Exam 2 Flashcards
(124 cards)
1
Q
Infection and necrosis of crypt epithelial cells and lymphocytes in Peyer’s patches are important in the pathogenesis of the disease caused by all of the following viruses EXCEPT
a) Feline panleukopenia virus
b) Canine parvovirus-2
c) Canine parvovirus-1
d) Bovine virus diarrhea virus
A
2
Q
Concerning neonatal diarrhea of farm animals, all of the following statements are false, EXCEPT
a) both rotavirus A and bovine coronavirus cause infection and necrosis of crypt epithelial cells in the small intestine
b) profuse diarrhea in an 8-month-old 350lb Jersey calf is most likely to be caused by rotavirus A
c) Malabsorption and osmotic diarrhea can be caused by both rotavirus A and Bovine coronavirus
d) Rotavirus can be transmitted from the dam (mother) to developing calf through the placenta
A
d
3
Q
What are the goals of neonatal diarrhea investigations?
A
Main goal is not just to identify pathogens, but to determine interactions between pathogens and :
- Host factors: age of calves and damns (which group of animals is showing clinical signs)
- Environmental factors
- Temporal factors (when is diarrhea happening, when in the calving season?)
4
Q
How are highly contagious viruses transmitted?
A
Fecal-oral route (virus in feces, feed, and water)
5
Q
Stability of enteric viruses in the environment
A
Many last long time in the environment (canine and feline parvovirus, rotavirus) and are resistant to actions of many disinfectants
6
Q
T/F: Adults are periodically re-infected and may be subclinical shedders for enteric viruses
A
True
–> they are the source of infection for neonate (may be adult dam or others)
7
Q
What may play a role in the protection of enteric viruses?
A
Milk
–> In the stomach milk buffers acid, coats virus and may offer some protection
8
Q
T/F: Antibody protection levels in young animals may vary
A
True
9
Q
What are neonates protected by?
A
Colostrum and milk (IgA)
10
Q
Failure of passive transfer number
A
<50mg/mL of IgG in the blood
11
Q
Refractometer reading for the failure of passive transfer
A
<5.5g/dL; <8.4% Brix
12
Q
Enteric viruses have predilection for the ______
A
intestinal tract
13
Q
For viruses that replicated in the intestinal tract, they must be able to …
A
escape the low pH of the stomach
14
Q
T/F: Enzymes found in the intestine may be able to help activate the virus
A
True
–> Ex: intestinal trypsin activates rotavirus
15
Q
Where are enteric viral particles shed?
A
in the feces after replication in the intestines
16
Q
Define enterocytes
A
Nutrient digestion and absorption
–> Turnover rate of 3-7 days
17
Q
Define crypt cells
A
Mitotic progenitor cells - gives rise to enterocytes
18
Q
T/F: Pathogenic viruses cause osmotic diarrhea
A
True
–> Villous Atrophy
19
Q
Define villous atrophy
A
Absorptive surface of intestine mucosa is reduced by shortening of the villi
–> The shortened villi become covered by immature enterocytes as the progenitor cells from crypts try to produce new enterocytes
–> Reduced absorptive area and reduced digestive function
20
Q
What are the brush border enzymes?
A
Lactases, Peptidases, Lipases
21
Q
Maldigestion/malabsorption syndromes are associated with
A
Osmotic Diarrhea
22
Q
What does osmotic diarrhea destroy?
A
- Destruction of enterocytes (villous epithelial cells)
Coronaviruses: severe lesion
Rotaviruses: milder lesion - Destruction of crypt epithelial cells
Feline and canine parvovirus
Bovine viral diarrhea
23
Q
Define exudative diarrhea
A
Inflammation and necrosis increase fluid exudation into the intestine
24
Q
In which of the two groups do you expect a longer time before enterocyte regeneration?
