Report on the Agricultural Experiment Stations, 1953 Page: 29
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LIVESTOCK PRODUCTION AFFECTED BY ANIMAL DISEASES 29
areas within a radius of 6 to 8 miles of Bismarck also eliminated the
mosquito populations normally breeding in impounded waters. All
insecticides used (Aldrin, Chlordane, DDT, and Toxaphene) were
equally efficient in controlling the mosquito larvae. Before mosquito
control was started about 90 percent of the mosquito infestation in
Fargo one year was Aedes vexans which was the most annoying species.
Only about 3 percent were Culex tarsalis mosquitoes, but this species
is a carrier of encephalitis. Since mosquito control programs were
started, the annoyance from mosquitoes has been greatly reduced in
both treated areas, and there has been a very low incidence of encephalitis
in Bismarck and Fargo as compared with the remainder of the
During the past 50 years there have been at least 19 cases of human
infection with cattle liver fluke in the Hawaiian Islands. It is also
believed that many additional cases were never recognized. Although
the source is not known, it is reasonable to assume, on the basis of
the life cycle of the fluke, that the infections resulted from ingesting
larval flukes encysted on vegetation grown in water. Since watercress
is grown in water and is commonly eaten raw, it was thought
that it might constitute a source of infection if grown in contaminated
On the basis of this suspicion, all the commercial watercress-producing
areas on the islands of Oahu and Hawaii have been studied
by the Hawaii station to determine the source of water used, the possibility
of pollution with feces of cattle, and the presence of lymnaeid
snails infected with liver flukes. Of 9 areas surveyed in Hawaii, all
contained lymnaeid snails, 5 showed evidence or possibility of pollution,
and in 1 area about 5 percent of the snails examined showed
heavy infection with liver flukes. Of 13 areas on Oahu, 10 contained
lymnaeid snails, 8 showed evidence of pollution, and none of the
snails examined showed fluke infection. The present survey has
shown that risk of watercress infection with liver flukes does exist
in the Territory. This risk can be reduced if watercress growers
abstain from the use of stream water which is likely to be infected,
utilizing only spring water at its source of origin; lymnaeid snails
are controlled; cattle are prevented from grazing in or near watercress
areas; and fluke control in cattle is promoted to reduce infection
Fireflies may control flukes
It is possible that fireflies from Japan may be used to control certain
small fresh-water snails which are the only carriers of the
cattle liver fluke, a damaging parasitic disease of cattle as well as a
potential threat to man in the Hawaiian Islands.
In recent years, the Hawaii station has been interested in reports
by Japanese scientists that the larvae of two species of firefly, Luciola
cruciata and L. lateralis, feed actively on fresh-water snails, some of
which are known to be carriers of flukes. The beneficial nature of the
fireflies is accepted, although some scientists feel that they do not kill
enough snails to be effective. With their possible value in mind, the
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1953, book, 1953; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5989/m1/31/: accessed May 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.