Monitoring rodents movements with a biomarker around introduction and feeding foci in an urban environment in Tanzania

Abstract

Rodents are of concern as reservoirs and transmitters of pathogens that cause zoonotic and other diseases in domestic animals and humans. The contact between wild and urban rodent fauna is increasing in expanding cities in Africa, and this arguably increases the risk of disease transmission to urban populations. When rodents from rural areas are accidentally introduced into cities and encounter urban rodents, for example, in markets, grain mills and butcheries, there is a potential that pathogens are transferred between rural and urban rodent populations. Using a non-toxic biomarker, Rhodamine B (RB), we investigated the distances over which rodents are active around such potential introduction sites. Animals feeding at such sites were traced up to 100 m distant within a period of 10 days. We found that RB is a practical alternative for studying rodent movements. These results may be useful in designing management strategies to reduce the risk of the introduction of new rodent-borne pathogens in cities.

Episodic outbreaks of small mammals influence predator community dynamics in an east African savanna ecosystem

“…Third, it is possible that a higher level of background food available in the form of spilled grains and grain storage units in agricultural areas (Mohr et al ) could result in a higher density of small mammals at the onset of breeding, altering the rapidity of build‐up to an outbreak cf. the natural savanna ecosystem.…”

“…Outbreaks have been linked to emerging infectious diseases of humans (Gratz 1997, Morens et al 2004, Elmore et al 2010) when land use change or human encroachment on natural ecosystems increase contact with wildlife (Jones et al 2008). Hence the population dynamics of small mammals are linked to two substantive drivers of environmental change in Africa: land use intensifi cation (Blaum et al 2006, Mohr et al 2007) and climate change (Sinclair et al 2013). Predicted long-term changes in both the frequency and intensity of rainfall postulated for east Africa (Hulme et al 2001, Ritchie 2008), high growth rates in the human population, and rapid land use change to the west of Serengeti National Park (SNP) (Estes et al 2012) are likely to have substantial impacts on small mammal communities.…”

Rodent-borne diseases and their risks for public health

“…Moreover, there is a tendency of encroachment of human populations into wildlife habitat (Molyneux 2003). In many places in the world (though mainly in developing countries), former wildlife territory is gradually transformed into agricultural land, but the original inhabitants (e.g., rodents) are often still there (Mino et al 2007;Mohr et al 2007;Villafane and Busch 2007). Thus, disease burden in both humans and livestock can be enlarged.…”

Genetic distinction between contiguous urban and rural multimammate mice in Tanzania despite gene flow

“…We investigate the population genetic structure of M. natalensis in central lowland Tanzania, centred on an area where the animal's biology and population ecology have previously been studied intensively Mohr et al, 2007;Sluydts et al, 2007). We sampled across a 180-km transect, along which the landscape includes agricultural land in a rural setting, natural woodland, rivers, roads and a central city: Morogoro, where the human population has expanded by almost a factor of 30 since 1948 (8000-228 000 in 2002) (Mtatifikolo, 1997;National Bureau of Statistics, 2006).…”