Browsing by Author "Hieronimo, Proches"

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Anthropogenic soils and land use patterns in relation to small mammal and flea abundance in plague endemic area of Western Usambara Mountains, Tanzania
(Tanzania Journal of Health Research, 2014-07) Kimaro, D. N.; Msanya, B. M.; Meliyo, J.; Hieronimo, Proches; Mwango, Sibaway; Kihupi, N. I.; Gulinck, Hubert; Deckers, Jozef, A.
Heterogeneity in the landscapes of West Usambara Mountains on land use and human activities has been reported. However, the interface of land use patterns and human modified soils with small mammal and flea abundance for possible explanation of plague has not been explored. This study was carried out to determine the link between anthropogenic soils and land use patterns on small mammal and flea abundance and the occurrence of reported plague in the Western Usambara Mountains in Tanzania. Standard soil survey methods were used to identify and describe soils and land use patterns on lower slopes and valley bottoms on which the surrounding villages are reported to have high and medium plague frequencies. The identified soils were characterised in terms of their morphological and physico-chemical properties and classified according to FAO-World Reference Base for Soil Resources. Small mammals were trapped on the same landscape positions and identified to genus/species level. Fleas were removed from the trapped small mammals, counted and identified to species level. In total 57 small mammals were captured from which 32 fleas were collected. Results show that human settlements and mixed cultivation on lower slopes and continuous vegetable cropping in the valley bottoms are dominant land use types. Intensive use of forest soils, manuring and irrigation on farms in the studied landscapes have contributed to the development of uniquely human modified soils namely Hortic Anthrosols in the lower slopes and Plaggic Irragric Hortic Anthrosols in valley bottoms. The identified anthropogenic soils and land use patterns are associated with high abundance of small mammals (Mastomys natalensis) and flea species (Xenopsylla brasiliensis and Dinopsyllus lypusus). This phenomenon is vividly apparent in the villages with medium to high plague frequencies. The study suggests that plague surveillance programmes should consider the existing relationship between anthropogenic soils, land use patterns, small mammal and flea abundance.
Application of normalized difference vegetation index (NDVI) to forecast rodent population abundance in smallholder agro-ecosystems in semi-arid areas in Tanzania
(ResearchGate, 2019-05) Hieronimo, Proches; Isabirye, Moses; Kifumba, David; Mulungu, Loth; Kimaro, Didas N; Makundi, Rhodes H.; Leirs, Herwig; Mulungu, Loth S.; Mdangi, Mashaka E.; Massawe, Apia W.
This study aimed to evaluate the potential use of normalized difference vegetation index (NDVI) from satellite- derived remote sensing data for monitoring rodent abundance in semi-arid areas of Tanzania. We hypothesized that NDVI could potentially complement rainfall in predicting rodent abundance spatially and tem- porally. NDVI were determined across habitats with differ- ent vegetation types in Isimani landscape, Iringa Region, in the southern highlands of Tanzania. Normalized differ- ences in reflectance between the red (R) (0.636–0.673 mm) and near-infrared (NIR) (0.851–0.879 mm) channels of the electromagnetic spectrum from the Landsat 8 [Opera- tional Land Imager (OLI)] sensor were obtained. Rodents were trapped in a total of 144 randomly selected grids each measuring 100 × 100 m 2 , for which the corresponding values of NDVI were recorded during the corresponding rodent trapping period. Raster analysis was performed by transformation to establish NDVI in study grids over the entire study area. The relationship between NDVI, rodent distribution and abundance both spatially and tempo- rally during the start, mid and end of the dry and wet sea- sons was established. Linear regression model was used to evaluate the relationships between NDVI and rodent abundance across seasons. The Pearson correlation coefficient (r) at p ≤ 0.05 was carried out to describe thedegree of association between actual and NDVI-predicted rodent abundances. The results demonstrated a strong linear relationship between NDVI and actual rodent abundance within grids (R 2 = 0.71). NDVI-predicted rodent abundance showed a strong positive correlation (r = 0.99) with estimated rodent abundance. These results support the hypothesis that NDVI has the potential for predicting rodent population abundance under smallholder farming agro-ecosystems. Hence, NDVI could be used to forecast rodent abundance within a reasonable short period of time when compared with sparse and not widely available rainfall data.h
Contribution of land use to rodent flea load distribution in the plague endemic area of Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Kihupi, Nganga I.; Kimaro, D. N.; Gulinck, Hubert; Mulungu, Loth S.; Msanya, B. M.; Leirs, Herwing; Deckers, J
