Effects of altitude, distance and waves of movement on the dispersal in Australia of the arbovirus vector, Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae)

The dispersal of the biting midge and arbovirus vector Culicoides brevitarsis in the Bellinger, Macleay and Hastings river valleys and up the escarpment of the great dividing range (GDR) of mid-northern coastal New South Wales, Australia, from 1995 to 2003 was studied. The midge moved up these valleys from the endemic coastal plain in at least two waves between October and May, and both waves were modelled. Dispersal time can be explained by direct distance from the coast and the altitude of the sites. Dispersal times due to distance were similar at 18.2 ± 2.2 (S.D.) and 15.9 ± 2.6 weeks per 100 km for first- and second-occurrences at fixed altitude. Time of the first wave was extended 0.48 ± 0.22 weeks for every 100-m rise in altitude and the second by 1.14 ± 0.24 weeks for every 100-m rise for a set distance. Although C. brevitarsis can move up the escarpment of the GDR (and possibly transmit virus), vector dispersal, survival and establishment at and beyond the top of the range are limited. A third model showed that previously described slower movement of C. brevitarsis up the more-southerly Hunter valley relative to movements down the coastal plain also was related to increasing altitude.     

Association between risk of seroconversion of sentinel cattle to bluetongue viruses and Culicoides species (Diptera: Ceratopogonidae) in Queensland, Australia

The association between risk of seroconversion of sentinel cattle to bluetongue viruses and the number of Culicoides brevitarsis Kieffer and C. wadai Kitaoka caught by light traps was investigated using survival analysis. Eight sentinel herds that seroconverted to bluetongue viruses between 1990 and 1994, and for which insect-trapping data were available, were selected for inclusion in the study. These herds were located at six sites along the eastern coast of Queensland, Australia, from approximately latitude 10 °South to 25 °South. C. brevitarsis was detected at all locations where sentinel herds were maintained, whereas C. wadai was detected at only two locations in northern Queensland where four sentinel herds were maintained during the study period. The mean number of C. brevitarsis and C. wadai caught per month was 230 and 21, respectively. A significant (P = 0.05) positive association was found between the risk of seroconversion of sentinel cattle to bluetongue viruses and the number of C. wadai caught in the same month.     

Endemic type of animal trypanosomiasis is not associated with lower genotype variability of Trypanosoma congolense isolates circulating in livestock

In order to verify whether the low impact on livestock production in endemic areas is related to a low number of trypanosome strains circulating in livestock, 37 Trypanosoma congolense isolates collected from cattle in 11 sites in an endemic trypanosomiasis area in Eastern Zambia were characterised for genotype variability using a modified amplified fragment length polymorphism technique (AFLP). Isolates were further cloned to evaluate the occurrence of mixed infections in individuals. The results obtained revealed a high genotype diversity (94.6%) among these isolates. Apart from one site, all isolates gave different AFLP profiles in each of the sites. When clones were compared, three (8%) of the 37 isolates had mixed infections. These results indicate the circulation of a high number of strains in this trypanosomiasis endemic area despite the low impact the disease has on livestock production.     

Analysis of spatio-temporal patterns of African swine fever cases in Russian wild boar does not reveal an endemic situation

African swine fever (ASF) is a highly lethal viral disease of domestic pigs and wild boar. ASF was introduced into the southern Russian Federation in 2007 and is now reported to be spreading in populations of wild and domestic suids. An endemic situation in the local wild boar population would significantly complicate management of the disease in the livestock population. To date no sound method exists for identifying the characteristic pattern of an endemic situation, which describes infection persisting from generation to generation in the same population. To support urgent management decisions at the wildlife–livestock interface, a new algorithm was constructed to test the hypothesis of an endemic disease situation in wildlife on the basis of case reports. The approach described here uses spatial and temporal associations between observed diagnostic data to discriminate between endemic and non-endemic patterns of case occurrence. The algorithm was validated with data from an epidemiological simulation model and applied to ASF case data from southern Russia. Based on the algorithm and the diagnostic data available, the null hypothesis of an endemic situation of ASF in wild boar of the region was rejected.     

