemonchus contortus and Trichostrongylus colubriformis, compared to controls. The preventive effect of CON (4 g) on worm establishment was monitored for 2 months in animals experimentally infected with H. contortus and for 3 months in naturally infected animals on a farm exhibiting predominant infections with T. circumcincta and Oesophagostomum venulosum. In both experimental and natural conditions, the efficacy of CON was nil against Teladorsagia, Trichostrongylus and Oesophagostomum infections. In contrast, the efficacy of CON against Haemonchus was clearly established in reducing the worm burden (75%) as well as in lowering the egg output (37–95%) in relation to the establishment of new infections over several weeks. Copper oxide needles may represent an alternative to conventional anthelmintics in the control of Haemonchus infection in some goat farms.  相似文献   

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