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Programme Against African Trypanosomosis (PAAT)

Stage 2: Sustainable AAT Reduction

The focus of Stage 2 is a sustainable and economically-profitable reduction in AAT risk and burden by creating areas of low AAT incidence and impact, whereby only sporadic treatments with trypanocides are needed and the risk of emergence and/or spread of drug resistance is minimized [1, 2].

The intervention strategy hinges on the integrated management of AAT [2, 3], a community/farmer based approach that relies on the collaboration of local veterinary services and farmers associations, taking into account eco-epidemiological settings, livestock production systems [4], and cattle breeds. Effective strategies will require the combined use of tsetse control methods, diagnostic tests and trypanocidal drugs. Improved nutrition and the control of other parasitic diseases would also be beneficial [5, 6].

Baseline and monitoring data, including parasitological, entomological, and socio-economic data, need to be collected in the intervention areas to guide field activities, fine-tune intervention strategies and measure progress and impact. The possible presence of drug resistance should be considered, and if necessary investigated.

Regarding capacity development, all actors involved in the integrated AAT management should be targeted, including livestock keepers and farming communities at large, public and private veterinary services, as well as the SNS. Emphasis should go on the correct use of trypanocides to limit the emergence and spread of drug resistance [1] and on efficient and cost-effective vector control techniques, particularly insecticide treated cattle (ITC) [7, 8], livestock protective fences (LPF) in the case of zero-grazing rearing systems [9] and insecticide treated targets (ITT), especially where tsetse pressure from protected areas has to be prevented [10].

The main challenge in Stage 2 is sustainability, which will have to rely on the sensitization and training of veterinary services, farmer associations and individual farmers. Funding mechanisms must be put in place to ensure that interventions are sustained with minimal support from extension services [11]. The latter should focus on maintaining awareness and securing the availability and appropriate use of affordable, efficient and cost-effective control tools [12]. Importantly, farmer communities must be fully involved in the devolvement of the integrated disease management strategies to ensure that they are adapted to the target livestock-agricultural production systems and more generally to local constraints. Adoption of new technologies, such as tiny targets, LPF, restricted application of insecticide on animals and repellent–insecticide associations, normally requires external support, a good knowledge of local socio-technical networks, a strong participatory approach and co-learning processes to adjust the techniques to the users [13]. The degree of adoption of the proposed strategy by stakeholders will depend on their appreciation of the benefits and risks derived from the intervention activities and the associated changes required within their farming system [14].

Stage 2 could be sustained indefinitely, with AAT management becoming a fixed production cost [15]. However, the strategy should be reassessed at regular intervals (three to five years). Should the epidemiological and socio-economic conditions become favourable, a shift towards an elimination strategy (Stage 3) can be envisaged. 

References

  1. Giordani, F. et al., The animal trypanosomiases and their chemotherapy: a review. Parasitology (2016), pp. 1-28
  2. Van den Bossche, P. and Delespaux, V.,  Options for the control of tsetse-transmitted livestock trypanosomosis. An epidemiological perspective. Vet. Parasitol., 181 (2011), pp. 37-42
  3. Bouyer, J. et al., ​Community- and farmer-based management of animal African trypanosomosis in cattle. Trends Parasitol., 29 (2013), pp. 519-522
  4. Cecchi, G. et al., ​Geographic distribution and environmental characterization of livestock production systems in Eastern Africa. Agric. Ecosyst. Env., 135 (2010), pp. 98-110    
  5. Mungube, E.O. et al., Best-bet integrated strategies for containing drug-resistant trypanosomes in cattle. Parasit. Vectors, 5 (2012), p. 164
  6. Katunguka-Rwakishaya, E. et al., The influence of supplementation with cotton seed cake on the resistance of Ugandan goats to primary and secondary challenges with Trypanosoma congolense and on their response to treatment. Vet. Parasitol., 70 (1997), pp. 67-76
  7. Bouyer, J. et al., Control of bovine trypanosomosis by restricted application of insecticides to cattle using footbaths. Vet. Parasitol., 161 (2009), pp. 187-193
  8. Torr, S.J. et al., Less is more: restricted application of insecticide to cattle to improve the cost and efficacy of tsetse control. Med. Vet. Entomol., 21 (2007), pp. 53-64
  9. Bauer, B. et al., Managing tsetse transmitted trypanosomosis by insecticide treated nets—an affordable and sustainable method for resource poor pig farmers in Ghana. PLoS Negl. Trop. Dis., 5 (2011), e1343  
  10. Van den Bossche, P., A changing environment and the epidemiology of tsetse-transmitted livestock trypanosomiasis. Trends Parasitol. 26 (2010), 236-243  
  11. Catley, A. and Leyland, T., Community participation and the delivery of veterinary services in Africa. Prev. Vet. Med., 49 (2001), pp. 95-113
  12. Sutcliffe, O.B. et al., Animal trypanosomosis: making quality control of trypanocidal drugs possible. Rev. Sci. Tech. OIE, 33 (2014), pp. 813-830
  13. Bouyer, J. et al., Community- and farmer-based management of animal African trypanosomosis in cattle. Trends Parasitol., 29 (2013), 519-522
  14. Bouyer, J. et al., Restricted application of insecticides: a promising tsetse control technique, but what do the farmers think of it? Vet. Parasitol., 161 (2009), 187-193
  15. Shaw, A. et al., Mapping the benefit–cost ratios of interventions against bovine trypanosomosis in Eastern Africa. Prev. Vet. Med., 122 (2015), pp. 406-416