Samuel Thumbi Mwangi
Clinical Assistant Professor & Director of Rabies Free Kenya
WSU Paul G Allen School for Global Animal Health
Center for Global Health Research, Kenya Medical Research Institute - https://www.kemri.org/
University of Nairobi Institute of Tropical and Infectious Diseases - http://unitid.uonbi.ac.ke/
University of Nairobi - Wangari Maathai Institute for Peace and Environment Studies - http://wmi.uonbi.ac.ke/
Thumbi Mwangi qualified as a veterinarian from the University of Nairobi and as an infectious disease epidemiologist from University of Edinburgh, before joining the Allen school to coordinate research and education activities in East Africa. Primarily based in East Africa, he leads a research group working on zoonoses and linkages between human and animal health.
My research is focused on understanding the epidemiology of infectious diseases in animals and people in the tropics, and designing programs that reduce their burden. I find working in field settings tackling these real health problems, with a fantastic group of collaborators and graduate students, as great fun, exciting and worth the while.
Education and Training
- 2013: Post-doc: Paul G Allen School for Global Animal Health, Washington State University
- 2012: PhD in infectious disease epidemiology – University of Edinburgh, UK
- 2008: Masters in Genetics and Animal Breeding – University of Nairobi, Kenya
- 2005: Veterinary Medicine and Surgery – University of Nairobi, Kenya
General Research / Expertise
My research is focused at the human-animal interface in East Africa investigating the relationship between animal health and productivity, and human health, nutrition and welfare. I use epidemiological methods to identify and quantify the main animal infections and their combinations (co-infections) responsible for animal morbidity, mortality and production losses, those that jump species to infect humans (zoonoses), and design innovative control strategies that reduce this dual burden of disease in people and their animals. We measure the impact of these interventions at the household level by determining improvement in health of household members, their nutritional status and overall household wealth. The goal of this research is to improve human health and livelihood among rural households in East Africa, through improvement of animal health and productivity, and reducing the risk of transmission of zoonotic diseases. Previously I worked on the epidemiology and molecular diagnostics of African animal trypanosomiasis, and on the consequences of hosts harboring multiple infections concurrently.
Together with colleagues, our research has informed the surveillance, diagnosis and control of zoonoses in the East Africa region. The region is endemic with several dozen zoonotic diseases, making the decision on which disease to focus on challenging. Our quantitative prioritization [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161576] of these diseases has provided a ranked list that health and veterinary departments can use to decide their resource allocation. We have studied distribution of zoonoses diseases, identified hotspot zones e.g areas at risk of outbreaks of Rift Valley fever [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0144570] and used these maps to target surveillance during high-alert periods for outbreaks occurring. For diseases such as rabies, our work has informed the development of the national strategic plan for the elimination of dog-mediated rabies by 2030 [http://zdukenya.org/wp-content/uploads/2012/09/National-Rabies-Elimination-Strategy.pdf]. We are conducting implementation research including developing tools [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5708230/] that improve the planning, efficiency and effectiveness of rabies elimination activities. To understand and quantify links between human and animal health, we have designed studies [http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0120761] estimating human illness that can be explained by animal illness, and how livestock ownership impacts household economics, access to health, food consumption and growth of children below 5 years of age [https://www.cambridge.org/core/services/aaop-caambridge-core/content/view/2280D58216FA4834DB293A7E78F8ECD0/S136898001600210Xa.pdf/child_height_gain_is_associated_with_consumption_of_animalsource_foods_in_livestockowning_households_in_western_kenya.pdf]. These data provides us with opportunities for interventions targeting animals that can affect health, nutrition and economic wellbeing of people living in close interactions with animals.
Taken together, my research is aimed at improving and understanding human health through the lens of animal health.
