MOD 4 Infectious Disease Flashcards
Prions
A mutated protein molecule causes brain disease in humans and animals
-Mad cow disease (encephalitis)
-Incubates for decades before s/s appear
no cure
-nerve condition
-doesn’t reproduce but recruits
Virus
Requires a host cell (often bacteria) to inject its “virion” particle into the host cell, which then triggers the host cell’s DNA or RNA to replicate a virus.
NEEDS A HOST TO REPLICATE AND SURVIVE
Bacteria
Single-cell organisms classified as either REPRODUCES INDEPENDENTLY DOES NOT NEED A HOST
Gram Positive
Exotoxin producing
releases a toxin while alive and reproducing
some exotoxins are potent enough to kill the host
EX: botulism, diphtheria, and tetanus
needs toxoid immunizations: DPT shot (diphtheria, pertussis, and tetanus
Gram Negative
Endotoxin producing
does not release its toxin until the bacteria dies
high levels of endotoxin can trigger a systemic inflammatory response leading to SEPTIC SHOCK, DIC, AND ARDS
Chlamydia and rickettsia
REPRODUCE INDEPENDENTLY LIKE BACTERIA, BUT NEED A HOST CELL FOR ENERGY, LIKE VIRUSES
Chlamydia
is a sexually transmitted disease
Rickettsia
Carried by ticks and lice
causes Rocky Mountain Spotted Fever and Typhus
Fungal pathogens
Transmitted by spores (molds and yeast) the cause of many OPPORTUNISTIC INFECTIONS in an immunocompromised host
EX: people with AIDS or on chemotherapy are prone to get oral thrush
women taking antibiotics can develop a vaginal overgrowth of candida albicans
Protozoal Pathogens
Protozoa are parasitic animals that infect or colonize other animals, which then transmit them to humans.
parasites can be transmitted by food/water, feces, or insects (worms or ticks/fleas/lice)
Stages of infectious disease
Incubation
prodome or prodromal
acute
resolution or convalescence
Incubation period
NO S/S the number of pathogens in the body have not reached a large enough number to cause symptoms
Prodrome or Prodromal
First onset of signs and symptoms of an infection
EX: malaise and fever etc.
Acute
phase of maximum effect (damage) to the body. Can be further delineated by the invasive and decline phases of acute infection
Resolution of convalescence
the body’s defenses begin to overcome the pathogen and signs and symptoms decrease
Sign
Objective information regarding an illness. Can be SEEN FELT HEARD AND SMELLED by another person and or “measured”
Ex: temp, weight, condition of a wound, pulse, breath sounds, etc.
Symptom
subjective information regarding an illness. cannot be seen felt heard or smelled by another person or measured
Pain is always a subjective finding
Epidemiology
Study of health in populations to understand the causes and patterns of health and illness. Epidemiologists get to the root of a public health problem or emerging public health event affective a specific population.
Chain of infection
Transmission occurs when the agent leaves its RESERVOIR or host through a PORTAL OF EXIT is conveyed by some MODE OF TRANSMISSION and enters through an appropriate PORTAL OF ENTRY to infect a susceptible host.
Portal of entry
the routes an infection agent can infect a susceptible animal.
there is always a primary and secondary route for each agent
Salmonella primary: oral
Salmonella secondary: conjunctival or rectal
Portal of exit
the routes by which an infectious agent exits its host.
ex: feces, urine, saliva, expired air, blood, semen, or urogenital secretions
Primary: fecal for enteric infections
secondary: blood saliva or urine during septicemia
Vector
Blood-sucking insects such as mosquitoes, fleas, lice, biting flies, bugs, mites, and ticks
The term “vector” refers to any arthropod that transmits a disease through feeding activity.
Vectors typically become infected by a disease agent while feeding on infected vertebrates (birds, rodents, other larger animals or humans) and then pass on the microbe to a susceptible person or other animal
Reservoir
Carries of the disease
the reservoir is the habitat in which the agent normally lives, grows, and multiplies
include humans, animals, and the environment.
the reservoir may or may not be the source from which the agent is transferred to a host.
EX: the reservoir of Clostridium botulinum
Human Reservoir
Disease that are transmitted from person to person without intermediaries
Ex: sexually transmitted diseases, measles, mumps, streptococcal infection, and many respiratory pathogens
carriers are commonly transmitted because they do not realize they are infected.
Animal reservoir
Humans are also subject to dieseases that have animal reservoirs. Many of these diseases are transmitted from animal to animal, with humans as incidental hosts
EX: rabies, plague,
HIV, AIDS, Ebola, and SARS have been thought to be examples too
Environmental reservoir
plants, soil, and water in the environment
Fomites
Inanimate objects that pathogens live on. Any surface. Doorknobs, bedding, drinking glass, stair railing, etc.
