Predicting small mammal and flea abundance using landform and soil properties in a plague endemic area in Lushoto District, Tanzania

Abstract

Small mammals particularly rodents, are considered the primary natural hosts of plague. Literature suggests that plague persistence in natural foci has a root cause in soils. The objective of this study was to investigate the relationship between on the one hand landforms and associated soil properties, and on the other hand small mammals and fleas in West Usambara Mountains in Tanzania, a plague endemic area. Standard field survey methods coupled with Geographical Information System (GIS) technique were used to examine landform and soils characteristics. Soil samples were analysed in the laboratory for physico-chemical properties. Small mammals were trapped on pre-established landform positions and identified to genus/species level. Fleas were removed from the trapped small mammals and counted. Exploration of landform and soil data was done using ArcGIS Toolbox functions and descriptive statistical analysis. The relationships between landforms, soils, small mammals and fleas were established by generalised linear regression model (GLM) operated in R statistics software. Results show that landforms and soils influence the abundance of small mammals and fleas and their spatial distribution. The abundance of small mammals and fleas increased with increase in elevation. Small mammal species richness also increases with elevation. A landform-soil model shows that available phosphorus, slope aspect and elevation were statistically significant predictors explaining richness and abundance of small mammals. Fleas' abundance and spatial distribution were influenced by hill-shade, available phosphorus and base saturation. The study suggests that landforms and soils have a strong influence on the richness and evenness of small mammals and their fleas' abundance hence could be used to explain plague dynamics in the area. _________________________________________________________________________________________

Diversity, distribution and changes in communities of fleas on small mammals along the elevational gradient from the Pannonian Plain to the Carpathian Mountains

“…Most of the studies generally identified elevation to be the main factor influencing flea diversity, with an impact on factors such as rainfall, climate, habitat and environmental productivity, alongside anthropogenic influences (Benton and Altmann, 1964; Gong et al ., 2005; Eisen et al ., 2012; Meliyo et al ., 2014; Maestri et al ., 2017). Between the Pannonian Plain and the base of the Carpathian Mountains, air temperature falls and precipitation rises like it does in other increasing elevational diversity gradients.…”

“…On the other hand, our study found flea diversity growing during the spring as elevation increased, but no data were available to us for elevations above 1250 m. Nonetheless, a continual rise in the higher elevations along the gradient is unlikely from what is known in studies conducted at mountains in Africa (Eisen et al ., 2012; Meliyo et al ., 2014). This is especially due to the growing diversity of both the fleas and the hosts (Eisen et al ., 2012; Meliyo et al ., 2014).…”

“…Unimodal patterns of peak flea diversity were recorded in both the mountains of East Asia (Gong et al, 2005) and western Siberia (Sapegina, 2000) with a mid-peak, whereas Gong et al (2005) adds that species richness was influenced at varying elevations by factors such as precipitation, climate, habitat and human activity. Conversely, increased diversity among fleas has been recorded at higher elevations in East Africa (Eisen et al, 2012;Meliyo et al, 2014). In addition to altitude, other factors such as relief, landscape, human impact on the soil and therewith its effect on vegetation formations have all had a significant effect on the incidence of fleas.…”

Diversity, distribution and parasitism rates of fleas (Insecta: Siphonaptera) on sigmodontine rodents (Cricetidae) from Argentinian Patagonia

“…For example, for some hosts, mean flea abundance increased with an increase in mean annual air temperature/proximity to equator, while for others the abundance decreased with altitude (Linardi & Krasnov, 2012). Another contrasting study found that the abundance of fleas increased with elevation (Meliyo et al , 2014). In our study, lower values of flea prevalence and abundance were observed in the areas with higher elevations (such as the Humid Steppe region, see table 1).…”

Modelling the current distribution and predicted spread of the flea species Ctenocephalides felis infesting outdoor dogs in Spain

“…Statistical models help to determine the relative contribution of drivers to map vector occurrence or predict future vector distributions based on expected climate change [18]. In East Africa, scientists have had ample experience in surveying the bacterium Yersinia pestis, the causative agent of the plague, through GIS and Remote Sensing (RS) procedures [19][20][21][22][23]. However, so far only Beugnet et al [14] have modelled the distribution of the cat flea affecting pets based on climate forecasts for a large geographical area [14].…”