Infectious Diseases Exam 1

POOP (no really)

Edwin Chadwick contributions:

campaigns for better drainage and airflow for workers in London

William Farr contributions:

Cholera is more prevalent the closer inhabitants are to the Thames River

John Snow contributions:

finds cholera cases are clustered around a water pump and removes the pump, decrease in cases after this

The Great Stink contributions:

Redesign of London’s sewers which protects drinking water from sewage

Humourism:

the idea that all disease is the result of an imbalance of humors

Miasma Theory:

the idea that all diseases are spread by bad air in polluted cities

Pathophysiology of Cholera:

1. Etiological agent secretes a toxin which splits into several subunits

2. Subunit A activates a chloride efflux from the intestinal tissues into the lumen

3. Water follows the chloride ions, causing dehydration and watery diarrhea

Cholera etiological agent:

Vibro cholerae

Gold Standard for Cholera diagnosis:

TCBS differential media

Koch’s Postulates:

Association, Isolation, Inoculation, and Re-Isolation

Criticisms of Germ Theory:

1. Diseases become oversimplified

2. Koch’s Postulates only work well for highly virulent pathogens

3. Virulence is not a fixed trait

Makeup of a Virion:

A protein cap and a genome, sometimes an envelope can be included

Lifecycle of a Virion:

1. Attachment

2. Penetration

3. Uncoating

4. Biosynthesis

5. Assembly

6. Release

Viruses with a genome of double stranded DNA is classified as ________ in the Baltimore Classification System

Group 1

Viruses with a genome of single stranded sense (+) DNA is classified as ______ in the Baltimore Classification System

Group 2

Viruses with a genome of double stranded RNA is classified as ________ in the Baltimore Classification System

Group 3

Viruses with a genome of single stranded sense (+) RNA is classified as _________ in the Baltimore Classification System

Group 4

Viruses with a genome of single stranded antisense (-) RNA is classified as _________ in the Baltimore Classification System

Group 5

Viruses with a genome of single stranded RNA with reverse transcriptase are classifies as _________ in the Baltimore Classification System

Group 6

Viruses with a genome of double stranded DNA with reverse transcriptase are classifies as _________ in the Baltimore Classification System

Pathophysiology of HIV/AIDS:

1. Etiological agent receptor recognizes a host receptor on T-cells and fuses to the cell

2. RNA genome is reverse transcribed and double stranded DNA is integrated into the host genome

3. Viral genes are transcribed and translated

4. Virus is assembled and released, killing the host T-cell

HIV/AIDS etiological agent:

retrovirus

Gold Standard for HIV/AIDS detection:

Western Blot method which detects antibodies responsive to HIV

Treatment of HIV/AIDS:

ART (antiretroviral therapies) which combines three medications from two drug classes

HIV/AIDS drug treatment classes:

1. RT inhibitors

2. Attachment inhibitors

3. Fusion inhibitors

4. Protease inhibitors

5. Integrase inhibitors

Components to a Bacterial Cell:

plasma membrane, cell wall, and capsule or slime layer

Salmonellosis Pathophysiology:

1. Ingested etiological agent invades M cells of the intestine and trigger an inflammatory response

2. Neutrophils which fight foreign pathogens invade the M cells, allowing water to escape into the lumen of the intestines causing watery diarrhea and dehydration

Salmonella etiological agent:

Salmonella enterica

Aspergillosis Pathophysiology:

1. Etiological agent is inhaled and either no inflammatory response occurs or a dramatic inflammation response occurs

2. No inflammation leads to an uncontrolled growth of the spores and mycelium

3. Dramatic inflammation response can permanently damage the lungs

Aspergillosis etiological agent:

Aspergilla fumigatus

Aspergillosis treatment:

Azole, an antifungal drug

Groups of Protozoa:

1. Sarcodina (amoebas)

2. Mastigophores (flagellates)

3. Ciliophorans (ciliates)

4. Sporozoans (non-motile adult protozoa)

Lifecycle of Toxoplasmosis:

1. Environmental Stage- an un-sporulated oocyte matures into a sporozoite. Then defecated by a cat.

2. Reproductive Stage- the sporozoite matures into a tachyzoite, then a bradyzoite in humans.

Toxoplasmosis etiological agent:

Toxoplasma gondii

Helminth phylogenies:

1. Nematodes (roundworm)

2. Platyhelminths (flatworm)

3. Acanthocephalans

Flatworms can be _________ (tapeworms) or __________ (flukes).

cestodes/trematodes

Human Hookworm etiological agent:

1. Necata amercanus

2. Ancylostoma duodenale

Human Hookworm life cycle:

