Rotavirus

Question 1

Rotavirus general

Answer 1

Major cause of diarrhoea in many domestic species Short incubation period (12-24 hours)

Question 2

Clinical signs of Rotavirus

Answer 2

Profuse water diarrhoea (white scours), inappetence, depression, dehydration May stop suckling Low mortality, often associated with dehydration or secondary bacterial infection Disease usually seen in animals 1-8 weeks old Not in first week (colostrum) Reduced colostrum intake, overcrowding (environmental contamination builds up- immuno suppression), poor hygiene, chilling (using energy to stay warm)

Question 3

Transmission (part of pathogenesis)

Answer 3

Transmission by ingestion of contaminated food, water, or fomites *highly infectious/ contagious High concentrations shed in faeces, infectious dose is small, minimal env. contam. leads to widespread env. effects

Question 4

Rotavirus falls under what family?

Answer 4

Reoviridae (same as Orbivirus- blue tongue, African horse sickness)

Question 5

Coronavirus and Rotavirus same pathogenesis- opposite of what disease?

Answer 5

Opposite of Parvo Severe enteritis- intestinal epithelial destruction (apical cells)- on the tips of the villi of the small intestine. These cells ahve an absorptive and secretory function (for example disaccharides like lactose). So when you stop breaking down lactose and absorbing the fluid, you end up with malabsorption. High conc. of sugar in the lumen, you get a secretory diarrhoea and osmotic diarrhoea. FLUID ACCUMULATION IN THE GUT= secretory diarrhoea. One of the proteins on the capsid of the rotavirus also induces hypersecretory diarrhoea.

Question 6

Pathogenesis Rotavirus

Answer 6

Infection usually localised to SI, little local inflammation of infected enterocytes, little local inflammation of infected enterocytes, reduced ability to break down disaccharides such as lactose therefore osmotic diarrhoea in addition to secretory

Question 7

What disinfectants do not work on rotavirus?

Answer 7

Bleach does not work– too much organic material as well but rotaviruses are resistant anyway. Chlorine does not work.

Question 8

What is an enterotoxin?

Answer 8

Inflammation and secretory diarrhoea

Question 9

Epi of Rotavirus

Answer 9

Excreted at very high titres, survive in faeces for months, resistant to chlorine disinfection, waterborne transmission?

Question 10

Control of rotavirus

Answer 10

Improved hygiene (unlikely to control on its own), antibody in colostrum (crosses lumen of neonate gut and becomes systemic IgG), antibody in milk (lactogenic immunity- bind in the intestine- neutralize the virus and it passes through)- vaccination of dam that increases antibody in milk is protective. Dehydration and electrolyte imbalances are the major cause of death in rotavirus cases (fluid therapy and no milk).

Question 11

What happens in an endemic situation with rotavirus and immunity?

Answer 11

Lactogenic immunity (antibody from milk neutralizes virus and it passes through) because Mom has been exposed prior and has the antibodies to pass on. So it keeps getting passed on down the line like this

Question 12

What causes death with rotavirus?

Answer 12

Dehydration and electrolyte imbalances (fluid therapy and no milk)

Question 13

Coronaviridae

Answer 13

Coronavirus causes all kinds of dysfunction

Question 14

Bovine coronavirus diarrhoea

Answer 14

Very similar to rotavirus

Question 15

Coronavirus- SARS

Answer 15

Severe Acute Respiratory Syndrome- fever, general malaise, headaches, chills, cough, death About 8000 cases with 800 deaths reported Spread by close contact/ secretions

Question 16

Coronavirus

Answer 16

Enveloped, ss RNA

Question 17

Bovine Coronaviridae general and transmission

Answer 17

Second most common cause of diarrhoea in calves (after rotavirus), less than 2 weeks old- diarrhoea lasts 4-5 days, replicates in mature SI epithelial cells- fluid absoption and digestion of disaccharides reduced Fecal oral route of transmission (secretory and osmotic diarrhoea)

Question 18

Porcine Coronaviruses (4)

Answer 18

3 are exotic- we have Porcine Haemagglutinating Encephalomyelitis.

Porcine Resp Coronavirus acts as a natural vaccine to another coronavirus.

Porcine Epidemic Diarrhoea- massive US outbreak recently- watery dirrahoea

Question 20

Epi and Pathogenesis of Porcine Coronavirus

Answer 20

Question 21

Porcine Coronaviruses animals affected

Answer 21

Question 22

Feline Infectious Peritonitis Virus (FIPV) (Coronaviruses) is a mutant of what?

Answer 22

Feline enteric coronaviruses (FECV)

Question 23

FIPV Epi

Answer 23

Multi cat households, faecal oral transmission- enteric viruses that cause other disease, shed through GIT (faeces and oral/nasal), young cats and older cats see the most clinical signs. Kittens often infected from mom.

* In multi cat homes 15% of cats are persistently infected. Most cats are transiently infected (eliminate virus).

Question 24

Pathogenesis of FIPV

Answer 24

Infection does not always result in a disease.

Most infected kittens develop an effective cell-mediated immune response and eliminate the virus.

**FECV infection sensitizes cats to FIPV as antibody enhances uptake by macrophages.**

Question 25

What does the mutation of FIPV mean?

Answer 25

It can survive and replicate in macrophages (this is the mutation from FECV)

3 possibilities with immune response and therefore pathogenesis:

*If cat mounts effective cell mediated immune response infected macrophages get blasted away from cytotoxic T cells

*If there is a decreased immune response- normal cat periodic FIPV chronic ongoing shedder

*Non effective immune response- continuous FIPV replication- B cell activation- non protective antibodies- Abs enhance uptake by macrophages- immune complexes- vasculitis- and then either moderate lesions to dry FIPV (fatal over months) or severe vascular permeability (fatal over weeks)

*** MHC type makes certain breeds over represented with FIPV***

Question 26

With FIPV, if the cat shows clinical signs, what does that mean?

Answer 26

The cat will most likely die. So mostly you don’t know about it, and if you do, they will likely die.

Question 27

Infectious Bronchitis general

Answer 27

Highly contagious, economically important disease of chickens worldwide.

Respiratory system is the site of primary replication

Viraemia within 1-2 days of exposure

Virus distributed widely- oviducts, kidneys, Bursa, severity of lesions determined by strain virulence

Resp. transmission by aerosol (most imp route)

Shed from rep tract for several weeks

Also faeces and eggs of infected birds

Question 28

Infectious Bronchitis

Answer 28

Chickens.

48 hour incubation

Most severe in young birds (stretch out trachea- gasp for air)

Nasal exudate

Death is caused by inflammatory debris in trachea- so they suffocate

Older birds- rales (resp noise) and gasping, reduced egg production

* Nephrotrophic strain- higher mortality

7 days in individuals

10-14 days in a whole flock (meaning REALLY contagious- sweeps through flock in a couple weeks)

Question 29

Infectious Bronchitis Diagnosis

Answer 29

PCR

No Tx

Vaccines available