Characteristics of study subjects indulged in self-medication (N = 346).

<p>Characteristics of study subjects indulged in self-medication (N = 346).</p

Perception of students regarding methods to prevent the growing trend of self-medication (N = 440).

<p>Perception of students regarding methods to prevent the growing trend of self-medication (N = 440).</p

Categories of drugs commonly self-prescribed (N = 346).

<p>Categories of drugs commonly self-prescribed (N = 346).</p

Socio-demographic information of the patients (n = 83).

<p>Socio-demographic information of the patients (n = 83).</p

Indications for self-medication (N = 346).

<p>Indications for self-medication (N = 346).</p

Reasons for initaiating and continuingsubstance use (n = 83).

<p>Reasons for initaiating and continuingsubstance use (n = 83).</p

Attitude of the students towards self-medication (N = 440).

<p>Attitude of the students towards self-medication (N = 440).</p

Characteristics of the study population (N = 440).

<p>Characteristics of the study population (N = 440).</p

Age of initiation, duration, and types of substances used (n = 83).

<p>Age of initiation, duration, and types of substances used (n = 83).</p

Predicting the environmental suitability for onchocerciasis in Africa as an aid to elimination planning

Recent evidence suggests that, in some foci, elimination of onchocerciasis from Africa may be feasible with mass drug administration (MDA) of ivermectin. To achieve continental elimination of transmission, mapping surveys will need to be conducted across all implementation units (IUs) for which endemicity status is currently unknown. Using boosted regression tree models with optimised hyperparameter selection, we estimated environmental suitability for onchocerciasis at the 5 × 5-km resolution across Africa. In order to classify IUs that include locations that are environmentally suitable, we used receiver operating characteristic (ROC) analysis to identify an optimal threshold for suitability concordant with locations where onchocerciasis has been previously detected. This threshold value was then used to classify IUs (more suitable or less suitable) based on the location within the IU with the largest mean prediction. Mean estimates of environmental suitability suggest large areas across West and Central Africa, as well as focal areas of East Africa, are suitable for onchocerciasis transmission, consistent with the presence of current control and elimination of transmission efforts. The ROC analysis identified a mean environmental suitability index of 0.71 as a threshold to classify based on the location with the largest mean prediction within the IU. Of the IUs considered for mapping surveys, 50.2% exceed this threshold for suitability in at least one 5×5-km location. The formidable scale of data collection required to map onchocerciasis endemicity across the African continent presents an opportunity to use spatial data to identify areas likely to be suitable for onchocerciasis transmission. National onchocerciasis elimination programmes may wish to consider prioritising these IUs for mapping surveys as human resources, laboratory capacity, and programmatic schedules may constrain survey implementation, and possibly delaying MDA initiation in areas that would ultimately qualify