Nigeria, June 24 -- Sometime in mid-May, Joseph Osuigwe, 35, started noticing a sudden loss of the senses of taste and smell. He could not perceive the aroma of his wife's food; he thought her food that used to be irresistible tasted bland. The symptoms became worse.

"I started noticing I could no longer smell my bathing soap or perfume. I concluded that something was wrong when I bought a balm and rubbed it all over my nose but felt nothing," said Mr Osuigwe, a human rights activist.

The medical term of what Mr Osuigwe was experiencing is anosmia - the loss of sense of smell, and ageusia - an accompanying diminished sense of taste.

In April, the World Health Organisation (WHO) listed the loss of smell and taste as some of the less com...