Environmental Factors Associated With Loa loa Microfilaria Prevalence and Intensity in Diverse Bioecological Zones of Cameroon

Badia-Rius, Xavier, Betts, Hannah, Wanji, Samuel, Molyneux, David, Taylor, Mark J and Kelly-Hope, Louise A
(2021) Environmental Factors Associated With Loa loa Microfilaria Prevalence and Intensity in Diverse Bioecological Zones of Cameroon. Frontiers in Tropical Diseases, 2. 668641-.

[thumbnail of fitd-02-668641 (2).pdf] Text
fitd-02-668641 (2).pdf - Published version

Download (2MB) | Preview


<jats:p>Loiasis (African Eye Worm) is a filarial infection caused by <jats:italic>Loa loa </jats:italic>and<jats:italic> </jats:italic>transmitted by <jats:italic>Chrysops </jats:italic>vectors, which are confined to the tropical rainforests of Central and West Africa. Loiasis is a major impediment to control and elimination programmes that use the drug ivermectin due to the risk of serious adverse events. There is an urgent need to better refine and map high-risk communities. This study aimed to quantify and predict environmental factors associated with loiasis across five bioecological zones in Cameroon. The <jats:italic>L. loa</jats:italic> microfilaria (mf) prevalence (%) and intensity (mf number/ml) data from 42 villages within an Equatorial Rainforest and Savannah region were examined in relation to climate, topographic and forest-related data derived from satellite remote sensing sources. Differences between zones and regions were examined using nonparametric tests, and the relationship between <jats:italic>L. loa</jats:italic> mf prevalence, mf intensity, and the environmental factors using polynomial regression models. Overall, the <jats:italic>L. loa</jats:italic> mf prevalence was 11.6%, <jats:italic>L. loa</jats:italic> intensity 927.4 mf/ml, mean annual temperature 23.7°C, annual precipitation 2143.2 mm, elevation 790 m, tree canopy cover 46.7%, and canopy height 19.3m. Significant differences between the Equatorial Rainforest and Savannah region were found. Within the Equatorial Rainforest region, no significant differences were found. However, within the Savannah region, significant differences between the three bioecological zones were found, and the regression models indicated that tree canopy cover and elevation were significant predictors, explaining 85.1% of the <jats:italic>L. loa</jats:italic> mf prevalence (adjusted R<jats:sup>2</jats:sup> = 0.851; p&amp;lt;0.001) and tree cover alone was significant, explaining 58.1% of the mf intensity (adjusted R<jats:sup>2</jats:sup> = 0.581; p&amp;lt;0.001). The study highlights that environmental analysis can help delineate risk at different geographical scales, which may be practical for developing larger scale operational plans for mapping and implementing safe effective interventions.</jats:p>

Item Type: Article
Uncontrolled Keywords: 37 Earth Sciences, 3709 Physical Geography and Environmental Geoscience
Divisions: Faculty of Health and Life Sciences
Faculty of Health and Life Sciences > Institute of Infection, Veterinary and Ecological Sciences
Depositing User: Symplectic Admin
Date Deposited: 08 Sep 2021 08:40
Last Modified: 21 Jun 2024 00:48
DOI: 10.3389/fitd.2021.668641
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3136272