Articles, Conference and Workshop Papers Collection

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ProxLogs: Miniaturised proximity loggers for monitoring association behaviour in small mammals
(Hystrix, the Italian Journal of Mammalogy, 2021) Kirkpatrick, Lucinda; Olivares, Ivan Hererra; Massawe, Apia; Sabuni, Christopher; Leirs, Herwig; Berkvens, Rafael; Weyn, Maarten
The ability to monitor associations between wild animals is essential for understanding the processes governing gene transfer, information transfer, competition, predation and disease transmission. Until recently, such insights have been confined to large, visible or captive animals. However, the rapid development of miniature sensors for consumer electronics is allowing ecologists to monitor the natural world in ways previously considered impossible. Here we describe miniature (<1g) proximity loggers we have developed that use Bluetooth Low Energy transmission to register contacts between individuals. Our loggers are open source, low cost, rechargeable, able to store up to 2000 contacts, can be programmed in situ and can download data remotely or through a mobile phone application, increasing their utility in remote areas or with species which are challenging to recapture. We successfully trialled our loggers in a range of field realistic conditions, demonstrating that Bluetooth Low Energy is capable of logging associations in structurally complex habitats, and that changes in received signal strength can be equated to short range changes in distance between loggers. Furthermore, we tested the system on starlings (Sturnidae vulgaris).
A comparative assessment on rodent impacts and cultural perceptions of ecologically based rodent management in three Afro-Malagasy farming regions
(International Society of Zoological Sciences, 2020) Constant, Natasha Louise; Swanepoel, Lourens; Williams, Samual T.; Soarimalala, Voahangy; Goodman, Steven M.; Massawe,Apia T.; Mulungu, Loth S.; Makundi, Rhodes H.; Mdangi, Mashaka E.; Taylor, Peter John; Belmain, Steven R.
Rodents generate negative consequences for smallholder farmers in Africa that directly impact household and livestock damage, food security and public health. Ecologically Based Rodent Management (EBRM) seeks sustainable solutions for the mitigation of rodent damage through assessments of rodent population dynamics, agro-ecosystems and socio-cultural contexts. We adopt a comparative approach across three rural Afro-Malagasy smallholder farming regions in South Africa, Tanzania and Madagascar to assess the household impacts of rodent pests and current perceptions and preferences associated with several rodent control measures. We conducted focus groups questionnaires and interviews in different study site locations. Rodents assert multiple impacts on Afro-Malagasy farmers demonstrating recurrent and emerging agricultural and household costs, and public health impacts. We identify a significant knowledge gap in educating communities about the application of different EBRM approaches in favour of acute poisons that are perceived to be more effective. Cultural issues and taboos also have a significant impact on the social acceptance of rodent hunting as well as biological control using indigenous predators. We advocate for an enhanced investigation of the socio-cultural beliefs associated with different rodent practices to understand the factors underlying social acceptance. A collaborative approach that integrates the perspectives of
Ecologically based rodent management in Africa: potential and challenges
(CSIRO, 2011) Makundi, Rhodes H.; Massawe, Apia W.
Rodent management in agriculture remains a major challenge in developing countries where resource-poor farmers are ill equipped to deal with pest species. It is compounded by unpredictable outbreaks, late control actions, lack of/or inadequate expert interventions, expensive rodenticides and other factors. Ecologically based rodent management (EBRM) is recommended as the way forward for rodent management in Africa. EBRM relies on understanding the ecology of pest species and formulating this knowledge into management programs. The present paper evaluates the potential for establishing EBRM in Africa and the challenges that have to be overcome to implement it. The major constraints for establishing EBRM in Africa include the absence of key studies on the taxonomy and ecology of rodents, inadequate research on EBRM, lack of knowledge by farmers on available technologies and agricultural policies that are unfavourable. The development of EBRM and its success in Asia is a strong encouragement to African scientists to develop similar management strategies for the most important pest species such as the multimammate rats, Mastomys natalensis. EBRM initiatives such as the Development of Ecologically Based Rodent Management for the Southern Africa Region (ECORAT) project undertook studies on e.g. rodent ecology, taxonomy, knowledge, attitude and practices and rodent–human interactions in rural agricultural communities. Through this project, EBRM interventions were introduced in Tanzania, Swaziland and Namibia to provide solutions to local rodent-pest problems. Intervention actions including community-based intensive trapping of rodents, habitat manipulation and sanitary measures demonstrated that the impacts of rodents on communities could be drastically reduced. EBRM programs in Africa must address how to change attitudes of target communities, building scientific capacity, implanting rodent-management skills by translating the developed technologies and strategies into simple understandable and easy-to-implement actions and influencing policy makers to accept the concepts and practices to be introduced. Further, we need to demonstrate that EBRM is economically feasible and sustainable and that through community participation, EBRM will become deeply rooted in those communities.