Habitats and Dispersal of Southern African Anura

The data required to make it possible to relate dispersal of southern African Anura to the habitats occupied are considered. Habitat must be defined in terms of breeding populations; data on the breeding seasons of the taxon under consideration are needed, with comparative data on possible competitors in the breeding sites. Possible routes of dispersal under present conditions are considered; the distribution of the habitats of some taxa are considered in relation to presumed past conditions. Possible centres of origin and dispersal of genera and species endemic to southern Africa are discussed.     

不同动物对醉马草种子扩散的影响

动物通过皮毛携带、搬运等方式对种子在空间上的扩散产生不同影响,是植物种子实现远距离扩散的重要途径。以草原毒害草醉马草（Achnatherum inebrians）为研究材料,采用野外模拟及控制性试验,测定了马、牛、羊皮毛附着和保留种子的能力,以及鼠类、蚂蚁对种子的搬运能力,分析动物对醉马草种子的扩散规律。结果表明,马、牛、羊模型种子的附着率：羊 > 牛 > 马（P<0.05）,种子掉落率：羊 < 牛 < 马（P<0.05）;随着行走天数的延长,种子在马、牛、羊皮毛上的附着率呈下降趋势。马的背部以及牛、羊的背、侧部最易附着种子;种子的侧部最易附着在皮毛上,以种子顶部附着的种子最不易掉落。24 h内鼠类、蚂蚁对种子的扩散范围分别为0~15 cm和0~40 cm。综上所述,家畜对醉马草种子起到远距离扩散作用,且羊比马、牛更容易增加种子的扩散强度。蚂蚁、鼠类对醉马草种子起到短距离扩散作用。     

家畜排泄物对牧草种子传播和萌发的作用

放牧调控牧草的生殖格局,包括牧草有性繁殖和无性繁殖分配、种子生产、传播和萌发等,其中家畜的排泄物是重要的作用途径之一。放牧家畜的排泄物促进种子生产、远距离扩散和种子萌发,同时也会损伤种子、抑制萌发等。本文从种子生产、传播及萌发等方面阐述放牧家畜排泄物对牧草种子的作用,认为其是牧草自然更新有效途径之一。放牧家畜排泄物能够增加种子产量、采食几率、散布距离及改变萌发自身与生境条件,从而提高种子传播数量和质量,以促进牧草的有效自然更新。通过了解家畜排泄物在牧草种子传播和萌发中的作用并再此基础上探讨牧草自然更新的机制,以期为草地更新和退化草地恢复提供理论参考。     

Options for the control of tsetse-transmitted livestock trypanosomosis. An epidemiological perspective

Tsetse-transmitted livestock trypanosomosis affects livestock in large parts of sub-Saharan Africa. In southern Africa two epidemiological situations can be distinguished. The disease can have an endemic nature with high morbidity and low mortality in the livestock population. Endemic livestock trypanosomosis is found mainly in areas where cattle constitute the main host of tsetse and reservoirs of trypanosomes. Epidemic trypanosomosis, with high morbidity and high mortality is found in areas where wildlife persist as main reservoir and where livestock come into contact with tsetse flies transmitting trypanosomes from the sylvatic reservoir. Based on the differences in impact of the disease on livestock health in these two epidemiological settings, the appropriateness of the available trypanosomosis control tools differs. In trypanosomosis endemic areas, trypanocidal drug use could be the most suitable approach. Possible problems associated with the development of resistance in trypanosomes to the drugs need to be investigated further. In epidemic situations, vector control seems the most appropriate long-term solution.     

First evidence of bluetongue virus in Kazakhstan

We report the results of the first serological survey for bluetongue virus in Kazakhstan. We analysed blood samples collected from 958 livestock and 513 wild saiga antelopes over a large area of the country, and found 23.2% seroprevalence in livestock and 0% in saigas. Seroprevalence in livestock did not vary by species, but increased significantly with age. There was no evidence for variation in seroprevalence at the regional level, but there was significant clustering at the farm level. Bluetongue has never before been reported in Kazakhstan, yet our results suggest that it may be endemic. We found seropositive animals at the furthest known northern limits of the bluetongue virus in this region of the world. Recorded vectors are not known to be present in Kazakhstan, so a novel vector is likely to be operating. The lack of evidence for bluetongue virus in saigas is unexpected and suggests a need for further investigation.     

