The cultural, morphological and pathogenic characteristics of Nocardia farcinica were studied.
Guinea pigs were susceptible to Nocardia farcinica,
showing typical lesions following injections with cultures or infected tick materials.
Rabbits readily acquired a generalized infection
with Nocardia farcinica but only a small proportion of
those so injected developed lesions.
Generalized Nocardia farcinica infections did not
result from minor skin traumata (pin -pricks and scarification) made in rabbits' ears and guinea pigs' backs
which had previously been painted with cultures of the
organism, and neither did they result when ticks were
fed on surfaces so treated.
The feeding performance and developmental periods of
Amblyomma variegatum and Hyalomma anatolicum excavatum
were also precisely studied.
Larvae and nymphs of Amblyomma variegatum acquired
Nocardia farcinica infection from rabbits and, at periods
of up to nine weeks, transmitted these infections to
other rabbits when feeding as the subsequent instars.
Trials proved that this period of retention of transmissible infection can extend up to 33 weeks.
Nymphs and adults of Amblyomma variegatum showed
their ability to retain transmissible infection under
various environmental conditions.
Larvae and nymphs of Hyalomma anatolicum excavatum
acquired Nocardia farcinica infection from rabbits and,
at periods of up to eight weeks, transmitted the infection to other rabbits when feeding as the following
instars. However, subsequent trials showed that
Hyalomma anatolicum excavatum cannot retain naturally
transmissible Nocardia farcinica infection for longer
Trans-ovarial transmission was not achieved with
These clear demonstrations of the trans-stadial
transmission of the bovine farcy organism confirmed the
existence of an epidemiological feature which has
previously only been suspected.