Exam 1 Flashcards by Anika Lewis

What type of pathogen is canine parvovirus?

Non-enveloped virus

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How is canine parvovirus persistent in the host?

The virus is shed in dogs within 4 to 5 days of exposure
Throughout the disease course and approximately 10 days following clinical recovery. It is not persistent in the host

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Is canine parvovirus stable in the environment? If so, how long?

Can persists in the environment for months to years away from sunlight and disinfectants, refractory to most disinfectants (except Bleach)

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Does canine parvovirus produce any toxins?

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How does canine parvovirus enter cells?

Cell mediate endocytosis
Can enter most cells, replicates only in rapidly dividing cells

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What is the tropism of canine parvovirus?

Replication in tissue cells that rapidly divide
Lymphoid, intestinal epithelium and in fetal tissue
Invades cells in S phase
Intestinal crypt epithelium and bone marrow hematopoietic precursors

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What is the mode of entry for canine parvovirus?

Fecal-oral exposure

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How does canine parvovirus structure affect the host response?

Targets and replicated in actively dividing cells
This results in leukopenia and lymphopenia and decreased number of active immune cells able to fight off the infection

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What type of pathogen is salmonella?

Rod-shaped
Gram negative bacteria

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How is salmonella persistent in the host?

Salmonella=umbrella term
Most common one is S. enterica
Both symptomatic and asymptomatic shedder depending on the species

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Is salmonella stable in the environment?

Depends on the strain
usually few hours to several days on surfaces

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Does salmonella produce any toxins?

O antigens are associated with the LPS chains that are found in the cell wall of all gram-negative bacteria

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How does salmonella enter cells?

Depends on the species
Cell receptor mediated endocytosis is the most common

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What is the cell tropism for salmonella?

Depends on the species
Intestinal epithelial cells and macrophages

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What is the most common route for salmonella?

Fecal oral

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How does salmonella affect host response?

Creates special membrane bound compartments within the host cells to shelter and protect it from host immune mechanisms

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What type of pathogen is Rhodococcus equi?

Gram positive bacteria

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What is the source of Rhodococcus equi infections?

It is a ubiquitous in the environment
But infected foals shed a tremendous amount of bacteria in their feces

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What specific factor is associated with development of Rhodococcus equi?

Animals that produce little to no IFN-y are at an increased risk

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What is the tropism of Rhodococcus equi?

Macrophages and replicates when there is a failure of the formation of the phagolysosome after receptor mediated engulfment
This results in an absence of the respiratory burst and destruction of the bacteria
Host factor

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How might an animal be exposed to Rhodococcus equi but not develop disease?

Animals are exposed all the time, only those lacking the IFN gamma are at an increased risk

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What demographic of horses commonly present with clinical signs of R. equi infection?

Foals 1-4 months old

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What are some respiratory pathogens that infect adult horses and not foals?

Equine herpesvirus, equine influenza and equine arteritis virus

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What type of pathogen are equine herpesvirus, equine influenza and equine arteritis virus ?

Enveloped viruses

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Where is equine influenza typically found?

Maintained in the population by sporadic clinical cases and inapparent infections in susceptible horses

What specific factors is associated with the development of equine influenza?

The virus can mutate and create new strains in a population rapidly Exposure of the virus to a naive population, particularly those that are immune suppressed

What are the common portal of entry for PRRS?

Direct contact (oral, respiratory, semen) Indirect (fomites)

Is PRRS persistent within the pig?

Highly persistent in the pig but not in the environment because it is enveloped

What is PRRS tropism?

Macrophage cell Viremia spread Trojan horse spread within host

How does the characteristics of PRRS evade the immune system?

RNA virus Generates mutations

What type of immune response is associated with PRRS?

Humoral (serum neutralizing antibodies) and cell mediated immune response

How does the structure of PRRS affect the immune response?

Enveloped virus Development of neutralizing antibodies and or cell-mediated immunity have been related with clearance of PRRSV infection

How is the pathogenesis of Ascaris suum different with PRRS?

Ascaris sum is from direct trauma of the parasites migrating through the tissues resulting in secondary bacterial infection While in PRRS the virus destroys macrophages which decreases the immune response

What are the common portals of entry for Ascaris suum?

Fecal-oral Paratenic-earthworms and beetles

Is ascaris suum and indirect or direct life cycle?

Direct

Where do adult parasites of Ascaris suum establish infection?

