Modeling the effect of improved diagnostics and antibiotic treatment on the dynamics of Contagious Bovine Pleuropneumonia (CBPP)
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Modeling the effect of improved diagnostics and antibiotic treatment on the dynamics of Contagious Bovine Pleuropneumonia (CBPP)

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Poster prepared by Amos Ssematimba and Jeffrey Mariner for the Fourth International Conference on Infectious Disease Dynamics, Amsterdam, The Netherlands, 19-22 November 2013

Poster prepared by Amos Ssematimba and Jeffrey Mariner for the Fourth International Conference on Infectious Disease Dynamics, Amsterdam, The Netherlands, 19-22 November 2013

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Modeling the effect of improved diagnostics and antibiotic treatment on the dynamics of Contagious Bovine Pleuropneumonia (CBPP) Document Transcript

  • 1. Modeling the effect of improved diagnostics and antibiotic treatment on the dynamics of Contagious Bovine Pleuropneumonia (CBPP) November 2013 Amos Ssematimba* and Jeffrey Mariner Epidemics 4 conference, 2013, Amsterdam, The Netherlands, 19-22 November 2013 Methods II: modeling details Background CBPP is a livestock disease that has continuously devastated the industry in the sub-Saharan Africa. Control intervention is mainly through vaccination but seems unsuccessful due to vaccine- and management-specific factors. Currently, uninformed use of antibiotics is rampant in the field; much as it is against OIE recommendations. • studies to unravel the “myths” about their use are in place with hope to guide reconsideration of the OIE position. Above: Reported CBPP cases (red) 2010-2013; Below left: Cow standing legs apart and extended neck, a sign of CBPP; Below right: A typical encapsulation in the lungs of a CBPP “recovered” animal Methods I: The model Currently, better diagnostic tools are being sought and antibiotic efficacies being assessed. • Study aims • Given the current CBPP research interests, there is need for predictive tools to guide field implementation of the improved control strategies. Pictures • Assumed a gamma-distributed waning of vaccine induced immunity (i.e. method of steps); protection=8months. • A seasonally forced transmission rate: 𝛽 𝑡 = 𝛽0 1 + 𝐴sin 2𝜋𝑡 with 𝛽0 =0.5. • Effects of pulse vaccination or treatment scenarios are explored in isolated herd. • Six year period is simulated in a herd of 500 (S=205, E=10, I=10, R=275) heads. • Treated animals are assumed 50% less infectious. • New recruits are all susceptible to CBPP and for clarity, between herd mixing is ignored in the comparison. Sample graphical results SVEIRQT compartmental model implemented stochastically using Gillespie direct algorithm. incorporates vaccination and treatment. The aim here is to develop mathematical models to assess how effectively antibiotics can be used in the field as supplements to vaccination campaigns. Preliminary results Conclusions and next steps Simulation outcomes for the different interventions Antibiotic treatment can provide the much wanted supplement to the current vaccination campaigns and should be supported. Synchronizing intervention at regional level is paramount due to the cross-boarder animal movements. Cheaper diagnostic tools should be availed to aid CBPP identification and better antibiotics with higher cure rate are needed. Next step: obtain field data to calibrate the models . Intervention scenario Cure rate/ detected Extinction Epidemic fraction/ vaccination chance duration coverage (%) (days) a) Annual pulse vaccination 30% 72 1194 315 110 90% 100 996 222 77 b) Treatment (default detected fraction=80%); different cure rates 1/7 per week 13 1296 526 29 1/2 per week 100 322 18 1 65 937 254 18 77 808 193 8 c) Treatment (default cure 20% rate = 1/4.5 per week): different detected fraction 90% Cumulative number of cases Cumulative number of CBPPinduced deaths Amos Ssematimba a.ssematimba@cgiar.org ● Box 30709 Nairobi Kenya ● +254 20 422 3867 Nairobi Kenya ● ilri.org This project was funded by BBSRC and partly by BMZ This document is licensed for use under a Creative Commons Attribution –Non commercial-Share Alike 3.0 Unported License November 2013