Fleas associated with different rodent species are considered as the major vectors of bubonic plague, which is still rampant in different parts of the world. The objective of this study was to investigate the contribution of land use to rodent flea load distribution at fine scale in the plague endemic area of north-eastern Tanzania. Data was collected in three case areas namely, Shume, Lukozi and Mwangoi, differing in plague incidence levels. Data collection was carried out during both wet and dry seasons of 2012. Analysis of Variance and Boosted Regression Tree (BRT) statistical methods were used to clarify the relationships between fleas and specific land use characteristics. There was a significant variation (P ≤ 0.05) of flea indices in different land use types. Fallow and natural forest had higher flea indices whereas plantation forest mono-crop and mixed annual crops had the lowest flea indices among the aggregated land use types. The influence of individual land use types on flea indices was variable with fallow having a positive effect and land tillage showing a negative effect. The results also demonstrated a seasonal effect, part of which can be attributed to different land use practices such as application of pesticides, or the presence of grass strips around fields. These findings suggest that land use factors have a major influence on rodent flea abundance which can be taken as a proxy for plague infection risk. The results further point to the need for a comprehensive package that includes land tillage and crop type considerations on one hand and the associated human activities on the other, in planning and implementation of plague control interventions.
Contribution of land use to rodent flea load distribution in the plague endemic area of Lushoto District, Tanzania
(Sokoine University of Agriculture,, 2014-07-01) Hieronimo, Proches; Kihupi, Nganga I.; Kimaro, Didas N.; Gulinck, Hubert; Mulungu, Loth S.; Msanya, B. M.; Leirs, Herwing; Deckers, Jozef A.
Fleas associated with different rodent species are considered as the major vectors of bubonic plague, which is still rampant in different parts of the world. The objective of this study was to investigate the contribution of land use to rodent flea load distribution at fine scale in the plague endemic area of north-eastern Tanzania. Data was collected in three case areas namely, Shume, Lukozi and Mwangoi, differing in plague incidence levels. Data collection was carried out during both wet and dry seasons of 2012. Analysis of Variance and Boosted Regression Tree (BRT) statistical methods were used to clarify the relationships between fleas and specific land use characteristics. There was a significant variation (P ≤ 0.05) of flea indices in different land use types. Fallow and natural forest had higher flea indices whereas plantation forest mono-crop and mixed annual crops had the lowest flea indices among the aggregated land use types. The influence of individual land use types on flea indices was variable with fallow having a positive effect and land tillage showing a negative effect. The results also demonstrated a seasonal effect, part of which can be attributed to different land use practices such as application of pesticides, or the presence of grass strips around fields. These findings suggest that land use factors have a major influence on rodent flea abundance which can be taken as a proxy for plague infection risk. The results further point to the need for a comprehensive package that includes land tillage and crop type considerations on one hand and the associated human activities on the other, in planning and implementation of plague control interventions. ________________________________________________________________________________
Human activity spaces and plague risks in three contrasting landscapes in Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Gulinck, Hubert; Kimaro, D. N.; Mulungu, Loth S.; Kihupi, Nganga I.; Msanya, B. M.; Leirs, Herwing; Deckers, J.
Since 1980 plague has been a human threat in the Western Usambara Mountains in Tanzania. However, the spatial-temporal pattern of plague occurrence remains poorly understood. The main objective of this study was to gain understanding of human activity patterns in relation to spatial distribution of fleas in Lushoto District. Data were collected in three landscapes differing in plague incidence. Field survey coupled with Geographic Information System (GIS) and physical sample collections were used to collect data in wet (April to June 2012) and dry (August to October 2012) seasons. Data analysis was done using GIS, one-way ANOVA and nonparametric statistical tools. The degree of spatial co- occurrence of potential disease vectors (fleas) and humans in Lushoto focus differs significantly (p ≤ 0.05) among the selected landscapes, and in both seasons. This trend gives a coarse indication of the possible association of the plague outbreaks and the human frequencies of contacting environments with fleas. The study suggests that plague surveillance and control programmes at landscape scale should consider the existence of plague vector contagion risk gradient from high to low incidence landscapes due to human presence and intensity of activities.
