Browsing by Author "Makundi, Rhodes"

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Arenavirus dynamics in experimentally and naturally infected rodents
(EcoHealth Alliance, 2017-06) Marien, Joachim; Borremans, Benny; Gryseels, Sophie; Broecke, Bram Vanden; Becker-Ziaja, Beate; Makundi, Rhodes; Massawe, Apia; Reijniers, Jonas; Leirs, Herwig
Infectious diseases of wildlife are typically studied using data on antibody and pathogen levels. In order to interpret these data, it is necessary to know the course of antibodies and pathogen levels after infection. Such data are typically collected using experimental infection studies in which host individuals are inoculated in the laboratory and sampled over an extended period, but because laboratory conditions are controlled and much less variable than natural conditions, the immune response and pathogen dynamics may differ. Here, we compared Morogoro arenavirus infection patterns between naturally and experimentally infected multimammate mice (Mastomys natalensis). Longitudinal samples were collected during three months of bi-weekly trapping in Morogoro, Tanzania, and antibody titer and viral RNA presence were determined. The time of infection was estimated from these data using a recently developed Bayesian approach, which allowed us to assess whether the natural temporal patterns match the previously observed patterns in the laboratory. A good match was found for 52% of naturally infected individuals, while most of the mismatches can be explained by the presence of chronically infected individuals (35%), maternal antibodies (10%), and an antibody detection limit (25%). These results suggest that while laboratory data are useful for interpreting field samples, there can still be differences due to conditions that were not tested in the laboratory.
Community structure and seasonal abundance of rodents of maize farms in Southwestern Tanzania
(Belg. J. Zool, 2005-12) ODHIAMBO, Richard; Makundi, Rhodes; Leirs, Herwig; Verhagen, Ron
Community characteristics and seasonal abundance of rodents were investigated in a small-scale maize field-fallow land mosaic in southwestern Tanzania between February 2001 and May 2002. During the study, a total of 2568 rodents were captured in 9150 trapnights giving a 28 % trap success. Also shrews of the genus Croci- dura (Soricidae) were recorded. Mastomys natalensis comprised the highest proportion of rodents caught account- ing for 82.9 % of all captures. Other rodent genera captured included : Tatera, Saccostomus, Graphiurus, and Steat- omys. Relative densities as measured by both trap success and the number of rodents per hectare, and biomass varied between seasons with and without crop in the field but not between habitat types. The work reports seasonal- ity in breeding for the two most commonly trapped species, Mastomys natalensis and Tatera leucogaster.
Effects of land use on plague (Yersinia pestis) activity in rodents in Tanzania
(American Society of Tropical Medicine and Hygiene, 2015) McCauley, Douglas J.; Salkeld, Daniel J.; Young, Hillary S.; Makundi, Rhodes; Dirzo, Rodolfo; Eckerlin, Ralph P.; Lambin, Eric F.; Gaffikin, Lynne; Barry, Michele; Helgen, Kristofer M.
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.
"Gairovirus,anovelarena virusof the widespread Mastomys natalensis: genetically divergent,but ecologically similar to Lassa and Morogoro viruses
(ElsevierInc, 2015) Gryseels, Sophie; Rieger, Toni; Oestereich, Lisa; Cuypers, Bart; Borremans, Benny; Makundi, Rhodes; Leirs, Herwig; Günther, Stephan; Goüy de Bellocq, Joëlle
Despite itsnearpan-Africanrange,theNatalmultimammatemouse, Mastomysnatalensis, carriesthe human pathogenLassavirusonlyinWestAfrica,whiletheseeminglynon-pathogenicarenaviruses Mopeia, Morogoro,andLunahavebeendetectedinthissemi-commensalrodentinMozambique/ Zimbabwe,TanzaniaandZambia,respectively.Here,wedescribeanovelarenavirusin M. natalensis from Gairo districtofcentralTanzania,forwhichweproposethename “Gairo virus”. Surprisingly,thevirusis not closelyrelatedwithMorogorovirusthatinfects M. natalensis only 90kmsouthofGairo,butclusters phylogeneticallywithMobala-likevirusesthatinfectnon-M. natalensis host speciesinCentralAfrican RepublicandEthiopia.Despitetheevolutionarydistance,Gairovirussharesbasicecologicalfeatures with theother M. natalensis-borne virusesLassaandMorogoro.Ourdatashowthat M. natalensis, carrying distantlyrelatedviruseseveninthesamegeographicalarea,isapotentreservoirhostfora varietyofarenaviruses.
