Demographic and spatio-temporal variation in human plague at a persistent focus in Tanzania

Davis, Stephen; Makundi, Rhodes H.; Machang’u, Robert S.; Leirs, Herwig

doi:10.1016/j.actatropica.2006.10.006

Cited by 36 publications

(44 citation statements)

References 12 publications

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“…14,18 Since 1998, polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) techniques were also used to confirm the presence of plague bacteria in human-serum samples. 19 Davis and others 15 calculated mean plague-incidence rates and case frequency per village for the 49 villages recording at least one plague case during 1986-2003 and found a positive correlation between the two variables. Geographic coordinates were recorded with a global positioning system (GPS) receiver (spatial precision finer than 30 m) at village offices for 48 of 49 plague villages, as well as for 57 other villages located in the same region but without recorded plague cases during the same time period.…”

Section: Methodsmentioning

confidence: 99%

“…6,15,16 Earlier, long-term microscale research comparing distributions of rodent and flea populations and examining socio-cultural factors favorable to plague transmission in plague-positive and plague-negative villages could not explain the details of the spatio-temporal distribution of the disease in the region. 6,8,[15][16][17] In this study, we aim to (1) explore the geographic distribution and coarse-resolution ecology of human plague in Lushoto District of Tanzania, (2) identify environmental conditions correlated with human-plague occurrences in Lushoto, (3) reflect on predictability of plague transmission in the region, and finally, (4) extend our local Lushoto model across East Africa. To this end, we developed ecological-niche models (ENM) based on human-plague case-occurrence data of Lushoto and project them across the broader region.…”

Section: Introductionmentioning

confidence: 99%

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Predicting Potential Risk Areas of Human Plague for the Western Usambara Mountains, Lushoto District, Tanzania

Neerinckx¹,

Peterson²,

Gulinck³

et al. 2010

The American Society of Tropical Medicine and Hygiene

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Abstract. A natural focus of plague exists in the Western Usambara Mountains of Tanzania. Despite intense research, questions remain as to why and how plague emerges repeatedly in the same suite of villages. We used human plague incidence data for 1986-2003 in an ecological-niche modeling framework to explore the geographic distribution and ecology of human plague. Our analyses indicate that plague occurrence is related directly to landscape-scale environmental features, yielding a predictive understanding of one set of environmental factors affecting plague transmission in East Africa. Although many environmental variables contribute significantly to these models, the most important are elevation and Enhanced Vegetation Index derivatives. Projections of these models across broader regions predict only 15.5% (under a majority-rule threshold) or 31,997 km 2 of East Africa as suitable for plague transmission, but they successfully anticipate most known foci in the region, making possible the development of a risk map of plague.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Predicting Potential Risk Areas of Human Plague for the Western Usambara Mountains, Lushoto District, Tanzania

Neerinckx¹,

Peterson²,

Gulinck³

et al. 2010

The American Society of Tropical Medicine and Hygiene

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“…39 Field sampling was carried out in this vicinity during June and July 2011, the onset of the dry season, shortly after the typical annual peak in human plague cases. 23 We sampled rodents, as well as their fleas and pathogens, at six sites for this study. All sites were placed in a matched-pair design (across three site pairs, one in each of the three regions).…”

Section: Methodsmentioning

confidence: 99%

“…Y. pestis, the bacterium that causes plague, is an example of a vector-borne organism that constitutes an important public health concern in many parts of Africa. 4,23,24 Research on the eco-epidemiology of plague in East Africa has given relatively little direct attention to the role of land-use change in disease transmission, and has focused instead on the roles of factors such as climate, context, large mammal presence, and host abundance. 1,[25][26][27][28][29][30][31][32] One of the most common types of landscape change underway in East Africa, and elsewhere in the global tropics, is the conversion of wildlands to agricultural uses.…”

Section: Introductionmentioning

confidence: 99%

Effects of Land Use on Plague (Yersinia pestis) Activity in Rodents in Tanzania

McCauley

Salkeld

Young

et al. 2015

The American Society of Tropical Medicine and Hygiene

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Abstract. Understanding the effects of land-use change on zoonotic disease risk is a pressing global health concern. Here, we compare prevalence of Yersinia pestis, the etiologic agent of plague, in rodents across two land-use types-agricultural and conserved-in northern Tanzania. Estimated abundance of seropositive rodents nearly doubled in agricultural sites compared with conserved sites. This relationship between land-use type and abundance of seropositive rodents is likely mediated by changes in rodent and flea community composition, particularly via an increase in the abundance of the commensal species, Mastomys natalensis, in agricultural habitats. There was mixed support for rodent species diversity negatively impacting Y. pestis seroprevalence. Together, these results suggest that land-use change could affect the risk of local transmission of plague, and raise critical questions about transmission dynamics at the interface of conserved and agricultural habitats. These findings emphasize the importance of understanding disease ecology in the context of rapidly proceeding landscape change.

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“…These results shed light in explaining partly why there is plague where it is and why it is not where it is not in the West Usambara Mountains. For example the Plain part of the landscape was found to harbour small mammals species that have not been reported to host the plague bacterium as compared to those species in the Plateau where the plague disease has been reported frequently (Kilonzo et al, 2005;Davis et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

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

Meliyo

Kimaro

Msanya

et al. 2014

Tanzania J Hlth Res

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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. _________________________________________________________________________________________

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Demographic and spatio-temporal variation in human plague at a persistent focus in Tanzania

Cited by 36 publications

References 12 publications

Predicting Potential Risk Areas of Human Plague for the Western Usambara Mountains, Lushoto District, Tanzania

Predicting Potential Risk Areas of Human Plague for the Western Usambara Mountains, Lushoto District, Tanzania

Effects of Land Use on Plague (Yersinia pestis) Activity in Rodents in Tanzania

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

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