Microbial Pathogenesis and infection

Microbial Pathogenesis and infection
Infection is presence and multiplication of pathogenic microbe within human body, and cause symptoms of infection. The infection differs from other diseases is that caused by living microbial pathogens.
Infection (or not) is determined by balance between number and virulence of microbe and competency of that host defense. If microbes are overcome, the disease results.Outcome of most host-parasite relationship is dependent on three main factors ;
a. Number of pathogenic microorganism infecting the host(dose).
b. Degree of pathogenicity of organism(virulence).
c. Degree of host defense (resistance).
The infectious disease equation:
Number of organisms(dose) x Virulence
= Infectious Disease
Host resistance
The infection does not arise in vacuum. It results from interaction of several factors include mainly three factors:
a. Virulent microbe.
b. Susceptible host.
c. Environmental factors
Stages of microbial pathogenesis:
1. Encounter of microbe with susceptible host.
2. Entry and adhere to susceptible host tissues.
3. Multiply and spread to adjacent cells or to specific cells.
4. Evade host defense mechanism.
5. Damage the host tissues and disease symptoms.
6. Progression or resolution of the disease.
7. Shedding of microbial pathogen into environment.
Sources of