Contributions to Science
Risk mapping and modelling of infectious diseases
Calvin’s research work on risk mapping, modelling and prediction of infectious diseases in Tanzania, using Rift Valley fever (RVF) as an exemplar mosquito-borne diseaseinvolved data mining of disease datasets for the period of past 80 years. This work,which was part of his PhD work (2011-2015) under SACIDS programme, characterized spatial and temporal pattern of RVF risk stratifying the country into different risk profiles to inform cost-effective risk-based disease surveillance, prevention and control strategies. Subsequently, he led the work on prediction of RVF occurrencein Tanzania using ecological niche modelling approach based on the country-disease historical data, soil types and climate-related data, followed by ground-truthing of RVF predictive algorithms, which refined the country disease risk profile. Bridging these experiences to other ecosystems in Africa, Calvin collaborated with International Livestock Research Institute to assess the effects of climate change on the occurrence and distribution of livestock diseases with reference to specific case studies. Based on these experiences, he assumed a consultative and leadership role to revise and update the National Rift Valley feverEmergency Preparedness and Response Plan in Tanzania.
Having characterised the RVF transmission dynamics, it was plausibly suggested that, the most effective strategy to prevent occurrence of RVF in animals and humans is the vaccination of animals as outbreaks typically occur first in animals. However, the vaccines for animals are limited and there are no approved effective vaccines against RVF for humans. These observations suggested the need to develop and test the efficacy and effectiveness of new/candidate vaccines. In this regard, Calvin took lead in the designing and implementation of RVF Clone 13 vaccine (recently developed RVF vaccine) trial to assess its effectiveness and safety in real world environments. The results provided evidence on effectiveness and safety of new vaccine that can be used strategically to prevent disease occurrence in the high riskregion.
Impact of movement networks on spread of infectious diseases
Calvin’s postdoctoral fellowship with SACIDS in 2016/2017, focused onnetwork analysis approach for guiding risk-based surveillance and intervention strategies for infectious diseases; using cholera as an exemplar disease. This work employed simultaneously, social network and spatial analytical modelling approaches to characterize human movement network structure and its influence on short and long-distance transmission of cholera.In this study, he demonstrated the usefulness of social network indicators to predict the susceptibility of an area and thence its population to infectious diseases to guide design of appropriate control and prevention measures.
Strentherning of disease surveillance systems
From November 2015 to date, Calvin has been serving as a lead SACIDS One Health Epidemiologist to enhance community-based disease outbreak detection and response in East and Southern Africa. In this work, his major role has been to define user requirements; design, pilot and deploy disease surveillance models powered by digital technology. In collaboration with team members in the Enhancing Community-based Disease Outbreak Detection and Response in East and Southern Africa project, a digital disease surveillance app branded AfyaDatawas developed (http://afyadata.sacids.org). AfyaDatahas improved timeliness related to detection, reporting and feeback/responses to health events in human and animal populations at community level. The strategy has enhanced contaiment of events and suspected disease outbreaks at the primary sources before they could spread further. The app has also been applied in the collection of research data and monitoring of their quality.
Calvin led the assessment of functionalities of disease surveillance systems in the cross-border ecosystems of East Africa, and gaps were identified that could be addressed to strethern cross-border disease surveillance. This work was part of inter-network project (INP) that was implemented by six international disease surveillance networksunder Connecting Organisations for Regional Disease Surveillance in 2018/2019. Calvin served as chairman of the INP Technical Working Group.
Calvin is a co-investigator and coordinator of the research project tiled “Strengthening scientific capacity for preparedness and response to viral haemorrhagic fevers in Tanzania” (2017/2019). The project is geared towards establishment of research base centre in Africa through international collaborative research for viral haemorrhagic fevers. In addition, Calvin is part of the research group working on policy analysis of the drivers of antimicrobial resistance within Tanzania’s formal and informal healthcare and animal health care systems. He has taken part in the development of national event-based surveillance guidelines and the priority setting of national research agenda in Tanzania.Calvin is leading the work on strentherning of event-based surveillance in Africa CDC member states, 2019/2020.
Mentorship/supervision to students
PhD students: 5, MSc/Mphil students: 10
Calvin serves as a reviewer of eight peer review international journals. He is a chief editor of SACIDS TechnoHealth Surveillance Newsletter. Calvin is a member of One Health Disease Surveillance Technical Working Group under National One Health Coordination Unit in Tanzania, a member of SACIDS Community of Practice; Emerging Diseases and Arboviral Infections, and a member of Community of Practice; One Health Sciences.
Publication(s): The changing landscape of public health in sub-Saharan Africa: Control and prevention of communicable diseases needs rethinking , Spatial Heterogeneity of Habitat Suitability for Rift Valley Fever Occurrence in Tanzania: An Ecological Niche Modelling Approach , A Smartphone App (AfyaData) for Innovative One Health Disease Surveillance from Community to National Levels in Africa: Intervention in Disease Surveillance