1.It is certain that mature Margaropus annulatus australis and Amblyoma cayenense can both be found attached to cattle and deer in Panama. No experiments have been made, with the last named type, by us.
2.Hunting experience in and near the Canal Zone has afforded one of us an excellent opportunity to examine a relatively large number of white tailed deer (Odocoileus chiriquensis Allen) and these animals usually showed the presence of a scant number of piroplasma in some of the blood cells of the cortical capillaries of the brain (crushed brain cortex film) and in some instances the peripheral blood film showed the parasites. One deer suffering from a verminous broncho-pneumonia and liver fluke disease had an associated acute attack of piroplasmosis.
3.In one instance, the progeny of ticks removed from this sick deer were capable of producing a mild attack of piroplasmosis in a half-breed, non-immune calf. The ticks in question were Margaropus annulatus australis.
4.In another instance, a mild attack of piroplasmosis was produced in a brocket deer (Mazama sartorii reperticia Goldman) by biting the animal in a massive manner with the progeny of Margaropus annulatus australis taken from prime beef cattle at the time these animals were slaughtered in Panama City.
5.Probably cervine and bovine piroplasma are identical. If not, then the tick Margaropus annulatus australis is capable of being a carrier agent for two types of piroplasma and the tick uses the deer as well as cattle for a host.
6.The practical value of these experiments is the indication that the deer makes an important reservoir for cattle piroplasmosis.