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parts of the globe when, in 1926, the disease was reported in the jungles of
Brazil and Bolivia, where it occurred in areas not frequented by
mosquitoes. True to form, the ailment again reached the seacoasts and in
1928-'29 there was an epidemic at Rio de Janeiro in which 435 persons
perished. (12)

Florida medical authorities were at once disturbed over the
possibility that the fever might again be transmitted to these shores
because the same species of mosquito which had formerly spread the
virus is still present in many sections of this State. One case of yellow
fever, transported to Florida, might easily be multiplied into new
epidemics, and the danger of spreading the infection had been greatly
increased since the advent of the automobile and airplane.

Modern Preventive Measures. On September 19, 1929, Dr.
George N. MacDonnell, director of public health at Miami, wrote to
Surgeon General Hugh S. Cumming of the United States Army, calling
attention to the fact that Colonel Charles Lindberg would soon fly from
Miami to South America, establishing the first regular inter-continental
passenger plane service, and expressing the fear that yellow fever (at that
time prevalent in Brazil) might be re-introduced into this country. Shortly
afterward Dr. T. H. D. Griffiths of the United States Public Health
Service tested the possibility of carrying mosquitoes in planes. He
liberated 100 tinted insects in an airliner at Cristobal, Canal Zone, and 22
of them were still aboard when the machine arrived at Miami. (13)