|
Main
- books.jibble.org
My Books
- IRC Hacks
Misc. Articles
- Meaning of Jibble
- M4 Su Doku
- Computer Scrapbooking
- Setting up Java
- Bootable Java
- Cookies in Java
- Dynamic Graphs
- Social Shakespeare
External Links
- Paul Mutton
- Jibble Photo Gallery
- Jibble Forums
- Google Landmarks
- Jibble Shop
- Free Books
- Intershot Ltd
|
books.jibble.org
Previous Page
| Next Page
Page 38
Few hypotheses have been advanced in science which are more ingenious,
in better accord with the facts, have had greater importance in
enabling the student to grasp the intricacies of an obscure problem,
and which have had an equal influence in stimulating research. The
immunity which results from disease in accordance with this theory, is
due not to conditions preventing the entrance of organisms into the
body, but to greater aptitude on the part of the cells to produce
these protective substances having once learned to do so. An
individual need not practise for many years, having once learned them,
those combinations of muscular action used in swimming; but the habit
at once returns when he falls into the water.
Infectious diseases and recovery are phases of the struggle for
existence between parasite and host, and illustrate the power of
adaptation to environment which is so striking a characteristic of
living matter.
FOOTNOTES:
[1] The comparison here is with the atrium of a Pompeiian house.
CHAPTER VIII
SECONDARY, TERMINAL AND MIXED INFECTIONS.--THE EXTENSION OF INFECTION
IN THE INDIVIDUAL.--TUBERCULOSIS.--THE TUBERCLE BACILLUS.--FREQUENCY
OF THE DISEASE.--THE PRIMARY FOCI.--THE EXTENSION OF BACILLI.--THE
DISCHARGE OF BACILLI FROM THE BODY.--INFLUENCE OF THE SEAT OF DISEASE
ON THE DISCHARGE OF BACILLI.--THE INTESTINAL DISEASES.--MODES OF
INFECTION.--INFECTION BY SPUTUM SPRAY.--INFECTION OF WATER
SUPPLIES.--EXTENSION OF INFECTION BY INSECTS.--TRYPANOSOME
DISEASES.--SLEEPING SICKNESS.--MALARIA.--THE PART PLAYED BY
MOSQUITOES.--PARASITISM IN THE MOSQUITO.--INFECTION AS INFLUENCED BY
HABITS AND CUSTOMS.--HOOKWORM DISEASE.--INTER-RELATION BETWEEN HUMAN
AND ANIMAL DISEASES.--PLAGUE.--PART PLAYED BY RATS IN
TRANSMISSION.--THE PRESENT EPIDEMIC OF PLAGUE.
The infectious diseases are often complicated by secondary infections,
some other organism finding opportunity for invasion in the presence
of the injuries produced in the primary disease. In many diseases,
such as diphtheria, scarlet fever and smallpox, death is frequently
due to the secondary infection. The secondary invaders not only find
local conditions favoring a successful attack, but the activity of the
tissue cells on which the production of protective substances
essentially depends has suffered by the primary infection, or the
cells are occupied in meeting the exigencies of this. The body is in
the position of a state invaded by a second power where all its forces
and resources are engaged in repelling the first attack.
What are known as terminal infections occur shortly before death. No
matter what the disease which causes death, in the last hours of life
the body usually becomes invaded by organisms which find their
opportunity in the then defenceless tissues, and the end is often
hastened by this invasion.
There are also mixed infections in which two different organisms unite
in attack, each in some way assisting in the action of the other. The
best known example of this is in the highly infectious disease of
swine known as hog cholera. It has been shown that in this disease two
organisms are associated,--one an invisible and filterable organism,
and the other a bacillus. It was first supposed that the bacillus was
the specific organism; it was found in the lesions and certain, but
not all, the features of the disease were produced by inoculating hogs
with pure cultures. The disease so produced is not contagious, and the
contagious element seems to be due to the filterable virus.
The modes of transmission of infectious diseases are of great
importance and are the foundation of measures of public health. In the
preceding chapter we have seen that in the infected individual the
disease extends from one part of the body to another. There is a
primary focus of disease from which the extension takes place, and the
study of the modes of extension in the individual throws some light on
the much more difficult subject of the transmission of disease from
one individual to another. There are four ways by which extension in
the individual may take place.
1. By continuity of tissue, an adjoining tissue or organ becoming
infected by the extension of a focus of infection.
Previous Page
| Next Page
|
|