Mopeia Virus– related Arenavirus in Natal Multimammate Mice, Morogoro, Tanzania
(2009-12-12) Günther, Stephan; Hoofd, Guy; Charrel, Remi; Röser, Christina; Becker-Ziaja, Beate; Lloyd, Graham; Sabuni, Christopher; Verhagen, Ron; Groen, Guido van der; Kennis, Jan; Katakweba, Abdul; Machang’u, Robert; Makundi, Rhodes; Leirs, Herwig
A renaviruses are segmented negative-strand RNA vi- ruses. Their natural hosts are various rodent species. The virus family comprises several human pathogens caus- ing hemorrhagic fever, namely Machupo, Guanarito, Junin, Sabia, and Chapare viruses in South America, and Lassa and Lujo viruses in Africa (1–3). In addition, Africa har- bors arenaviruses that are not linked with human disease: Mobala, Ippy, Mopeia, and Kodoko viruses (4–7). We con- ducted a systematic search in wildlife in Tanzania to iden- tify new African arenaviruses.
Presence of Mopeia Virus, an African Arenavirus, Related to Biotope and Individual Rodent Host Characteristics: Implications for Virus Transmission
(2011) Borremans, Benny; Leirs, Herwig; Gryseels, Sophie; Gu¨ nther, Stephan; Makundi, Rhodes; de Bellocq, Joe¨ lle Gou¨ y
The East African Mopeia virus (MOPV) is an arenavirus closely related to the highly pathogenic West African Lassa virus, even sharing the same reservoir rodent host Mastomys natalensis. Because MOPV is not known to cause human disease, it offers a unique alternative for studying Lassa virus transmission. We investigated how habitat, population density, and host characteristics are related to MOPV occurrence in M. natalensis populations in Morogoro, Tanzania. In 3 contrasting habitats, 511 M. natalensis individuals were trapped, 12.1% (58/480 tested individuals) of which tested seropositive for antibodies and 8.4% (41/489 tested individuals) for MOPVRNA. Although population densities differ among habitats, density and habitat were not significantly correlated to MOPV-RNA or antibody presence. Antibody presence was not significantly correlated with any host characteristics. In contrast, MOPV-RNA presence was inversely related to weight, age, sexual maturity, and body mass index. The model with body mass index as predictor was the best at predicting infection probability. Thirty-five individuals were exclusively MOPV-RNA positive, 52 were exclusively antibody positive, and 6 were both MOPV-RNA and antibody positive. Interpreting these data using experimental infection results from studies on other arenaviruses, this would mean that these infections were very recent, old, and roughly 1–3 weeks after infection, respectively. The higher RNA prevalence in juveniles implies vertical transmission, or that horizontal transmission occurs mainly in this age group due to lack of immunity, higher susceptibility, and/or higher juvenile contact rates. This study demonstrates the strength of combining information on antibody and RNA presence with host characteristics, and how this information can provide valuable insights into transmission dynamics.
Rodent outbrakes in Sub-Saharan Africa
(International Rice Research Institute, 2010) Leirs, Herwig; Sluydts, Vincent; Makundi, Rhodes
The impacts of rodents in both developing and developed countries are legendary. Myths and dogma about rodents and their outbreaks abound. They are imbedded in the culture and language of many societies. In many instances, it is the acceptance of these outbreaks by society that is our greatest challenge as crop protection special- ists or conservation biologists. The reason these episodic outbreaks become etched in the socio-cultural psyche from the sparsely populated uplands of Laos to the considerably more affl uent agricultural lands of Europe is that the impacts are often staggering—economically, socially, and even politically. There becomes a degree of acceptance of these impacts—rural people are born with rodents and will die with them. Their presence and impacts become a part of life; they become accepted and farmers become fatalistic about the losses they incur. Indeed, farmers in some areas of the Philippines say they “plant two rows of rice for rats, one for the birds, and seven for my family.” This need not be the case given the progress of our knowledge on the factors that cause population outbreaks of rodents. Indeed, it is our responsibility as scientists to document and make this knowledge widely available, particularly with more than 1 billion people suffering chronic hunger and rodent pests contributing signifi cantly to this burden (see Singleton 2003, Meerburg et al 2009). Moreover, in Asia, the 640 million people suffering from chronic hunger (FAO 2009) mainly rely on agriculture for their subsistence. The impetus for this collation of contributions from Asia, Africa, Oceania (Aus- tralia and New Zealand), Europe, and North America was an international conference on “Impacts of Rodent Outbreaks on Food Security in Asia” held following an increase in reports during 2007-09 of population outbreaks of rodents in the rice-cropping systems of Asia. In Asia and Africa, there are few widely accessible publications on these outbreaks. Most appear in the gray literature as brief reports in the annals of provincial or state departments of agriculture. They are doomed to gather dust and be lost to future generations. If this happens, then the lessons from previous outbreaks are not learned and therefore the infl uence of myth and dogma often outweighs evidence- based scientifi c knowledge developed from our successes and failures of management Rodent outbreaks: an age-old issue with a modern appraisal 1actions undertaken during previous outbreaks. One message, among many, that we hope to convey to readers is that we have made strong advances in our understand- ing of the factors that lead to rodent outbreaks (see also Singleton et al 2010). And, with such knowledge, local people and offi cials should be better placed to reduce the potentially devastating impacts associated with “fl oods” of rodents in the agricultural, periurban, and natural landscapes