In school, Anas Mohammadu's mates call him horror" and make fun of him. But Anas is lucky to be alive. Other children who were used in the controversial 1996 drug trial by US pharmaceutical giant Pfizer died. Anas, then only three years old, was the first child to be given the experimental antibiotic Trovan at the Infectious Diseases Hospital, Kano, during the drug trial. Pfizer tested the then unregistered drug in Nigeria's north-western Kano State during an outbreak of meningitis which had affected thousands of children. Officials in Kano say more than 50 children died in the experiment, while many others developed mental and physical deformities. But Pfizer says only 11 of the 200 children used in the drug trial died. Following pressure from rights groups and families affected by the trial, the Nigerian government set up an expert medical panel to review the drug trial. The experiment was "an illegal trial of an unregistered drug", the Nigerian panel concluded, and a "clear case of exploitation of the ignorant". After more than a decade of silence, the Nigerian government has decided to sue Pfizer, seeking $7bn (3.5bn) in damages for the families of children who allegedly died or suffered side-effects in the experiment. Kano State government has also filed separate charges against Pfizer.