362 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [III, IV.
of a more suitable subject at the time, had to be fed upon dogs showing only
" rare " or " very rare " parasites.
As has been mentioned earlier in this note, the infectivity of the nymphs and
adults derived from one or more of the six lots of larvae was tested upon five dogs.
The results of these tests are summarized in the following Table :—
Dog |
Number of ticks |
Number |
Duration |
Number |
Result |
Incuba- |
Number |
Remarks |
194 |
300-400 nymphs |
*About |
6 days |
56 days |
+ |
29 days |
9 days |
*Collar found |
236 |
About 200 |
All . |
6 „ |
73 „ |
+ |
30 „ |
24 „ |
Dog discon- |
248 |
About 100 |
All . |
6 „ |
89 „ |
+ |
28 „ |
18 „ |
Dog discon- |
34 |
About 100 |
All . |
8 „ |
31 „ |
.. |
.. |
.. |
Died of sus- |
29 |
About 90 adults |
74 |
10 „ |
11 „ |
.. |
.. |
.. |
Died of pneu- |
The incubation period shown in the foregoing table against each of the three
dogs that developed the infection represents the interval between the date on which
the ticks were placed upon the host and the first appearance of the parasites in
the circulating blood. It is noteworthy that this period was more or less constant
in the three animals, for this is a strong confirmatory evidence that the animals
actually developed the infection as a result of being bitten by the ticks and pre-
cludes the possibility of natural infection or resuscitation of dormant parasites.
It has already been remarked that an elevation in body temperature has not
been found to be a reliable indication of the development of artificial P. gibsoni