Spatial distribution patterns of plague hosts : point pattern analysis of the burrows of great gerbils in Kazakhstan Reference (original) (raw)
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Journal of Biogeography, 2015
Aim The spatial structure of a population can strongly influence the dynamics of infectious diseases, yet rarely is the underlying structure quantified. A case in point is plague, an infectious zoonotic disease caused by the bacterium Yersinia pestis. Plague dynamics within the Central Asian desert plague focus have been extensively modelled in recent years, but always with strong uniformity assumptions about the distribution of its primary reservoir host, the great gerbil (Rhombomys opimus). Yet, while clustering of this species' burrows due to social or ecological processes could have potentially significant effects on model outcomes, there is currently nothing known about the spatial distribution of inhabited burrows. Here, we address this knowledge gap by describing key aspects of the spatial patterns of great gerbil burrows in Kazakhstan.
Potential corridors and barriers for plague spread in central Asia
International Journal of Health Geographics, 2013
Plague (Yersinia pestis infection) is a vector-borne disease which caused millions of human deaths in the Middle Ages. The hosts of plague are mostly rodents, and the disease is spread by the fleas that feed on them. Currently, the disease still circulates amongst sylvatic rodent populations all over the world, including great gerbil (Rhombomys opimus) populations in Central Asia. Great gerbils are social desert rodents that live in family groups in burrows, which are visible on satellite images. In great gerbil populations an abundance threshold exists, above which plague can spread causing epizootics. The spatial distribution of the host species is thought to influence the plague dynamics, such as the direction of plague spread, however no detailed analysis exists on the possible functional or structural corridors and barriers that are present in this population and landscape. This study aims to fill that gap.
International journal of applied earth observation and geoinformation : ITC journal, 2018
In Kazakhstan, plague outbreaks occur when its main host, the great gerbil, exceeds an abundance threshold. These live in family groups in burrows, which can be mapped using remote sensing. Occupancy (percentage of burrows occupied) is a good proxy for abundance and hence the possibility of an outbreak. Here we use time series of satellite images to estimate occupancy remotely. In April and September 2013, 872 burrows were identified in the field as either occupied or empty. For satellite images acquired between April and August, 'burrow objects' were identified and matched to the field burrows. The burrow objects were represented by 25 different polygon types, then classified (using a majority vote from 10 Random Forests) as occupied or empty, using Normalized Difference Vegetation Indices (NDVI) calculated for all images. Throughout the season NDVI values were higher for empty than for occupied burrows. Occupancy status of individual burrows that were continuously occupied...
Plague metapopulation dynamics in a natural reservoir: the burrow system as the unit of study
Epidemiology and Infection, 2007
The ecology of plague (Yersinia pestis infection) in its ancient foci in Central Asia remains poorly understood. We present field data from two sites in Kazakhstan where the great gerbil (Rhombomys opimus) is the major natural host. Family groups inhabit and defend burrow systems spaced throughout the landscape, such that the host population may be considered a metapopulation, with each occupied burrow system a subpopulation. We examine plague transmission within and between family groups and its effect on survival. Transmission of plague occurred disproportionately within family groups although not all gerbils became infected once plague entered a burrow system. There were no spatial patterns to suggest that family groups in close proximity to infected burrow systems were more at risk of infection than those far away. At one site, infection increased the chances of burrow-system extinction. Overall, it is useful to consider the burrow system as the unit of study within a much larger metapopulation.
Journal of infection in developing countries, 2016
Plague, caused by Yersinia pestitis, is an infectious bacterial disease that has a high fatality rate if untreated. Rodents are plague reservoirs and play an important role in disease spread. Plague cases have been reported extensively since the second pandemic from the 14th century in countries sharing borders with Pakistan, such as China and India, as well as nearby countries including Russia and central Asia. Despite being centrally located in a plague-infested geographical zone, there has been no plague incidence reported from Pakistan. This study aims to pinpoint some of the potentially important aspects of the disease, which have to be considered when assessing potential risk associated with a plague outbreak in Pakistan. In this context, the occurrence and distribution of plague-associated rodent reservoirs in different regions of Pakistan in relation to those found in the neighboring countries were mapped. In addition, the climatic factors that may also influence disease spr...
Emergence, spread, persistence and fade-out of sylvatic plague in Kazakhstan
Proceedings of the Royal Society B: Biological Sciences, 2011
Predicting the dynamics of zoonoses in wildlife is important not only for prevention of transmission to humans, but also for improving the general understanding of epidemiological processes. A large dataset on sylvatic plague in the Pre-Balkhash area of Kazakhstan (collected for surveillance purposes) provides a rare opportunity for detailed statistical modelling of an infectious disease. Previous work using these data has revealed a host abundance threshold for epizootics, and climatic influences on plague prevalence. Here, we present a model describing the local space–time dynamics of the disease at a spatial scale of 20 × 20 km 2 and a biannual temporal scale, distinguishing between invasion and persistence events. We used a Bayesian imputation method to account for uncertainties resulting from poor data in explanatory variables and response variables. Spatial autocorrelation in the data was accounted for in imputations and analyses through random effects. The results show (i) a ...
International Journal of Biology and Chemistry, 2015
The article shows that a relatively quick obtaining direct and most importantly absolutely accurate data on individual movements of marked individuals, based on field research in 2012-2014 makes telemetry a very promising direction in mobility study of the potential plague hosts in natural focus of this infection. It is concluded that methods of telemetry are likely applicable not only for rodents but also for any other small mammals, for which catch methods on alive animals are practiced.
Natural ecosystems have their own specific combination of pathogens, and in the areas of Kazakhstan described in this article, that includes Yersinia pestis. In fact, it's almost universally acknowledged by recent studies that Kazakhstan is the likely origin of the bacterium (Spyrou et al., 2022). The examination of the combination of natural foci for zoonotic pathogens has become increasingly crucial, as it addresses pressing issues in the area of human infectious diseases. This is due to the potential for people to become infected with multiple natural focal pathogens from different causes, resulting in a mixed infection (Demidova et al., 2022).