PREPARASITIC STAGES IN THE LIFE HISTORY OF THE 
CATTLE HOOKWORM (BUSTOMUM PHLEBOTOMUM) 1 
By Benjamin Schwartz 
Zoological Division , Bureau of Animal Industry, United States Depart?nent of 
Agriculture 
INTRODUCTION 
The occurrence of hookworm in¬ 
festation in cattle in the United States 
attracted considerable attention sev¬ 
eral years ago because of the supposed 
etiological relation of these parasites 
(Bustomum phlebotomum) to a disease 
of cattle commonly known as “salt 
sick.” Following the report of Stiles 
( 14 ), 2 who called attention to the oc¬ 
currence of hookworms in cattle in 
Texas, Dawson (5) pointed out the 
resemblance between the clinical pic¬ 
ture of hookworm anemia in man and 
“salt sick” in cattle, and in 1906 the 
same writer expressed a more definite 
opinion regarding the relation of cattle 
hookworms to “salt sick,” which he 
characterized as “an acute or chronic 
parasitic disease manifested at first by 
low fever, diarrhea, loss of appetite; 
soon becoming chronic, with continu¬ 
ance of low fever, constipation, loss of 
appetite, progressive emaciation and 
pronounced anemia, which in many 
cases terminates fatally.” While it 
has not been conclusively established 
that the condition in cattle commonly 
known as “salt sick” is actually due to 
hookworm infestation, the fact that 
cattle heavily infested with these para¬ 
sites develop a progressive anemia, as 
shown by Dawson ( 6 ), has been con¬ 
firmed by other observers, notably by 
Reisinger (13). 
With a single exception, the pub¬ 
lished reports dealing with hookworm 
disease in cattle contain no information 
based on original investigations con¬ 
cerning the life history of Bustomum 
phlebotomum. This exception is a 
paper by Conradi and Barnett (4) 
which contains a very brief account of 
the development of the egg up to the 
infective stage, but lacks essential de¬ 
tails. Since precise information con¬ 
cerning the preparasitic stages in the 
life history of strongyle parasites is 
generally useful in connection with 
control measures against these para¬ 
sites, it is important that pertinent 
facts concerning the life cycle of cattle 
hookworms become available in order 
that such control measures may be de¬ 
vised. Hence the observations and ex¬ 
periments described in this paper were 
undertaken. As the work progressed 
some observations and experiments of 
a less practical nature were included in 
order to compare the behavior of cattle 
hookworm larvae with those of other 
strongyle parasites. 
MATERIAL AND METHODS OF 
INVESTIGATION 
Specimens of hookworms from cattle, 
collected in the course of post-mortem 
examinations of the viscera, were 
washed several times in physiological 
salt solutions and then chopped with a 
pair of fine scissors to liberate the eggs 
from the uteri of the females. With 
the aid of a pipette chopped-up worm 
material was added to the surface of 
feces and charcoal mixtures in glass 
dishes and bottles (solid culture media) 
and to water and filtrate from boiled 
feces in staining jars and Petri dishes 
(liquid culture media). 
The solid culture media were made 
up as follows: Sheep or cattle feces 
were boiled in water and filtered 
through ordinary filter paper. Suffi¬ 
cient charcoal was added to the fil¬ 
trate to make a thick paste, which was 
spread out in Petri dishes, wide-mouth 
bottles, and other glass containers, care 
being taken to smooth down the sur¬ 
face of the medium and to keep the 
latter moist by adding water whenever 
necessary in order to make up the loss 
due to evaporation. When diluted 
with water sufficient to make a trans¬ 
parent medium, the filtrate from the 
boiled feces was found to be an excel¬ 
lent culture medium for the examina¬ 
tion of contents from day to day. A 
thin layer of the liquid was added to 
the glass containers, thus affording a 
supply of oxygen, which is requisite 
to rapid development. Culture media 
were kept at room temperature (70° 
1 Received for publication Apr. 10,1924—issued January, 1925, 
Reference is made by number (italic) to “Literature cited," p. 458. 
Journal of Agricultural Research, 
Washington, D. C. 
(451) 
Vol. XXIX, No. 9 
Nov. 1, 1924 
Key No. A-80 