1. Surveillance, burden estimates and control of zoonotic diseases
Over 60% of the pathogens that infect man have their origin in animals. To minimize the risk of zoonotic diseases spreading from animals to humans, my research has included development of surveillance systems that simultaneously collect health data from people and the animals they own and using these data to increase our understanding of the relationship between human and animal health. Additionally, I conduct research aimed at estimating the burden of neglected zoonotic diseases such as brucellosis and anthrax, and testing interventions against zoonotic diseases such as vaccination against Rift Valley Fever disease. Below are some recent publications on the work described:
McElwain TF and Thumbi SM (2017) Animal pathogens and their impact on animal health, the economy, food security, food safety and public health. Rev. Sci. Tech. Off. Int. Epiz 36 (2)
Mosites E, Aol G, Otiang E, Bigogo G, Munyua P, Montgomery JM, Neuhouser ML, Palmer GH, Thumbi SM (2017) Child height gain is associated with consumption of animal-source foods in livestock-owning households in Western Kenya. Public Health Nutr. 2017 Feb;20(2):336-345
Munyua P, Bitek A, Osoro E, Pieracci EG, Muema J, Mwatondo A, Kungu M, Nanyingi M, Gharpure R, Njenga K, Thumbi SM (2016) Prioritization of Zoonotic Diseases in Kenya, 2015, PLoS One. 2016 Aug 24;11(8):e016157
Thumbi S.M, Njenga M.K, Marsh T.L, Noh S, Otiang E, Munyua P, Ochieng L, Ogola E, Yoder J, Audi A et al (2015) Linking human health and livestock health: a “One-Health” platform for integrated analysis of human health, livestock health, and economic welfare in livestock dependent communities. PLoS One Mar 23; 10(3): e0120761. PMCID: PMC4370696
Njenga MK, Njagi L, Thumbi S.M, Kahariri S, Githinji J, Omondi E, Baden A, Murithi M, Paweska J, Ithondeka P et al (2015) Randomized controlled field trial to assess the immunogenicity and safety of Rift Valley fever Clone 13 vaccine in livestock. PLoS Negl Trop Dis Mar 10; 9(3): e0003550. PMCID: PMC4355591
2. Multiple infections and clinical outcomes of co-infections
In natural settings, many individual hosts are infected with multiple parasite species, and this may increase or decrease the pathogenicity of the infections. Although co-infections can be an important determinant of both patterns of morbidity and mortality and impact of disease control measures, disease studies have largely been based on single infections while ignoring impact of co-infecting pathogens. My research has contributed to this knowledge gap by studying the consequences of co-infections on clinical outcomes in cattle. Through the work, we have discovered previously unreported parasite-parasite co-infections including protective effects (as strong as vaccine effect) of certain parasite species against their more lethal closely related species. This work has provided the first quantitative estimates of the effects of heterologous reactivity of any parasitic disease, and resulted in 15 publications to date, four of which are highlighted below:
Woolhouse M.E.J, Thumbi S.M, Jennings A, Chase-Topping M, Callaby R., Kiara H, Oosthuizen M.C, Mbole-Kariuki M.N, Conradie I, Handel I.G, et al (2015) Co-infection protects against mortality due to parasite infection. Science Advances. March 20 Vol 1 no. 2: e1400026
Thumbi SM, Bronsvoort BMDC, Poole EJ, Kiara H, Toye PG, Mbole-Kariuki MN, Conradie I, Jennings A, Handel IG, Coetzer JAW, Steyl JCA, Hanotte O, Woolhouse MEJ: (2014) Parasite co-infections and their impact on survival of indigenous cattle. PLoS One, 9:e76324
Thumbi, S., Bronsvoort, M., Poole, J., Kiara, H., Handel, I., Jennings, A.E., Conradie van Wyk, I., Ndila, M., Toye, P.G., Hanotte, O., Coetzer, J. and Woolhouse, M. (2013) Cost of infection and coinfections on growth performance of East African zebu cattle under one year. Parasitology, Sep; 4: 1:10