Morbidity
an incidence of ILL health
classified by how many individuals got SICK per thousand people from a given disease
Mortality
Incidence of death in a population. measured in various ways
classified by how many individuals DIED per thousand people from a given disease
Comorbidity
The simultaneous presence of 2+ morbid conditions or diseases in the same patient,
EX: a person with heart failure should have a “comorbidity” of diabetes that will have to be treated also
-could make the primary condition harder to treat/ heal
Agent
Microorganisms that actually cause the diease in question
-bacteria, virus, fungus, or parasite
“what” the disease-causing organism
Host
The agent infects the host which is the organism that carries the disease
host can act as carriers for an agent without displacing any outward symptoms of the disease. Some part of their physiology is hospitable or attractive to the agent
“who” the person or population with the disease
Environment
the environment includes any factors that affect the spread of the disease but are not directly a part of the agent or the host
“where” place in which the host and agent interact
Rubella
german measles
droplets transmission
teratogen
(mean one)
Rubeolla
measles
airborne
You’re on the air with MTV
airborne transmissions
M- measles (rubeola)
T- Tuberculosis
V- varicella
Precautions: N95 mask, private room
MR PIMP drops in
M- Meningitis
R- Rubella
P- pertussis
I- Influenza
M- Mumps
P- Pneumonia
Precautions: Gown, gloves, eye protection
MRS WEE says can’t touch this
M- Multidrug resistant organism
R- respiratory infection
S- Skin infections
W- wound infection
E- enteric infection
E- eye infection
Artificial active acquired immunity
vaccine, dead or attenuated pathogens
Artificial passive-acquired immunity
injection of immune serum
Naturally passive
antibodies pass from mother to fetus via placenta
Naturally Active
Infection
contact with pathogen
Vaccines
Protections against viruses
Viruses are either attenuated live or killed viruses
trigger the body to produce antibodies against the virus
“artificial acquired active immunity”
EX: measles, mumps, rubella
Toxoids
protection against bactera
made from innactivated bacterial toxins
this immunization is called toxoid not a vaccine
toxoid stimulates the body to create its own antibodies against the pathogen
EX: tetanus, pertussis, and diphtheria
Immunoglobulins (antibodies)
Given by IV or injection to provide SHORT TERM protection and or treatment
IgG (gamma globulin) make up 75% of the total circulating antibodies.
IgG can be obtained through blood plasma donations.
Has: antiviral and antitoxin and antibacterial properties
-crosses the placenta
-artifically passively acquired
-given to patients with immuno deficiencies
Antimicrobial drug
Treatment, antibiotics antivirals, antifungals, antiprotozoals, etc.
The pathogen can be eradicated completely; slowed down; or there may be minimal beneficial results from the medication
there are often negative side effects
hypersensitivity disorders occur when:
antigen enters the body and the immune system OVER-REACTS to it reactions can be delayed or immediate
four types of hypersensitive reactions
A - Anaphylactic/ Allergy: Type 1
C - Cytotoxic: Type 2
I - Immune complex disease: type 3
D - Delayed hypersensitivity (cell mediated): Type 5
Anaphylactic/ Allergy occurs because
Immunoglobulin E (IgE) triggers multiple chemical reactions in response to allergens. Mast Cells (in the tissue) release numerous chemical mediators such as HISTAMINES cause symptoms ranging from mild allergic skin reactions to life-threatening anaphylactic shock
Anaphylactic shock steps
-Laryngeal edema causing air obstruction
-Smooth muscle contraction CONSTRICTED AIRWAYs so lungs are unable to take in air
-Vasodilation HYPOVOLEMIA or low blood volume that in turn causes HYPOTENSION (low blood pressure)
-VOMITING a circulation problem and ABDOMINAL CRAMPING
Severe allergic reactions cause
Death in 6 minutes, anaphylactic shock, because the blood flow to the brain and vital organs is decreased to the point that the organs begin to die from lack of oxygen. Eosinophils (in the blood) are leukocytes that are responsible for the late response
Examples of type 1 hypersensitivity
asthma, bee stings in sensitized individuals, pollen exposure, and food allergies
Cytotoxic
Antibody-mediated response to an antigen on a cell surface. The antibody attacks the antigen, it also kills the cell to which it is attached.
Examples of Cytotoxic responses
Blood incompatibilities: when a Rh-negative mother develops antibodies against her Rh-positive babys blood, moms antibodies attack babys blood cells
Delayed hypersensitivity (cell-mediated)
Cell-mediated rather than antibody-mediated. These T-cell lymphocytes attack some types of viruses and microbes. Triggered in contact dermatitis (like poison ivy antigens).
It takes up to 24-72 hours to show.
-visual on the skin
-it takes a while before T-cells get on board
-previous exposure: mild reaction, exposure: blow-up reaction
Immune complex disease: Type 2
When an antibody binds to an antigen it can make a complex that the body cannot absorb. These complexes then trigger the inflammatory response. Causes damage to organs and blood vessels causing kidney damage or vasculitis. Immune complexes play a damaging role in lupus as well as glomerulonephritis
Autoimmune disease Definition
The body is unable to distinguish self from foreign
cells of the immune system attack various parts of the body depending on the type of AI disease involved. AI diseases are currently INCURRABLE.
