Variation of H. Influenzae During Acute Respiratory Infection in the Chimpanzee

Abstract

In a previous communication1 the striking resemblance of the bacterial flora of the upper respiratory tract of the chimpanzee to that of human beings has been described. To what extent these animals possess a similar flora in their native environment, or to what extent the organisms present represent new acquisitions after landing in the United States is not known.

The chimpanzee is highly susceptible to the common cold, whether naturally communicated by contact with infected human beings or artificially induced by bacterium-free filtrates of naso-pharyngeal washings from subjects suffering from acute colds. One of the striking phenomena of these chimpanzee colds is the great increase both in numbers and in area of distribution during the early stages of the cold, whether spontaneous or experimental, of the common pathogens of the upper respiratory tract such as H. influenzae, pneumococcus and S. hemolyticus.

In particular, we have noticed from the beginning of our study of the common cold in apes, during periods of infection, a change in the number and character of the colonies of H. influenzae on rabbit's blood agar plates. During the healthy period cultures from the naso-pharynx and nose give few colonies of H. influenzae from the naso-pharynx and usually none from the nose. The colonies themselves are small and opaque. During the period of infection numerous colonies of H. influenzae are obtained both from the naso-pharynx and the nose. Furthermore, the colonies themselves are of an obviously different character, very large, translucent and moist.

A more careful study of this phenomenon has revealed facts of great interest and importance. In April, 1932, an outbreak of spontaneous colds occurred among our chimpanzees.