Flashcards in Viruses Deck (200):
1. noncellular infectious particle
2. obligate intracellular parasites
- can only live and reproduce inside other cells.
Basic Virus Anatomy
Nucleic Acid Core
Protein Coat (capsid)
Are all viruses the same?
There is a great variation between virus types.
Do antibiotics work against viruses?
No, they are not sensitive to antibiotics.
Are vaccinations effective against viruses?
vaccinations are generally very good at protecting host against viruses.
What is the fomite lifespan of a virus?
Some have very long fomite lives.
Nucleic Acid Core (virus)
-DNA or RNA
-ss or ds
-Contains genes needed for virus replication
Protein Coat (virus)
What does it do for the nucleic acid?
It surrounds and protects the nucleic acid
Protein Coat (virus)
Many of these proteins are highly antigenic.
-produce an immune response in host
-may be used to make vaccines
Protein Coat (virus)
They are responsible for host specificity.
-because they have to bind to specific receptors (ex: infect dogs, but not cats)
Outer Envelope (virus)
-only present in some viruses
-surrounds protein coat of some viruses
-made of remnants of host cell plasma membrane
Virus Life Cycle
-virus specifically recognizes host cell (protein-protein recognition)
-binds to specific receptor on host cell surface
Virus Life Cycle
Entire virus particle or just its nucleic acid enters inside of host cell.
Virus Life Cycle
If virus enters cell intact, its nucleic acid comes out of protein coat.
Virus Life Cycle
Viral Replication and Protein Synthesis
-viral nucleic acid reproduces
-more viral proteins are synthesized
Virus Life Cycle
New viral particles are assembled in the host cell from the newly made viral nucleic acid and protein.
Virus Life Cycle
-virus particle are released from host cell by various mechanisms
-may be released slowly over time (“shedding”) or all at once
-may or may not kill host cell
Virus Life Cycle
4. Viral replication and protein synthesis
Name the 3 outcomes of viral infection.
1. No viral replication, no disease (abortive)
2. Shedding (restrictive)
3. Large rapid release of viral particles – cell death and host disease. (productive)
What is "shedding"?
-slow steady release of viral particles
-no cell death
-may or may not cause disease of host
How do you diagnose viruses in mammals?
1. Patient history very important
2. Vaccination status very important
3. Respiratory sounds (dorsal-viral)
4. X rays
5. Blood tests for virus or antibodies against the virus.
How does vaccination status help?
If pt is unvaccinated, lean to viral diagnosis.
- err on side of caution
If pt is vaccinated, lean to another cause (bacterial, parasitic, etc.)
What types of blood tests?
-ELISA (enzyme-linked immunoabsorbent assay)
What are the 3 major treatment strategies for viruses?
1. supportive care
2. nutrition and fluids
If antibiotics are not effective against viruses, why would they be given to a patient as part of a viral treatment?
Often given to treat or prevent secondary bacterial infections.
What is a retrovirus, and what does it do?
Reverse transcriptase. They become part of the host DNA.
What does FeLV stand for?
Feline Leukemia Virus
What type of virus is FeLV?
It is a retrovirus – small ss RNA virus.
Is FeLV fatal?
It is often fatal, 2nd leading cause of death behind trauma.
Is FeLV hard to kill?
Virus is easily killed in the environment.
What are the 6 ways FeLV is transmitted?
1. direct contact through saliva and nasal secretions of infected cats.
2. persistently infected cats may shed virus for many years in body secretions.
3.shared litter boxes, toys, food dishes
4. nose to nose contact, sneezing
5. queen to kitten
6. some cats successfully eliminate the infection (but often become carriers)
Why can FeLV be transmitted via direct contact?
- virus mostly found in saliva
- also through urine and feces
FeLV Carrier Statistics
-1-3% in single cat households become persistently infected
-30% in multiple cat households become persistently infected
-infection rate increases with cat population density
What is the FeLV fatality rate?
Up to 80% fatal within 3 years of infection.
How many types of FeLV virus are there?
