Field research requires effort and resilience. Achieving my research goals and seeing the positive impact on the community makes it worthwhile.
Onchocerciasis, or river blindness, is a neglected tropical disease caused by the parasite Onchocerca volvulus, transmitted by the blackfly. The infection manifests clinically as skin and eye problems; the parasite can also induce neurological conditions such as epilepsy and neurocognitive decline. The blackfly bites are a painful source of nuisance and distress among the affected communities.
Blackflies breed in fast-flowing fresh waters, traditionally eliminated by chemical larvicides being put into the water body. Dr Joseph Siewe Fodjo is testing a greener, more sustainable solution through the novel ‘slash and clear’ technique that will reduce the blackfly population. Trailing vegetation and other breeding substrates on the fast-flowing stream in the Nachtigal rapids are cut down with machetes. A single ‘slash and clear’ intervention is enough to decrease the blackfly population in the surrounding villages for months.
Dr Joseph Siewe Fodjo coordinating ‘slash and clear’ operations at the Sanaga River.
He originally planned to conduct the study around the Edea dam, but administrative bottlenecks were unsurmountable. The work has been transferred to another segment of the Sanaga River. In this more accessible area, one round of slashing and clearing was completed in the short dry season between the two major rainy seasons in Cameroon. “We have noticed a considerable decrease in the blackfly population and a 50% reduction in biting rates. We have also been collecting water samples at the site and will evaluate whether the water properties have changed after the intervention.”
Another hurdle proved to be procuring water analysis equipment, but Dr Siewe Fodjo eventually purchased the needed during a European trip and took it home. The field's water analysis kit is being used to measure pH, electrical conductivity, temperature, turbidity, Free Chlorine, Cyanide, and alkalinity. These parameters will be compared at different time points, considering the timing of the ‘slash and clear’ interventions.
Besides the administrative and procurement issues, Dr Siewe Fodjo faced field challenges at the riverside. Fast-flowing waters present dangers mitigated by providing life jackets to all those involved in ‘slash and clear’ activity at the river. There is the threat of encounters with snakes; thus, the teams are provided with protective gear. Volunteers from the village are selected for their youth, strength, ability to swim, and swift reactions. The second ‘slash and clear’ intervention occurred when the water level in the river was lower to allow the team to clear blackfly breeding sites, which were submerged and too dangerous to access in the previous round.
Volunteers from the Nachtigal village and the BRAIN team will be there for on-site ‘slash and clear’ training at the Sanaga River.
“The uptake of the intervention by the village volunteers was amazing. They went beyond themselves to destroy all accessible breeding sites of the blackfly vector because they understood the nuisance caused by these insects and the diseases they transmit in their community. Field research requires effort and resilience. Achieving my research goals and seeing the positive impact on the community makes it worthwhile.”
Capacity building for the volunteers who implemented the intervention included training to identify suitable blackfly breeding spots, information about the dangers presented by the blackfly, and training on the slashing and clearing method. Dr Siewe Fodjo changed his approach from the blackfly traps (initially planned) to using the human landing catch technique for biting rate assessment. The human bait is a village volunteer trained during a previous blackfly project. This human landing catch technique is the gold standard method the World Health Organisation recommends for entomological monitoring. Volunteers receive incentives for their time during fieldwork and receive the necessary medication against Onchocerca volvulus infections: ivermectin prophylaxis.
As part of his FAR-LeaF activities, Dr Siewe Fodjo enrolled in an online course in environmental assessment to broaden his knowledge base and used the visit to Future Africa to spend time at the entomology laboratory of his UP mentor, Prof Megan Riddin.
Heidi Sonnekus | FAR-LeaF Team
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