Deer, wolves, and people: costs, benefits and challenges of living together.

Human-driven species annihilations loom as a major crisis. However the recovery of deer and wolf populations in many parts of the northern hemisphere has resulted in conflicts and controversies rather than in relief. Both species interact in complex ways with their environment, each other, and humans. We review these interactions in the context of the ecological and human costs and benefits associated with these species. We integrate scattered information to widen our perspective on the nature and perception of these costs and benefits and how they link to each other and ongoing controversies regarding how we manage deer and wolf populations. After revisiting the ecological roles deer and wolves play in contemporary ecosystems, we explore how they interact, directly and indirectly, with human groups including farmers, foresters, shepherds, and hunters. Interactions with deer and wolves generate various axes of tension, posing both ecological and sociological challenges. Resolving these tensions and conflicts requires that we address key questions using integrative approaches: what are the ecological consequences of deer and wolf recovery? How do they influence each other? What are the social and socio-ecological consequences of large deer populations and wolf presence? Finally, what key obstacles must be overcome to allow deer, wolves and people to coexist? Reviewing contemporary ecological and sociological results suggests insights and ways to improve our understanding and resolve long-standing challenges to coexistence. We should begin by agreeing to enhance aggregate benefits while minimizing the collective costs we incur by interacting with deer and wolves. We should also view these species, and ourselves, as parts of integrated ecosystems subject to long-term dynamics. If co-existence is our goal, we need deer and wolves to persevere in ways that are compatible with human interests. Our human interests, however, should be inclusive and fairly value all the costs and benefits deer and wolves entail including their intrinsic value. Shifts in human attitudes and cultural learning that are already occurring will reshape our ecological interactions with deer and wolves.

A review of Hyalomma scupense (Acari, Ixodidae) in the Maghreb region: from biology to control.

Hyalomma scupense (syn. Hyalomma detritum) is a two-host domestic endophilic tick of cattle and secondarily other ungulates in the Maghreb region (Africa). This species transmits several pathogens, among which two are major livestock diseases: Theileria annulata and Theileria equi. Various other pathogens are also transmitted by this tick species, such as Anaplasma phagocytophilum and Ehrlichia bovis. Hyalomma scupense is common in sub-humid and semi-arid areas of several regions in the world, mainly in the Maghreb region. In this region, adults attach to animals during the summer season; larvae and nymphs attach to their hosts during autumn, but there is a regional difference in H. scupense phenology. There is an overlap between immature and adult ticks, leading in some contexts to a dramatic modification of the epidemiology of tick-borne diseases. This tick species attaches preferentially to the posterior udder quarters and thighs. Tick burdens can reach 130 ticks per animal, with a mean of 60 ticks. Calves are 70 times less infested than adult cattle. The control can be implemented through six options: (i) rehabilitation of the farm buildings by roughcasting and smoothing the outer and inner surfaces of the enclosures and walls. This control option should be recommended to be combined with a thorough cleaning of the farm and its surrounding area. With regard to Theileria annulata infection, this control option is the most beneficial. (ii) Acaricide application to animals during the summer season, targeting adults. (iii) Acaricide application during the autumn period for the control of the immature stages. (iv) Acaricide application to the walls: many field veterinarians have suggested this option but it is only partially efficient since nymphs enter deep into the cracks and crevices. It should be used if there is a very high tick burden or if there is a high risk of tick-borne diseases. (v) Manual tick removal: this method is not efficient since the ticks can feed on several other animal species in the farm. This control option can lead to a reduction of the tick population, but not a decrease in tick-borne disease incidence. (vi) Vaccination: this control option consists of injecting the protein Hd86; trials have shown a partial effect on nymphs, with no effect on adult ticks. Combination of two of these control options is recommended in regions where there are high burdens of important tick vectors. Further studies are needed to improve our knowledge on this tick species in the Maghreb region, since the number of published studies on Hyalomma scupense in this region is very limited.