Insights into land use/cover and human activities pattern for explanation of plague infection risks in western Usambara mountains, Tanzania
(Sokoine University of Agriculture., 2015) Hieronimo, Proches
Land cover, land use, and human activities pattern have been reported to be important determinants of vector borne diseases transmission including plague. Plague, still occurring in different parts of the world, has been a threat in the Eastern Africa region including the Western Usambara Mountains, Tanzania. Plague is a severe, rodent associated, bacterial zoonosis caused by Yersinia pestis. Literature suggests that factors influencing the critical contact between rodent hosts, flea vectors, and humans as well as human behaviours that may enhance or diminish this contact are not well understood in many areas particularly in the Eastern Africa region. Hence, studies that link a complete geographic perspective including land use and land cover, host, vector and human activities pattern dimensions are important. Understanding the influence of the landscape factors on small mammals like rodents and flea abundance and their spatial distribution as well as the human exposure risks is vital and can assist in formulating prevention and surveillance mechanisms. Studies carried out in East Africa and elsewhere report a wide variety of potential health impacts arising from land use and land cover and terrain factors most of which are not well studied in the Western Usambara Mountains. Hence, the current research aimed to contribute to efforts of giving an insight into the roles of land cover, land use and human activities pattern in plague infection risks in the Western Usambara Mountains, Lushoto District, Tanzania. Specifically the study aimed: (i) to map land cover and terrain attributes and determine their association with plague hosts and vectors at landscape level (ii) to identify land use and land management practices associated with abundance and distribution of plague hosts and vectors at farm level iii (iii) to model people’s movements and activities pattern in order to determine chances of their exposure to plague in space and time. The study was carried out in three selected landscapes in the Western Usambara Mountains in Lushoto District, Tanzania. Study sites were selected to reflect a geographic gradient in plague incidence for the period 1980-2004, based on results from previous research on rodents, fleas and plague casualties in the area. The findings from those studies concur in distinguishing high, medium, and low incidence zones. Within this gradient three representative landscapes were selected differing in terms of (i) the incidence of plague, (ii) diversity in land use and associated human activities, (iii) landform characteristics, and (iv) climatic conditions. The selected landscapes are named Shume (high plague incidence), Lukozi (medium plague incidence) and Mwangoi (low plague incidence). In the context of the current study, Landscape is defined as “an area of land covering two to three villages with a repetition of similar relief types or an association of dissimilar relief types (valleys, plateaus, mountaineous hilly relief types), more or less homogeneous land use/cover types (natural forest, cultivated land, plantation forest and built up areas) and having specific historical plague incidence rate”. Twenty four observation sites (quadrats) of 100 x 100 m were established per sample landscape area. A Stratified random sampling procedure based on broad land cover types and topography was used to locate the observation sites in each sample landscape area. Decision on the number of observation sites considered representative sample size, time and human resources availability. Data collection was done in the iv wet season (April-June 2012) and the dry season (August-October 2012). The study used a geospatial approach to examine the influence of land cover/use and terrain factors on the abundance and spatial distribution of plague hosts (small mammals) and plague vectors (fleas). The approach included use of remote sensing and Geographic Information System (GIS), field observational survey and household questionnaire survey for mapping land cover/use, human movements and activities pattern, and, trapping of small mammals. Isolation and counting of fleas was done from the trapped rodents. During field survey, various visible indicators of land use were mapped and quantified within the quadrats. Two major categories of land use were defined: (a). Land management practices e.g. terrace, (b). Crop types and their associated elements e.g. maize farming. These land uses are named as ‘individual land use types’ in the current study. Each quadrat was also classified based on its aggregated land uses. For example whenever the quadrat was dominated by both annual and perennial crops, the aggregated land use type for that particular quadrat was classified as ‘Mixed annual perennial crops’. Data analysis on land cover/use and terrain factors was done using remote sensing image processing tools and GIS. The approach used to determine the human activity spaces was kernel density estimation. Interpolation and zonal statistics GIS analyses were used to determine human-flea co-occurrence. Analysis of Variance (ANOVA) was used to evaluate differences in the data (Aggregated land use types, small mammal and flea abundance, human-flea co-occurrence) whenever the data passed normality and homogeneity tests and in case of non-success the non-parametric ANOVA on Medians (Mood’s Median test) was used. The Boosted Regression Tree v (BRT) modeling technique was used to clarify the relationships between the individual land use types, land cover types, and terrain attributes, with small mammal and flea abundance. Results indicate that elevation positively influenced the presence of small mammals (plague hosts). This could be attributed to the increased resource availability (water and food) as one moves from low to high