Easy diagnosis of livestock diseases |
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| Effective decision support tools for diagnosis of endemic diseases of livestock in sub-Saharan Africa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
New methods have been developed to check the health of animals in areas of sub-Saharan Africa where vets are in short supply. One is a cheap, reliable low-tech instrument which can be used to test whether or not livestock are anaemic. Known as a haemoglobinometer, this easy-to-carry device could make a real difference to smallholder farmers since the presence or absence of anaemia is a key indicator of animal health in the tropics. A decision-support tool has also been developed to complement the haemoglobinometer. The colour-banded card helps users to match symptoms to eight major diseases and guides them towards the most likely diagnosis. The decision tool is already being used in Uganda and Eastern Zambia. However, great scope exists to expand its use. Project Ref: AHP07:
Research Programmes:
Relevant Research Projects: R7597, R8318
The outputs are: (i) A simple, low-cost, low-technology instrument for measurement of haemoglobin in the blood of cattle and other livestock (ii) A low cost decision support tool for the diagnosis of endemic bovine diseases in the mixed crop-livestock production system of sub-Saharan Africa (iii) A generic methodology for development of decision support tools for diagnosis of disease in livestock in developing regions Endemic diseases of sub-Saharan African cattle are a major constraint to sustainable rural livelihoods but their control is constrained by contraction of veterinary services, with devolution of diagnosis and treatment to less well trained cadres of veterinary service providers, change agents and non-professional cattle keepers who lack clinical knowledge or diagnostic tools. These outputs will improve the quality and accessibility of disease diagnosis to resource poor cattle keepers, through the development of a rapid, reliable and cheap haemoglobinometer as a diagnostic test for anaemia, a key indicator of the health status of animals in the tropics, and a decision support tool enabling simple diagnosis and treatment of these diseases. Anaemia is a cardinal sign of many important vector-borne and other endemic diseases of cattle, particularly in the smallholder rainfed humid farming system. Anaemia or its absence has been shown to be an excellent indicator of bovine health in vector-borne or helminth disease endemic areas (Hendrickx et al., 1999). A novel, low-cost haemoglobinometer developed in conjunction with a commercial partner, enables animal health workers to measure anaemia in domestic livestock. The instrument is small enough to be carried on foot, on a bicycle or motor scooter, typical modes of transport for end-users, uses a sampling and measuring consumable costing a few pence, and is battery operated or solar powered. The decision support tool has been developed as a diagnostic method complementary to the haemoglobinometer, and focuses on eight endemic bovine diseases, including trypanosomiasis, helminths and tick-borne diseases, which are widely recognised as key constraints to animal productivity. The tool is a colour-banded card utilizing a scoring system and differential diagnosis is performed by comparing observed clinical signs (including anaemia) with disease profiles and constructing a ranked list indicating the most likely diagnoses. While low tech in its implementation, the decision support tool approach represents a generic method for encoding a wealth of expert opinion surveyed using the Delphi method, which could be applied to diseases of any species of livestock in any production system.
Main commodity: livestock Other commodities: crops, through provision of manure and draught power. Also, human health, through prevention of zoonotic diseases, such as trypanosomiasis, brucellosis, tuberculosis, cysticercosis etc.
