38 
NOTES ON THE COMMON PATHOGENIC 
the bite of the infecting tick, and in a fatal case the ox dies 
ten to eighteen days later. In the course of the disease there 
is no destruction of the blood corpuscles and no anaemia. In 
South Africa the mortality is about 95 per cent, of affected 
animals. In East Africa it is impossible yet to arrive at any 
exact estimate. In some outbreaks the mortality has closely 
approximated to the South African figure, whilst in others 
losses have been small. This is probably largely accounted for 
by the fact now becoming recognised that this disease is endemic 
in some parts of this Protectorate. In these areas some or all 
of the cattle are attacked as calves. Either by virtue of 
their age, or possibly owing to some inherited influence, a 
large proportion of these recover and resist infection when 
subsequently exposed. The experience in South Africa 
has been that the immunity following recovery from East 
Coast Fever is absolute, that is to say it cannot be broken 
down. One observation in German East Africa and one 
instance in this Protectorate lend colour to a view that the 
immunity may break down. There is yet, however, no evidence 
to indicate that the parasite remains in the body after recovery, 
or that a tick feeding thereon could acquire infection. Another 
point of distinction from Babesia bigemina and B. canis is 
that the parasite cannot be inoculated by means of blood. 
Eecently K. F. Meyer has been able to reproduce infection by 
the transference of portions of spleen from a recently dead 
animal into the peritoneal cavity of a susceptible ox, and we 
have succeeded in corroborating this experiment. It is con- 
ceivable that it is necessary for certain forms of Koch’s bodies 
to gain entrance before infection can be established, and since 
these bodies are only very exceptionally formed in the blood, 
non-transmission by inoculation of blood corpuscles, even 
though heavily invaded by Theileria, is explained. 
Genus, Anaplasma. Theiler, 1910. 
Species, Anaplasma marginale. Theiler. 
The exact zoological position of this parasite is still an 
open question, and must remain so until more knowledge 
of its life cycle is obtained. There is, however, small room 