The southward spread of buffalo fly (Haematobia irritans exigua) in eastern Australia and its survival through a severe winter

The southward spread of buffalo fly (Haematobia irritans exigua) in coastal eastern Australia from Bororen, Queensland in 1974 to Coffs Harbour, New South Wales in 1982 is documented. Surveys after a cold, dry winter in 1982 recorded overwintering sites and subsequent spread of flies in southern Queensland and northern New South Wales. Buffalo fly overwintered at several places in the Maryborough-Bauple districts and further north. Overwintering also occurred in the Currumbin Valley-Mudgeeraba area on the Queensland-New South Wales border. Other infestations detected early in the season and believed to have arisen from local overwintering populations were observed at Kin Kin, Mount Tamborine and Flinders Peak. By May 1983 flies had recolonised much of coastal south eastern Queensland, and as far south as Ballina and west to the Richmond Range in New South Wales. Implications of these findings for control are discussed.     

The dispersal of Culicoides brevitarsis in eastern New South Wales and associations with the occurrences of arbovirus infections in cattle

Distributions of the vector Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae) (determined from light trap data) and 2 arboviruses (determined from seroconversions in sentinel cattle) were studied in eastern New South Wales in 1993–94. C brevitarsis was recorded progressively from endemic areas on the north coast, to Nowra on the south coast, and westward to Scone, in the Hunter Valley. C brevitarsis also survived through winter at Paterson, in the Hunter Valley. Its apparently focal reappearance in this marginal area had no obvious effect on the broad pattern of its progression or the dispersal of Akabane and bluetongue viruses. These viruses were first recorded from foci near Coffs Harbour, on the mid-north coast. Their first occurrences at different locations were associated with those of C brevitarsis, but not with each other. The viruses were found only within the recorded limits of the vector's distribution. Delays between the initial occurrence of C brevitarsis and first evidence of virus transmissions at locations ranged from 2 to 7 months. The delays decreased away from the points of focus and were negatively associated with the time of initial occurrence of the vector. Seroconversions to the viruses were related to the presence of C brevitarsis. However, the densities of C brevitarsis had no apparent effect on the initial numbers of cattle seroconverting to either virus. The results support the conclusion that the progressions of C brevitarsis and Akabane and bluetongue viruses were the result of gradual movements by the vector.     

An epizootic of bovine ephemeral fever in New South Wales in 2008 associated with long-distance dispersal of vectors

Objective To report the rapid transmission of bovine ephemeral fever ( BEF) virus from north-western New South Wales south to the Victorian border in January 2008 and to present data that suggests an uncommon meteorological event caused this rapid southward dispersal of vectors. Procedure The locations of reported clinical cases, data from sentinel herds and results from a survey of cattle in the southern affected area were examined to delineate the distribution of virus transmission. Synoptic weather charts for January 2008 were examined for meteorological conditions that may have favoured movement of vectors in a southerly direction. Results Cases of BEF and exposure to BEF virus in NSW were confirmed west of the Great Dividing Range, extending from the Queensland border to Finley, on the far North Coast and around the Hunter Valley. A low-pressure system moved south across the state on 18–19 January 2008, preceding the first cases of BEF in the south of NSW by 1–2 days. Conclusion Heavy rainfall in December 2007 provided a suitable environment for vector breeding, resulting in the initiation of and support for continuing BEF virus transmission in north-western NSW. The movement of a low-pressure system south across central western NSW in mid-January 2008 after the commencement of BEF virus transmission in the north-west of the state provided a vehicle for rapid southward movement of infected vectors.     