Added value would be obtained by clustering with the following animal health related RNRRS outputs: (i) Sleeping sickness
(ii) Integrated tsetse control
(iii) TB/Brucellosis
(iv) Control of worms in goats in southern Africa
(v) Delivery of research findings
How the outputs were validated: The diagnostic decision support tool implemented as a printed, laminated decision support card (DSC) was initially validated during a workshop involving 30 experts on sub-Saharan cattle diseases, where the decisions of each pair of experts were compared to those of recommended by the card for a limited number of exemplar cases (see Magona et al. 2003). This provided some initial evidence of validity while also indicating the need for a more formal and field-based assessment.A formal field trial was conducted in Uganda during 2004-2005. This trial was based around the involvement of 15 veterinary staff with a variety of levels of training. The trial was organised by one of the Ugandan project partners, LIRI, while the field staff were government employees in the Ministry of Agriculture, Animal Industries and Food. The trial comprised two field-based exercises with a training and dissemination workshop between the first and second phase (see Eisler et al. 2006). During the first phase the diagnostic practices of the veterinary staff were monitored by means of a self-completed log book, using a standard recording template for each case encountered. Around 750 cases of diseased animals and their diagnosis by the 15 staff involved, over 5 districts in S.E. Uganda, were recorded in this manner. A workshop was then organised by project staff to which the 15 field-based veterinary staff were invited. At this workshop they were introduced to the DSC and the associated diagnostic methodology. They were also given a set of cases to work on during the workshop to ensure that the DSC was being appropriately used. During the second phase of the validation the actions of the veterinary staff were again recorded, this time while using the DCS as part of the process. An assessment of both the differences in diagnostic practice as well as clinical outcomes and treatment was then carried out. Diagnostic practice appeared to be significantly altered following the introduction of the DCS, most obviously in terms of the number and range of clinical signs observed by the practitioners. In addition the diagnosis suggested by the card was largely in agreement with that made by the more senior veterinary staff, suggesting that the card may be of particular benefit to less well trained livestock assistants, enabling them to engage in disease diagnosis tasks which would previously have only been possible through the less accessible and more expensive process of calling out a veterinarian. The low-cost haemoglobinometer has been validated under laboratory settings, using (i) bovine blood samples titrated to known haemoglobin concentrations and (ii) commercially available haemoglobin quality assurance samples. A number of existing commercially-available haemoglobinometers have been validated for zebu and sanga cattle under field conditions during extensive longitudinal studies of endemic infectious disease in Uganda and Eastern Province, Zambia and the approach been demonstrated to be useful. Unfortunately these instruments are impractical for routine use under these conditions, see below. This assessment conducted by the Livestock Health Research Institute, Uganda, supported by the University of Edinburgh. Where the Outputs were Validated: Validation of the prototype low-cost haemoglobinometer was conducted in the UK (laboratory-based studies) 2001-2006. It is presently undergoing electrical compliance testing prior to human medical clinical trials and full-scale manufacture. The haemoglobinometer concept has been validated widely in cattle in the field in Busia, Bugiri, Kamuli Soroti, and Tororo Districts Uganda, and in the Eastern Province of Zambia using currently available alternative instruments (2001-2006). These instruments provided proof of concept of the practicability of measurement of haemoglobin in cattle under endemic infectious disease challenge. However, none of these existing instruments is suitable for routine use in rural Africa, owing to two key constraints, (i) cost and (ii) requirement for a precise, quantitative pipetting step. For instance, the promising HemoCueT is too expensive for routine use in resource poor farming communities; the unit has a high initial cost (ca £400) and individual tests require a new non-reusable cuvette costing approximately £1, putting it well out of reach of poor livestock keepers and the animal health workers who serve them. The DSC was initially validated by 30 international experts on sub-Saharan cattle diseases. This exercise took place during a workshop held in Nairobi, Kenya in 2003, under the auspices of the ICPTV and RNRRS-AHP projects. Subsequently, field-based validation took place over eight months in 2004-2005 and was based in 5 districts of Uganda: Iganga, Kayunga, Sironko, Soroti