Relationship between population density and viral infection: a role for personality?
(Wiley, 2019) Broecke, Bram Vanden; Mariën, Joachim; Sabuni, Christopher Andrew; Mnyone, Ladslaus; Massawe, Apia W.; Matthysen, Erik; Leirs, Herwig
Conspecific density and animal personality (consistent among‐individual differences in behavior) may both play an important role in disease ecology. Nevertheless, both factors have rarely been studied together but may provide insightful information in understanding pathogen transmission dynamics. In this study, we investigated how both personality and density affect viral infections both direct and indirectly, using the multimammate mice (Mastomys natalensis) and Morogoro arenavirus (MORV) as a model system. Using a replicated semi‐natural experiment, we found a positive correlation between MORV antibody presence and density, suggesting that MORV infection is density‐dependent. Surprisingly, slower explorers were more likely to have antibodies against MORV compared to highly explorative individuals. However, exploration was positively correlated with density which may suggest a negative, indirect effect of density on MORV infection. We have shown here that in order to better understand disease ecology, both personality and density should be taken into account.
Malaria prevalence in asymptomatic and symptomatic children in Kiwangwa, Bagamoyo district, Tanzania
(Malaria Journal, 2017) Sumari, Deborah; Mwingira, Felista; Selemani, Majige; Mugasa, Joseph; Mugittu, Kefas; Gwakisa, Paul
Malaria prevalence continues to decline across sub-Saharan Africa as a result of various intervention strategies. However, the diseases still poses a public health concern in the region. While symptomatic malaria is recog- nized and treated, asymptomatic infections become increasingly important for interrupting transmission. A cross-sec- tional survey was conducted to assess malaria prevalence in symptomatic and asymptomatic children in Kiwangwa ward in Bagamoyo District in Tanzania. Methods: Four hundred school-aged children in Kiwanga ward were recruited in the study; 200 from Kiwangwa dispensary and 200 from nearby schools. Primary health parameters were examined and blood samples collected and examined for Plasmodium falciparum prevalence using rapid diagnostic test (RDT), light microscopy (LM) and reverse transcription quantitative PCR (RT-qPCR) targeting transcripts of A-type 18s rRNA of P. falciparum. Gametocytes were detected by LM and RT-qPCR targeting transcripts of gametocyte specific marker, Pfs25. Results: Overall P. falciparum prevalence was 73.3, 40.8 and 36.3% by RT-qPCR, RDT and LM in the study area, respec- tively (P < 0.001). As expected symptomatic children had a significantly higher prevalence of 89, 67.5 and 64.5% by qPCR, RDT and LM, compared to 57.5, 14 and 8% in the asymptomatic group, respectively. However, gametocyte prevalence in asymptomatic individuals was higher by both LM (2%) and qPCR (14%) than in symptomatic individuals LM (0.5%) and qPCR (3%). Conclusions: A substantial difference in prevalence of symptomatic and asymptomatic infections observed in Kiwangwa ward underpins the use of molecular tools in malaria surveillance aiming at estimating prevalence and transmission. Notably, the higher gametocytaemia observed in asymptomatic children indicates the reservoir infec- tions and points to the need for detection and treatment of both asymptomatic and symptomatic malaria.
Antifungal effect of a local bacillus subtilis, isolate TM07, on Fusarium oxysporum f.sp. Lycopersici in Morogoro, Tanzania
(Tanzania Journal of Agricultural Sciences, 2021) Machang’u, R; Maerere, A.; Mwinuka, B; Nashon, J; Makingi, G
Fusarium oxyporum f.sp. lycopersici causes tomato wilt, a severe disease that leads to extensive yield and quality loss of tomatoes in Tanzania. Management of Fusarium infection is particularly challenging given the health and environmental concerns over continued use of chemical pesticides on horticultural food crops. However, there is an increasing focus towards the use of biocontrol agents to combat phytopathogens worldwide. In this study, bacterial isolates from tomato rhizosphere were screened for their antagonistic activity in vitro on F. oxysporum. Based on its superior effectiveness, one isolate, designated TM07, was selected and characterized as Bacillus subtilis by morphological, biochemical and molecular procedures. On potato dextrose agar (PDA) the isolate showed an appreciable degree of radial growth inhibition (RGI) of 40.5% of the Fusarium, compared to control (55.9%). Further investigations are recommended to elucidate on the mechanism behind the inhibitory effect of isolate TM07. In vivo studies are also recommended to assess the possibility of applying the B. subtilis, isolate TM07, as a local biocontrol agent of Fusarium wilt of tomato and other susceptible crops.
