Infection

INFECTION

An infection is a condition in which contaminating micro organisms overcome host defense multiply and cause disease damaging tissues and organs.

TYPES OF INFECTION

• LOCALIZED INFECTION: Microbe remain in isolated site e.g. boils, fungal skin infection.
• SYSTEMIC INFECTION:, Microbe is present through the tissues by circulation e. measles, rubella, chickenpox, anthrax and typhoid
• FOCAL INFECTION: Microbes spread from local site to atria body e.g. tuberculosis, and streptococcal infection.
• PRIMARY INFECTION: The initial infection in a series.

• SECONGRY INFECTION: Secondary infection that complicates primary infection.
• ACUTE INFECTION: Appears suddenly has a short course and is relatively severe.
• CHRONIC INFECTION: Persists over a long period of time.
• NOSOCOMIAL INFECTION: It is acquired in a hospital from surgical procedures, equipment, personnel and exposure to drug resistant micro organism.
• ENDOGENOUS INFECTION:  the causative agent come from another part of the patient’s own body.
• EXOGENOUS INFECTION: originates from the outside the body i.e.  from other person or object.

MAINS OF TRANSMISSION

The main routes of transmission of infection fall into five categories.

1. Contact transfer.
• Direct contact.
• Indirect contact.
2. Air-borne transfer.
• Aerosols.
• Droplet nuclei.
3. Common vehicle.
4. Vector-borne.
5. Blood-borne.

1)      CONTACT TRANSFER- The most importance in nonsocial infection.

a)      Direct contact

·         Transfer of organism from one patient to another via staff hands.

·         Endogenous infection where commensally organism to a susceptible site during surgery.

·         Sexually transmitted diseases.

b)      INDIRECT CONTACT.

Via formats”(inanimate ate objects that harbor and transmit pathogens)such as bedding or communal equipment.

2)       AIR-BORNE TRANSFER.

Involving inhalation of organism.

a)      AEROSOL.

Are suspension of fine dust or moisture particles in the air that contain live pathogenic.

·         fever

·         psittacosis.

a.       ROPLET NUCLAI(Air-borne dried particles containing infectious agents formed by sneezing and coughing).

Tuberculosis. Bacteria and viruses in protective droplets of fluid which remain suspended in the air indefinitely to be inhaled by another individual.

Example of air-borne infections are.

·         Chickenpox.

·         Measles.

·      Influenza.

3)      COMMON VEHICLE-contaminated materials.

A material (vehicle) contaminated with pathogens serve  as intermediate source infection.

·        Contaminating food e.g.  salmonellas.

·         Milk e.g. tuberculosis.

·         Water e.g. cholera, polio , hepatitis.

·         Solution e.g. pseudomonas sop.

·        Drugs or blood products e.g. hepatitis Band others.

SOURCES OF INFECTION

There are three sources of infection .

1.        human.

2.        environment(inanimate including food and water)

3.        animals and birds.

1.      HUMAN.

NORMAL FLORA.

                  People are not sterile. They are colonized by 1 kg of a wide variety of micro organism, most of whish can became of pathogenic give right condition. For example Ecolab is a normal inhabitant of a gut where it cause no harm ,if it is transfer to the bladder it will cause a urinary infection.

CARRIERS AND INFECTION INDIVIDUALS.

In addition to normal flora, a person may be incubating an infection or acutely ill, recovering form the infection but still a potential source of the organisms,or be a chronic carrier of the organism of an organism of an organism without having any symptoms.

2.      ENVIRONMENT.

Soil, food and water can harbor organisms which act as a source of infection for example soil can contain clostridium sop and if a traumatic penetrating injury organism to multiply.

3.      ANIMALS AND BIRDS.

A variety of diseases can be spread from animal to man and theses are called ZOONOSES. Many animal products can transmit it from infection poultry, their eggs and dairy products.

ROUTES OF ENTRY

1.      RESPIRATORY TRACT (by inhalation of organism)

EXAMPLES.

v      Common cold viruses.

v      Tuberculosis.

v      Diphtheria.

vInfluenza.

v                       Mumps.

2.      ALIMENTARY TRACT(by ingestion of organism).

EXAMPLES.

v      Dysentery bacilli.

v      Hepatitis a virus.

v      Polio virus.

v      Salmonella sop.

3.      SKIN AND MUCOUS MEMBANCE

(by inoculation to deeper tissues).

EXAMPLES.

v      Surgery (strap aurous)

v      Insect bites.

v      Injections with contaminated products.

v      Trauma(clostridium sop)

v      Sexual contact(HIV virus).

4.      TRANSPLACENTALLY

(transmitted from mother to fetus)

v     Rubella virus.

v     Wisteria monocytogenes.

5.      VECTOR-BORNE.

            Vector are live animals that transmit an infection agent from one host to another such as flies ,mosquito's dog and birds etc.

6.      . BLOOD-BORNE

            Via inoculation,  injury and sexual transmission.

v      Hepatitis .

v      Aids.