and Tororo. This validation involved the diagnosis of disease in cattle within peri-urban and high potential production systems based on smallholder, rainfed humid farming. Individual animal health workers made use of the DSC in their own areas, among the communities in which they routinely practice A further evaluation of the DSC has been on-going in the Eastern province of Zambia since the early part of 2006, based in Nyimba, Katete and Petauke Districts. Who are the Users? The DSC is being used as a tool to support differential diagnosis by veterinarians across Uganda. Subsequent to the workshop and validation exercise a number of veterinary colleagues of the validating group requested access to additional cards. This uptake has happened despite the fact that there is not yet any formal channel through which the cards can be distributed to veterinarians, e.g. although the Ministry of Agriculture, Animal Industries and Food has expressed interest in taking on a training and dissemination role. In addition to veterinary staff, the DSC is also being used by animal health assistants. This not only improves diagnostic outcome but also acts to train these individuals in basic skills of clinical observation. Without the cards, diagnosis is frequently peremptory or omitted altogether and treatment is made on an ad-hoc basis; use of the cards promotes proper clinical examination of cases and prompts animal health workers to make a rational differential diagnosis and then administer treatment on this basis. Where the outputs have been used: The areas where validation took place, i.e. within peri-urban and high potential production systems based on smallholder, rainfed humid farming, are primarily those where the system is being used; both in Uganda and latterly in Eastern Zambia. In order to be used in other contexts the knowledge coded on the DSC would have to be altered and some re-validation carried out. Some initial work on modifying the card to other countries (Southern Sudan and Rwanda) has been initiated. The low-cost haemoglobinometer is not currently in use in Africa, since it is not yet widely available although the underlying principle of examining animals for the presence of anaemia is embedded in the DSC. Clinically, anaemia may be detected by examination of mucous membranes, such as the palpebral conjunctiva or the vulva, and in the absence of the haemoglobinometer or any non-subjective other means of assessing the erythron (i.e., the mass of haemoglobin containing red blood corpuscles or erythrocytes in the peripheral circulation and haemopoietic tissues), this is worthwhile. However, this approach is less sensitive and highly subjective and may be confounded by other factors. By using an instrument such as the haemoglobinometer it is far less likely that anaemia will be missed or misdiagnosed. Scale of Current Use: The DSC was adopted by practitioners immediately after its introduction at a project-sponsored workshop. Requests for additional cards came from veterinary colleagues of those using the DSC - i.e. the only mode of 'advertisement' that existed was word of mouth. It is difficult to know what proportion of veterinary staff in Uganda use the card now, just over one year since its introduction, but it has been widely adopted and usage appears to be increasing. One of the regrets of the project team was that there was not more provision for dissemination workshops as it was felt that the DSC is most effectively used in combination with a short training session. Such short workshops would also have allowed for observation of the impact of introducing the card to other types of users - such as minimally trained animal health assistant and indeed farmers themselves. Policy and Institutional Structures, and Key Components for Success:
Lessons Learned and Uptake Pathways Promotion of Outputs: There is on-going promotion of the DSC within Uganda by the Livestock Health Research Institute, working with veterinary officers in Government and other extension workers in a number of districts as described above. Awareness of the DSC is also being raised in the Eastern province of Zambia through the current validation exercise being conducted by the Tsetse and Trypanosomosis Control Section of the Ministry of Agriculture and Cooperatives. The haemoglobinometer methodology has been adopted by a commercial company (Elcomatic ltd.), which while sympathetic to the needs of animal health in the developing world sees its primary potential market as human health the developed world. The company has an agreement with the University of Edinburgh to allow marketing the instrument at a preferential rate in Africa, but its promotion and marketing in the developing world are unlikely to become a priority without further support from DFID in creating the necessary markets. Potential Barriers Preventing Adoption of Outputs: Lack of awareness among policy makers, veterinary services and animal health professionals in Africa of the technological advantages and cost-effectiveness of both the haemoglobinometer and the