Thumbi, S., Bronsvoort, M., Poole, J., Kiara, H., O., Handel, I., Jennings, A.E., Conradie van Wyk, I., Ndila, M., Toye, P.G., Hanotte, O., Coetzer, J. and Woolhouse, M. (2013) Mortality in zebu cattle under one year: predictors of infectious-disease mortality. BMC Veterinary Research, 9:175
3. Molecular diagnostics and spatial distribution of Trypanosomiasis in Western Kenya
Cattle can be infected by a range of Trypanosoma species concurrently, some of which like T.brucei rhodesience can be transmitted to humans. Previously in order to determine all trypanosoma species infecting an animal, most researchers depended on species-specific PCR-based diagnostic tests, requiring up to 5 PCR reactions per sample investigated. My research work tested the epidemiological utility of multiple species PCR tests, based on the internal-transcribed spacers of ribosomal DNA, that allow for detection of all infecting trypanosomes in one PCR reaction. This work, conducted and completed as part of my Masters thesis research, led to greater uptake of these multispecies diagnostics for epidemiological studies on trypanosomiasis:
Thumbi S.M, Jung’a J., Mosi R., McOdimba F (2010) Spatial distribution of African Animal Trypanosomiasis in Suba and Teso districts in Western Kenya, BMC Res Notes. Jan 15; 3:6
Thumbi S.M, Mosi R., McOdimba F., Jung’a J (2008) Comparative evaluation of three PCR based diagnostic assays for the detection of pathogenic trypanosomes in cattle blood, Parasite and Vectors. Dec 24:1(1): 46
- Munyua P, Bitek A, Osoro E, Pieracci EG, Muema J, Mwatondo A, Kungu M, Nanyingi M, Gharpure R, Njenga K, Thumbi SM. (2016) Prioritization of Zoonotic Diseases in Kenya, 2015. PLoS One. 11(8):e0161576. doi: 10.1371/journal.pone.0161576. PMID: 27557120 PMCID: PMC4996421
- Thumbi SM, Njenga MK, Marsh TL, Noh S, Otiang E, Munyua P, Ochieng L, Ogola E, Yoder J, Audi A, Montgomery JM, Bigogo G, Breiman RF, Palmer GH, McElwain TF. (2015) Linking human health and livestock health: a "one-health" platform for integrated analysis of human health, livestock health, and economic welfare in livestock dependent communities. PLoS One. 10(3):e0120761. doi: 10.1371/journal.pone.0120761. PMID: 25798951 PMCID: PMC4370696
- Mosites E, Aol G, Otiang E, Bigogo G, Munyua P, Montgomery JM, Neuhouser ML, Palmer GH, Thumbi SM. (2017) Child height gain is associated with consumption of animal-source foods in livestock-owning households in Western Kenya. Public Health Nutr. 20(2):336-345. doi: 10.1017/S136898001600210X. PMID: 27515059 PMCID: PMC5233559
- T.F. McElwain & S.M. Thumbi (2017) Animal pathogens and their impact on animal health, the economy, food security, food safety and public health Rev. Sci. Tech. Off. Int. Epiz. 36 (2), 423-433
- Woolhouse ME, Thumbi SM, et al. (2015) Co-infections determine patterns of mortality in a population exposed to parasite infection. Sci Adv. 1(2):e1400026. doi: 10.1126/sciadv.1400026. PMID: 26601143 PMCID: PMC4643819
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- 2017: Affiliate Fellow of the African Academy of Sciences
- 2016: The New Voices Fellowship in Global Health Award by the Aspen Institute, US.
- 2016: Public Health and Tropical Medicine Fellowship Award by the Wellcome Trust.
- 2015: First Place Award for Outstanding Research Article in Biosurveillance (Scientific Achievement Category) by the International Society for Disease Surveillance (ISDS).
- 2015: Veterinarian of the Year Award (Research Category) by the Kenya Veterinary Association (KVA)
- 2013: Grand Challenge Exploration Award by the Bill and Melinda Gates Foundation.
- 2011: Davies Biological Science Expedition Award, University of Edinburgh.
- 2009: Overseas Research Student Award, Scottish Funding Council.
- 2008: PhD Scholarship Award, Wellcome Trust Foundation.
- 2006: Graduate Fellow Award: Association for Strengthening Agriculture Research in East and Central Africa (ASARECA) and International Livestock Research Institute.
- 2005: Graduate Scholarship Award, University of Nairobi.