The Impact of Onchocerciasis Elimination Measures in Africa: A Systematic Review

Abstract

Background: Onchocerciasis, or river blindness, is one of the neglected tropical diseases (NTDs) that the WHO has set out to eliminate. To reach this elimination target, a number of challenges must be met, and the essential measures set out in the road map for NTDs 2021-2030 must be implemented. More than 99% of infected people live in 31 countries in sub-Saharan Africa. Our objective was to assess the impact of onchocerciasis interventions in Africa.

Methodology: A systematic peer review of the existing literature following the PRISMA guidelines was performed between November 2021 and April 2022. We selected studies on onchocerciasis control measures in Africa since the implementation of the first Onchocerciasis Control Programme (OCP) measures in 1974. All scientific articles indexed in the PubMed, Scopus, Embase, and CENTRAL databases written in Spanish, English, French, German, and Portuguese were considered. The study protocol was registered in the PROSPERO database.

Results: A total of 63 articles met the inclusion criteria and were finally selected. Publications were found from 19 out of 31 African endemic countries. The main intervention retained in the different published studies was mass distribution of ivermectin (n = 51). According to our results, 11 African countries have managed to interrupt transmission of onchocerciasis in at least one area in the country; 11 countries have not achieved this goal, while 1 country has managed to eliminate the disease, but it has resurged.

Conclusions: Control interventions showed a positive impact on the fight against onchocerciasis, demonstrating that these activities are effective. Nevertheless, they were not sufficient to achieve the proposed goals for a variety of reasons. Therefore, different aspects should be considered in order to fulfil the targets proposed by the WHO to be reached in 2030.

Keywords: Africa; community directed treatment; control measures; onchocerciasis.

Figure 1

PRISMA flow chart. * Consulted databases and registers were PubMed, Scopus, Embase, and CENTRAL. ** No automation tools were used.

Figure 2

Published articles by African endemic countries. Above: Countries with studies assessing only CDTI. Middle: Countries assessing only vector control strategies. Below: Countries assessing mixed methods. Countries where no studies were performed are represented in grey.

Figure 2

Published articles by African endemic countries. Above: Countries with studies assessing only CDTI. Middle: Countries assessing only vector control strategies. Below: Countries assessing mixed methods. Countries where no studies were performed are represented in grey.

Figure 2

Published articles by African endemic countries. Above: Countries with studies assessing only CDTI. Middle: Countries assessing only vector control strategies. Below: Countries assessing mixed methods. Countries where no studies were performed are represented in grey.

Figure 3

Intervention outcomes by country. Some studies were performed in certain regions of the countries. However the whole country shape is highlighted for better visibility. Countries where no studies were performed are represented in grey.