DSC, as well as lack of availability of the haemoglobinometer in the marketplace are currently limitations to adoption. Other than in the areas of Uganda and Zambia involved in its validation the diagnostic decision support tool is not yet widely available to animal health workers in most target countries. As a simple printed card, the costs of production are relatively trivial, but lack of awareness of its existence, and lack of training in its use are limitations for adoption by change agents in rural areas. Likewise, lack of awareness of the potential of decision support tools as a generic methodology for other diseases/livestock species/farming systems limits the uptake of the approach in a wider context. At a more immediate practical level, the haemoglobinometer is currently subject to electrical compliance testing. How to Overcome Barriers to Adoption of Outputs: The most critical barrier to success with this type of methodological/educational input is one of professional scepticism and/or inertia. In this the involvement of many local disease experts in creating the card was critical to its credibility. In addition the organisation and delivery of the key workshop introducing the DSC by a locally recognised centre known for its research into animal health issues was important. One potential barrier of the DSC may unfortunately be in its simplicity - i.e. it was conceived as a low cost/minimal technology solution, but its very success in this respect may also make it seem like a less 'exciting' or scientific tool to the veterinary user. While the project team feel that the approach adopted was key to generating useable technology for the farming context being targeted (as opposed to the more complex computer-based diagnostic systems they had experimented with in the past) it is also possible that alternative delivery mechanisms for the knowledge in the DSC could increase its uptake (see below). Lessons Learned: The outputs described in this proforma are not intended for direct use by poor people themselves, but by the various cadres of animal health workers that support them in maintaining the health of their animals. These include fully qualified veterinarians in government service and private practice, as well a range of paraprofessionals including veterinary assistants, animal health assistants and community animal health workers. Key to maximising the impact of these outputs on the lives of the poor is raising awareness of their existence, education with regard to their value, and training in their use. This will be best achieved by improved veterinary training and CPD for animal health workers. In this context, the model used by the Stamp Out Sleeping Sickness (SoS) campaign in Uganda is of particular note, wherein ambulatory teams of final year veterinary students from Makerere University together with their lecturers, themselves qualified veterinary clinicians have been actively involved in treating hundreds of thousands of cattle with drugs and insecticides to control both human and animal trypanosomiasis. While so doing, they have been exposed to a wealth of clinical material representing the natural spectrum of infectious disease of cattle in the very areas in which they are likely to practice once qualified. In a second, wider phase of this campaign, it is anticipated that the same teams will be equipped with the decision support tools described in this proforma. This will have the immediate effect of bringing these tools to bear on large populations of cattle undergoing natural disease change, but also profound longer term effects in terms of educating the next generation of veterinarians in the use of these methods. It will also serve to raise awareness amongst other cadres of animal health professionals working within the region. Poverty Impact Studies: The heads of state of the worlds most influential nations undertook in 2005 to "continue the G8 focus on Africa, which is the only continent not on track to meet any of the Goals of the Millennium Declaration by 2015" and to "Support a comprehensive set of actions to raise agricultural productivity, strengthen urban-rural linkages and empower the poor, based on national initiatives and in cooperation with the AU/NEPAD Comprehensive Africa Agriculture Development Programme (CAADP) and other African initiatives" (G8 Gleneagles Communiqué, 2005). Livestock underpin poor rural livelihoods in sub-Saharan Africa, but animal production is constrained by diseases, particularly infectious diseases, many of which are also zoonoses (Perry et al., 2002). The delivery of veterinary services in most developing countries was, until recently, considered to be the responsibility of the public sector. However, over the past four decades, economic constraints and the imposition of structural adjustment policies (SAPs) have led to a gradual decline in public sector investment in real terms and thus a reduction in the quality and quantity of services available to livestock keepers (Woodford, 2004). Infectious livestock diseases in sub-Saharan Africa can