Animal models for pertussis vaccine neurotoxicity

The long-held belief that pertussis vaccine (PV) may, albeit rarely, cause permanent brain damage in children was negated by the exhaustive weighing of evidence in the recent Loveday test case in the High Court in London. Therefore it may be impossible to have an animal model of a human condition whose own existence is not established. It is suggested here that, hypothetically, a satisfactory animal model should meet the following criteria for "classic" PV-encephalopathy: rapid (less than 24 h) onset; reproducible induction of a permanent neurological abnormality after a single injection of PV, without other agents; administration by a non-cerebral route, and in proportioniate body-weight dose. In the literature of the past 40 years there is no reported system that fulfills these suggested criteria. Massive doses of PV may kill laboratory animals but there are no reports of permanent neurological injury among survivors, even after intracerebral (ic) inoculation. PV given with neuroantigen or cryo-injury, may cause persistent neurological disability. Pertussis toxin injected ic into mice induced a durable neurological abnormality after a log period of one week. The absence of convincing evidence for PV causing permanent brain damage in children is thus mirrored by similar negative results in laboratory animals.