3 types of viruses – cat may have one or a combination of them.
-fever, depression, loss of appetite, swollen lymph nodes, rhinitis, gingivitis, etc. very wide range of symptoms.
-immunodeficiency leading to secondary infections
-cancer – esp. lymphosarcoma and bone marrow disorders
-anemia - leukemia
What happens if the cat does not die from FeLV?
They become a carrier.
How is FeLV diagnosed?
There are many blood tests available.
How do you treat a cat with FeLV?
You give supportive care.
Is there a vaccination for FeLV?
Yes. It is effective, but not completely.
What does FIV stand for?
Feline Immunodeficiency Virus
What is FIV?
Feline form of HIV.
What type of virus is FIV?
A retrovirus (ss RNA)
What is another name for FIV?
Also called FTLV – Feline T-lymphotrophic T cell lentivirus.
How is FIV transmitted?
Mostly through blood transfer, e.g. bite wounds from other cats.
What are the 3 major stages of FIV?
1. Acute Stage
2. Latent, Asymptomatic State
3. AIDS Stage
How long does the acute stage last in FIV, and what are the symptoms?
-lasts 2-9 weeks
-fever, neutropenia, enlarged lymph nodes
How long does the latent stage last in FIV, what are the symptoms?
-up to 10 years
-minor if any clinical signs
-cat is a carrier
How long does the AIDS stage last in FIV, what are the symptoms?
-months to a few years
-severe weight loss, opportunistic infections,
-immunodeficiency, tumors, etc.
What is the outcome of FIV?
Are the symptoms of FIV similar to another virus?
Yes. symptoms may be similar to FeLV (gingivitis, chronic diarrhea, fever, conjunctivitis, rhinitis, swollen glands, appetite loss, depression, etc.
How is FIV prevented?
What does neutropenia mean?
Decrease in neutrophil, white blood cells.
What does FPV stand for?
Feline Panleukopenia Virus
Is FPV serious?
Yes, it is a very serious disease.
What is another name for FPV?
Feline Distemper (VERY different from Canine Distemper or Parvo)
What type of virus is FPV?
A parvovirus. Very small ss DNA virus.
Is FPV fatal, why?
Highly. It kills the diving cells in the immune systems and GI systems.
Is FPV able to survive in the environment?
Yes, virus can survive extreme temperatures and humidity for years – can also survive many common disinfectants. This makes it very contagious.
Is FPV contagious?
Yes, it is very contagious.
How is FPV transmitted?
-sharing food, water, bedding, litter boxes with other cats
-mostly by contact with feces of another cat
-also by direct contact with infected cat
-in utero from infected mother to offspring
What happens when offspring is infected with FPV in utero?
cerebellar hypoplasia in offspring
Is FPV severe?
It is very sever and often fatal, some cats die suddenly.
How quickly to cats get sick once they have contracted FPV?
Cats can get sick within a few days of infection.
What are the symptoms of FPV?
-depression, loss of appetite, fever, vomiting, diarrhea
-pregnant cat may have stillborn kittens.
Is FPV preventable?
Yes, vaccinations are VERY effective.
What does FIP stand for?
Feline Infectious Peritonitis
Is FIP serious?
It is very serious and often fatal.
What cause FIP?
A feline coronavirus (large RNA virus).
Are there other feline coronaviruses and are they harmful?
-there are a variety of feline coronaviruses in the environment.
-almost all of them are basically harmless.
What about benign strains of coronavirus?
They can spontaneously mutate to the disease forming virus and cause illness.
What is an example of a coronavirus mutation?
FECV mutates to FIPV
What is the percentage of cats with feline coronavirus that develop FIP?
1% to 5%
Can cats be carriers of coronavirus?
Yes, there are asymptomatic carriers of benign Coranaviruses.
Can you test a cat to tell if it has FIP or is a carrier of a benign strain?
Diagnostic tests do not distinguish between carriers of harmless virus and those with FIP.
Is FIP easily transmitted?