altitude on the landscape. The presence of fleas (plague vectors) was clearly influenced by land management features such as miraba which tended to increase in intensity with increase in slope gradient. Miraba is an indigenous land management practice with grass strips surrounding crop fields in a rectangular shape in the Western Usambara Mountains, Tanzania (a unique indigenous soil erosion control practice in the Usambara Mountains). Medium to high resolution remotely sensed data and field collected data integrated in GIS have been found to be quite useful in studying plague infection risks. These findings contribute to efforts on plague surveillance and awareness creation among communities on the probable risks associated with various landscape factors during epidemics. The identified land cover/use and terrain characteristics integrated in the expert GIS engine provide future potential analysis and understanding of the association of plague risk indicators including human behaviour variables at farm scale. The results also show that there was a significant variation (p ≤ 0.05) of small mammal abundance among land use types. Plantation forest with crop farming, natural forest and fallow had higher populations of small mammals than the other aggregated land use types. Plantation forest with crop farming, and fallow which is mainly surrounded by agricultural fields, offer conducive environment for small mammals in terms of vi food and shelter. Natural forest also provides food, water and shelter for small mammals. Shelter and food are important factors in breeding, recruitment and survival of rodents. Both miraba and fallow tended to favour small mammals’ habitation whereas land tillage practices had the opposite effect in dry season. Tillage of land could have resulted in the destruction of rodents burrows and mounds, destruction of nest sites, alteration of microclimate, and removal of vegetation some of which comprise food sources and shelter for the rodents. In addition, during the wet season crop types such as potato and maize appeared to positively influence the distribution and abundance of small mammals which was attributed to both shelter and food availability. A significant variation (p ≤ 0.05) of flea indices in different land use types was also identified. Fallow and natural forest had higher flea indices whereas plantation forest mono-crop and mixed annual crops had the lowest flea indices among the aggregated land use types. The observed variations of flea index among aggregated land use types could be attributed to the impact of land use practices on flea habitat structure. Fallow structure, which in most cases is also surrounded by agricultural fields, provides conducive microclimate for fleas on one hand and a supply of both food and shelter for rodents on the other. The influence of individual land use types on flea indices was variable with fallow having a positive effect and land tillage showing a negative effect. Fallow fields have also been associated with plague cases in many countries including Uganda and hence findings from this study further lend credence to the hypothesis that plague infection risk could be associated with fallow in the study area. This is because previous studies showed that flea index could be used as vii an indicator of plague infection risk. Tillage of land which destroys surface and subsurface microclimate could be detrimental to flea survival. This observation is of practical significance with regard to the need of clearing surroundings of homesteads and avoiding long fallow cycles. The results also demonstrated a seasonal effect, part of which could be attributed to different land use practices such as application of pesticides. These findings suggest that land use factors have a major influence on rodent flea abundance which could be taken as a proxy for plague infection risk. The results further point to the need for a comprehensive package that includes land tillage and crop type considerations on one hand and the associated human activities on the other, in planning and implementation of plague control interventions. The results indicate further that, the degree of spatial co-occurrence of potential plague vectors (fleas) and humans in Lushoto focus differs significantly (p ≤ 0.05) among the selected landscapes for both dry and wet seasons. For the dry season, the Mood’s Median test indicated that Shume had the highest median average flea index (Median = 0.983) followed by Lukozi (Median = 0.575) and Mwangoi (Median = 0.380). For the wet season, the ANOVA means also followed the gradient of plague incidence rates i.e. 0.54 for Shume, 0.50 for Lukozi and 0.24 for Mwangoi. The study suggests that plague surveillance and control programmes at landscape scale should consider the existence of plague vector contagion risk gradient from high to low incidence landscapes due to human presence and intensity of activities. The current study has demonstrated the importance of land use/cover and human activity spaces viii in the study of plague infection risks. Based on the findings from the current study the following conclusions can be drawn: i. The relationship between land cover and terrain attributes on one hand and small mammals and fleas as potential hosts and vectors of plague, has been well elaborated by remote sensing and GIS integration of geodatabase at different spatial scales and resolutions. Hence a geomatic approach using remote sensing data and GIS technologies is valuable in studying plague infection risks. ii. Small mammals and fleas abundance and distribution is influenced by the specific land use and land management types namely Fallow, Miraba, Tillage, Plantation forest with farming, Natural forest and Woodlot. Tillage has a negative influence whereas the other five land use and management types have positive influence. iii. Small mammal presence in different land use types can influence abundance of fleas. These findings therefore, make a significant