Browsing by Author "Borremans, Benny"

Now showing 1 - 9 of 9

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.
Comparative study of movement patterns of Mastomys natalensis in irrigated rice and fallow fields in eastern Tanzania
(John Wiley & Sons Ltd, 2015) Mulungu, Loth S.; Borremans, Benny; Ngowo, V; Mdangi, Mashaka E.; Katakweba, Abdul S.; Tesha, P; Mrosso, Furaha P.; Mchomvu, M; Kilonzo, Bukheti S.
A 2-year capture–mark–recapture study was conducted to estimate home ranges and weekly travel distance of Mastomys natalensis (Smith 1834) in an irrigated rice ecosystem and fallow fields. We found that adults have larger home ranges than subadults in fallow fields but not in rice fields, indicating that fallow fields are more suitable for breeding. Travel distances were larger in rice fields, especially in the transplanting stage, during which rice fields are flooded and provide less food, causing movements into neighbouring fallow fields that then temporarily experience higher population density. A decrease in travel distance was observed in rice fields during the maturity stage, which can be explained by higher food availability and a more suitable, nonflooded situation. Movement of M. natalensis in rice-fallow mosaic landscapes thus seems to be driven by food availability and flooding status of the rice fields, which can be attributed to land use practices.
Does exploratory behavior or activity in a wild mouse explain susceptibility to virus infection?
(Oxford university press., 2017-09) Makundi, Rhodes H.; Massawe, Apia W; Leirs, Herwig; Hughes, Nelika K; Broecke, Bram V; Borremans, Benny; Mariën, Joachim
Exploration and activity are often described as trade-offs between the fitness benefits of gathering information and resources, and the potential costs of increasing exposure to predators and para- sites. More exploratory individuals are predicted to have higher rates of parasitism, but this relationship has rarely been examined for virus infections in wild populations. Here, we used the multimammate mouse Mastomys natalensis to investigate the relationship between exploration, activity, and infection with Morogoro virus (MORV). We characterized individual exploratory behav- ior (open field and novel object tests) and activity (trap diversity), and quantified the relationship between these traits and infection status using linear regression. We found that M. natalensis expresses consistent individual differences, or personality types, in exploratory behavior (repeat- ability of 0.30, 95% CI: 0.21–0.36). In addition, we found a significant contrasting effect of age on ex- ploration and activity where juveniles display higher exploration levels than adults, but lower field- activity. There was however no statistical evidence for a behavioral syndrome between these 2 traits. Contrary to our expectations, we found no correlation between MORV infection status and exploratory behavior or activity, which suggests that these behaviors may not increase exposure probability to MORV infection. This would further imply that variation in viral infection between individuals is not affected by between-individual variation in exploration and activity.
"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.
Laboratory and field tests of Carbaryl 5% against fleas in Lushoto district, Tanzania
(2015-04) Katakweba, Abdul A.S; Mhamphi, Ginethon. G; Mwalimu, Dismas C.; Mchau, Geophrey; Mbise, Thomas J.; Lugendo, Ramadhani M; Borremans, Benny; Kilonzo, Bukheti S.