Mice, rats, and people: the bio-economics of agricultural rodent pests
(The Ecological Society of America, 2003) Stenseth, Nils Chr; Leirs, Herwig; Skonhoft, Anders; Davis, Stephen A; Pech, Roger P; Andreassen, Harry P; Singleton, Grant R; Lima, Mauricio; Machang’u, Robert S; Makundi, Rhodes H; Zhang, Zhibin; Brown, Peter R; Shi, Dazhao; Wan, Xinrong
Mice, rats, and other rodents threaten food production and act as reservoirs for disease throughout the world. In Asia alone, the rice loss every year caused by rodents could feed about 200 million people. Damage to crops in Africa and South America is equally dramatic. Rodent control often comes too late, is inefficient, or is considered too expensive. Using the multimammate mouse (Mastomys natalensis) in Tanzania and the house mouse (Mus domesticus) in southeastern Australia as primary case studies, we demonstrate how ecology and economics can be combined to identify management strategies to make rodent control work more efficiently than it does today. Three more rodent–pest systems – including two from Asia, the rice-field rat (Rattus argentiventer) and Brandt's vole (Microtus brandti), and one from South America, the leaf-eared mouse (Phyllotis darwini) – are presented within the same bio-economic perspective. For all these species, the ability to relate outbreaks to interannual climatic variability creates the potential to assess the economic benefits of forecasting rodent outbreaks
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.
African centre of excellence for innovative rodent pest management and biosensor technology development (ACE IRPM and BTD- Rat-Tech)
(2016-10) Makundi, R. H; Massawe, A.W
Rodents are some of the most serious mammalian pests the world over. However, their economic and social impact is not quantified in Sub-Saharan Africa. Moreover, while some of the zoonotic diseases attributed to rodents such as Lassa fever and bubonic plague are endemic in rural Africa, occasionally leading to serious outbreaks, more often than not, rodent-borne diseases are not recognized, and hence are inadequately managed. The African Centre of Excellence (ACE) in Innovative Rodent Pest Management and Biosensor Technology Development (IRPM and BTD) will enhance scientific knowledge, Technology and Innovation (STI) on Rodent Pest Management in Africa. The IRPM and BTD activities will incorporate biosensor technology using trained rats for land mine detection and support their operational deployment to complement existing technologies to free mine afflicted lands in Africa and elsewhere and release these for safe use by humans (settlement, agriculture, mining, livestock, etc.). Novel diagnostic approaches are a key component to tackling Tuberculosis epidemic, yet in resource-limited settings in Africa, the latest advanced diagnostic technologies are lacking. Trained rats are efficient and reliable TB diagnostic biosensor technology. The ACE for IRPM and BTD will build capacity through training at the MSc and PhD levels in rodent taxonomy, ecology, innovative STI in rodent management and biosensor technology. IRPM and BTD will establish basic and applied research programs for African scientists to pursue high-impact projects in rodent management, understanding the impact of zoonotic diseases on communities and their mitigation, and how best to use biosensor technology for detecting landmines and diagnosis of diseases. A minimum of 60 Master of Science and 32 PhD students will be trained and faculty exchange between regional higher education institutions will be supported. Short courses will be conducted focusing on dissemination of sustainable STI solutions to rodent problems in Africa. Research will be focused to solve regional rodent problems that impact on rural communities in Africa.
