20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
Mertens (1950) describing the role of Blattella germanica in the 
transmission of Salmonella typhimurium. These workers observed 
the following facts during an epidemic of food poisoning in the 
nursery at the Clinique Pédiatrique de |l’Hopital Universitaire de 
Bruxelles: 1. Persistence of an epidemic of intestinal infection of 
Salmonella typhimurium in spite of quick isolation of the patients, 
the absence of healthy carriers, and the suppression of infecting con- 
tact, direct or indirect, between the babies, with the exception of in- 
direct contact through cockroaches. 2. Finding that cockroaches ran 
over the covers, clothing, and bodies of the babies at night. 3. Capture 
of a cockroach carrying numerous bacteria of the species S. typhi- 
murium, in the vicinity of the babies. 4. Immediate check of the 
epidemic when the nursery was disinfected with DDT. 
This epidemic prevailed for nearly 2 months in a nursery containing 
permanently 16 to 20 infants. Of the 50 children that passed through 
the nursery, 16 were contaminated with S. typhimurium. During most 
of the epidemic, cockroaches had not been suspected because they were 
not seen during the day. When the nursery was about to be closed, 
a night nurse called attention to the cockroaches. Thirty Blattella 
germanica, one of which was contaminated, were captured before the 
nursery was disinfected. It is highly significant that from the day the 
nursery was sprayed with DDT no more living cockroaches were 
seen, and no more cases of evident or hidden infections of S. typhi- 
murium were detected. 
Concerning salmonellosis, Watt (in Maxcy, 1951) stated that the 
case against arthropods as transmitters is circumstantial and the lack 
of direct evidence in itself indicates that insects probably play a 
minor part in the spread of human salmonellosis. However, the 
findings to date indicate that intensive control measures are warranted 
in any area where both cockroaches and Salmonella infections are 
prevalent and that strong efforts should be made to control these 
insects in hospitals and public eating places (Mackerras and Pope, 
1948; Graffar and Mertens, 1950; Janssen and Wedberg, 1952). 
In recent years, cockroaches as well as other insects have come under 
suspicion as possible vectors of the bacillus of Hansen’s disease. Doull 
(in Maxcy, 1951) stated that the evidence for insect vectors in the 
transmission of leprosy is based on analogy and is largely presumptive. 
Simons (1952) strongly inclined to the view that the cockroach and 
the bedbug should be suspected, because leprosy is the pauper’s dis- 
ease and the vector should be an insect that is important in the lives 
of unhygienically living people. 
Clinical evidence for the transmission of leprosy is conclusive 
