factors in the development of diseases

7/30/2019 Factors in the Development of Diseases

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THE MODERN CONCEPT OFDISEASES

Disease may be defined as afailure of the adaptive mechanics

of an organism to counteractadequately the stimuli and stress

to which it is subject, resulting in a

disturbance in function or

structure of some parts of the

body.


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Disease results when there is a

struggle between the organism

and the individual, there is a

visible evidence of the interaction. Disease is the detectable reaction

of the individual, the human hostto a parasite (an infectious agent in

a particular environment).


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FACTORS THAT CAUSE

DISEASETo understand disease and its

process, it is important to

consider the factors or forces that

produce a healthy state free from

disease, on one hand, or a diseasecondition on the other.


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FACTORS THAT

CAUSE DISEASE


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1. THE HOST

A. Man may become an obligatehost where the microbiologicalagent has been established in manand only in man for its survival.Man is an obligate host to the virusof measles. Only in cell of man can

the virus of measles survive. Man isits reservoir.


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C. Man may be an occasional

host. Animals are the principal

reservoir; man is not

unimportant reservoir.

Example:

Rabies- principal host is animal

- occasional host is man


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2. DISEASE AGENTS

There are substances or elements,

the presence or absence of

which may imitate or penetratea disease process.


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TYPES OF AGENTS

=> Amoebic dysentery

=> Fluorosis

=> Trauma or accident

=> anemia, goiter, beri-beri, etc

=> stress, tension,

neurosis, psychosis


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3. ENVIRONMENT

Ecological factors which mayfavorable or unfavorable.


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A. CAUSATIVE AGENTS

1. BACTERIA are microscopic

organism. Most bacteria have one of

the three basic shapes: rod (bacilli),round (cocci), or spiral (spirilla).

Bacteria that live in humans used the

materials from human tissue for food.Bacteria reproduce by growing in size

and splitting in half.


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Classification of bacteria according to

their shape:

A. Cocci or round shape common diseases

produced are tonsilitis, pharyngitis, rheumatic

fever, septic sore throat, furuncles, pimples,

gastroenteritis and pneumonia.

B. Bacilli or rod shaped bacteria common

disease produced are diphtheria, cholera, el tor,

leprosy, tuberculosis, typhoid fever, dysentery.

C. Spirilla or spiral-shaped bacteria common

diseases produced are syphilis and tropical

ulcer.


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Note: Antibiotic interfere with the growth of

bacteria

2. FUNGI are organisms that feed on

animal or plant tissues. The fungi that

cause disease in human grow either onskin surface or on mucuous

membranes. The fungi take nutrients

from the cells of these tissuesEx. Ringworm, athletes foot and tinea

flava.


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3. RICKETTSIAE are small bacteria

that can be produced only within living

cells. Rickettsiae usually live in cells of

insects such as lice, mites, ticks.

Some rickettsiae can cause disease toin humans. An infected organism, like a

tick, spreads the rickettsiae whet it

bites a human or an animal. Theyreproduce inside the cells of the

human or animal.


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factors in the development of diseases

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