contribution towards efforts in the control of plague risk factors in space and time. iv. Spatial co-occurrence of a potential disease vector and humans differs significantly among the plague incidence landscape areas and follows the established plague incidence gradient of high, medium and low for both dry and wet seasons. This trend gives a coarse indication of the possible ix association of the plague outbreaks and the human frequencies of contacting environments with fleas. v. The findings from this study are of public health relevance because they may guide plague surveillance, prevention and control programmes at fine scales by providing information to health workers to focus control measures on land use/cover and landscape units with high concentration of rodent fleas, especially during epizootic periods. vi. Systematic trapping of small mammals and collection of rodent fleas for surveillance should target miraba, fallow land, plantation forest with farming, natural forest and woodlot. The following recommendations are made in the light of gaps revealed from the findings of this study so as to provide further insights into the plague disease. i. Land management practices including tillage of land and crop types and the associated human activities should be included in the general scheme of plague control and management. ii. Future efforts to predict and map spatial and temporal human plague infection risk at farm scale should consider the role played by land use on small mammals and rodent fleas abundance and distribution. x iii. The study suggests that plague surveillance and control programmes at landscape scale should consider the existence of plague vector contagion risk gradient from high to low incidence landscapes due to human presence and intensity of activities. iv. Further studies should be conducted to investigate how land use practices influence surface and subsurface microclimate conditions of various small mammals and flea species v. Outdoor application of insecticides to control flea abundance has been found to be an effective measure against plague. However, further studies on timing of applications during epizootics vis-à-vis crop type should be considered.
Integrating land cover and terrain characteristics to explain plague risks in Western Usambara Mountains, Tanzania: a geospatial approach
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Meliyo, Joel; Gulinck, Hubert; Kimaro, D. N.; Mulungu, Loth S.; Kihupi, Nganga I.; Msanya, B. M.; Leirs, Herwing; Deckers, J.
Literature suggests that higher resolution remote sensing data integrated in Geographic Information System (GIS) can provide greater possibility to refine the analysis of land cover and terrain characteristics for explanation of abundance and distribution of plague hosts and vectors and hence of health risk hazards to humans. These technologies are not widely used in East Africa for studies on diseases including plague. The objective of this study was to refine the analysis of single and combined land cover and terrain characteristics in order to gain an insight into localized plague infection risks in the West Usambara Mountains in north-eastern Tanzania. The study used a geospatial approach to assess the influence of land cover and terrain factors on the abundance and spatial distribution of plague hosts (small mammals) and plague vectors (fleas). It considered different levels of scale and resolution. Boosted Regression Tree (BRT) statistical method was used to clarify the relationships between land cover and terrain variables with small mammals and fleas. Results indicate that elevation positively influenced the presence of small mammals. The presence of fleas was clearly influenced by land management features such as miraba. Medium to high resolution remotely sensed data integrated in a GIS have been found to be quite useful in this type of analysis. These findings contribute to efforts on plague surveillance and awareness creation among communities on the probable risks associated with various landscape factors during epidemics.
Land use determinants of small mammal abundance and distribution in a plague endemic area of Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Kimaro, D. N.; Kihupi, Nganga I.; Gulinck, Hubert; Mulungu, Loth S.; Msanya, B. M.; Leirs, Herwing; Deckers, J.
Small mammals are considered to be involved in the transmission cycle of bubonic plague, still occurring in different parts of the world, including the Lushoto District in Tanzania. The objective of this study was to determine the relationship between land use types and practices and small mammal abundance and distribution. A field survey was used to collect data in three landscapes differing in plague incidences. Data collection was done both in the wet season (April-June 2012) and dry season (August- October 2012). Analysis of variance and Boosted Regression Trees (BRT) modelling technique were used to establish the relationship between land use and small mammal abundance and distribution. Significant variations (p ≤ 0.05) of small mammal abundance among land use types were identified. Plantation forest with farming, natural forest and fallow had higher populations of small mammals than the other aggregated land use types. The influence of individual land use types on small mammal abundance level showed that, in both dry and wet seasons, miraba and fallow tended to favour small mammals’ habitation whereas land tillage practices had the opposite effect. In addition, during the wet season crop types such as potato and maize appeared to positively influence the distribution and abundance of small mammals which was attributed to both shelter and food availability. Based on the findings from this study it is recommended that future efforts to predict and map spatial and temporal human plague infection risk at fine scale should consider the role played by land use and associated human activities on small mammal abundance and distribution.