Trends in the control of heartwater.

Heartwater is an economically serious tick-borne disease of ruminants caused by the intracellular bacterium Ehrlichia ruminantium. The disease has traditionally been controlled by four different approaches: controlling the tick vector by dipping, establishing endemic stability, performing immunisation by infection and treatment, and preventing the disease by regular administration of prophylactic antibiotics. The first three of these methods are subject to failure for various epidemiological reasons, and serious disease outbreaks can occur. Prophylaxis is effective, but very expensive, and the logistics are daunting when large herds of animals are involved. The development of a safe, cheap and effective vaccine is the only likely way in which heartwater can be economically controlled, and over the past 15 years three new types of experimental vaccine have been developed: inactivated, attenuated, and recombinant vaccines. These new vaccines have shown varying degrees of promise, but none is as yet sufficiently successful to be marketable. We describe the experimental products, and the various technical and biological difficulties which are being encountered, and report on ways in which new technologies are being used to improve vaccine effectiveness.

Economic impact of ticks and tick-borne diseases on cattle production systems around Lake Mburo National Park in South Western Uganda.

A longitudinal economic impact study of Ticks and Tick-Borne Diseases (TTBDs) in cattle around Lake Mburo National Park (LMNP) was done. Impact was valued using Uganda Shilling (Ug. Shs) (exchange rate of 1USD to Ug. Shs 1,420). The costs for controlling TTBDs was constituting 85.6 +/- 3.2% (pastoral) and 73.8 +/- 4.2% (ranches) to total disease control costs. The main costs were on tick control, constituting 83.1% (ranches) and 87.9% (pastoral). In pastoral herds, the costs were negatively correlated to herd size (r = -0.99). The mean annual cost per cattle for controlling TTBDs for ranch and pastoral herds was similar Ug. Shs 5,900 +/- 545. The mean annual Economic Cost (EC) of TTBDs per cattle was not significantly different (p > 0.05) between pastoral (Ug. Shs 6,700 +/- 580) and ranch herds (Ug. Shs 7,600 +/- 970). The mean annual EC per cattle was negatively correlated (r = -0.99) with herd size in pastoral systems contrary to positive correlation (r = 0.99) observed among the ranches. The major component of EC of TTBDs of 88.2% (pastoral) and 78.6% (ranches) was due to their control. The other component was owed to mortality, which was positively correlated (p < 0.01) to the ranch herd size. The total annual EC of TTBDs around LMNP was Ug. Shs 437,754,600 (USD 308,144).

Prevention of tick-borne diseases.

Tick-borne diseases are on the rise. Lyme borreliosis is prevalent throughout the Northern Hemisphere, and the same Ixodes tick species transmitting the etiologic agents of this disease also serve as vectors of pathogens causing human babesiosis, human granulocytic anaplasmosis, and tick-borne encephalitis. Recently, several novel agents of rickettsial diseases have been described. Despite an explosion of knowledge in the fields of tick biology, genetics, molecular biology, and immunology, transitional research leading to widely applied public health measures to combat tick-borne diseases has not been successful. Except for the vaccine against tick-borne encephalitis virus, and a brief campaign to reduce this disease in the former Soviet Union through widespread application of DDT, success stories in the fight against tick-borne diseases are lacking. Both new approaches to tick and pathogen control and novel ways of translating research findings into practical control measures are needed to prevent tick-borne diseases in the twenty-first century.

Estimated direct economic costs associated with tick-borne diseases on cattle in Tanzania.