Small intestine Nematode attaches to the mucosa

What is resulting in the pig's pneumonia from Ascaris suum

Migration of the L3 larvae through the lungs results in pneumonia

What type of systemic immune response is associated with Ascaris suum and most helminth infections?

Induce a Th2 response that produces IL-5 and eotaxin that promote eosinophils Eosinophils are the main leukocyte involved in attacking migrating parasites

What structure on the ascaris suum nematode results in this type of response?

Combination of molting, metabolic waste and migration that triggers the response

How does ascaris suum persists in the environment?

Third stage is infective to the pig Chitinous structure of the shell protects it from environmental and chemical degradation The protein coat makes the egg sticky so that it is not washed away

Is there any zoonotic potential of the sanctuary workers contracting Ascaris suum from their vegetables?

Conflicting reports May be zoonotic in those that are severely immunocompromised

What are the sources of infection and modes of transmission for canine influenza H3N8?

Direct contact via aerosol or droplets Source are other infected dogs that are shedding

Once a dog has recovered from canine influenza H3N8 how likely is it that they will transmit it to other dogs?

Low Dogs often shed disease prior to showing clinical signs

What is the risk of H3N8 influenza persisting for long period of time in the dog?

Low Not persistent in the host and is not transmitted to humans and does not survive long in the environment

What is the anticipated period of shedding for H3N8 canine influenza?

Highest shedding is first 2-4 days during incubation period but can shed for up to 10-14 days

Is canine influenza H3N8 zoonotic?

What type of pathogen is equine infection anemia?

Retrovirus Lentivirus-enveloped

What are the potential routs of entry for EIA?

Flies Intermittent feeding, direct contact

What is the tropism of EIA?

Infects macrophages

How is EIA spread within the horse?

Infects macrophages resulting in viremia

What are the various manifestations of disease for EIA?

Acute: fever, non-specific signs, death Chronic: Animal alternates between remission and disease state, animal is losing condition Inapparent: Asymptomatic, reservoir for infection, stress may convert to acute form

How is EIA transmitted to other horses?

Flies are mechanical vectors Direct contact

Are there alternative hosts for EIA besides the horse?

Members of the Equus genus

What does the cogging test test for?

Identifies antibodies for EIA antigen

What are two unique structural features of Roundworm?

Eggs are resistant to harsh environmental conditions Eggs have pitted shell that is sticky from a protein coat that makes elimination from environment difficult Transplacental transmission is one of the most important routs of infection to puppies Single adult female can lay up to 85,000 eggs per day

What are two unique structural features of Porcine Epidemic Diarrhea Virus (PEDV)?

Specific natural host Virus is enveloped RNA Easily destroyed Structural proteins of PEDV interact with viral genomic RNA to protein viral genome forming a nucleocapsid N protein also perturb antiviral responses

How does roundworm enter the host and cause disease?

Egg ingested Larvae released in intestines Larvae migrate to other various organs where development is arrested

How does PEDV enter the host and cause disease?

Virus is excreted in feces Oral infection due to contaminated food Viral replication in the epithelial of the small intestine and colonic villi which causes malabsorption of the food and triggers an inflammatory response both leading to diarrhea

Is roundworm zoonotic?

Yes

Is PEDV zoonotic?

What are some strategies that break the cycle of transmission in roundworms?

Puppies and kittens dewormed at 2 weeks of age with deworming every 2 weeks until they are 4-8 weeks old Fecal tests 1-2 times a year

One infectious virus unit

Virion

Lipid bilayer with attachment glycoproteins

Envelope

Are enveloped or naked viruses more stable in the environment?

Naked Envelope is highly sensitive to drying and detergents

What is the difference between gram positive and gram negative bacteria?

Gram positive= Purple, thick peptidoglycan layer with techoic acids present Gram negative= pink, lipopolysaccharide layer present

Some bacteria for this to survive adverse environments Can survive for many months to years in soil Resistant to heat, dehydration Antibiotics dont work Ex: Clostridium tentani

Endospore (Sporulation)

This is the outermost layer covering certain bacteria Slime made of polysaccharides Helps to prevent desiccation Helps in attachment to host cell Prevents/disrupts phagocytosis Inhibits lysis by complement

Capsule

What is the main mechanism of protection of eggs/ova?

Shell/Wall Protein coat that helps it adhere to surfaces Wall structure may prevent desiccation Resistant to chemicals

What is the first and most critical step in viral infection?