Jigger flea infestation (tungiasis) in rural western Tanzania: high prevalence and severe morbidity
(Elsevier, 2011-12) Mazigo, H.D; Bahemana, E; Konje, E.T; Dyegura, O; Mnyone, L.L; Kweka, E.J; Kidenya, B.R; Heukelbach, J
Epidemiologic and clinical data on the parasitic skin disease tungiasis are limited from sub-Saharan Africa, and virtually nonexistent from the East African region. We performed a community-based cross-sectional study in two villages in Kasulu district, western Tanzania. Study participants were examined for the presence of tungiasis and disease-associated morbidity. In total, 586 individuals >5 years of age were enrolled, and 249 (42.5%; 95% CI: 38.5-46.5) diagnosed with tungiasis. The ≥45 year-olds showed highest prevalence of tungiasis (71.1%) and most severe parasite load (median number of embedded fleas: 17.5; interquartile range: 15-22.5). Prevalence was slightly, but not significantly, higher in males than in females (45.3 vs 39.7%; p=0.17). Itching (68.3%), pain (38.6%) and ulcers (30.1%) were common; 22.1% of individuals found it difficult to walk due to tungiasis, and in 21.3% loss of toenails was observed. Considering the high prevalence and considerable morbidity in the population, we conclude that tungiasis is a public health threat in the study villages and that the disease needs to be recognized by health authorities. Future studies on risk factors, animal reservoirs and evidence-based control measures are needed.
Quantitative analysis of risk factors associated with brucellosis in livestock in the Katavi-Rukwa ecosystem, Tanzania
(Springer.com, 2015-11-12) Assenga, J A; Matemba, E L; Malakalinga, J J; Muller, S K; Kazwala, R R
t Brucellosis is a neglected contagious bacterial diseaseofpublichealthand economicimportance.Nevertheless, its spread is not well known to many livestock farmers. Unmatched case control study was carried out to identify risk factors associated with brucellosis in cattle and goats at the herd level in Mpanda, Mlele and Nsimbo districts of Katavi region, in Tanzania between September 2012 and July 2013. A total of 138 adult respondents were selected randomly for the interview using a structured questionnaire. The criterion forinclusionwastohaveatleastoneBrucella-positiveanimal intheherdwhilethecontrolwaschosenfromamongtheherds whichtheseanimalstestednegative.Thepresenceofseropositive herds were statistically linked (P<0.1) by univariate analysis with such variables as lack of formal education amongtheherders;slaughteringofcattleorgoatsinthehousehold;thehistoryofoccurrenceofabortionintheherd;andthe historyofoccurrenceofretainedfoetalmembranesintheherd following parturition. However, in the multivariate analysis, lack of formal education among the herders and the previous history of occurrence of retained foetal membrane in the herd following parturition were significantly associated with Brucella seropositive (P<0.05). This study suggests the need forraisingcommunityawarenessontheriskfactorsassociated with the transmission of brucellosis between animals and humans and the implementation of disease prevention and control programmes.
Relationship between sampling intensity and precision for estimating damage to maize caused by rodents
(Blackwell Publishing and IOZ/CAS, 2007) Mulungu, Loth S.; Massawe, Apia W.; Makundi, Rhodes H.; Leirs, Herwing
In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodent damage. We used the systematic row sampling technique to provide data to achieve precision and accuracy in estimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maize in 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were used to simulate the sampling intensities that would provide precision and accuracy. The variations between estimates were plotted against the sampling intervals. The results of this study show that the relationship between average standardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plots caused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistently produced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to be made on the sampling intensity as a function of required precision using the systematic row sampling technique in maize fields. Key words: rodents, sampling interval, simulation, standard curve, systematic row sampling.
Impact of spatio-temporal simulations of rat damageon yield of rice (Oryza sativa L.) and implications forrodent pest management
(Taylor & Francis Group, 2014-11) Mulungu, L, S.; Lagwen, P, P.; Mdangi, M, E.; Kilonzo, B, S.; Belmain, S, R.
Rodents often damage crops throughout the growing season, from germination to harvest, thus making it difficult tounderstand the cumulative effects of rodent damage for crops such as rice that are able to partially compensate for damage.Compensation can make it difficult to understand the impact of variable rodent damage in terms of when the damageoccurs, its severity and thus when, whether and how rodent pests should be controlled. The compensatory responses of riceto simulated rat damage carried out at different growth stages and at different spatial levels of severity showed that higheryield was recorded during the wet season in comparison to the dry season. However, yield loss was observed during allcropping stages for all levels of simulated damage for wet and dry season crops, with significant compensation noted at thetransplanting [14 days after sowing (DAS)] and vegetative (45 DAS) stages. Only damage at the maturity (110 DAS) stageresulted in significant reductions in rice crop yield. Seasonal differences suggest water availability was an important factorthat perhaps enhanced rice production. The ability of rice to compensate for early rodent damage could potentially reducea farmer’s perception of damage. However, failing to control rodents at these earlier crop growth stages could lead toincreased rodent populations at the time of maturity when compensatory effects are limited.