Assessment of current disease surveillance activities for pigs post-farmgate in New South Wales

Objectives Evaluate current disease surveillance activities at saleyards and abattoirs in New South Wales (NSW) in order to establish the prevalence of clinical anomalies in pigs at different sites and to compare the sensitivity of detecting anomalies inside versus outside of pens. Procedure Routine inspections of pigs by staff and government inspectors were observed at two saleyards and two abattoirs in NSW during three visits over a 2-month period (January 2008–March 2008). All pigs presented for sale or slaughter were examined for 19 clinical anomalies from either the side of the pen or while animals were moving outside the pen, with data being combined to give an assumed ‘gold standard’. We compared the prevalence of anomalies among animals at the four sites using logistic regression, as well as the sensitivity of detection of the two inspection methods. Results Frequency and methodology of routine inspection varied among sites. Of the 7747 pigs inspected, 822 (10.6%) showed at least one clinical anomaly. There was moderate agreement between detecting anomalies in penned pigs versus while being moved. Pigs at one abattoir exhibited significantly fewer anomalies than pigs at the other sites. Conclusion The prevalence of anomalies among pigs at saleyards and abattoirs in NSW was relatively high (≈10%). Weaknesses in current disease surveillance activities for pigs post-farmgate have been identified. Increased regulation, surveillance training and modification of standard operational procedures for inspection have the potential to improve the current system.     

湖南省岳阳市麻塘垸牛羊血吸虫病疫情动态调查

目的在湖南省岳阳县湖沼型血吸虫病流行区的麻塘进行纵向观察,孵化法检测家畜血吸虫的感染率,分析实施查治病畜结合综合治理防治对策后的2001年到2005年血吸虫病防治效果。实施上述防治策略的五年,牛血吸虫感染率控制在3.09%到3.62%,但是,羊血吸虫感染率呈上升趋势。在湖沼型血吸虫病流行区实施查治病畜结合局部地区综合治理防治对策,能使牛血吸虫病感染率控制在4%以下,而要达到阻断血吸虫病标准难度很大。     

青南牧区牧户家畜生产及雪灾防治

采用入户访谈方法,对青南牧区典型雪灾地达日县、玛多县和称多县牧户家畜养殖结构、繁殖成活率、出栏量,冷季死亡、掉膘和补饲情况,牧户暖棚建设和收支及对冬春雪灾设计方案效益系统分析。结果表明,研究区户均家畜养殖数为82.5~423.2AU(羊单位,animal unit),家畜年补饲水平为1.2~26.5CNY·AU-1,牧户家畜几乎不出栏,有暖棚设施的牧户占总牧户的1/3,收入主要靠政府补贴,饲草料储备低,占家庭总开支不到5%。牧户应对雪灾能力弱,在大雪灾和中雪灾年份,研究区家畜繁殖成活率分别为41.5%~75.9%和65.0%~86.4%,冷季死亡率分别为13.2%~24.4%和8.2%~12.8%,掉膘率分别为30%~40%和20%~30%。针对牧户家畜管理存在主要问题,本研究提出了一定出栏量+补饲的对策,以减少家畜冬春雪灾死亡损失,提高牧户应对雪灾能力。     

Use of the ARC/INFO GIS to study the distribution of Lyme disease ticks in an Illinois county

Lyme disease is a bacterial disease of humans and domestic animals transmitted primarily through the bite of the deer tick, Ixodes dammini. Using the ARC/INFO geographic information system (GIS), the distribution of tick vectors can be associated simultaneously with a large number of environmental, biological and demographic factors. The Illinois GIS was used to study the associations of soil type, potential vegetation cover and distance from waterways with tick distributions, and to compare the dispersion patterns of tick-infested and uninfested deer in one northwestern Illinois county. Tick presence was associated with sandy soils, wooded vegetation, and proximity to rivers. Infested deer were clustered around an endemic focus I. dammini, while uninfested deer showed no such clustering. Changes in the spatial distribution of ticks over two years and likely sites for further establishment of ticks were also studied.     

