7

II.

THE PARASITE IN ITS MAMMALIAN HOST.

GEOGRAPHICAL DISTRIBUTION.

         Piroplasma canis was discovered by Piana and Galli Valerio in the blood of
hunting dogs in Lombardy and described by them. Five years later Celli (32)
noted its presence in hunting dogs brought from Lombardy to the Roman Cam-
pagna. In France the parasite is recorded by Leblanc (150) at Lyons and by
Nocard and Almy (155) at D'Alfort, indigenous cases of infection in both
instances being met with.

         It has been described by Marchoux (151) as occurring in the blood of dogs
in Senegal and by Koch (71) in a dog at Dareslam in East Africa.

         In South Africa Hutcheon (147) had recognised a disease in dogs related to
redwater in cattle and to biliary fever in horses even before the parasite had been
demonstrated by Carrington Purvis, and had described a fatal epidemic of this
disease which occurred at Herschell, Cape Colony, in the autumn of 1893.
Lounsbury says that the disease appears to occur throughout the colony, but to
be less prevalent in high inland districts than near the coast, a distribution which
coincides with that of the numerical abundance of ticks. In support of the view
that the disease is indigenous he cites the experience of old residents, who had
recognised the disease at Grahamstown, Mowbray, Humansdorp, Cradock, and
other places at dates varying between 1844-54, and quotes an extract from the
published letters of Lady Ann Barnard in which the writer refers in 1797 to a
disease which attacks all newly arrived dogs. On the other hand he quotes
farmers who recollect a time when the disease was apparently first introduced
among their dogs. Since the infecting tick H. leachi appears to be an African
species, it certainly appears probable that the disease was originally endemic in
Cape Colony, if not over the whole of Africa.

         In India P. canis has been recorded by myself (144) in Madras, and by
James (149) in Assam. In Madras infection with piroplasma is endemic among
native pariah dogs, which may show but few symptoms even when harbouring
considerable numbers of the parasite. In adult dogs of this class infection is
not common, but a very considerable, though varying, proportion of puppies
show parasites. Out of a batch of 18 young dogs brought from different villages
in the neighbourhood of the King Institute in October 1905 five were infected,