Population dynamics and breeding patterns of multimammate mouse,Mastomys natalensis (Smith1834),inirrigatedriceﬁeldsinEastern Tanzania
(Willey Online Library, 2012-06-21) Mulungu, L S; Ngowo, V; Mdangi, M; Katakweba, A S; Tesha, P; Mrosso, P F; Mchomvu, M; Sheyo, P M; Kilonzo, B S
Multimammate mice are the most important vertebrate pests in Sub-Saharan Africa and are also reservoirs of many zoonotic diseases, including sylvan plague. This study investigated the population dynamics and breeding patterns of this mouse in irrigated rice croppings ystems in easternTanzania. RESULTS:The multimammate mouse,Mastomys natalensis,population varied with habit at nd months.Fallow land had a more abundant population than rice ﬁelds. The highest population peak was observed during the dry season from July to October. Mastomysnatalensis is sexually active throughout the year in the study area, although it reaches the highest level in June and December when rice is at the maturity stage. This suggests that breeding is highly inﬂuenced by the presence of a rice crop in both seasons. More juvenile individuals were recorded in August and September, indicating that they were produced in the previous breeding months. The sex ratio of M.natalensis was not skewed to either males or females, indicating that it was at parity. CONCLUSION: Rodent population dynamics during the study periods in all habitats indicated that high birth rates accounted for the rapid population growth and turnover. Regular control and sustainable operations are thus essential if rodent pest populations are to be kept within tolerablel imits.
Population dynamics and breeding patterns of Multi-mammate mouse, Mastomys natalensis (Smith 1834) in irrigated rice field in Eastern Tanzania
(Wiley Online Library, 2012-06-21) Mulungu, Loth; Ngowo, Victoria; Mdangi, Mashaka; Katakweba, Abdul; Tesha, Protas; Mrosso, Furaha; Mchomvu, Mary; Sheyoe, Paul; Kilonzo, Bukhet
BACKGROUND: Multimammate mice are the most important vertebrate pests in Sub-Saharan Africa and are also reservoirs of many zoonotic diseases, including sylvan plague. This study investigated the population dynamics and breeding patterns of this mouse in irrigated rice cropping systems in eastern Tanzania. RESULTS:Themultimammatemouse,Mastomysnatalensis,populationvariedwithhabitatandmonths.Fallowlandhadamore abundant population than rice ﬁelds. The highest population peak was observed during the dry season from July to October. Mastomys natalensis is sexually active throughout the year in the study area, although it reaches the highest level in June and December when rice is at the maturity stage. This suggests that breeding is highly inﬂuenced by the presence of a rice crop in both seasons. More juvenile individuals were recorded in August and September, indicating that they were produced in the previous breeding months. The sex ratio of M.natalensis was not skewed to either males or females, indicating that it was at parity. CONCLUSION: Rodent population dynamics during the study periods in all habitats indicated that high birth rates accounted for the rapid population growth and turnover. Regular control and sustainable operations are thus essential if rodent pest populations are to be kept with intolerable limits.
Pattern of ovulation in an ancient, solitary mole-rat lineage: Heliophobius argenteocinereus emini from Tanzania
(CORNELL UNIVERSITY, 2017) Katandukila, J. V.; Ngalameno, M. K.; Mgode, G. F.; Bastos, A. D. S.; Bennett, N. C.
Heliophobius is an ancient subterranean rodent lineage within the family Bathyergidae, that displays seasonal breeding over a broad geographical range. In East Africa, reproduction in these solitary mole-rats has been shown to coincide with the long rains, but it is not clear whether Heliophobius argenteocinereus emini (Noack 1894) from Tanzania is an induced or spontaneous ovulator. To address this, urinary progesterone was measured every second day over a period of 132 days in six wild-caught females subjected to three sequential experimental treatments. In the first, control (C) treatment, females were housed singly for a period of 44 days, following which non-physical contact (NPC) with a vasectomised male and then physical contact (PC) with the same vasectomised male, occurred, in each of the subsequent 44-day treatments. Non-invasive monitoring of ovarian cyclicity confirmed that mean urinary progesterone concentration was higher during PC than during either NPC or C, despite the fact that the males were vasectomised and incapable of fertilising the females. Examination of penile morphology revealed that males possess epidermal projections on the glans penis which probably bring about cervical stimulation during coitus. These findings together with the female progesterone profiles imply the species is an induced ovulator stimulated by penile intromission.