Background and Objective: Lushoto district has been an active focus of plague disease since 1980 and many pesticides were used to control rodents and fleas from 1980 to 2003 when outbreaks occurred yearly. For over seven years ago commercial Carbaryl 5% powder has been used for controlling fleas in the area. However, there is no current research to substantiate its effectiveness either in the laboratory or in the field. Methods: Immature stages of Xenopsylla brasiliensis were collected from two villages in Lushoto and transported to Sokoine University of Agriculture (SUA), Morogoro and reared in an insectary to stock colony. Known weights of commercial Carbaryl 5% powder were thoroughly mixed with known weights of clean fine sand as to obtain a final concentration of 0.05% (WW) of Carbaryl/sand mixture. The same concentration was suspended in 50cc distilled water and pieces of filter paper were soaked in the solution, left at room temperature until the suspension was fully adsorbed and the papers were left to dry. Adult fleas of mixed ages and of both sexes were obtained from the stock colony and exposed to both Carbaryl/sand mixture and Carbaryl-adsorbed filter papers for various periods of time. Field trials were carried out at Manolo and Viti villages where house and rodent flea indices were determined before and after dusting with commercial Carbaryl 5% powder. Results: In the laboratory tests, 100% mortality occurred at 90 minutes exposure in Carbaryl/sand mixture experiments and at 35 minutes exposure to Carbaryl-adsorbed filter papers. LT50 in both sets of exposure was 48.2 min and 23.1 min in Carbaryl/sand mixture and Carbaryl-coated filter papers tests respectively. In field trials, X. brasiliensis and Pulex irritans were the most abundant flea species. Post-dusting flea populations were significantly lower in treated than in control houses (p=0.028). House flea indices dropped from 7.7 to 0.33 and 37.8 to 0 in Viti and Manolo villages respectively at 3 months post-dusting. Conclusion: Commercial Carbaryl 5% powder in current use was still effective against potential flea vectors in Lushoto.
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.
Prevalence of haemoparasites, leptospires and coccobacilli with potential for human infection in the blood of rodents and shrews from selected localities in Tanzania, Namibia and Swaziland
(African Zoology, 2012-02) Katakweba, Abdul A.S.; Mulungu, Loth S.; Eiseb, Seth J.; Mahlaba, Themb’alilahlwa A.; Makundi, Rhodes H.; Massawe, Apia W.; Borremans, Benny; Belmain, Steven R.
The prevalence of haemoparasites, leptospirosis and Yersinia pestis was investigated in rodents and shrews from Tanzania, Namibia and Swaziland. Blood smears originating from rodents and shrews from the three countries indicated the presence of Trypanosoma lewisi (72.7%; n =950), Bacillus spp. (25.6%; n =950), Borrelia sp. (0.01%; n =950) and bipolar coccobacilli (0.01%; n =950). The blood smears from Namibia (n =26) had no haemoparasites while only 1.33% (n =75) of those from Swaziland showed presence of T. lewisi. Leptospira interrogans was found in rodent blood sera from Tanzania in the following serogroup proportions (n =350): Icterohaemorrhagiae (10.29%), Pomona (2.86%), Hardjo (1.14%), Bullum (0.86%), Grippotyphosa (1.43%) and Canicola (1.14%). Serodiagnosis of antibodies against the F1 antigen of Y. pestis using the enzyme linked immunosorbent assay (ELISA) was negative for all the serum samples from central Tanzania, while two samples of serum from two species of rodents, Rhabdomys pumilio and Gerbilliscus leucogaster, collected in the Kavango Region of Namibia were positive. These results suggest an enzootic plague activity in this region in Namibia. It is concluded that zoonotic agents, that are infectious to humans, are prevalent in rodents and shrews in the three countries, and that local communities should apply rodent control measures to reduce the risk of human infections.
Sympatric occurrence of 3 arenaviruses, Tanzania
(Sokoine University of Agriculture, Tanzania., 2010-04) Bellocq, J. Goüy de; Borremans, Benny; Katakweba, Abdul; Makundi, Rhodes H.; Baird, Stuart J.E.
To determine the specifi city of Morogoro virus for its reservoir host, we studied its host range and genetic diversity in Tanzania. We found that 2 rodent species other than Mastomys natalensis mice carry arenaviruses. Analysis of 340 nt of the viral RNA polymerase gene showed sympatric occurrence of 3 distinct arenaviruses.
Sympatric Occurrence of 3 Arenaviruses, Tanzania
(2010-04) Goüy de Bellocq, Joëlle; Borremans, Benny; Katakweba, Abdul; Makundi, Rhodes H.; Baird, Stuart J.E; Becker-Ziaja, Beate; Günther, Stephan; Leirs, Herwig
To determine the specifi city of Morogoro virus for its reservoir host, we studied its host range and genetic diversity in Tanzania. We found that 2 rodent species other than Mastomys natalensis mice carry arenaviruses. Analysis of 340 nt of the viral RNA polymerase gene showed sympatric occurrence of 3 distinct arenaviruses.