(E)carrier state classified 1)convalescent carriers,2)carriers of incubation period,3)healthy carriers. acute or chronic carriers (less or more than 3 months) important sources of infection in many communicable diseases:typhoid fever,bacillary dysentery,cholera,hepatitis B,etc. common characteristic:release pathogens into the environment without apparent symptoms
(E) carrier state ◼ classified :1) convalescent carriers, 2) carriers of incubation period,3) healthy carriers. acute or chronic carriers (less or more than 3 months) ◼ important sources of infection in many communicable diseases: typhoid fever, bacillary dysentery, cholera, hepatitis B, etc. ◼ common characteristic: release pathogens into the environment without apparent symptoms
(E)Latent Infection Pathogen localized by the body's immunity and cannot cause apparent infection. Pathogens persistently reside in the body and cause apparent infection only when compromised,such as herpes zoster, tuberculosis,malaria,etc. The difference from carrier state:not to release pathogen. Generally,inapparent infections are the commonest,pathogen carrier states follow and the apparent infections account for the least
(E) Latent Infection ◼ Pathogen localized by the body's immunity and cannot cause apparent infection. ◼ Pathogens persistently reside in the body and cause apparent infection only when compromised, such as herpes zoster , tuberculosis, malaria, etc. ◼ The difference from carrier state: not to release pathogen. ◼ Generally , inapparent infections are the commonest, pathogen carrier states follow and the apparent infections account for the least
The pathogenecityof a pathogen 1. Invasiveness 2. Virulence:exotoxin,endotoxin 3.Number 4.Variability
The pathogenecityof a pathogen 1. Invasiveness 2. Virulence: exotoxin, endotoxin 3. Number 4. Variability
Invasiveness Invasiveness refers to the ability that a pathogen invades the body and spreads within the body. Leptospire can invade human body directly. Vbrio cholerae should adhere to intestinal mucosa firstly and then colonize to produce intestinal toxin or cause infection
Invasiveness ◆ Invasiveness refers to the ability that a pathogen invades the body and spreads within the body. ◆ Leptospire can invade human body directly. ◆ Vbrio cholerae should adhere to intestinal mucosa firstly and then colonize to produce intestinal toxin or cause infection
Virulence includes toxins and other toxic factors (like enzymes,etc).Toxin includes exotoxin and endotoxin. Endotoxin can activate mononuclear- macrophages to produce cytokines to function. Exotoxin (intestinal toxin)can attach the 'receptor of target organs and enter the cells to function
Virulence ◼ includes toxins and other toxic factors (like enzymes, etc). Toxin includes exotoxin and endotoxin. ◼ Endotoxin can activate mononuclearmacrophages to produce cytokines to function. ◼ Exotoxin (intestinal toxin) can attach the ‘receptor of target organs and enter the cells to function