Attachment Surface glycoproteins are essential for viral attachment Viruses have to enter the host cell to replicate

This allows bacteria to bind to host mucosal surface at portal of entry

Adhesions (Fimbria)

Virus is demonstrable continuously whether or not there is ongoing disease

Viral Persistence

Capacity of pathogen to tolerate exposure to lethal concentrations of bactericidal antibiotics

Bacteria, Fungi, Parasite Persistence

Virus is not demonstrable using diagnostic testing except when reactivated Ex: Herpes

Latent Infection

Infectious virus gradually increases during a very long preclinical phase, leading to a slow, progressive lethal disease Ex: HIV

Slow Infections

Continuing replication of the virus is not involved in progression of disease Ex: Fetal infection with feline panleukopenia virus causes cerebellar syndrome in young cats

Acute Infections with Late Clinical Manifestations

Animal has recovered from the illness No longer has clinical signs by remains in a status that could result in disease transmission to naive host Often still positive on routine testing Ex: BVDV

Persistently Infected (Carrier)

The dose of pathogen needed to infect 50% of the population

Infectious Dose

Describes a pathogen's ability to cause disease

Pathogenicity

Relative measure of pathogenicity Compares one pathogen's ability to cause disease compared to another

Virulence

Characteristics that provide the agent an advantage at any step of the infection to cause disease

Virulence Factors

The time from where the pathogen enter the body to first clinical signs

Incubation Period

Incubation period but in parasitology Time to observation of signs and also time to recovery of infective form

Prepatent Period

Defined by the active shedding of disease May come before symptoms start to show

Infectious Period

What are 4 reasons a pathogen was unable to establish disease?

Inadequate infectious dose Virulence of pathogen Entry of pathogen via wrong route but still resulted in an immune response Immune response was able to defeat pathogen

What are the common portals of entry for a pathogen into the host?

Mouth Nose Conjunctive Damage to skin Capillary Anus Urogenital Respiratory

Only produced by gram negative bacteria Lipopolysaccharides Released when bacteria is lysed Heat stable Cause disease by triggering systemic inflammation Ex: Salmonella

Endotoxins

Gram - or Gram + Secreted proteins that act on the host cell Heat labile Cause disease by destroying cell wall Disrupt cell metabolism Ex: Clostridium botulinum, Staph aureus

Exotoxins

Affinity of the pathogen for certain types of host cells and tissues that support its growth Largely determine by specific receptors for entry Specific metabolic requirements for the pathogen Pathogen may have different this depending on the course of the disease or stage of development

Tissue and Cellular Tropism

Effective for quick widespread dissemination of disease Free or cell associated Free pathogen encounter vascular endothelium and macrophages which leads to local inflammation and invasion into tissue adjacent

Bactermia/Viremia/Parasitemia

How do pathogens destroy host tissues?

Damage the immune system Induce immune system to cause disease

What are some examples of tumor-inducing viruses?

Feline leukemia virus Feline sarcoma virus Bovine leukemia virus Human papillomavirus

Host in which sexual reproduction occurs

Definitive Host

Host in which asexual reproduction occurs

Intermediate host

Host in which no reproduction occurs It is just keeping the parasite alive until its eaten by the next host Often this is tastier than the intermediate host

Paratenic Host

Maintains the parasite in the environment The whole life cycle or just part of it may be maintained in wildlife Presents a problem or eradication

Reservoir Host

Only one host needed to complete the life cycle

Direct Life Cycle

Need two or more hosts One host is the definitive host where sex occurs One or more hosts are intermediate where asexual reproduction or development from one stage to another occurs

Indirect Life Cycle

What host is the definitive host in the heartworm life cycle?

Dog

What host is the intermediate host in the heartworm life cycle?

Mosquito

Parasites are often very specific for their host If it ends up here it will not be able to develop They behave as if they are lost

Accidental (Dead-End) Host

Spreads through direct or indirect contact Fomites Airborne zoonotic

Horizontal Mode of Transmission

Spread from dam to embryo or fetus During or shortly after parturition to newborn

Vertical Mode of Transmission

A susceptible host contracts an infection by physical contact with an infected host Percutaneous BItes (monkeypox)

Direct Transmission

Intermediary vehicle that transmits the infectious agent between infected and susceptible hosts Fomites

Indirect Transmission

Transmission by the doctor Contamination with pathogen during medical or surgical procedures Dirty instruments

Iatrogenic

When an insect vector is involved in transmission of the disease

Arthropod-borne Transmission

Carry pathogens that can multiply within their bodies and be delivered to new hosts, usually by biting Infectious agent replicates in vector

