Cyanide in Cassava

Monday, July 9, 2018, 13:00 - 15:00

University of Zurich, Lecture Hall HS 95

Minisymposium: Cyanide in Cassava

13:00 Opening of the Minisymposium Felix Zelder (Chemist, University of Zurich, Switzerland)

Konzo, Cyanide Intoxication, and Cassava in Mozambique

Julie Cliff (Epidemiologist, Eduardo Mondlane University, Maputo Mozambique)

Cassava-derived cyanide toxicity exists both in konzo and konzo-free areas in South-Kivu (DRC): would nutrional status make the difference? 

Joelle N. Chabwine (Neuroscientist, Fribourg University, Switzerland; Catholic University of Bukavu, Democratic Republic of the Congo (DRC)

Predicting the Growth, Resource Allocation and Nutritional Value of Cassava in Response to Environmental Challenges

Ros Gleadow (Plant Scientist, Monash University, Melbourne Australia)

Corrin-based Chemosensors for the Detection of Endogenous Cyanide in Cassava

Felix Zelder (Chemist, University of Zurich, Switzerland)

Detecting Endogenous Cyanide with a Smartphone at the Point-of-Need

Walter Karlen (Engineer and computer scientist, ETH Zurich, Switzerland)


Julie Cliff


Julie Cliff is an Australian physician and epidemiologist who has worked in Mozambique since 1976, teaching at Eduardo Mondlane University.

Following graduation in medicine from the University of Melbourne, she trained in London in internal medicine (Fellow of the Royal College of Physicians) and community health and tropical medicine (London School of Hygiene and Tropical Medicine).

In the United States, she has been an International Epidemiologic Fellow at the Centers for Disease Control and is an Affiliate Professor at the University of Washington, Seattle.


Konzo, the paralytic disease associated with eating cassava, became a research interest in 1981, when she investigated the first large epidemic in Mozambique. Since then she has continued to document konzo and cyanide intoxication from cassava in the field in Mozambique.

Joelle N. Chabwine


Joelle N. Chabwine has a double background and affiliation at Fribourg University and Fribourg Hospital).

After she was graduated at the Medical school of the Catholic University of Bukavu (DRC), she came to Belgium for postgraduate training and completed her Master and PhD in fundamental neuroscience (Physiology) at the Katholieke Universiteit Leuven. Then she moved back to the clinics and trained as Neurologist (FMH Neurology and EEG). Meanwhile, she kept links with her mother university in DRC and continued teaching and conducting field research on konzo and other clinical aspects of cassava-derived cyanide toxicity in South-Kivu Province.


Konzo is a well-known disease in the western part of DRC. However since late 1990’s, new outbreaks appeared in the war-torn province of South-Kivu (in the eastern DRC). Cassava toxicity and malnutrition were both documented in the affected area. However, it appeared, from recent data, that toxic cassava was also consumed in regions where no case of konzo was reported. The only difference between these two populations seemed to be their nutritional level. Hence the question whether both risk factors of konzo are equivalent or not and if cyanide toxicity is appropriately evaluated in konzo-diseased patients, given possible interaction between sulphur amino-acid-deficiency and endogenous production of thiocyanate (used to assess cyanide intoxication).    

Ros Gleadow


Ros Gleadow is Professor of Plant Sciences at Monash University. She researches the effect of climate change on food security with a focus on plants that make cyanide and the impact on human and animal health. Current projects are on the effect of CO2, drought, temperature and salinity on growth and allocation of resources in sorghum, cassava and taro working in Africa, the Pacific Islands and Australia. Gleadow also leads the undergraduate science program at Monash on scientific practice and communication and leads the Faculty of Science on a new interdisciplinary Agtech initiative. She is a former President of the Australian Society of Plant Scientists and is a member of the Australian Academy of Science's Committee for Agriculture, Fisheries and Food. 


Below ground storage organs are an important component of global food security but are likely to respond differently to climate change relative to other crops. There is a trade-off in the allocation of resources to growth, storage organ and plant toxins, affecting crop yield and nutritional value. We have tested the effect of a range of environmental variables (e.g. drought, CO2, salinity, soil nutrients) on cassava in greenhouses and in the field. Measurements of photosynthesis, growth, water use efficiency and nutritional quality showed that nutritional status, growth rate and crop yield is dependent on plant age and treatment, sometimes in unexpected ways. The underlying drivers are not clear. Here I present a simple model of how the trade-offs between growth and defence may be integrated to accommodate the various, sometimes confounding, responses and the implications for food security. Some of the challenges of testing for cyanide in the field will be discussed.

Felix Zelder


Felix Zelder is a group leader at the Department of Chemistry of the University of Zurich working in the area of synthetic and analytical chemistry. One of his research interests is the development of chemical sensors for applications in remote locations and resource limited settings.


A short overview on the corrin-based chemosensor technology for the ASSURED detection of cyanide in biological samples is given.

Walter Karlen


Walter Karlen is an Assistant Professor in the Department for Health Sciences and Technology at the Eidgenössische Technische Hochschule Zürich (ETH Zurich). He founded the Mobile Health Systems Lab in 2014 where he focuses on enabling the diagnosis, monitoring, and treatment of major global health burdens by researching automated and personalized systems that can be used at the point-of-care. Walter Karlen holds a MSc (microEngineering) and PhD (Computer, Communication and Information Sciences) from Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. Walter Karlen held post-doctoral research positions at the University of Stellenbosch, South Africa and the University of British Columbia (UBC) in Vancouver, Canada.

Walter Karlen currently leads multiple large projects that aim to deliver medical interventions through technology and Big Data analytics. Applications are personalized low back pain management, sleep enhancement, tracking of chronic wounds, pneumonia diagnosis, and monitoring of fluid status in dengue patients.


Smartphones are powerful sensing and data processing tools which can also be applied to biomedical and biochemical sensing challenges. We have developed an automated readout device for the detection of endogenous cyanide using corrin-based Cyanokit technologies. This method demonstrated high repeatability and discriminative power and compared equally well to a controlled spectrophotometer readout. The proposed system has the potential to easily and objectively detect levels of cyanide with high granularity at the point-of-need.