Tick-borne diseases, namely, anaplasmosis, babesiosis, cowdriosis and theileriosis, constrain cattle production and improvement in Tanzania, leading to considerable economic losses. A simple spreadsheet model was used to estimate the economic losses resulting from production losses, treatment and control costs associated with tick-borne diseases (TBD) in Tanzania. Model parameters included the national cattle population, reported TBD morbidity, fatality risk, and chemotherapy and control measures used. The total annual national loss due TBD was estimated to be 364 million USD, including an estimated mortality of 1.3 million cattle. Theileriosis accounted for 68% of the total loss, while anaplasmosis and babesiosis each accounted for 13% and cowdriosis accounted for 6% of the total loss. Costs associated with mortality, chemotherapy and acaricide application accounted for 49%, 21% and 14% of the total estimated annual TBD losses, respectively, infection and treatment method milk loss and weight loss accounted for 1%, 6% and 9% of the total annual loss, respectively. Despite the inadequacies of the data used, the results give evidence that tick-borne diseases inflict substantial economic losses on cattle production and resource use in Tanzania.

Effects of a novel pesticide resistance management strategy on tick control in a smallholding exotic-breed dairy herd in Kenya.

Effects of a novel pesticide resistance management strategy on tick control are evaluated in this study. The study is based on a temporal analysis of tick management practices on a smallholding in western Kenya. Results are reported of an innovation to tackle individual resistance in a pair of alternative pesticides using relay application. Incidence of tick-borne diseases at the farm were reduced from 79.6% per annum to 4.5% and no cases were observed in the last two years of the study. Negative cross-resistance is believed to be the mechanism in play for this effective tick control practice. Tick-borne disease control and management costs were halved in comparison to application of a single ineffective pesticide at the same treatment frequency. The acaricide relay strategy is suitable for smallholdings and is expected to significantly extend the useful lifespan of the pesticide pair.

Strategies, effectiveness and rationale of vector-borne disease control in the pastoralist system of south-western Uganda.

In Uganda, control of vector-borne diseases is mainly in form of vector control, and chemotherapy. There have been reports that acaricides are being misused in the pastoralist systems in Uganda. This is because of the belief by scientists that intensive application of acaricide is uneconomical and unsustainable particularly in the indigenous cattle. The objective of this study was to investigate the strategies, rationale and effectiveness of vector-borne disease control by pastoralists. To systematically carry out these investigations, a combination of qualitative and quantitative research methods was used, in both the collection and the analysis of data. Cattle keepers were found to control tick-borne diseases (TBDs) mainly through spraying, in contrast with the control of trypanosomosis for which the main method of control was by chemotherapy. The majority of herders applied acaricides weekly and used an acaricide of lower strength than recommended by the manufacturers. They used very little acaricide wash, and spraying was preferred to dipping. Furthermore, pastoralists either treated sick animals themselves or did nothing at all, rather than using veterinary personnel. Oxytetracycline (OTC) was the drug commonly used in the treatment of TBDs. Nevertheless, although pastoralists may not have been following recommended practices in their control of ticks and tick-borne diseases, they were neither wasteful nor uneconomical and their methods appeared to be effective. Trypanosomosis was not a problem either in Sembabule or Mbarara district. Those who used trypanocides were found to use more drugs than were necessary.

The global importance of ticks.

Ticks and tick-borne diseases affect animal and human health worldwide and are the cause of significant economic losses. Approximately 10% of the currently known 867 tick species act as vectors of a broad range of pathogens of domestic animals and humans and are also responsible for damage directly due to their feeding behaviour. The most important tick species and the effects they cause are listed. The impact on the global economy is considered to be high and although some estimates are given, there is a lack of reliable data. The impact of ticks and tick-borne diseases on animal production and public health and their control are discussed.

The current status of major tick borne diseases in Zambia.

