THE house fly (Musca domestica)
has been incriminated as a vector
of food poisoning bacteria on many
occasions. Classical epidemics of foodborne
infections such as the typhoid
epidemics among soldiers during the
Boer1 and Spanish-American 2 wars,
each of which involved more than
20,000 cases, and the widespread cases
of diarrhea in Southend-on-Sea 3 in 1901
were traced to the contamination of
food by flies. These and numerous
other food poisoning epidemics, in
which flies were thought to have been
responsible for infecting food supplies,
have led many investigators to study
the potentialities of house flies as carriers
of pathogenic bacteria. A more
complete review of the literature and
the results of some preliminary experimental
data have been reported in a
previous publication4 in which it was
shown that flies are capable of depositing
on food by defecation or regurgitation
countless numbers of bacteria, an(d
further that the bacterial flora deposited
is largely determined by the nature of
the material on which the flies feed.
Flies infected with Salmonella enteritidis
and allowed to come in contact
with sterile pecan meats deposited these
*Read at a Joint Session of the Engineering and
Food and Nutrition Sections of the American Public
Health Association at the Seventieth Annual Meeting
in Atlantic City, N. J., October 15, 1941.
pathogens in large numbers on the
pecans left exposed for only 15 minutes.
Since the publication of those data
several hundred flies trapped in and
around crabmeat producing establishments
were found to contain total bacterial
counts of 750 million and as
many as one million Escherichia coli
per fly.