IL4 and infection: There has been little close study of the progress or causes of pathology, apart from a recent thorough histological investigation of the distribution of the virus during the early stages of infection [10], which showed that the virus spread in a similar way to measles virus spread in humans [11,12], and a study of interleukin 4 (IL-4) and gamma interferon (IFNγ) induction during PPRV infection [13].