An inquest has been hearing of the death of Essex teenager Amie Miller.
Amie, from Stanford-le-Hope, died of encephalitis, which causes inflammation of the brain.
The origin of her condition, characterised by vomiting and flu-like symptoms, is unknown.
Doctors believed she was getting better and missed signs she was deteriorating.
Errors included misinterpreting the results of a CT scan and failing to carry out a MRI scan which would have identified the condition, despite one being recommended.
Stepfather Mbarek Aitmarri said the family would be considering legal action.
From the moment Amie died we faced constant evasion and were passed from one person to another.
We feel our daughter has been treated as collateral damage and there's no real recognition of our loss.It has taken five years to reach this stage and, if our concerns had been addressed sooner, perhaps other people's lives could have been saved.Procedures have not changed in five years - the inquest heard basic neurological checks are still not carried out as standard. It is this which worries us most.
For us there's no doubt that systematic failings caused Amie's death.I drove her to hospital and I ask myself everyday whether, if I had taken her to another hospital, she would still be alive.
Amie Miller, 15, was taken to Basildon Hospital A&E in November 2008 after suffering headaches while studying for her GCSEs.
A jury returned a narrative verdict, saying that the medics had seriously failed to meet Amie's needs by failing to carry out basic checks, administering inappropriate treatment and failing to properly communicate with one another.
Speaking afterwards, Amie's family told how she was a promising student who had dreamed of becoming a paediatrician.