Effectiveness of the domestic cat (Felis silvestris catus) urine extracts odour against commensal rodents
(COSTECH, 2017) Mulungu, L. S.; Ngowo, V.; Mdangi, M. E.; Magadula, A. J. J.; Kapingu, M.; Mbukwa, E.; Mgina, C. A.; Mwatawala, M. W.; Kichuki, M.; Mwakalobo, A. S.; Mgode, G. F.
The aim of this study was to investigate the effects of an extract of cat urine odour as a repellant of commensal rodents in houses. Cat urine was drawn and stored frozen in universal bottles at -20 0 C until use. The stored cat urine was then thawed and mixed with maize starch to form a thick dough and then granulated and dried at room temperature before being packed in a hermetically closed jar. Initially, rodent foot marks on tracking soot coat tiles were used to estimate the rat population before the cat urine extracts application. Twenty households with high and low rodent activities were selected purposively in the study area. Ten houses were treated with the urine extracts and ten others were kept untreated (control). Both treated and untreated houses were categorized at two levels (i.e. low and high rodent activities) as determined by the tracking tile foot prints. One tracking tile was placed in each of the selected houses and rodent foot marks were counted. Collected data were subjected to analysis of variance and the results showed a significant difference in rodent activities which however, depended on the sex of the cat that donated the urine base. Female cat urine extract repelled significantly more commensal rodents as compared to male cat urine extract. The repellent effect was observed from day 1 to 4; but not beyond. Our findings suggest that cat urine odour has the potential to repel commensal rodent pest species; with female cat urine being more effective than male cat urine.
Using giant african pouched rats to detect human tuberculosis: A review
(Pan African Medical Journal, 2015-08-31) Poling, A.; Mahoney, A.; Beyene, N.; Mgode, G.; Weetjens, B.; Cox, C.; Durgin, A.
Despite its characteristically low sensitivity, sputum smear microscopy remains the standard for diagnosing tuberculosis (TB) in resource-poor countries. In an attempt to develop an alternative or adjunct to microscopy, researchers have recently examined the ability of pouched rats to detect TB-positive human sputum samples and the microbiological variables that affect their detection. Ten published studies, reviewed herein, suggest that the rats are able to detect the specific odor of Mycobacterium tuberculosis , which causes TB, and can substantially increase new-case detections when used for second-line TB screening following microscopy. Further research is needed to ascertain the rats' ability to detect TB in children and in HIV-positive patients, to detect TB when used for first-line screening, and to be useful in broad-scale applications where cost- effectiveness is a major consideration.
Tuberculosis detection by pouched rats: Opportunities for reinforcement under low-prevalence conditions
(2017 Elsevier B.V, 2017) Edwards, T. L.; Ellis, H.; Watkins, E. E.; Mulder, C.; Mgode, G.; Cox, C.; Poling, A.
Giant African pouched rats (Cricetomys ansorgei) have been employed successfully in two operational tuberculosis-detection projects in which they sniff sputum samples from symptomatic individuals who have visited tuberculosis clinics. The prevalence of pulmonary tuberculosis in this population is high, approximately 20% in the regions where the rats have been used. If the rats are to be used to screen individuals from lower- prevalence populations, their performance under such conditions must first be evaluated. In this study, the prevalence of tuberculosis-positive samples presented to eight pouched rats was reduced to approximately 5%, and the percentage of known-positive samples included as opportunities for reinforcement was varied in sequence from 10 to 8, 6, 4, 2, 4, and 2. Liquid food reinforcers were delivered for identification responses to known-positive samples and at no other time. The rats’ accuracy was clinically and statistically significantly lower at 2% than at the other values. These results indicate that the rats can perform well in low-prevalence scenarios but, if they are used under the conditions of the present study, at least 4% of the samples presented to them must be opportunities for reinforcement.
Active tuberculosis detection by pouched rats in 2014: more than 2,000 new patients found in two countries
(2016 Society for the Experimental Analysis of Behavior, 2016) Poling, A.; Beyene, N.; Valverde, E.; Mulder, C.; Cox, C.; Mgode, G.; Edwards, T. L.
Tuberculosis (TB) is a major problem in poor countries because sensitive diagnostic tools are unavail- able. In 2014, our pouched rats evaluated sputum from 21,600 Tanzanians and 9,048 Mozambicans whose sputum had previously been evaluated by microscopy, the standard diagnostic for TB. Evalua- tion by the rats revealed 1,412 new patients with active TB in Tanzania and 645 new patients in Mozambique, increases of 39% and 53%, respectively, when compared to detections by microscopy alone. These results provide further support for the applied use of scent-detecting rats.

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