Yes, VERY easily.
How is FIP transmitted?
ingestion of viral particles from feces ( or saliva) of infected cats.
Where is FIP prevalent?
-multiple cat households, over 50%-70%
-may be up to 20% infection rate in catteries, as it is difficult to prevent.
Where is FIP not prevalent?
In single cat homes.
What are the 2 forms of disease with FIP?
Wet Form (acute)
Dry Form (chronic)
– both caused by the same virus
- depends on strength of infected cat’s immune response
How common is the acute form of FIP?
3/4 of cats with FIP have the acute, wet form.
Is the wet form of FIP fatal?
What are the symptoms of the wet form of FIP?
-fluid accumulates in abdominal and thoracic cavities.
-fluid in thoracic cavity can make it difficult for cat to breathe.
How common is the dry form of FIP?
1/4 of cats with FIP have the dry, chronic form.
Is the dry form of FIP fatal?
Usually, thought it is less fatal than the wet form.
What are the symptoms of the dry form of FIP?
-symptoms depend on which organ(s) is affected
-neurological, kidney, liver failure, eyes, others
Can cats be vaccinated against FIP?
There is a vaccine, but it is not recommend. There is suspicion that it may stimulate the disease.
What does FCV stand for?
What is another name for FCV?
What causes FCV?
A Calicivirus. Small naked ss RNA virus.
What disease complex is FCV a part of?
The feline respiratory disease complex.
What viruses are part of the feline respiratory disease complex.
-Feline Rhinotracheitis Virus
-Feline Herpes Virus
What is the percentage of URI's that can be attributed to the feline respiratory disease complex?
85%-90% of cats with a URI are infected with a virus from the feline respiratory disease complex.
How long can FCV survive outside the body?
8 to 10 days
-in dishes, litter boxes, clothing
In what 2 ways is FCV transmitted?
1. Contact with nasal, ocular, or oral secretions and feces of infected cats.
2. By direct contact or contact with a contaminated object (feed bowl, toy, etc.).
Is FCV contagious?
Very. It has a long fomite life for a virus.
What are the symptoms of FCV?
-mild flu-like, like a cold .
- sneezing, runny nose, fever. Loss of appetite, sores around mouth, nose, lips, upper respiratory disease, possibly arthritis (lameness.)
-ulceration of tongue – sometimes lips and nose also.
Is FCV serious in adult cats?
It is usually not serious in adults.
Is FCV serious in kittens?
It may be fatal in kittens.
What is the FCV vaccine usually combined with?
Feline Distemper Vaccine
Is the vaccine for FCV effective?
It does not totally prevent disease, but it may make it less severe.
What is the most serious zoonoses?
What does rabies virus look like?
It is bullet shaped.
Who can rabies infect?
All mammalian species.
What does the rabies virus attack?
The nervous system.
How is rabies transmitted?
By transfer of saliva or other tissue fluids
- virus can be present in saliva of infected animals for several days before the onset of clinical symptoms.
- bite or spit into an open wound.
What can rabies penetrate?
It can penetrate intact mucous membranes such as the mouth, nose, or eyes.
What are the 4 major reservoirs in the US?
Once an animal is showing symptoms of Rabies, how long until death?
10 days from the onset of symptoms.
How long does it take for symptoms to begin?
It can take 6 weeks or more for the first onset of symptoms after the initial infection.
What are the 3 stages of Rabies?
What is the Rabies Prodromal stage?
-1 to 3 days
-vague CNS symptoms that rapidly progress
-animals often show shyness and apprehension and seek solitude (behavioral changes)
-may excessively lick the bite site
What is the Rabies Excitation stage?
-irrational, aggressive, anxious, loss of caution and fear
-biting and licking at wound site
What is the Rabies Paralytic stage?
-paralysis begins in the hind legs
-disorientation, ataxia, seizures
-first paralysis of throat and masseter muscles
-profuse salivation and inablility to swallow
-not vicious or trying to bite
-paralysis rapidly progresses throughout body and death occurs within hours
What happens if an unvaccinated cat or dog is exposed?
