Spatio-Temporal Analysis of Dog Ecology and Rabies Epidemiology at a Wildlife Interface in the Lowveld Region of South Africa
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SPATIO-TEMPORAL ANALYSIS OF DOG ECOLOGY AND RABIES EPIDEMIOLOGY AT A WILDLIFE INTERFACE IN THE LOWVELD REGION OF SOUTH AFRICA by Michael Grover Submitted in fulfilment of the requirements for the degree Magister Scientiae (Veterinary Science) in the Department of Veterinary Tropical Diseases Faculty of Veterinary Science University of Pretoria December 2015 Dedication This thesis is dedicated to God for the strength to carry on and to my family for all the understanding and support you provided me throughout my thesis. i Declaration I hereby declare that this dissertation, which I submit in fulfilment of the degree of Master of Science at the University of Pretoria, South Africa, is my own work. This work has not been previously submitted by me for a degree at another university. …………………………………………………… Michael Grover This dissertation emanates from Protocol V002/14 approved by the Research Committee of the University of Pretoria on 25th June 2014 and the Animal Ethics Committee of the University of Pretoria on 5th October 2014. ii Acknowledgements I would like to acknowledge my Supervisor Dr Darryn Knobel for his patience, understanding and steady leadership throughout this process. The long journey you have lead me on has been a constant learning curve and I appreciate your patience. My co-supervisors Dr Paul Bessel and Dr Anne Conan, for the many hours of reading and editing you have put in. Dr Bessel for your statistic and spatial analysis help, which was the foundation on which this analysis was done. Dr Conan for taking the time to walk me through the statistical framework for a solid thesis. To Dr Bjorn Reininghaus, this database would not be possible without the dedication of you and your team from the State Veterinary Department. Your willingness to go the extra mile, resulted in a complete dataset which allowed for powerful information. Thank you for your efforts. To (Dr) Jacques van Rooyen, for creating the platform for me at the beginning and the encouragement throughout. To the conservation managers within the study area for your tireless and often thankless commitment to conservation of the wildlife. May this information assist management decisions and understanding of rabies in wildlife areas. To my parents and parents-in-law for being there for my family when I could not. The many hours of understanding have not gone unnoticed. To my family, for the relentless support and love you gave to me throughout the writing up of this thesis. But most specially my wife, Candice you have been the rock at the centre of it all. Words cannot explain what you have done and how thankful I am for your patience in this journey. iii Spatio-temporal analysis of dog ecology and rabies epidemiology at a wildlife interface in the Lowveld region of South Africa Candidate: Michael Grover Student no.: U13418875 Supervisor: Prof Darryn Knobel Co-supervisors: Dr Anne Conan Dr Paul Bessell Department: Veterinary Tropical Diseases Degree: MSc (Veterinary Science) iv Abstract It is estimated that free-roaming dogs comprise on average 75% of dog populations. Interactions between free-roaming dogs and wildlife occur across the globe but little is known about these interactions in the Lowveld region of South Africa, where wildlife areas are fenced off from surrounding communities. Even with extensive fences dogs are still entering the reserves. The study site, a private reserve in eastern Mpumalanga Province on the western boundary of the Greater Limpopo Transfrontier Park, has a high density of human settlements on its boundary. These communities own dogs, many of which are free- roaming. Between January 2009 and March 2014, 170 stray dogs were destroyed inside the reserve and 65.3% of the samples returned a positive result for rabies. Dogs are not limited to the reserve edges and have been documented several kilometres into the reserve. Eleven geographical factors were used in the spatial analysis: (i) camps or lodges in the reserve, (ii) fence line of the reserve, (iii) water points within the reserve, both natural and man-made (excluding rivers but including pans, dams and waterholes which hold water for most of the year), (iv) access roads from gates to camps and lodges, (v) access gates into the reserve, (vi) pickets (field ranger accommodation) and general staff accommodation, (vii) rivers in stream order from 1 to 6, (viii) vulnerable points for erosion along the fence line, and (ix) villages bordering the reserve. GPS locations of dogs shot were used to obtain nearest distance to each factor. Generalized linear models (GLM) were then used to analyse the spatial data of distance of dogs shot to the nearest factor. Dogs were significantly more likely to be shot further away from pickets and closer to minor rivers. There was a significant interaction between these two factors (p < 0.0001). Dogs that were shot further from villages (odds ratio 1.42, 95% confidence intervals 1.18 – 1.71, p = 0.0002) and closer to water (odds ratio 0.41, 95% confidence intervals 0.21 – 0.81, p = 0.009) were more likely to test positive for rabies. A univariate GLM, with distance to fence as the only explanatory variable, showed a significant association between this and rabies test result: for every 1 km further away from the fence the odds of a dog testing rabies positive increases by 1.68 (95% confidence intervals 1.20 – 2.36, p = 0.002). However the fence is likely not to be the influencing factor but rather other factors close to the fence. To remove the effect of the fence an analysis of the subset of dogs found further than 200m into the reserve found a positive association between distance from a village and a positive rabies test result (odds ratio 1.58, 95% confidence intervals 1.18-2.32, p = 0.007). Temporal analysis of the data shows a higher average monthly number of dogs shot during the wet season (Oct-Mar) as well as a higher variance although the cycle is not strictly seasonal. An upgrade of the reserve fence for security reasons coincided with a decrease in number of dogs destroyed in the reserve in 2012-1014. Home range analysis of most susceptible predators was collected from daily sightings data and overlaid with rabies hotspots, which gives management an indication of the need to vaccinate predators with home ranges in close proximity to the fence. v The spatial results gives management an indication to increase efforts to destroy free- roaming domestic dogs further into the reserve as the likelihood of a positive rabies result is greater. Ultimately efforts should be focused outside the reserve in the communities to eradicate rabies from the host (domestic dogs) before there is a significant transfer of rabies to wildlife. vi Table of Contents 1. INTRODUCTION ............................................................................................................................... 1 1.1. Overview ................................................................................................................................. 1 1.2. Literature review .................................................................................................................... 3 1.2.1 Overview of rabies ...................................................................................................................... 3 1.2.2 Overview of rabies in Southern Africa ....................................................................................... 4 1.2.3 Rabies in Mpumalanga Province, South Africa .......................................................................... 5 1.2.4 Rabies in wildlife ......................................................................................................................... 8 1.2.5 Dog ecology in rural areas ........................................................................................................ 10 1.2.6 Vaccination in rural areas ......................................................................................................... 11 1.2.7 Dog movement ......................................................................................................................... 13 1.3. Problem statement ................................................................................................................ 14 1.4. Aims and objectives ............................................................................................................... 15 2. MATERIALS AND METHODS .......................................................................................................... 16 2.1. Study location ........................................................................................................................ 16 2.2 Study design and data collection ........................................................................................... 21 2.3 Data analysis .......................................................................................................................... 24 2.3.1 Dataset ..................................................................................................................................... 24 2.3.2 Temporal analysis ..................................................................................................................... 25 2.3.3 Spatial analysis ......................................................................................................................... 26 2.3.4 Predator home range analysis .................................................................................................. 32 2.4 Ethics