Leishmanioses and Insects 
221 
Brumpt objects that they and other workers who thought to trace 
the development of Leishmania infantum were apparently misled by 
the presence of a harmless Herpetomonas which infests dog fleas in all 
countries, even where the leishmaniasis is unknown. 
Basile (1910 and 1911) however, carried on numerous experiments 
indicating that the disease was transferred from children to dogs 
and from dog to dog by the dog flea, and was able to find in the 
tissues of the insects forms perfectly identical with those found in 
children and in dogs suffering from leishmaniasis. He also found 
that Pulex irritans was capable of acting as the carrier. 
Of the cutaneous type of leishmaniasis, the best known is the so- 
called “Oriental sore,” an ulcerative disease of the skin which is 
epidemic in many tropical and subtropical regions. The causative 
organism is Leishmania tropica, which occurs in the diseased tissues 
as bodies very similar to those found in the spleen in cases of 
kala-azar. The disease is readily inoculable and there is no doubt 
that it may be transferred from the open sores to abraded surfaces of 
a healthy individual by house-flies. It is also believed by a number 
of investigators that it may be transferred and directly inoculated 
by various blood-sucking insects. 
Ticks and Diseases of Man and Animals 
We have seen that the way to the discoveries of the relations of 
arthropods to disease was pointed out by the work of Leuckart and 
Melnikoff on the life cycle of Dipylidium, and of Fedtschenko and 
Manson on that of Filaria. They dealt with grosser forms, belonging 
to well-recognized parasitic groups. 
This was long before the role of any insect as a carrier of patho¬ 
genic micro-organisms had been established, and before the Protozoa 
were generally regarded as of importance in the causation of disease. 
The next important step was taken in 1889 when Smith and Kil- 
bourrie conclusively showed that the so-called Texas fever of cattle, 
in the United States, is due to an intracorpuscular blood parasite 
transmitted exclusively by a tick. This discovery, antedating by 
eight years the work on the relation of the mosquito to malaria, had a 
very great influence on subsequent studies along these lines. 
While much of the recent work has dealt with the true insects, 
or hexapods, it is now known that several of the most serious diseases 
of animals, and at least two important diseases of man are tick 
borne. These belong to the types known collectively as babesioses 
(or “ piroplasmoses”) , and spirochcetoses. 
