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Piroplasmosis 
Our experiments showed that a horse after recovery from P. caballi 
infection succumbed to the inoculation of iV. equi blood. Conjoined 
pairs of piriform parasites are never observable in N. equi infection, 
about 90 7o of fcf’o infected corpuscles contain single parasites of all 
shapes and sizes, many of them being much smaller than any true 
piroplasm, 2-5"/o of the corpuscles contain two to four parasites, and 1-5 Vo 
containing dividing, or “cross-forms.” The accompanying diagram repre¬ 
sents our conclusions as to the usual mode of multiplication of N. equi 
in the circulating blood; we studied the parasite in the living condition 
as well as in stained films. 
Nuttalliosis resembles piroplasmosis in its symptomatology and 
pathology. I have a “salted” horse whose blood was virulent when last 
tested, a period of three years having elapsed since it was first infected. 
In Africa, as first shown by Theiler, the parasite is transmitted by 
Rhipicephalus evertsi. This tick, when fed upon infected horses in its 
larval and nymphal stages, is infective when adult. We do not know 
what species of tick serves to carry the parasites in other parts of the 
globe. 
East Coast Fever of Cattle. 
This devastating disease, which appears to be confined to Africa, 
is ushered in by the onset of fever following upon an incubation period 
of 10-20 days after the cattle have been attacked by the ticks which 
convey the parasite. The fever continues usually for about 12 days, 
death taking place 18-34 days after the ticks have attacked the host. 
The characteristic symptoms of redwater, haemoglobinuria, icterus and 
anaemia, are absent in East Coast fever. The mortality may amount 
to 80-90 7o- Cattle which are immune to redwater are susceptible 
to East Coast fever. In marked contrast to what is observed in 
redwater, we find in East Coast fever, as the disease progresses, that 
there is no appreciable decrease in the number of I’ed blood corpuscles 
present in the peripheral circulation. 
The cause of the disease, Theileria qnirva, Fig. 11, differs in important 
respects from the parasites I have previously mentioned, and the disease 
cannot be communicated by the inoculation of blood containing the 
parasite even when large quantities—up to 7 litres—are injected. 
Theileriaparva is conveyed by Rhipicephalus appendiculatus, R. simus, 
R. evertsi, R. nitens and R. capensis, the first-named species of tick being 
the usual carrier. The parasites are not hereditarily transmitted in 
Rhipicephalus, but when taken up by the carrier at one stage of its 