1. Adult worms live in humans and lay eggs which are pooped out.

2. Eggs hatch in the L-3 phase and grow into the grass, traveling to the top of grass blades and infect human feet.

3. Foot to gut migration takes 4-6 weeks in which the disease is in the pre-patent period.

Gold Standard for Diagnosis of Human Hookworm:

Microscopic examination of a fecal sample

Epidemiological Triad:

Agent of disease, host, environment

Incubatory period:

time from first exposure to first signs and symptoms

Latent period:

time between exposure and infectious period

convalescent carrier:

a carrier who feels better but is still infectious

sign:

an objective measure (like a fever)

symptom:

a subjective measure (like a headache)

reservoir:

a human, animal, or environmental component which supports the agent of infection

portal of exit:

route by which agent leaves the reservoir

portal of entry:

route by which the agent enters a susceptible host

Directly transmissible agents are _________ compared to indirectly transmissible agents.

more fragile

Mucocilory Escalator:

Cilia in the respiratory tract move upwards and contain mucous to move agents which have been inhaled back to the airway to be swallowed and destroyed by the stomach acid

Two types of immunity:

1. Innate

2. Adaptive

Steps to nonspecific, innate neutralization:

1. Pathogen recognition

2. Phagocytosis

3. Release of Cytokines and Chemokines

4. Antigen Presentation to the Adaptive System with Dendrites

Virus PAMP:

genome

Bacteria PAMP:

LPS (gram-), LTA, flagella, peptidoglycan (gram+)

Fungus PAMP:

zymosan, chitin

Helminth PAMP:

non-uniform secretions or excretions

Protozoa PAMP:

GPI/glycophosphatidylinositol

Cells characteristic of Innate Responses:

Macrophages, Neutrophils, Cytokines/Chemokines, Dendritic Cells

Macrophage Function:

travels from tissues to site of pathogen entry to engulf the pathogen and release cytokines

Neutrophil Function:

travels from blood to infection site and releases destructive enzymes to kill pathogenic agent

Cytokine/Chemokine Function:

promotes inflammation by vasodilating blood vessels, attracting circulating immune cells, and activating neutrophils

Dendritic Cell Function:

link adaptive and innate immune responses, contains PRR’s which recognize PAMPs and activate the dendrite

Cells characteristic of Innate Responses:

B lymphocytes, T lymphocytes, Dendritic cells

T effector cell function:

migrate to site of infection and kill infectious agent

T memory cell function:

protect against secondary infection

B cell function:

produce antibodies to bind to the antigen

Negative selection:

lymphocytes with reactivity to self-antigens will be eliminated

___________ can result in excessive inflammation.

Hypercytokemia

Bystander Activation:

Activation of T cells in response to cytokine presence rather then to an antigen

Case:

a lab validated positive test for infection

Incidence:

the number of cases in a given time period

Prevalence:

the number of cases at a specific time

Attack rate:

the proportion of those exposed to an infectious disease that become clinically ill

Reproductive Rate (R):

the potential for a disease to spread

Basic reproductive rate (R0):

the average number of individuals directly infected by a single infected person during their entire infectious period when they enter a totally susceptible population

R0 calculation equation:

R0= attack rate x (number of contacts) x infectious period

OR B x k x D

R0 < 1 =

disease will disappear in a population

R0 = 1 =

disease will become endemic

R0 > 1 =

disease will become an epidemic

Measles etiological agent:

Measles morbillivirus

Measles Pathophysiology:

Airborne particles enter the airway and infect dendrites via SLAM receptors. The viral cell cycle occurs and the infected dendrite moves to the lymph nodes where viral particles are released. New particles infect memory cells via SLAM receptors, killing them and infecting respiratory epithelium for exit of the host.

Koplik Spots:

red bumps in the mouth which are a pathognomic sign of measles

Measles Detection:

anti-measles virus antibodies in serum

Treatment of measles:

antibiotics and/or antifungals for superinfections

Prevention of measles:

vaccination

Herd Immunity:

the level of immunity in a population which prevents against epidemics

Formula for determining proportion of population which should be vaccinated to gain herd immunity:

p> 1-(1/R0)

where p is the proportion of the population

Formula for R:

R=R0 x S

where S is the fraction of the population which is susceptible

Types of Vaccines:

1. Live and Attenuated

2. Whole and Inactivated

3. Viral Protein Subunit

4. Virus-like Particle

5. Viral Vector

6. Whole Genome'

7. mRNA

8. Antigen Presenting Cells

___________ vaccines are easiest to make.

mRNA

3 Classes of Diagnostics:

1. Detection of the agent of agent derived products

2. Detection of specific immune response

3. Molecular diagnostics

The best diagnostics optimize _______, _________,________, and _________.

sensitivity/ specificity/ turnaround time/ required technology

Sensitivity:

ability of a test to identify the presence if a disease or illness correctly

Specificity:

ability of a test to identify the absence of a disease or illness accurately