Dr Siewe Fodjo Joseph Nelson

Dr Siewe Fodjo Joseph Nelson


Brain Research Africa Initiative (BRAIN)

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Work and Research

I am a research physician passionate about neglected tropical diseases and their interaction with the central nervous system. My PhD focused on the association between onchocerciasis and epilepsy, which I am now extending to investigate the role of the parasite O. volvulus on the cognitive function of children. I am also passionate about interventions that would curb onchocerciasis transmission, such as the novel "slash and clear" vector control technique against blackflies. I am open to collaborate on subjects that touch public health and tropical neurology.

Fields Of Expertise

Public Health / Epidemiology


Onchocerciasis (river blindness) is a neglected tropical disease manifesting clinically as skin and eye problems. It is caused by the parasite Onchocerca volvulus, transmitted by the blackfly insect, and is the world’s second leading cause of preventable blindness – with 99% of the almost 21 million infected people living on the African continent.


Epidemiological evidence suggests that infection with this parasite can also induce neurological conditions such as epilepsy and neurocognitive decline; furthermore, the painful bites of blackflies are a source of nuisance and psychological distress among the affected communities. Blackflies breed best in fast-flowing fresh waters – a pest in several countries including Cameroon where the construction of dams has created conducive circumstances for the blackfly vector to thrive.


Thus far, attempts to control these insects have employed chemicals to kill the developing larvae in rivers, often with adverse repercussions for the environment and the emergence of resistance against the larvicides used. This option is also expensive and requires advanced technical skills for implementation, thus the approach was eventually abandoned leaving several communities helpless in the face of blackfly nuisance and onchocerciasis-associated morbidity.


During his PhD, Dr Siewe Fodjo was involved in testing a greener and more sustainable solution to this problem around the Maridi dam in South Sudan. He is extending the scope of his work with his FAR-LeaF project, titled Eco-friendly approach to reduce onchocerciasis transmission around the Edea Dam in Cameroon.


Our novel slash and clear’-technique will reduce the blackfly population around the dam. With the use of machetes, we will cut down trailing vegetation and other breeding substrates on the fast-flowing downstream section of the dam. In South Sudan, we found that a single ‘slash and clear’ intervention was enough to drastically decrease the blackfly population in the surrounding villages for months. Mathematical models suggest the process can significantly accelerate onchocerciasis elimination prospects in endemic sites.


The technique has the advantage of being less dangerous for the aquatic environment compared to larvicidal chemicals being poured into rivers and it can be done by trained local villagers – sustainable and a source of income in the long term. This is important since several dams are being constructed across the Sanaga river of Cameroon for hydroelectricity generation – many villages and communities nearby have experienced a surge in blackfly bites which have rekindled onchocerciasis transmissions.

The research will investigate whether the new technique does not derange the ecological balance around the rivers during the months following its implementation. The project will be piloted around the Edea dam where important blackfly nuisance and high burdens for both onchocerciasis and epilepsy have been documented. If proven to be more beneficial than harmful, the technique could be replicated in other dam sites and improve the health and well-being of communities.


Dr Siewe Fodjo will measure blackfly biting rates before and after the intervention by way of specially designed blackfly traps, and interview indigenous peoples about notable changes regarding blackfly nuisance and diseases in their community. The reduction of blackflies in the area is expected to last many months and local volunteers will be taught to repeat the intervention without supervision.