usefully be considered in two distinct categories. Epidemic diseases, such as rinderpest, foot and mouth disease and contagious bovine pleuropneumonia, often referred to as transboundary diseases, have major implications for international trade in livestock and livestock products. Their control remains the prerogative and responsibility of governments and international organisations and they are generally managed by national and regional control programmes. In contrast, endemic infectious diseases such as tsetse-transmitted trypanosomiasis, tick-borne disease and helminthoses, are now regarded as 'Production diseases' or 'private good diseases' and the onus of their control falls to the individual farmer, with communities and local organisations providing support in decentralised and privatised systems. Endemic diseases, frequently parasitic and/or vector-borne, constitute a major economic problem in affected regions, reducing livestock product yields and devaluing farmers' investments. Annual costs have been estimated at US$700 million for African animal trypanosomiasis (Kristjanson et al., 1999), $168 million for East Coast fever (Mukhebi, A.W. et al., 1992) and, in the Southern African Development Community (SADC) alone, $37-47 million for heartwater (Minjauw et al., 2000). Despite considerable progress that has been made in the control of some of the more dramatic major bacterial, viral and protozoan diseases, the significance of production losses caused by less visible chronic diseases is becoming more evident than before. These remain responsible for significant losses which prevent much needed increases in productivity. This is particularly true for the infections of livestock with helminths, especially liver flukes, and gastro-intestinal nematodes (Over et al.,1992). How the Poor have Benefited (including gender and other poverty groups): The detailed economic impacts of the outputs of this cluster of projects in individual countries has not yet been determined. This is in part because of the wide range of animal diseases and their individual impacts, the complex spatial and temporal variation in incidence and severity of these diseases, and the complex relationships among livestock, rural economies and livelihoods. Moreover, these outputs are unlikely to be used in isolation from other animal health related outputs in the RiU portfolio, (see under "Potential for Added Value"), and the importance of synergies amongst the various outputs should not be underestimated. An example would be where animal health workers diagnose animal disease using decision support tools and use the resultant information not only as a rational basis for therapy of individual cases but also to inform wider use of interventions for instance restricted application of insecticide for integrated control of sleeping sickness, animal trypanosomiasis and other vector-borne diseases. Direct and Indirect Environmental Benefits: Indirect environmental benefit will accrue due to improved targeting of veterinary interventions such as use of injectable drugs and topical use of insecticides and acaricides. Improved diagnosis of diseases will result in a reduction of inappropriate use of these products where they are not indicated, and hence a reduction in drug residues in animal products such as meat and milk and a reduction in environmental contamination with acaricides and insecticides. One example of this would be improved targeting of trypanocidal drugs, one of the most widely used categories of veterinary intervention sub-Saharan Africa; these drugs may be the only means of maintaining cattle productively in areas of high tsetse challenge, but may have adverse consequences when used inappropriately (Eisler et al., 1997). Adverse Environmental Impacts: None Coping with the Effects of Climate Change, or Risk from Natural Disasters: Livestock are particularly important for people living in marginal zones, including pastoralists living in the more arid tsetse-infested regions of Africa. Such people are vulnerable to drought and to cope with this they move to less marginal habitats at certain times of year. These movements often involve balancing the availability of grazing and water against the increased risk of vector-borne and other parasitic diseases associated with more humid habitats. This coping strategy is increasingly compromised by government policies and encroachment of arable farmers, which in turn forces pastoralists to utilise habitats heavily infested with disease vectors such as ticks and tsetse. The decision support tools would provide pastoralists with a better strategy for reducing disease risk and hence decrease their vulnerability to drought. More generally, livestock provide an important hedge against socio-political and economic emergencies such as war and hyperinflation and improved animal health would also reduce vulnerability of people in tsetse-infested areas to these events. Appendix 1. References & Further Reading. Bett, B., Machila, N., Gathura, P.B., McDermott, J.J. & Eisler, M.C. (2004). Characterisation of shops selling veterinary medicines in a tsetse-infested area of Kenya. Preventive Veterinary Medicine, 63, 29 - 38. de Castro J.J., (1997). Sustainable tick and tick-borne disease control in livestock improvement in developing countries. Vet. Parasitol. 