Health officials in Kiru area of Kano State say 11 children have been killed by whooping cough, which is highly infectious and spread by spit or cough droplets. About 40 others are also receiving treatment.

The outbreak in Kano is attributed to poor routine immunisation and poor health services. The authorities say they are making efforts to contain the outbreak.

It is also known as pertussis and is caused by a species of bacteria, Bordetella pertussis. It mostly affects infants, who are at highest risk of complications and death. The earliest signs are similar to a common cold, then develop into a cough and can even result in pneumonia.

Babies may turn blue while coughing due to a lack of oxygen. The cough tends to come in short bursts followed by desperate gasps for air - the whooping noise. Adults can be infected - but the infection often goes unrecognised.