1. There has been isolated from a lamb a pantropic virus with neurotropic
properties and a well-marked affinity for embryonic tissue.
2. In the field the vectors are mosquitoes which have yet to be identified
3. In sheep infection with the virus causes a febrile reaction after a short
incubation period of about one to four days, the mortality rate not being high.
Pregnant ewes may abort during the febrile reaction in which case virus could not be
isolated from the foetuses. Subsequently the virus invades the foetus causing
death usually with abortion. The mortality amongst foetuses carried to full term
and new-born lambs is very high (practically 100%). New born lambs suckling
reacting ewes did not become infected by contact with the reacting ewe.
4. In addition to sheep, cattle, horses, pigs, mice, rabbits, guinea-pigs and
man are susceptible.
5. Infant and adult mice are equally susceptible to intracerebral inoculation,
the mortality being 100%. Infant mice are fully susceptible to intraperitoneal
infection but in adult mice the reaction is at most inapparent.