空间电场对冬春季畜舍温室气体的净化效果

[目的] 探讨空间电场对冬春季畜舍内温室气体的净化效果以及对舍内温湿度的影响。[方法] 在畜舍内安装空间电场净化设备和温湿度监测仪,舍内外均设置3个取气点,每个取气点分0 m、0.5 m、1.0 m和1.5 m 4个采集高度,系统监测冬春季畜舍温室气体浓度以及温湿度变化情况。[结果] 空间电场显著（P<0.05或P<0.000 1）降低了冬春季畜舍内CH₄、NH₃和CO₂气体的浓度,降低幅度分别可达39.8%、26.3%和24.0%。空间电场可显著（P<0.05）降低冬季舍内20：00—8：00和12：00—15：00的环境湿度,分别降低了4.5%和15.3%。春季湿度在9：00—17：00降低了31.9%（P<0.05）。[结论] 空间电场可有效地降低冬春季畜舍内CH₄、NH₃和CO₂气体浓度,同时显著降低畜舍内不同时间段的环境湿度。     

Last occurrence and survival during winter of the arbovirus vector Culicoides brevitarsis at the southern limits of its distribution

SUMMARY: Linear regression analysis was used to describe the decline in numbers of Culicoides brevitarsis Kieffer into winter with monthly maximum, average and minimum temperatures at the southern limits to its distribution in New South Wales. From this, low temperature thresholds were derived when C brevitarsis would be absent from the field. The low minimum threshold ± 2 SE (95% Confidence Interval) of 8.1 ± 0.3°C was used with historical temperature data to estimate the last month that the species should occur (March to June) and the mean number of months (2 to 6.5) below the threshold at 17 selected sites. Probability for survival during winter at these sites was estimated from years when the number of consecutive months below the threshold was ≤ 2 months. This varied from zero to 51% depending on the location of the site. Last occurrence was 0.7 months later on average and absolute probabilities for survival ranged from zero to 100% when the temperatures were increased by an arbitrary 2°C.     

Modeling and mitigating winter hay bale damage by elk in a low prevalence bovine tuberculosis endemic zone

Wildlife causes extensive crop damage throughout much of North America and these shared feeds are a key risk factor in the transmission of diseases between wildlife and livestock, including bovine tuberculosis (TB). Predicting wildlife use of agricultural crops can provide insight directed toward targeted disease mitigation at areas of potential indirect interaction. In this study, we quantified use of hay bales by elk (Cervus canadensis) during the winter in southwestern Manitoba, Canada using a database of 952 damage claims paid compensation from 1994 to 2012. We evaluated environmental factors predicted to determine risk of hay bale damage on each quarter section by elk using a Resource Selection Probability Function (RSPF) model. The most important variables (as measured for each quarter section and based on cumulative Akaike weights that scale from 0 to 1) were distance to protected areas (1.00), forest including a buffer around the quarter section (1.00), forage crop including a buffer around the quarter section (1.00), distance from streams (0.99), forage crop (0.92), cereal and oilseed crop cover including a buffer (0.85), and forest cover (0.82). We then developed an RSPF-based predictive map of damage to hay bales by elk that identified key areas with high probability of damage (RSPF ≥ 0.6), accounting for 3.5% of the study area. We then multiplied the RSPF values by the inverse of the proximity to known cases of TB positive elk and determined that 0.51% of the study area had an overall high combined probability of hay bale damage and proximity to TB positive elk (i.e. adjusted probability of ≥0.6). In the southern half of the study area where 164 hay yard barrier fences have been implemented since 2002, there has been a significant decrease in the number of annual claims. Barrier fencing around Riding Mountain National Park has been successful at reducing elk damage where it has been implemented. In our study area, prevalence of TB in both cattle (0.003%) and elk (0.89%) is very low, precluding conventional epidemiological analyses. In the absence of clear evidence of specific routes of TB transmission, we advocate that on-farm risk assessments and mitigation efforts should continue to address areas where elk cause damage to hay bales in winter using barrier fencing. Mitigation effort should especially focus on areas where TB positive elk have been identified, as these sites provide potential for indirect interaction between cattle and elk.