PORTALS OF ENTRANCE FOR PATHOGENIC BACTERIA 49 



Some mucous membranes on or near the external surface of the 

 body seem to possess a stronger power of resistance to certain bacteria 

 than to others. The nasal mucosa, which is very frequently exposed 

 to the tubercle bacillus, is rarely affected by it. Tuberculosis of the 

 nasal mucosa is rare. On the other hand, the nasal mucosa of the 

 horse cannot offer any resistance to the glanders bacillus by which 

 it is so often invaded. Pathogenic bacteria frequently find a portal 

 of entrance through the tonsils and the nasopharynx. 



Respiratory Tract. The mucous membranes of the nose and the 

 nasopharynx are structures which belong to the respiratory tract. 

 This leads to a consideration of this tract as a portal of entrance. 

 Infections of this type are very common, and they occur in such dis- 

 eases as tuberculosis, glanders, influenza, pneumonia, nasal catarrh 

 of birds, and in strangles of horses, the latter caused by the Strepto- 

 coccus equi. Sometimes anthrax and the pneumonic type of plague 

 are also contracted by inhalation. 



Gastrointestinal Tract. The infection is brought about by the 

 ingestion of food and water, in numerous diseases of man and the 

 domestic animals, such as typhoid, Asiatic cholera, anthrax, actino- 

 mycosis, hog erysipelas, fowl cholera, tuberculosis, bacilliary dysen- 

 tery, plague in rats, various hemorrhagic septicemias. The par- 

 ticular point where these pathogenic microorganisms gain entrance into 

 the tissues varies greatly. It may be the mucosa of the mouth, as in 

 actinomycosis of cattle, or it may be the small intestine, as in typhoid 

 fever and Asiatic cholera in man, or again it may be the large intes- 

 tine, as in anthrax or tuberculosis. 



Genital Tract. The genital tract forms the portal of entrance for 

 pathogenic bacteria in sexual intercourse. Infectious diseases devel- 

 oped in this manner are perhaps more prevalent in man (gonorrhea, 

 soft chancre, syphilis), but there are also dieases of this type among 

 the domestic animals. Tuberculosis of the testicles of the bull has 

 given rise to tuberculosis in the vagina of the cow, but this is exceed- 

 ingly rare. There are, however, other animal infections more com- 

 monly transmitted in sexual intercourse. In cows, infectious abor- 

 tion due to the korynebacterium abortus infectiosi of Bang is spread 

 by the bull from already infected to healthy cows. The latter after 

 the abortion harbor and discharge the bacterium for a long time, 

 often for years, and abort again and again, continuing the spread of 

 the disease through the bull. The infectious abortion of mares, due 

 to a bacillus first discovered by Ostertag, is likewise spread by sexual 

 intercourse, and its entrance is made thro ugh the genital tract. Another 

 bacterial disease which finds its portal of entrance in the genital 

 organs in sexual intercourse is the infectious vaginal catarrh of cows 

 (kolpitis granulosa infectiosa bovum), caused by a specific strepto- 

 coccus discovered by Ostertag and Hecker. Dourine of horses also 

 makes its entrance in a similar manner. This disease, however, is not 

 a bacterial but a protozoan infection (a trypanosomiasis). 

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