Infectious Diseases and Cancer Flashcards
symbiosis
benefits only the human; no harm to the microorganism
mutualism
benefits the human and the microorganism
commensalism (satelliteism)
benefits the microorganism; no harm to the human
pathogenicity
ability of an agent to produce disease – success depends on communicability, infectivity, extent of tissue damage and virulence
opportunism
situation that occurs when benign microorganisms become pathogenic because of decreased human host resistance
communicability
ability to spread from one individual to others and cause disease
ex. measles, pertussis spread very easily
human immunodeficiency virus (HIV) is of lower communicability
immunogenicity
ability of pathogens to induce an immune response
infectivity
ability of the pathogen to invade and multiply in the host
mechanism of action
manner in which the microorganism damages tissue
pathogenicity
ability of an agent to produce disease – success depends on communicability, infectivity, extent of tissue damage and virulence
portal of entry
route by which a pathogenic microorganism infects the hose
direct contact, inhalation, ingestion, bites of animal / insect
toxigenicity
ability to produce soluble toxins or endotoxins, factors that greatly influence the pathogen’s degree of virulence
virulence
capacity of a pathogen to cause severe disease
ex. measles = low
rabies = high BATS!!! :)
Exotoxins
proteins released during bacterial growth
usually enzymes that have highly specific effects on host cells; they include:
cytotoxins, neurotoxins, pneumotoxins, enterotoxins, hemolysins
^immunogenic and elicit the production of antibodies known as antitoxins
vaccines are available for many of the exotoxins (tetanus, diphtheria, pertussis)
Endotoxins (lipopolysaccharides LPSs)
contained in the cell walls of gram - bacteria and are released during lysis, or destruction of bacteria
may be released also from the mbn of the bacteria during bacterial growth or during treatment with antibiotics → cannot prevent toxic effects of the endotoxin
Bacteremia
presence of bacteria in the blood
Septicemia
growth of bacteria in the blood and is caused by a failure of the body’s defense mechanisms
once in blood, endotoxins cause the release of vasoactive peptides and cytokines that affect blood vessels by producing vasodilation (reduces BP) = decreased O2 delivery → cardiovascular shock
six phases of the viral replication cycle
- Adsorption: attachment to cell
- Penetration
- Uncoating
- Replication
- Assembly
- Release
clinical manifestations of infection
Vary depending on pathogen and infected/affected organ system
May come from infecting microorganism and/or its products
Mostly come from host’s inflammatory immune response
Manifestations include: fatigue malaise weakness loss of concentration general aching loss of appetite FEVER- hallmark trait
Vaccines
intended to introduce a biological pathogen to the host’s immune system to cause a long-lasting protective immune response under conditions that will not result in disease
Primary response is often short lived
Thus the need for Boosters
Vaccine Types
Killed: use of inactive virus (does not normally lead to infection)
Attenuated: Live viruses that are weakened
Toxoids: purified toxins that have been chemically detoxified without the loss of immunogenicity
primary (congenital) immune deficiency
result of single gene defect, generally sporadic; not inherited; mutations occur before birth
GENERALLY RARE
5 groups of deficiencies: B Lymphocyte T Lymphocyte Combined Immune Complement Phagocyte
secondary (acquired) immune deficiency
Not related to genetic defects
ARE complications of physiologic or pathologic conditions
Common, but many are not clinically relevant
May be very mild; can be very serious and life-threatening (AIDS)
HIV (human immunodeficiency virus)
Routes of transmission include:
- blood or blood products
- IV drug use
- heterosexual and homosexual activity
-maternal-child transmission (before, during or after birth): contracted across the placenta, infected blood during delivery, through milk during breastfeeding
HIV Pathology
retrovirus: carry RNA
A viral enzyme reverse transcriptase converts RNA → ds DNA.
A second viral enzyme integrase, inserts the new DNA into the infected cell’s genetic material.
Protease processes the proteins needed from the capsid
The primary receptor on HIV is the envelope protein, gp120.
NOTE: The major immunologic finding in AIDS is the striking decrease in the number of CD4-positive (CD4+) T helper cells.
HIV Manifestations
Early stages of HIV initially presented as influenza-like symptoms. Symptoms are relatively mild and non-specific; disappearing after 1-6 weeks of onset
Window period: is the amount of time that passes between infection and appearance of antibody.
Diagnosis of HIV/AIDS : cell count
initially diagnosed by decrease in CD4+ T cells:
Normal range: 600/mm3-1200/mm3
HIV/AIDS: less than 200/mm3
Time frame from infection of HIV to development of AIDS is 10 years.
HIV Symptoms
Fever, Fatigue, Weight loss, Diarrhea
Swollen lymph nodes — often one of the first signs of HIV infection
Cough, Shortness of breath
Progression to AIDS
Fever, Fatigue, Weight loss, Diarrhea
Swollen lymph nodes — often one of the first signs of HIV infection
Cough, Shortness of breath
All of the above, PLUS: Soaking night sweats Shaking, Chills, Fever higher than 100F for several weeks Headaches Persistent, unexplained fatigue Blurred and/or distorted vision Persistent white spots or unusual lesions on your tongue or in your mouth Skin rash or bumps
opportunistic infection
infection that would normally not bother someone with a “healthy” immune system, however, can be life-threatening to someone with HIV/AIDS. Some of their severities depend on certain levels of CD4+ cell count.
reverse transcriptase inhibitors
nucleoside and nonnucleoside inhibitors of reverse transcriptase; try to block recoding of RNA to DNA