Tick-borne diseases occurring in Zambia are assuming more importance as they continue to be a major economic problem not only in Zambia, but in many parts of Eastern, Southern and Central Africa. The current control methods, which include the use of toxic acaricides to kill ticks, and the virulent sporozoite infection and treatment method have limitations. Recombinant vaccines, currently in their experimental stages, offer hope for the future. The use of acaricides is hampered by the development of acaricide resistance and live vaccines are dependent on cold chain facilities, which are a formidable obstacle in the poorly developed infrastructure in parts of Zambia where the vaccine is most needed. Amidst these drawbacks are the results of the recent research on parasites and vector recombinant vaccines which promise to circumvent these problems. The history, current status and attitudes regarding the control of these diseases, taking into account their complexity, are reviewed. The establishment of the well-designed Central Veterinary Research Institute (CVRI) and Japanese International Cooperation Agency (JICA) sponsored veterinary school, both have a potential for high quality research, with access to a wealth of specimens a veritable goldmine of research material. It is thus hoped that this review will stimulate the desire to maximize the value of the tick and tick-borne disease research in both Zambia and the international research community.

The economic impacts of endemic diseases and disease control programmes.

The authors discuss the evaluation of the economic impacts of endemic livestock diseases, and economic issues in control of these diseases. Particular attention is focused on helminths and on endemic vector-transmitted infections (particularly ticks and tick-borne diseases). Decisions relating to disease control have to be made by government and by the producer. Government requires information on the level of control to adopt, the extent of involvement needed, and how to fund animal health programmes (particularly how to share costs between taxpayers and livestock producers). Individual producers require information as to how much effort to invest in disease control, including information collection effort, and how to design control strategies. Economics can shed light on these issues. However, experience suggests that animal health policies are particularly difficult to evaluate from an economic viewpoint, with complex relationships between animal health, production impacts, market access, and non-production benefits of livestock. While little information is available concerning the cost of helminth diseases, many estimates have been made of the costs of ticks and tick-borne diseases at a regional and national level, sometimes demonstrating that eradication is warranted.

The control of heartwater on large-scale commercial and smallholder farms in Zimbabwe.

As part of a series of studies associated with the development of improved vaccines for heartwater (a tick-borne disease of ruminant livestock caused by Cowdria ruminantium), field surveys were carried out to assess losses associated with the disease and the costs associated with controlling it in the two main agro-ecological zones of Zimbabwe (lowveld and highveld) where heartwater is believed to be endemic and epidemic, respectively. In each zone, a cross-sectional study was performed in the main farming systems (smallholder (SH) and large-scale commercial (LSC) beef and dairy), followed by longitudinal studies in the same sectors to improve data accuracy for some parameters. Suspected heartwater-specific mortality in cattle was similar in all LSC sectors (p = 0.72) accounting for a median 1% mortality risk. Heartwater-specific mortality in SH areas was not assessed due to poor diagnostic ability of the farmers. Few LSC farms and SH households kept sheep; suspected heartwater-specific mortality in LSC sheep was 0.8% in the lowveld and 2.4% in the highveld. Goats were a major enterprise in SH areas but not on LSC farms. Suspected heartwater mortality in LSC goats was 0.8% at one site in the highveld and 17.5% on a farm in the lowveld. Application of acaricides was the major control method for heartwater and other tick-borne diseases on both SH and LSC farms. On LSC farms, plunge dipping was used most frequently and the number of acaricide applications ranged widely between 3 and 52 per year. The total cost of acaricides per head per annum was higher in highveld dairies than in highveld and lowveld beef enterprises (p = 0.03). In SH areas, cattle plunge dipping was conducted by the government with an average frequency of 8 +/- 2 (sd) immersions per annum in both the lowveld and highveld. The type of tick control on sheep and goats in all production systems was highly variable (ranging from none to hand removal or intensive acaricide treatment). Suspected heartwater cases on LSC farms were treated with tetracyclines; treatment was not reported in SH areas. Reported treatment costs were high (median Z$ 120) and highly variable (range Z$-833). Vaccination against heartwater with the live, blood-based vaccine was reported on only one LSC farm. LSC farms applying acaricide 30 or more times per year reported higher morbidity (p < 0.0001) and mortality (p < 0.0001) than farms applying acaricides less than 30 times a year. This finding supports the use of reduced tick control in the management of heartwater in Zimbabwe.

Financial analysis of dipping strategies for indigenous cattle under ranch conditions in Uganda.

