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. 2020 Dec 12;9(12):1043.
doi: 10.3390/pathogens9121043.

Collateral Impact of Community-Directed Treatment with Ivermectin (CDTI) for Onchocerciasis on Parasitological Indicators of Loa loa Infection

Hugues C Nana-Djeunga  1 , Cédric G Lenou-Nanga  1 , Cyrille Donfo-Azafack  1 , Linda Djune-Yemeli  1 , Floribert Fossuo-Thotchum  1 , André Domche  1 , Arsel V Litchou-Tchuinang  1 , Jean Bopda  1 , Stève Mbickmen-Tchana  1 , Thérèse Nkoa  2 , Véronique Penlap  3 , Francine Ntoumi  4   5 , Joseph Kamgno  1   6
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Collateral Impact of Community-Directed Treatment with Ivermectin (CDTI) for Onchocerciasis on Parasitological Indicators of Loa loa Infection

Hugues C Nana-Djeunga et al. Pathogens. .

Abstract

Ivermectin (IVM) is a broad spectrum endectocide whose initial indication was onchocerciasis. Although loiasis is not among its indications, IVM also exhibits antiparasitic activity against Loa loa. IVM-based preventive chemotherapies (PCs), so-called community-directed treatment with ivermectin (CDTI), have led to the interruption of transmission of onchocerciasis in some foci. A cross-sectional study was conducted in the Yabassi Health District where CDTI have been implemented since 20 years to fight onchocerciasis. All volunteers aged ≥ 5 years underwent daytime calibrated thick blood smears to search for L. loa microfilariae (mf). The prevalence of loiasis was 3.7% (95% CI: 2.2-6.2), significantly lower than its baseline prevalence (12.4%; 95% CI: 10.1-15.2; Chi-Square = 21.4; df = 1; p < 0.0001). Similarly, the microfilarial density was significantly low (mean = 1.8 mf/mL; SD = 13.6; max = 73,600) compared to baseline microfilarial density (mean = 839.3 mf/mL; SD = 6447.1; max = 130,840; Wilcoxon W = 179,904.5; p < 0.0001). This study revealed that the endemicity level of loiasis was significantly low compared to its baseline value, indicating a significant impact of IVM-based PC on this filarial disease. However, transmission is still ongoing, and heavily infected individuals are still found in communities, supporting why some individuals are still experiencing severe adverse events despite > 2 decades of CDTI in this Health District.

Keywords: CDTI; Cameroon; collateral impact; loiasis; onchocerciasis.

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Conflict of interest statement

The authors declare no conflict of interest. The funding sponsor has no role in the choice of research project; design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Figures

Figure 1
Figure 1
Trends in Loa loa microfilarial densities between 2000 (baseline) and 2018 (follow-up). For a better visualization of the plot, microfilaremia densities from 26 individuals (median: 8980 mf/mL; mean: 19,020 mf/mL; max: 130,840 mf/mL) in 2000 (baseline) and one individual (73,600 mf/mL) in 2018 (follow up) were considered as “outliers” and removed from the plotting.
See this image and copyright information in PMC

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