Abstract:
Anthrax spatial distributions and the potential driving factors remain poorly understood
worldwide and in Kenya. This study aimed at establishing environmental and social economic predictors of the spatial distribution of anthrax in Kenya through (1)
determining the relationship between selected environmental and socio-economic
factors on spatial distribution of anthrax through use of an ecological niche modelling
framework; (2) predicting the effect of climate change on the future spatial distribution
of anthrax; and (3) establishing the influence of socio-economic factors in vulnerability
to anthrax. Ecological Niche Model (ENM) of boosted regression trees (BRT)
algorithm was applied to predict the suitable spatial environments for anthrax under
current and future climate scenarios in Kenya. The model fitted confirmed anthrax
occurrences from three distinct sources of retrospective records (2011 to 2017),
sporadic anthrax outbreaks (2017 to 2018) and active surveillance (2019 to 2020)
against selected predictor variables to yield current and future anthrax risk maps.
Finally, the underlying socio-economic vulnerability due to the risks of anthrax
distribution was assessed by laying over socio-economic indicators in spatial
multicriteria decision analysis to produce socio-economic vulnerability maps. The
high-risk areas for anthrax outbreaks were identified predominantly in: regions around
western Kenya bordering Uganda; southwestern regions bordering Tanzania and
regions around central highlands of Kenya. Based on the current scenario, the number
of humans affected was estimated at ~ 193,00,840 people/sq.km while that of livestock
was at ~7,750,675 animals / sq.km. The important contributing predictor variables were
predominantly cattle density, rain of the wettest month, monthly precipitations, soil
clay, soil pH, soil carbon, longest dry season and temperature range. The anthrax highly
suitable areas expanded from current to future climatic scenarios with current at 36131
km2, RCP 4.5, 40012 km2, and RCP 8.5, 39835 km2. Highly socio-economic
vulnerable areas closely correlated with areas of high anthrax risk currently and into the
future. At current vulnerability index > 75%, approximately 40,369,455 people were
estimated to be at risk. This study results will guide risk-based surveillance and
strategies for managing anthrax under One Health approach and also contributes to
future research studies within Kenya and beyond.
