According to a comment below the video, the dose approved by WHO for Ivermectin use as an anti-parasitic is the dose doctors are using for COVID19.
The WHO dosing is:
200 micrograms/kg of body weight. That works out to 3 milligrams/15kg.
100 lb person = 9 milligrams single dose Ivermectin
200 lb person = 18 milligrams dose.

Here is the World Health Org. writeup on treatment of Onch. in Africa. Onchocerciasis – or 'river blindness' – is a parasitic disease caused by the filarial worm Onchocerca volvulus. It is transmitted through the bites of infected Simulium blackflies, which breed in fast-flowing streams and rivers.

[link to www.who.int (secure)]

"Ivermectin
The treatment for onchocerciasis is ivermectin (brand name Mectizan®). Unlike previous treatments, which had serious – sometimes fatal – side effects, ivermectin is safe and can be used on a wide scale. It is also a very effective treatment, and has single-handedly transformed the lives of millions of people suffering from onchocerciasis since its introduction in 1987."

"Dosage
Ivermectin is taken orally as tablets. A single dose of 150 to 200 µg/kg body weight needs to be taken annually to be effective. The dosage depends on a person’s body mass, which can be simply calculated according to height.

Availability
In 1987, the manufacturer of ivermectin – Merck & Co., Inc. – declared that it would donate ivermectin free of charge for as long as is needed. This unprecedented donation is administered through the Mectizan Donation Program, which works with ministries of health and other partners to distribute the drug"


I suppose this could explain why Covid has not killed so many people in Africa. The parts of Africa that are dealing with dangerous parasites are likely already prophylactically protected by Ivermectin.