This clinical trial compares two treatments - ivermectin and moxidectin - to learn which is better at reducing the proportion of people with onchocerciasis (river blindness) when given through mass drug administration (MDA) in Angola. Both drugs are approved by the United States Food and Drug Administration (FDA) to treat this disease. The study also explores how these treatments affect other infections common in the region, including intestinal worms (soil-transmitted helminths) and scabies. The trial aims to answer the following key questions: * How do moxidectin and ivermectin compare in reducing the prevalence (how common the disease is) and intensity (amount of parasites per person) of onchocerciasis in the community? * Do the treatments differ in their effect on the prevalence and intensity of soil-transmitted helminths and the prevalence of scabies? * Does moxidectin reduce transmission of onchocerciasis more effectively than ivermectin, based on genetic testing of parasites in people and lab testing of the blackflies that carry the infection? * How many more years of treatment would be needed to reach elimination with each drug, based on mathematical disease modelling? * How do communities feel about receiving moxidectin versus ivermectin, and what factors help or make it harder to carry out MDA programs with moxidectin versus ivermectin? The study takes place in Bié Province, Angola, and involves 20 groups of villages randomly assigned to receive either moxidectin or ivermectin once a year for four years. Prior to every round of MDA, researchers will collect skin, stool and blood samples from a sample of the people living in the study area. We believe the results will help guide global policy on the use of moxidectin in efforts to eliminate onchocerciasis and control related diseases.