Biological Vectors

Simply convey pathogens to a susceptible individual and is not essential to the development of the organism Physical transfer of infectious agent only

Mechanical Vector

Hospital acquired infection

Nosocomial

Disease of vertebrate animals that can be transmitted to man

Zoonoses

The population of organisms or the specific environment in which an infectious pathogen naturally lives and reproduces or upon which the pathogen primarily depends for its survival Does not result in severe disease in this host

Reservoir

Severe fever and non-specific signs developing 2-3 weeks after exposure Virus is most actively replicating May result in death

Acute Disease Form

Animal alternates between remission and disease state Animal losing condition Swamper

Chronic Disease Form

Asymptomatic Acting as reservoir of infection Lower virus concentration in blood, stress may convert to acute form

Inapparent Disease Form

An eosinophilic virus inclusion body is?

Intracellular collection of virions

Negative staining Strengths: Visual image, structural Limitation: Presence of large number of particles required, viruses with similar morphology difficult to distinguish

Electron Micropscopy

Test samples are either inoculated in embryonated eggs or cell cultures Strengths: Unknown is possible, come up with an isolate for further characterization Limitations: Not all viruses can be isolated

Virus Isolation

The most rapid and effective way to test for rabies virus in suspect tissue from wildlife is?

Immunofluorescence

Differentiating infected from vaccinated animals

DIVA

The test for FeLV tests for what?

Antigens

The test for FIV tests for what?

Antibodies

What is the most common diagnostic for viruses?

PCR

Evaluate consistency, color, blood, intact worms, tapeworm segments

Gross Examination of Feces

Used to evaluate motile forms of parastates only need a small amount of feces Overall low sensitivity Need to evaluate within 25 minutes of collection Good for giardia or trich

Saline Direct Fecal Smear Examination

Floats common helminth and protozoa eggs/cysts preferred for flotation of giardia and some lungworm larvae Less effective for tapeworm Does not float flukes SG: 1.18

Zinc Sulfate

Floats common helminth and protozoa eggs/cysts Distorts giardia cysts Does not float flukes and some tapeworm and nematode eggs SG: 1.2-1.33

Sodium Nitrate

Floats common helminth and protozoa eggs/cysts Distorts giradia cysts Does not float flukes SG: 1.2

Sodium Chloride

Floats common helminth and protozoa eggs/cysts Preferred for floation fo cryptosporidium oocysts Causes less damage to parasite eggs than salt Does not float flukes Less sensitive than zinc for giardia sticky SG: 1.25

Sugar Solution

Floats common helminth and protozoa eggs/cysts Distorts giardia Does not float flukes SG: 1.32

Saturated Magnesium Sulfate

Let float sit for too long Not a fresh sample Too small a sample Pseudoparasite or egg Coprophagy

Fecal Floatation Errors

Sensitivity 1-5 epg Easier for animals that you expect lower egg counts naturally Technique of choice for the quantification of helminth ova

Wisconsin Technique

Sensitivity 100 epg Easier for animals with higher egg counts Technique of choice for the quantification of protozoan structures

Modified McMaster's Technique

Used to recover dense eggs that do not readily float in common flotation solutions Flukes and tapeworms Less sensitive for detecting nematode eggs, coccidian oocysts, larvae or giardia

Fecal Centrifugal Sedimentation

Technique used to isolate nematode larvae from fresh fecal samples Principle of this test is that the nematode larvae cant swim against gravity when completely immersed in water Stronglyoides Dictyocaulus

Baermann Exam

Inhibits microbial metabolism and growth Does not kill the microbe Ex: Tetracycline

-Stasis/static

Permanently inactivates microbes Ex: Penicillin

-cide/cidal

Uses chemicals, processes, or environmental conditions to destroy or eliminate all microorganisms on non-living objects Physical Mechanical Chemical

Sterilization

Mechanism of action is it denatures proteins Autoclave Pasteurization

Heat Sterilization

Mechanism of action is to create DNA breaks in bacteria and inhibit cell division Requires the use of radioactive isolate cobalt 60 Used to sterilize single use plastic

Gamma Radiation

Hand washing Air filtration

Mechanical Sterilization

An agent that kills microorganisms or stops their growth

Antimicrobials

Chemicals that are applied to non-living surfaces to prevent or inhibit growth of microorganisms Nondestructive to surfaces Biodegradable

