Social Costs Socioeconomic Factors Leading to Chemoresistance to Trypanosomiasis By: D. OUEDRAOGO et al. Université Polytechnique de Bobo-Dioulasso (UPB) Institut du Développement Rural (IDR)

Outline 1.Introduction and problem statement 2.Objectives 3.Study design 4.Results and discussion 5.Conclusion

1. Introduction and the problem Trypanocidal drugs are the most widely applied method that farmers use to treat and prevent trypanosomosis in sub-Saharan Africa. 25 to 50 million doses of trypanocides are administered each year to the approximately 45 million cattle at-risk of trypanosomosis (Kristjanson et al. 1999; Sones 2001).

The efficacy of trypanocides in cattle appears to be threatened by the widespread development of resistance in trypanosomes to the two drugs licensed for use in WA (isometamidium, and diminazene; Peregrine 1994). There is a general lack of information on the prevalence, distribution and impact of resistance to trypanocides (Geerts and Holmes, 1998), and ignorance about the most important factors leading to the development of trypanocidal resistance in the field.

On biological side: Resistance is the loose of the sensitivity by an organism to a drug it is previously sensitive (Uilenberg 1998). On economic side: Resistance appears like a waste of resources (many treatments without success, externalities, source of transaction costs, …) Resistance is a big constraint for animal production in endemic area with induced effects on agricultural production.

As new trypanocides for use in cattle are unlikely to be developed in the near future, field studies to better understand factors influencing the prevalence, distribution and impact of drug resistance are required. This information could support strategies to improve the use and efficacy of currently available trypanocides in key production systems under trypanosomosis risk.

 Estimate the proportion of trypanosome infections in cattle due to drug-resistant strains.  Analyze the trypanocides market.  Identify the factors leading to resistance in trypanosomoses.  Make recommendations for a better use of trypanocides in the study area. 2. Objectives of the study

To better understand the occurrence, impact and factors influencing the development of trypanocidal drug resistance in the cotton belt, of the sub-humid zone of West Africa (south- western Burkina Faso, south-eastern Mali and northern Côte d’Ivoire). Kenedougou province of Burkina Faso 3. Study design

Team: Entomologists Epidemiologists Biologists Agricultural / resources economists Cross sectional studies Characterization of tsetse challenge and trypanosomosis risk (“block treatment”) Mains characteristics of production systems Longitudinal study Six villages (low, medium and high level of resistance)

Modeling resistance factors Econometric model K: Vector of variables β, η: Vector of parameters µ: stochastic variables Market study Trypanocides demand functions

Socioeconomic factors: Age of household head (+), education (+), production systems [crops producers / herdsmen] (-), wealth level (+) Environmental factors: Tsetse flies infection rate (+), accessibility (-), previous treatment failure rate (-) 4. Main results and discussion

Expenditures of trypanocidal drugs represent about 45% of total animal health cost. About 60% of trypanocides used are preventive ones. Price is higher on official market (high transaction costs) than on parallel markets (asymmetric information and hazard moral problems). Impact on some parameters: Mortality: 10 et 26% Milk production: 10 et 40% Performance of oxen: 33% FAO (1994): USD1-1.5 billion of loss for Africa.

Field studies undertaken in Kénédougou province provided valuable information on the widespread presence, but variable pattern, of trypanocidal drug resistance and changing patterns of trypanosome risk. The resistance cost appears to be high: Externalities for individual and society Impact on productivity Increase of treatment cost (4-5 treatments per year vs. two treatments without resistance 5. Conclusion

This information has important implications for managing tsetse and trypanosomosis risk in the area. The results suggest reducing drug use in areas with very low risk, and helping livestock keepers to improve tsetse control and minimize trypanocidal drug use in higher risk areas.

To tackle the complexity of trypanosomosis, it is necessary to adopt multidisciplinary approach. The results presented here are preliminary ones. An ongoing study try to evaluate the total cost of the resistance to trypanosomosis in the Cotton belt in West Africa. [CIRDES, ILRI, BMZ, Free University of Berlin, NARS]