Infection: Meaning and Its Types | Medical Microbiology

In this article we will discuss about the meaning and types of infection.

Meaning of Infection:

Infection can be defined as the process of lodgment and multiplication of a parasitic organism within or on a host. Infection is a common natural event and does not invariably result in disease. In fact, disease is a rare consequence of infection.

Whenever, an infection so progresses that it results in a disease, the latter is called an infectious disease. The infectious disease therefore differs from infection and can be defined as any change from a state of health in which part or all of the host body is not capable of carrying on its normal functions under the influence of a parasite or its products. The parasite that produces an infectious disease is called a pathogen and its ability to cause infectious disease is called pathogenicity.

The nature of an infection may vary widely with respect to location, severity, and number of parasitic organisms involved.

Types of Infection:

Various types of infections are categorized and are given as follows:

1. Abscess:

A localized infection with a collection of pus surrounded by an inflamed area.

2. Acute Infection:

Short but relatively severe course of infection.

3. Bacteremia:

Presence of viable bacteria in the blood.

4. Chronic Infection:

Infection that persists over a long period.

5. Convert Infection:

Subclinical infection; no symptoms.

6. Cross Infection:

A new infection acquired by a patient while already suffering from a disease.

7. Focal Infection:

A condition where, due to infection or sepsis at localized sites such as appendix or tonsils, generalized effects are produced.

8. Fulminating Infection:

Infection occurs suddenly and the infectious agent multiplies with great intensity.

9. Latent Infection:

Infection that persists in tissues for long periods, during most of which symptoms do not manifest.

10. Localized Infection:

Restricted to a limited region or to one or more anatomical areas.

11. Nosscomial Infection:

The infection that develops during a stay at a hospital or other clinical care facility.

12. Primary Infection:

Initial infection with a parasite.

13. Pyogenic Infection:

Infection that results in pus formation.

14. Reinfection:

Subsequent infections by the same parasite in the host.

15. Secondary Infection:

When a new parasite sets up an infection in a host whose resistance is lowered by a pre-existing infectious disease.

16. Septicemia:

Blood poisoning associated with persistence of pathogenic organisms or their toxins in the blood.

17. Sub-Clinical Infection:

Infection during which clinical symptoms are not manifested.