What is it about?
Onchocerciasis or River blindness is a neglected tropical disease caused by the parasitic nematode Onchocerca volvulus that can lead to blindness and permanent skin damage. The infestation has recently been associated with epilepsy and nodding syndrome. All known vectors of the parasite are hematophagous,or blood-sucking, blackflies of the Simuliidae family which breed in fast flowing rivers and white waters. In this study, we explored a small area that we named the Kakoi-Koda focus, located in the Ituri Province, Djugu Territory in Eastern DRCongo. We tried to identify the blackfly transmitting the parasite locally. We identified Simulium dentulosum as the main vector of human River Blindness within the Kakoi-Koda focus, and S. vorax may be a secondary vector.
Featured Image
Why is it important?
Approximately 20.9 million people are infected with the parasite that causes onchocerciasis, with more than 240 million at risk of the disease in sub-Saharan Africa, Latin America, and Yemen. While River Blindness is endemic in the Democratic Republic of Congo, many rural areas were not surveyed for various reasons such as remoteness or insecurity. The discovery of a new vector of River blindness in the 21st Century highlight the spatial and knowledge gaps which may challenge the ultimate goal of River blindness eradication.
Perspectives
On the basis of current information, there seems to be no reason to apply any onchocerciasis elimination interventions other than the already current mass drug administration (ivermectin). The unique vector means that it would be wise to monitor progress towards elimination more closely than in other foci which have the classical vectors and to carry out surveys in data deficient areas .
Anne Laudisoit
EcoHealth Alliance
In a small onchocerciasis endemic focus (the Kakoi-Koda focus), on the western slopes of the rift valley in the Democratic Republic of Congo above Lake Albert we unexpectedly identified Simulium dentulosum (and possibly S. vorax) as the vector blackfly. In the surrounding endemic areas, the vectors are S. damnosum complex and/or S. neavei (as normally expected), and because S. dentulosum is not a vector in these surrounding areas, it follows that this focus is entomologically isolated from immigrant blackfly species which might otherwise have carried new infections into the Kakoi-Koda focus (and vice-versa). This is of local importance, because it makes elimination of the parasite easier, but our findings have wider significance across Africa, because they raise the possibility that under the right conditions, other common and widely-distributed blackfly species might unexpectedly become human-biters and significant vectors
Prof Robert Colebunders
Global Health Institute, University of Antwerp
Read the Original
This page is a summary of: Identification of the onchocerciasis vector in the Kakoi-Koda focus of the Democratic Republic of Congo, PLoS Neglected Tropical Diseases, November 2022, PLOS,
DOI: 10.1371/journal.pntd.0010684.
You can read the full text:
Resources
Collecting blackflies pre-imaginal stages in an Onchocerciasis focus
Collection of larvae and pupae of Simulium spp. on aquatic vegetation , Ituri, Democratic Republic of Congo, 2015 (Anne Laudisoit).
NSETHIO
In this project we aimed to investigate our hypotheses in South Sudan, Uganda, Tanzania, Cameroon and the DRC with a trans-disciplinary approach. We studied the effect of vector control methods and ivermectin distribution on the incidence of river epilepsy. So far a multi-country study on NS was never done and nearly all previous studies were cross-sectional, carried out during short country visits. With this long term research plan we hope to finally discover the cause of NS and detect effective control strategies.
Contributors
The following have contributed to this page
