Transmission of East Coast Fever by Ticks. 
337 
(Eef. No. 342). On July 28th 9 ticks were found fast. On August 4th 
no ticks could be seen. No reaction followed, but the animal eventually 
died at " Burnside " of East Coast Fever. 
Conclusion. 
The infestation of two susceptible heifers with adult brown ticks 
which in their larval stage had been feeding on cattle suffering from East 
Coast Fever (and as nymphae proved infective for cattle) did not convey 
East Coast Fever as adults after they had passed their nymphal stage 
on a rabbit. 
EXPERIMENT No. 4. 
TO NOTE WHETHER BROWN ADULTS WHICH FED AS NYMPHS ON 
CATTLE IMMUNE TO EAST COAST FEVER WILL TRANSMIT THE 
DISEASE TO SUSCEPTIBLE CATTLE. 
Particulars of Ticks. 
Heifer 914 had been infested with brown nymphae (Eef. Nos. 268, 335, 
and 309) on June 28, 1910, and contracted East Coast Fever, from which 
it recovered. Plasma bodies were found in the glands and Theileria parva 
in the blood. The heifer showed a typical East Coast Fever reaction, and 
by the end of May had completely recovered. 
History of Ticks used to Infest the Immune Heifer, 
Brown nymphae (Eef. No. 298) off Heifer 868, susceptible to East Coast 
Fever, were placed on Heifer 914 on September 2, 1910. These nymphae 
engorged and dropped on Septembei' 6 and 7, 1910. 
Testing the Ticks. 
They moulted into adults on October 19, 1910, and on December loth 
these adult ticks were placed on Heifer 1021. The following day the 
ticks were found fast. No reaction followed. Heifer Calf 1130 was 
infested on January 6th with ticks of the same batch as above (brown 
adults, Eef. No. 298), and the following day they were found attached. 
No reaction followed. 
Conclusion. 
The infestation of two susceptible cattle with adult brown ticks which 
had passed their nymphal stage on a heifer immune to East Coast Fever 
did not convey the disease. This observation supports some conclusions 
made as far back as 1903. 