Any unvaccinated dog or cat that is exposed to a rabid animal should be destroyed or placed in strict isolation for 6 months and vaccinated.
What kind of virus is Canine Distemper?
A respiratory virus.
What is another name for Canine Distemper?
Hardpaw or hardpad.
Is Canine Distemper serious?
Is Canine Distemper the same as Feline Distemper?
No. They are caused by a different virus.
What causes Canine Distemper?
A paramyxovirus (RNA virus)
What is Canine Distemper related to in humans?
The measles virus.
Can Canine Distemper infect other animals?
Yes. Raccoons and weasels are 2 examples.
Is the Canine Distemper virus common?
Yes, it is common in the environment.
Does Canine Distemper have a long fomite life?
Yes. It may live several weeks or months in the environment.
What does paramyxo mean?
Near respiratory - mainly respiratory infections.
Is Canine Distemper fatal?
It can be, especially in puppies.
Is Canine Distemper contagious?
What are the 3 ways that Canine Distemper is transmitted?
1. spread by aerosol-droplet route
-upper respiratory discharge is inhaled by another dog
2. direct contact
3. possibly by contact with contaminated objects
What are the symptoms of Canine Distemper in the early stages?
-coughing, labored breathing
-conjunctivitis with ocular discharge – “ gooey eyes”
-vomiting, diarrhea, dogs may become anorectic
What are the symptoms of Canine Distemper in the later stages?
-hyperkeratosis of foot pads and nose
-may be severe neurological symptoms esp. late in infection
-seizures, tremors especially of jaw
-dog will eventually die or have permanent neurological damage
What are the two stages of Canine Distemper?
1. Early Stage
2. Later Stage
How is Canine Distemper prevented (3 ways)?
1. Vaccination is very effective and should be routine for every dog
2. routine disinfection effective
3. removal from population of dogs to prevent spread
What does CPV stand for?
Canine Parvo Virus
What is the mortality rate with CPV?
Is CPV serious?
Yes, it is very serious. It has a very high death rate.
What is the cause of CPV?
Parvovirus, ss DNA virus.
Is CPV tough and can it survive in the environment?
-very tough and resistant
-survives for long time in environment (over a year)
-common in the environment in dog parks, etc.
What is CPV the most common of?
It is the most common viral disease of dogs.
What does CPV mainly affect?
Puppies up to one year of age.
What does CPV do?
The virus attacks and kills rapidly dividing cells
How is CPV transmitted?
Via the fecal oral route.
-virus is discharged in the feces
-dogs eat fecal contaminated material
What are the 5 symptoms of CPV?
1. diarrhea – often bloody
3. leucopenia (wbcs), neutropenia (neurophils)
4. fever, lethargy
What can CPV do in a puppy?
It may cause sudden death due to the infection of the heart muscle.
What is kennel cough complex?
Infectious tracheobronchitis (ITB)
What is another name for kennel cough?
Canine Infectious Respiratory Disease (CIPD)
What can cause kennel cough?
It can be caused by about 13 different agents.
What two viruses is kennel cough usually caused by?
1. CAV-2 (Canine Adenovirus-2)
2. CPI (Canine Parainfluenza Virus)
Is kennel cough serious?
It is usually mild and self limiting.
What can kennel cough progress to?
From viral infection, it can progress into fatal pneumonia.
Can kennel cough lead to secondary infections?
It often leads to secondary infections with Bordatella (bacterium).
What causes the symptoms in kennel cough?
Usually Bordatella, it is responsible for the dry cough.
Is kennel cough easily transmitted?
Yes, it is highly contagious.
-often infects dogs in close confinement with other dogs (kennels, shelters, pet stores, hospitals)
How is kennel cough transmitted?
By oronasal contact, or aerosol contact.
What are the 3 symptoms of kennel cough?
3.sometimes nasal discharge
How long until the symptoms of kennel cough fade?
Symptoms usually fade in 5-20 days.