There are 100 different types of autoimmune diseases.
Most common autoimmune disease
Systemic autoimmune disease
Organ/body system-specific autoimmune disease
Systemic Autoimmune disease
**Rheumatoid arthritis (RA) most common - 1% of world population
*Type 1 diabetes
*Lupus (systemic lupus erythematosus - SLE)
Organ/ Body System - Specific autoimmune diseases
-Inflammatory bowel disease (IBS); Crohn’s Disease (GI system)
-Psoriasis (skin)
-Multiple sclerosis; myasthenia gravis (nervous system)
-Graves’ disease; Hashimoto’s disease (thyroid)
Mechanisms of Autoimmune Disease
a) the body makes antibodies against itself - and does not recognize some tissues as belonging to the body
b) Genetic predisposition is common (runs in families)
c) triggered by: chemical/ biological substances (VIRUSES, BACTERIAL INFECTION)
d) MORE COMMON IN WOMEN (especially of childbearing age (16-35)
e) all ages affected
MAB drugs
Must avoid bugs
A monoclonal antibody that inhibits TNF (tumor necrosis factor) and suppresses the immune system. MABS can target specific cell types (such as cancer cells) without damaging surrounding tissue as traditional chemotherapy does.
TX for:
Autoimmune disorders
Cancer
Treatment for Autoimmune Disorders
Immunosuppression drugs (also used to treat cancer)
Steroids and methotrexate; and MONOCLONAL ANTIBODIES
Human Immunodeficiency Virus (HIV) Etiology
HIV is transmitted via body fluids. The most common transfer is through sexual transmission (anal, oral, vaginal sex). also transferred through syringe needles. and from mother to baby in utero or breastfeeding or during birth.
Pathology of HIV
Exposure to the virus leads to antibody formation called the “window period” in which infection is PRESENT AND TRANSMITTABLE BUT NOT DETECTABLE by HIV screening test
Seroconversion
refers to the ability to detect HIV antibodies in the blood. Occurs in 1-3 months but can be delayed for up to 6 months. However, the disease may be latent for years
(flu-like symptoms often accompany seroconversion because antibody are starting to attack the virus)
Disease progression of HIV
HIV infection enters the body
Seroconversion (1-6 month period when the body makes antibodies against HIV)
AIDS disease
Typical Path of disease follows three phases
1- primary infection phase
2- latency phase
3- overt aids phase
Three things needed to diagnose aids
1) HIV test positive
2) Opportunistic infection is present (aids- defining conditions)
3) CD4 cell count less than 200
how they are HIV positive
ELISA test is a lab test that identifies various antibodies in blood (seroconversion)
If the test is positive, the test is repeated then a Western blot test is performed. If the WB detects a virus then HIV infection is confirmed
Opportunistic Infections assosciated with HIV
AIDS-DEFINING CONDITIONS
opportunistic infections and cancers that are life-threatening to a person with HIV and they account for MOST DEATHS FROM AIDS. Because the immune system is malfunctioning patients are susceptible to respiratory gastrointestinal and nervous system infections
aids patients are also more susceptible to malignancies such as Kaposi sarcoma as well as CMV retinities, pneumocystis Jiroveci pneumonia; mycobacterium TB: etc.
CD4 Cells
Helper t-cells tell CD8 cells to do their jobs (CD4 cells are helper t-cells)
HIV pathogens specifically attack CD4 helper t-cell lymphocytes. These helper t-cells do not neutralize infection but rather initiate the body’s immune response. Active aids is diagnosed when CD4 level is less than 200. Less than 200 means the immune system is severely weakened. Makes you must greater risk to opportunistic infections.
CD8 Cells
These types of T-cells have a glycoprotein called CD8 on their surface. Also called killer t cells. they are instrumental in fighting cancer and viruses. they produce antiviral substances that help fight of the foreign invader. However without helper CD4 T-cells which slowly disappear during HIV disease, the CD8 T-CELLS ARE UNABLE TO KEEP UP with the increasingly diverse population of HIV pathogens inside the body
ART or highly active ART
are medications that treat HIV, do not kill or cure the virus . prevent the growth of the virus. antiretrovial drugs are usually used in combinations of three or more drugs.
What is the diff between CD4 cells and CD8 cels
CD4 = helper T cells, initiate body response, CD8 kills antigens
Which of these Abnormal HIV
CD4 levels
Is the blood level of the abnormal cell elevated or low in the blood
LOW
restate the definition of SEROCONVERSION in your own words
when the presence of HIV antibodies can be detected in the blood
What is an opportunistic infection?
a secondary infection that grows because of decreased immune function
What is the impact of opportunistic infections on an HIV+ patient
serious complications and death
What three factors are required to diagnose AIDS in a patient
Test positive
Opportunistic Infections present
CD4 is Lower than 200
