Wide Spread of Nairobi Fly in Freetown, Sierra Leone Capital.
There seems to be high breeding of Nairobi fly which are commonly known as Champion around the country. The “Nairobi fly” is actually a red-and-black beetle of the genus Paederus that is found from India to West Africa but hatches only rarely.

It does not bite but contains pederin, a stinging acid, to drive off predators. Smacking it on the skin releases the acid, which can leave a nasty welt; touching an eye with the acid can blind it for days. The condition is, of course, not contagious.
If the beetles are found on the skin, brushing them off, rather than crushing them, avoids producing dermatitis. Treatment includes rapidly washing the affected area, applying cold, wet compresses, and possibly treating with antibiotics, steroids, and antihistamines.