71, 77-97. Eisler, M.C., Stevenson, P., Munga, L. & Smyth, J.B.A. (1997). Concentrations of isometamidium chloride (Samorin®) in sera of Zebu cattle which showed evidence of hepatotoxicity following frequent trypanocidal treatments. Veterinary Pharmacology and Therapeutics, 20, 173-180. Eisler, M.C., Magona, J.W., Jonsson, N.N. & Revie, C.W. (2006). A low cost decision support tool for the diagnosis of endemic bovine infectious diseases in the mixed crop-livestock production system of sub-Saharan Africa. Epidemiology & Infection, Forthcoming article; Published online 02 Jun 2006. G8 Gleneagles Communiqué, 2005. http://www.g8.gov.uk/. Ganaba R., Bengaly Z., Ouattara L., (2002) Calf morbidity, mortality and parasite prevalences in the cotton zone of Burkina Faso. Prev. Vet. Med. 55 209-216. Geerts, S., Holmes P.H., Diall O. & Eisler, M.C. (2001). African Animal Trypanosomiasis: The Problem of Drug Resistance. Trends in Parasitology, 17, 25-28. Hendrickx, G. (1999). Georeferenced decision support methodology towards trypanosomosis control in West Africa. PhD. Thesis. University of Ghent. Kirigia J.M., (1997). Economic evaluation in schistosomiasis: using the Delphi technique to assess effectiveness. Acta. Trop. 64, 175-190. Kristjanson P.M., Swallow B.M., Rowland G.J., Kruska R.L., de Leeuw P.N., (1999). Measuring the cost of African animal trypanosomosis, the potential benefits of control and returns to research. Agricult. Sys. 59, 79-98. Linstone H.A., Turoff, M., (1975). General application, in: Linstone H.A, Turoff, M. (Eds.), The Delphi method: technique and applications. Addison-Wesley, Reading, Massachusetts, pp. 73-226. McKendrick I.J., Gettinby G., Gu Y., Reid S.W.J., Revie C.W., (2000). Using a Bayesian belief network to aid differential diagnosis of tropical bovine diseases. Prev. Vet. Med. 47, 141-156. Machila N., Wanyangu S.W., McDermott J., Welburn S.C., Maudlin I., Eisler M.C., (2003). Cattle owners' perception of African bovine trypanosomiasis and its control in Busia and Kwale Districts of Kenya. Acta. Trop. 86, 25-34. Magona, J.W., Anderson, I., Olaho-Mukani, W., Jonsson, N.N., Revie, C.W. and Eisler, M.C. (2003). Diagnosis of endemic diseases in village cattle herds in southeast Uganda: a low technology decision support system. Newsletter on Integrated Control of Pathogenic Trypanosomes and their Vectors (ICPTV) No.8, 42-45. Magona, J.W., Walubengo, J., Olaho-Mukani, W., Revie, C.W., Jonsson, N.N. and Eisler M.C. (2004). A Delphi survey on expert opinion on key signs for clinical diagnosis of bovine trypanosomosis, tick-borne diseases and helminthoses. Bulletin of Animal Health and Production in Africa, 52, 130 - 140. Magona, J.W., Walubengo, J., Anderson, I., Olaho-Mukani, W., Jonsson N.N. and Eisler, M.C. (2004). Portable haemoglobinometers and their potential for penside detection of anaemia in bovine disease diagnosis: a comparative evaluation. The Veterinary Journal, 168, 343 - 348. Middleton K., (2001). Low cost, low technology approaches to the delivery of decision support systems. Master of Science thesis, CIS Dept., University of Strathclyde, Glasgow, UK. Minjauw, B., Kruska, R., Odero, A., Randolph, T., McDermott, J., Mahan, S. & Perry, B. (2000). Economic impact assessment of Cowdria ruminantium infection and its control in southern Africa. ISVEEE IXth Symposium, August 6-11, 2000, Breckenridge, Colorado, USA. Mukhebi, A.W., Perry, B.D. & Kruska, R. (1992). Estimated economics of theileriosis control in Africa. Preventive Veterinary Medicine, 12, 73 - 85. Over, H.J., Jansen, J. & van Olm, P.W. (1992). Distribution and impact of helminth diseases of livestock in developing countries. FAO Animal Production and Health Papers - 96. FAO, Rome. Perry, B. D., Randolph, T. F., McDermott, J. J., Sones, K. R. & Thornton, P. K. (2002). Investing in animal health research to alleviate poverty. International Livestock Research Institute (ILRI) Nairobi, Kenya, 130 pp. plus annexes. Vatta, A.F., Krecek, R.C., van der Linde, M.J., Motswatswe, P.W., Grimbeek, R.J., van Wijk, E.F. & Hansen, J.W. (2002) Haemonchus spp. in sheep farmed under resource-poor conditions in South Africa--effect on haematocrit, conjunctival mucous membrane colour and body condition. J. S. Afr. Vet. Assoc. 73, 119-23. Woodford, J.D. (2004). Synergies between veterinarians and para-professionals in the public and private sectors: organisational and institutional relationships that facilitate the process of privatising animal health services in developing countries. Rev. sci. tech. Off. int. Epiz., 23, 115-135. Appendix 2. Decision Support Card.
Relevant Research Projects,
with links to the
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For relevant research projects, with links to further information
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