Are vaccines effective against kennel cough, why?
Not totally effective.
-There are my possible causes of kennel cough.
-It can be a mixture of viral and bacterial infection.
How can kennel cough be prevented?
Try to avoid transmission between animals.
What does EIA stand for?
Equine Infectious Anemia
Is EIA serious?
It is the most serious illness a horse could get.
What is EIA?
It is a persistent viral disease of horses. It can be acute or chronic.
What virus does EIA relate to in humans?
Human HIV virus.
What causes EIA?
-ARthropod BOrne VIRUS
How is EIA transmitted?
Animal to animal by blood sucking insets.
-mainly by horseflies, also deerflies and mosquitoes.
Can a horse be cured of EIA?
No. Once infected, they become permanently infected - becomes a carrier - reservoir.
What happens once a horse is infected with EIA?
It can become an asymptotic carrier for the rest of its life.
What are the symptoms of EIA?
-Progressive weakness and weight loss.
-Edema (seen on mucous membranes).
-Progressive or transitory anemia.
What percentage of cases of EIA are fatal?
30% to 40%
How is EIA treated?
There is no specific treatment or vaccine.
What happens to a horse that has EIA?
It is quarantined for life or euthanized in many states.
How can EIA be prevented?
Reduce exposure to biting insects.
-use of repellents
-spraying and screening
-source reduction (eliminate stagnant water).
How is EIA diagnosed?
With a Coggins Test
In NYS, how often is the Coggins Test administered?
It must be administered once a year.
What are the restrictions on a horse that tests positive?
Cannot cross state lines or enter a horse in an event with a positive Coggins Test.
When is another time that a Coggins Test may be done?
When the horse is sold, or moves to a new stable.
Is EIA able to infect humans?
Yes, and it can be fatal. Very serious in humans.
What does WNV stand for?
West Nile Virus
Can WNV affect humans / zoonotic?
Yes. It can cause death and disease in humans.
What is the reservoir for WNV?
The wild bird population.
Are all birds infected with WNV killed by it?
No. Some are, most are not.
Do all horses bitten by a WNV carrier mosquito get ill?
Most horses bitten by carrier mosquitoes do not develop the disease.
Can a horse that contracts WNV get better?
Most of them do, about 2/3 recover.
What happens to the horses that do not fight WNV off?
They die. This only happens to about 1/3.
What does WNV do?
It goes tot he brain and causes neurological disease.
How is WNV transmitted?
Blood transfer from wild birds to horses (and many other animals) by mosquitoes.
Can a horse with WNV infect others?
There is no known horse to horse or horse to human transmission.
What are the symptoms of WNV?
They are neurological in nature (CNS).
-weakness of limbs
What is ataxia?
The loss of full control of bodily movements.
Can horses die from WNV?
Death is possible. It has a 33% to 40% mortality rate.
How is WNV treated?
-Prevent exposure to mosquitoes (as you would in EIA)
What is Equine Viral Encephalitides?
A group of viruses in horses that are all neurological.
What are the 3 most common forms of Equine Viral Encephalitides?
-EEE: Eastern Equine Encephalitis
-WEE: Western Equine Encephalitis
-VEE: Venezuelan Equine Encephalitis
Is WNV an Equine Viral Encephalitis?
It is considered to be, but they are caused by different kinds of viruses.
What is Equine Viral Encephalitides caused by?
Togaviruses acting as arboviruses.
What is the most common reservoir of Equine Viral Encephalitides?
Birds and rodents.
How is Equine Viral Encephalitides transmitted?
From the reservoir animal (usually wild birds) to horses by mosquito bites.
What are the symptoms of Equine Viral Encephalitides?
They are neurological in nature (CNS).
-weakness of limbs
What are the mortality rates of Equine Viral Encephalitides?
How is Equine Viral Encephalitides treated and controlled?
-Preventing exposure to mosquitoes.
Is Equine Viral Encephalitides zoonotic?
Yes, and it is very serious or fatal in humans.