A financial analysis was performed to assess the performance of three acaricide-treatment groups of indigenous breeds (Zebu and Nganda) of cattle on a ranch in Luwero District, Uganda. The treatments were based on different frequencies: twice-a-week dipping, once-a-month dipping and no tick control. The objective was to evaluate the economic justification for intensive acaricide application for tick and tick-borne disease control in Uganda. Data were collected by monitoring cattle performance over a period of 34 months. Biological data collected included the number of cows at the beginning and end of the study, net starting liveweight, number of calves born, number of animals dying due to tick-borne diseases and other causes, number of animals sold or slaughtered and milk yield. Records of variable costs (acaricides, drugs, labour, etc.) and output prices were assembled and calculated by treatment group. Gross margin and marginal analysis were used in the financial analysis. The exchange rate in 1990-1993 was one US$ to 1200 Uganda shillings. The gross benefits obtained from animal sales, herd value and milk yield were Uganda shillings 1175, 1389 and 1311 per kg of net starting liveweight for animals dipped twice-a-week, once-a-month and not dipped, respectively. The variable costs were Ug. shs. 424, 390 and 360 per kg of net starting liveweight, respectively. Consequently, the gross margins were Ug. shs. 751, 999 and 951 per kg of net starting liveweight. Furthermore, the marginal rate of return (MRR) in changing from no tick control to once-a-month dipping was 160%, while changing from no tick control to twice-a-week dipping was negative (-313%). The above results showed that the value of increased gains in production obtained from twice-a-week dipping strategy does not offset the costs of inputs for intensive dipping. Once-a-month dipping (strategic) therefore appears to be the most-profitable tick-control strategy for the farmer. The need to conduct further studies in different livestock- production systems and to rationalise future tick control policies is discussed.

Sustainable tick and tickborne disease control in livestock improvement in developing countries.

Tick and tickborne disease (TTBD) control is a major component of animal health programmes protecting livestock, thereby enhancing global food security. The present methods for TTBD control are reviewed and an integrated use of the tools is recommended with a broader view of how to link TTBD control to the control of other parasitic diseases. The work of FAO in this field is presented and it is advocated that, although there are still areas that need further investigation, a stage has been reached where robust integrated TTBD control schemes, based on ecological and epidemiological knowledge of ticks and their associated diseases, can be promoted and implemented. Major challenges are the implementation of these policies in the field through the continuation of the present on-going programme in Africa and support to Latin America and Asia. The importance of involving all parties, governments, international and private organisations and the agrochemical industry in developing sustainable, cost-efficient control programmes is stressed and a global strategy is proposed. The main thrust should now be to convince policy makers on the adoption of the strategies and veterinarians and farmers on their implementation.

Ticks and tick-borne diseases as a constraint to sheep and goat production in Italy. Selected features.

The paper reviews basic information on small ruminant production in Italy and on the tick species commonly found on them. A total of 13 Ixodidae species have been reported to parasitise sheep in the country. The tick species were belonging to five genera: Ixodes (two species), Haemaphysalis (four species), Dermacentor (one species), Rhipicephalus (three species) and Hyalomma (three species). The same species, with the exception of Haemaphysalis inermis and Hyalomma detritum have been reported also on goats. Scarse data are available on the impact of tick borne diseases on small ruminants productivity. The zoonotic role which may be played by ticks in transmitting occupationally acquired diseases to people involved in animal husbandry and to common public which may accidentally invade grazing areas is also discussed.

General review of tick-borne diseases of sheep and goats world-wide.

A general review of the tick-borne diseases of sheep and goats is given, with the emphasis on those thought to be of greatest economic importance. These include babesiosis, theileriosis, cowdriosis, anaplasmosis, ehrlichiosis, Nairobi sheep diseases and tick paralysis. A commented list of tick-borne diseases and their vectors is presented. It is stressed that large gaps remain in our knowledge of the real importance in the field of many of these diseases, especially in local stock.