Land use/cover changes and their influence on the occurrence of landslides: a case study of the northern slopes of the Uluguru mountains, Morogoro, Tanzania
(Sokoine University of Agriculture, 2007) Hieronimo, Proches
The present study was conducted to assess land use/cover changes and their influence on the occurrence of landslides in the northern slopes of Uluguru Mountains, Tanzania. The study focused on the determination of the historical land use/cover changes between 1964 and 2004, evaluation of the biophysical and socio-economic factors influencing land use/cover changes, and examination of the influence of land use/cover changes on the occurrence of landslides. Field survey, remote sensing and GIS techniques were employed to assess land use/cover dynamics. Landslides were mapped through field surveys using GPS and imported in GIS environment. A questionnaire survey was conducted to collect information on socio-economic activities responsible for land use/cover changes and on landslides. Statistical analysis was done using SAS and SPSS softwares. The study demonstrated that land use/cover is dynamic and varies spatially both in terms of coverage and change. Natural vegetation is increasingly replaced by cultivation and urbanisation. Change to rainfed agriculture is more intensive on the mountain ridges by two-fold that of mountain foothills. Urban expansion is very rapid on undulating plains at a mean rate of about 15 ha per year compared to 2 ha per year on the mountain foothills and <1 ha per year in the mountain ridges. Geomorphic characteristics, soils, rainfall distribution and demographic changes are key factors influencing land use/cover dynamics. Land use/cover dynamics (increase in rainfed and irrigated agriculture) greatly influence the occurrence of landslides (R = 0.999, P< 0.05). The observed land use/cover dynamics and their relationship with the occurrence and frequency of landslides call for further research on the effectiveness of different land use options on landslide rehabilitation. Farmers should be sensitised on the influence of land use changes on land degradation and the importance of appropriate soil and water conservation measures to mitigate landslides disasters in the study area.
Landform and surface attributes for prediction of rodent burrows in the Western Usambara Mountains, Tanzania
(Tanzania Journal of Health Research, 2014-07) Meliyo, Joel, L.; Massawe, Boniface H. J.; Msanya, B. M.; Kimaro, D. N.; Hieronimo, Proches; Mulungu, Loth S.; Kihupi, N. I.; Deckers, Jozef, A.; Gulinck, Hubert; Leirs, Herwig
Previous studies suggest that rodent burrows, a proxy for rodent population are important for predicting plague risk areas. However, studies that link landform, surface attributes and rodent burrows in the Western Usambara Mountains in Tanzania are scanty. Therefore, this study was conducted in plague endemic area of the Western Usambara Mountains in northern, Tanzania, to explore the relationship between rodent burrows, and landform and surface attributes. The study was carried out in three areas corresponding to high (Lokome), medium (Lukozi) and low (Mwangoi) frequency of reported plague cases. Data were collected from 117, 200 and 170 observation sites for Lokome, Lukozi and Mwangoi, respectively using 100 m x 200 m quadrats. Remote sensing and field surveys were used to collect data on landform and surface attributes. Rodent burrows were surveyed and quantified by counting the number of burrows in 20m x 20m grids demarcated on the main 100m x 200m quadrats. The collected data were analysed in R software using boosted regression trees (BRT) technique. Rodent burrows were found at an elevation of above 1600m in the high and medium plague frequency landscapes. No burrows were found in the low plague frequency landscape situated below 1500m. BRT analysis shows a significant relationship between landform characteristics and rodent burrows in both high and medium plague frequency landscapes. Overall, elevation and hillshade are the most important determinants of rodent burrow distribution in the studied landscapes. It is concluded that in high altitudes, specific landform attributes (hill-shade, slope, elevation) and vegetation cover- favour rodent burrowing.
Predicting small mammal and flea abundance using landform and soil properties in a plague endemic area in Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Meliyo, Joel, L.; Kimaro, D. N.; Msanya, B. M.; Mulungu, L. S.; Hieronimo, Proches; Kihupi, N. I.; Gulinck, Hubert; Deckers, Jozef, A.
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.