Disinfectants

Chemicals that are applied to the surface of living organisms or tissue to prevent or inhibit growth of microorganisms Applied on tissues to suppress or prevent microbial infection Non toxic to host tissue Does not impede or delay healing

Antiseptics

Disinfectant Disrupts DNA of microorganisms Kills bacteria, spores, fungi, and viruses Gas sterilization of heat sensitive items Carcinogenic to humans Needs special equipment to use the gas

Ethylene Oxide

Antiseptic Damage cell wall especially in gram negative nacteria Pseudomonas aeruginosa proteus vulgaris E. Coli Staph auerus Ear cleaning

Tris-EDTA

antiseptic and disinfectant Denatures proteins, dissolves lipids and desiccates surfaces Bactericidal Virucidal against enveloped virus Not effective against spores or prions Water is required to be effective Ethyl and isoproply

Alcohol

Disinfectant and antiseptic Denatures proteins Formaldehyde (foot baths) Glutaraldehyde (cold sterilization) slow acting

Aldehyde Compounds

Antiseptic Distrupts negatively charge microbial cell membrane Limited activity against mycobacteria and fungi Effective against enveloped viruses Not effective against spores or prions Maintains activity in presence of organic material

Chlorhexidine

Disinfectant Oxidation of peptide links and denaturation of proteins Organic matter reduced efficacy Broad spectrum bactericidal and everything else

Chlorine Compounds

Antiseptic and Disinfectant Denatures proteins in cytoplasmic membrane Blood reduces efficacy Limited activity with non-enveloped virus Effective against spores after 15 min Naval treatment Pyoderm

Iodine

Disinfectant Denatures proteins and lipids Works on most bacteria and viruses Not effective against spores Plasma sterilization of equipment that can not be steam sterilized Remove blood from clothing

Hydrogen Peroxide?

Hydrogen Peroxide

Disinfectant Denatures proteins and disrupts cell walls Effective in presence of organic material Skin irritant Kills most bacteria but best at gram + Effective against enveloped viruses

Phenols

Disinfectant Denatures proteins and binds to phospholipids of cell membranes Effective against gram positive and enveloped viruses

Quaternary Ammonium Compounds

The ability for a pathogen to attach to a host cell is an important virulence factor for all pathogens. Which of the following virulence factors is used specifically for attachment in bacteria?

Fimbria

A unique property of parvoviruses determines the tropism of the virus in its host. Which cell types would effectively support parvovirus replication?

Hematopoietic precursors

Virus Z takes about 45 – 60 days to cause clinical signs in a dog after infection. The virus is shed by the animal 3 days before clinical signs appear and shedding continues for about 7 days after clinical disease starts and the animal dies. What is the infectious period of virus Z in a dog?

10 days

In bacteriology and virology, the incubation period is defined as the point from when the pathogen enter the body to first clinical signs. What is this time period called in parasitology?

Prepatent period

Hamilton is a 10 week old, male intact, Boston Terrier dog that is presenting for fever, lethargy, leukopenia (low white blood cells), and severe foul-smelling diarrhea. After treating him for several weeks in the hospital for Canine parvovirus (CPV), you are interested in determining if he has begun to mount an immune (host) response to the virus. Which sample and test would you recommend to determine if Hamilton has mounted a host response?

serum; CPV antibody ELISA

A new deadly respiratory disease is sweeping through the pig farms in Iowa with major fears that quickly will have huge consequences on the food supply. This pathogen has been challenging to isolate using routine diagnostic testing methods. As a last-ditch effort to determine the cause for the disease, your team decided to determine what the disease is, based on the structural and morphologic characteristics of the pathogen. Which uses the structural morphology of an organism to make a diagnosis?

Electron Microscopy

You are called out to a farm with 200 Virgin Island White sheep that the producer has been deworming every other month with ivermectin for Haemonchus contortus. Over the past month, he has been losing 5-6% of his flock and on necropsy thousands of small barber pole appearing nematodes are observed and consistent with Haemonchus contortus. To gain a better understanding of which animals are the high egg shedders, you decided to run a quantitative fecal exam. Which technique would you recommend?

McMaster's exam

Which bacterial diagnostic techniques uses mass spectrophotometry and bacterial proteomics to identify a pure culture?

MALDI-TOF (Matrix-Assisted Laser Desorption Ionization Time-of-Flight)

Which of the following techniques or tests can be used to detect either antibodies or antigens depending on the test design?

ELISA

What is specifically being tested for in the ELISA snap test for FeLV

p27 FeLV structural antigen present in the blood of infected individuals