Mapping the risks of Peste des Petits Ruminants spread in the Republic
of Kazakhstan
Abstract
Peste des petits ruminants (PPR) is a viral transboundary disease of
small ruminants that causes significant damage to agriculture. The
disease has not been previously registered in the Republic of Kazakhstan
(RK). This paper presents an assessment of the susceptibility of the RK
territory to the spread of this disease in case of its importation from
infected countries. Ordinary Least Squares (OLS) and Geographically
Weighted Regression (GWR) models trained on the PPR outbreaks in China
were used to rank municipal districts of the RK in terms of the risk of
PPR spread. Spatial density of outbreaks was used as a risk indicator
while a number of socio-economic, landscape and climatic indicators were
considered as explanatory variables. The Exploratory Regression tool was
used to reveal a best combination of independent variables based on
specified thresholds of R-squared, variables’ multicollinearity and
residuals’ normality and autocorrelation. The small ruminants’ density,
the maximum green vegetation fraction, the annual mean temperature, the
road length and density as well as the cattle density were the most
significant factors. Both OLS and GWR demonstrated nearly similar model
performance providing a global adjusted R-squared of 0.61. Applied to
the RK, the models show the greatest risk of PPR spread in the
south-eastern and northern regions of the country, especially within
Almaty, Zhambyl, Turkistan, West Kazakhstan and East Kazakhstan regions.
As part of the study, a country-wise survey was carried out to collect
data on the distribution of livestock population the RK, which resulted
in compiling a complete geo-database of small ruminants’ holdings in the
country. The research results can be used to form a national strategy
for the prevention of the importation and spread of PPR in Kazakhstan
through targeted monitoring in high-risk areas.