DR. S. H. LONG ON THE MOSQUlTO-MALARlA THEORY. 203 
It will be both interesting and instructive to see if, with the 
return of our troops from South Africa, there will be any increase 
in the number of indigenous cases of Malaria in this country. It 
is not improbable that, other conditions being suitable, a certain 
number of our local Mosquitoes will become infected by these 
men. I may say that up to the present time I am accredited with 
being the only observer in England who has found the malaria 
parasite in a case of Ague indigenous to this country : the case 
being that I have referred to as coming to the Norfolk and 
Norwich Hospital, from Acle, in the year 1897. A reference to 
this case will be found in the first number of the ‘Journal of 
Hygiene,’ 1901, p. 31. As it was of the greatest importance to 
decido whether or not the parasite was present in this case — one 
of Tertian Ague — I was anxious to get my opinion confirmed by 
an expert. I therefore sent one of the blood preparations I made 
from the case to Dr. Nuttall of Cambridge, who has paid particular 
attention to this subject, and I have had a good deal of corres- 
pondence with him about it. He very kindly undertook to re-stain 
and re-mount the specimen — a proceeding always attended with 
considerable risk — and in his last communication to me on the 
subject (dated March 4th, 1901) he says : “You will be pleased to 
hear that I have found malarial parasites in the film after re-staining 
it to-day. There is about one parasite to every 3-4 fields, and this 
time there is no doubt about it.” 
Summary. 
(1) Malaria is now known to be caused by a parasite, which 
passes one cycle of its existence in the blood of man, who acts as 
the intermediate host ; whilst the Mosquito plays the part of the 
definitive host for the other cycle of its life-history. 
(2) Only certain Mosquitoes — those of the Anopheles species — 
have so far been shown to be capable of acting as the definitive 
host of this parasite. 
(3) Man becomes infected with Malaria through the bite of the 
Mosquito, and up to the present time no other means of infection 
is known. It has been conclusively proved that in certain highly 
malarious districts, e.tj., the Roman Campagna, man can live 
without fear of contracting Malaria if he adopts such measures as 
will insure complete protection against Mosquitoes. 
