Trovan, a Pfizer drug tested on 200 children and intended to treat a deadly regional outbreak of meningitis, killed 11 children and left several more permanently injured in 1996.

In 2009, the US pharmaceutical company agreed to pay $75m to the claimants in compensation.

However, Pfizer introduced DNA testing as part of the process to qualify for the payment.

Many of the victims do not understand what DNA testing is and, fearing it is an attempt by the company to use them in another drug trial, have abandoned their compensation claims.

Al Jazeera's Yvonne Ndege reports from Kano State, northern Nigeria.