Blackfly Biting and the Transmission of Onchocerciasis

World Brain Day 2022 is dedicated to “Brain Health for all”. Research Fellow Dr Joseph Nelson Siewe Fodjo is a medical doctor and research officer at the Brain Research Africa Initiative (BRAIN) in Yaoundé, Cameroon. Currently, he is participating in the Future Africa Leader Fellowship Programme (FAR-LeaF) at the University of Pretoria.

His PhD provided compelling epidemiological evidence that the neglected medical condition onchocerciasis, a tropical parasitic disease, can cause neurological symptoms such as epilepsy and neurocognitive decline. Dr Siewe Fodjo’s research specifically involves vector control activities to eradicate the blackfly that transmits onchocerciasis. Onchocerciasis is commonly known as river blindness and is regarded as an infectious disease that is poverty related.

River blindness commonly manifests clinically as skin and eye problems. It is the world’s second leading cause of preventable blindness. 99% of people infected by river blindness live in Africa. The black fly is responsible for causing onchocerciasis and related neurological conditions such as epilepsy and neurocognitive decline. The painful blackfly bites are a nuisance and a cause of psychological distress among affected communities.

Earlier attempts to control the abundance of blackflies at dam sites deployed chemicals to kill the developing larvae in the rivers, often with adverse repercussions for the environment and the emergence of resistance against the larvicides used.

Larvicides are also expensive and require advanced technical skills to administer. This approach was eventually abandoned. The alternative that Dr Siewe Fodjo proposes is both eco-friendly and sustainable – and is urgently warranted.

“Using a novel slash and clear technique – cutting down trailing vegetation around fast-flowing rivers where the blackflies breed – we are successfully reducing blackfly biting rates and thus the transmission of onchocerciasis.” Although this technique is more eco-friendly than toxic larvicides, its full impact has yet to be studied. Dr Siewe Fodjo plans to fill this gap to minimise the negative ecological impacts of the lifesaving interventions around the Edea dam in Cameroon.

As shown by earlier PhD research conducted by Dr Siewe Fodjo in Sudan, a single intervention was enough to decrease the blackfly population for several months dramatically. Mathematical modelling suggested that the process can significantly accelerate the elimination of blackflies in endemic sites.

If the proposed method proves beneficial, Dr Siewe Fodjo believes that the technique can be replicated at diverse water sites that will not only enhance but also ensure the general and brain health and well-being of the affected communities.

Siewe Fodjo will ensure that his study can establish a stronger scientific network among African institutions, as well as relevant indigenous communities. He sees the project as being pivotal in bringing together experts from several fields and mobilising relevant stakeholders in a transdisciplinary manner to address not just a pestering, but a wicked problem.

Using a novel slash and clear technique – cutting down trailing vegetation around fast-flowing rivers where the blackflies breed – we are successfully reducing blackfly biting rates and thus the transmission of onchocerciasis


Heidi Sonnekus | FAR-LeaF Program

 

The Future Africa Research Leader Fellowship (FAR-LeaF) is a fellowship programme, focussed on developing transdisciplinary research and leadership skills, to address the complex, inter-linked challenges of health, well-being, and environmental risks in Africa.