The acquisition of an infectious disease is influenced by factors related to:
Both the microorganism and the host.
Which facts can influence exposure and development of an infectious diseases:
The immune status of an individual. (Immunocompromised individuals have a much higher rates microbial disease.)
Overall incidence of an organism in the population.
Pathogenicity or virulence of the agent.
Presence of a succiciently large dose of the agent or organism to produce an infection
Appropriate portal of entry
Phagocytosis and complement activation may be initiated within minutes of
invasion by a microorganism .
Unless primed by previous contact with the same or a similar antigen, antibody and cell mediated responses
do not become activated for several days
Toxoplasmosis is a widespread
disease in humans and animals.
Toxoplasmosis is caused by
toxoplasma gonidii, recognized as a tissue coccidian.
Two members of the human herpesvirus family are
Other members of the human herpesvirus family include
herpes simplex, VZV and human herpesvirus-6
Facts that influence the exposure to and actual development of infectious disease:
immune status of the individual
overall incidence of an organism in the population
pathogenicity or virulence of the organism
dosage of the organism
portal of entry
For an infectious disease to develop in a host, the organism must:
penetrate the skin or mucous membrane barrier
survive the other natural and adaptive defense mechanisms
--------- phagocytosis and complement activation is initiated within minutes of invasion
--------- antibody and cell mediated responses require several days ( unless its a second exposure to the same antigen)
Immunity of bacterial diseases
lysozyme and phagocytosis are the major natural defense against bacteria
Immunity of parasitic disease
parasites can avoid phagocytosis by migrating away from inflamed area.
They are relatively large have resistant body walls
Immune responses to parasites include: immunoglobulins, complement, antibody-dependent, cell-mediated cytotoxity, cellular defenses such as eosinophils and T cells
Immunity to fungal disease
Fungal infections are increasing due to the use of immunosuppressive drugs and AIDS
Types of fungal infections seen:
histoplasmosis, aspergillosis, coccidiomycosis, blastomycosis, sporotrichosis, cryptococcosis
Toxoplasmosis is a
Immunity to viral diseases
Interferon plays a major role in defense against viral infections
Herpes virus family includes:
cytomegalovirus CMV, Epstein-barr virus EBV, herpes simplex type 1 and 2, varicella zoster (chicken pox), and human herpesvirus-6
laboratory detection of infectious Disease by serelogy
1. detection of IgM specific antibodies (elevation means recent or current infection)
2. detection of IgG specific antibodies (elevation means past exposure)
3. acute and convalescent specimens, (draw an acute sample and one 3 weeks after.
a TORCH test
is a set of serological tests for Toxoplasma gondi i ( parasite)
herpes 1 and 2