A
The group that destroys the crypt epithelial cells
25
Tropism of Enteric viruses for intestinal epithelial cells
Mature Enterocytes
--> Rotavirus: virus is local infection - no viremia
--> Coronavirus: primary infection in the GIT, viremia may occur
Crypt Epithelial Cells
--> Parvovirus: will also infect lymphocytes in GALT, cells in bone marrow. Arrives via secondary viremia
--> Pestivirus (BVDV): lymphocytes in GALT. Arrives via secondary viremia
26
When does blunting of villi occur?
Blunting and atrophy of villi in the small intestine following rotavirus infection and necrosis of enterocytes
27
What does rotavirus affect?
Small intestine (jejunum + ileum) and mature enterocytes
28
What does coronavirus affect?
Affects the small intestine mature enterocytes (also bovine coronavirus causes necrosis of gland epithelial cells in the colon)
29
What do parvoviruses and pestiviruses affect?
Virus replicates in and destroys lymphocytes, disseminates via secondary viremia to crypt cells in the small intestine and lymphocytes in Peyer's patches --> crypt necrosis and lymphocyte necrosis
30
Viruses that affect mature enterocytes but NOT mitotic crypt cells tend to cause _____ disease with ______ mortality
milder
lower
--> Mitosis can be up-regulated, enterocytes can be replaced, and the animal can recover if it can tolerate the electrolyte losses and dehydration caused by the diarrhea
31
Viruses that destroy crypt epithelium and lymphocytes tend to produce _____ disease with a ______ mortality
Severe
High
--> Recovery is longer = mitotic cells are lost and have to be replaced before mature enterocytes can be replaced
--> Lymphocyte depletion = immunosuppression = secondary invasion by bacteria and other organisms
32
Neonatal Calf Diarrhea
Major causes of disease in calves <30 days
--> Economic losses due to ..
- Mortality - 75% calves die before weaning
- Cost of medication
- Labor to treat sick
- Delayed growth
- Higher age at first calving
33
Enteric Bacteria
E.Coli (ETEC)
Salmonella
34
Enteric Protozoa
Cryptosporidium parvum
35
Rotavirus symptoms
Diarrhea within the first 96hrs of like (0-4d)
--> Yellowish liquid feces
36
Bovine coronavirus symptoms
Diarrhea at 5days-6weeks
--> May also cause respiratory disease
37
Diarrhea in calves less than 3 weeks could be
Rotavirus & Bovine Coronavirus
38
Diarrhea in calves 1-6weeks could be
Rotavirus and Bovine Coronavirus
--> co-infection is common
--> Main Point: Rotavirus and BCV must always be under consideration
39
Bovine common cause of diarrhea
Rotavirus and Coronavirus
40
Equine common cause of diarrhea
Rotavirus
41
Swine common cause of diarrhea
Rotavirus and 3 strains of Coronavirus
42
Sheep/Goats common cause of diarrhea
Rotavirus
43
Bovine Rotavirus
Non-enveloped dsRNA virus
---> Segmented genome - possible recombination
44
What are the 3 antigenic specificities of bovine rotavirus?
Group Antigens: A, B C
--> Group members are cross protected
--> NCD = Group A is most common (group B sometimes causes diarrhea)
45
Family Reoviridae
Segmented double stranded RNA genome - 10-12 segments
--> Can reassort genome segments (antigenic shift) when a cell is co-infected by 2 different viruses as in influenza virus
--> Non-enveloped viruses
46
Group A Rotavirus
Diarrhea in young swine, cattle, equine, goats, sheep, poultry
47
What group of Rotavirus is the most common cause of diarrhea
Group A
48
Group C Rotavirus
Associated with diarrhea in swine
49
Group D Rotavirus
Diarrhea in poultry
50
T/F: Most PCR tests for Rotavirus A will detect Rotavirus B
False
51
T/F: Reassortment could generate Rotaviruses that can "jump" to a new host
True
52
Rotavirus kills _______ at the tips of the villi which results in _______ diarrhea
enterocytes
osmotic
53
NSP4 enterotoxin causes _______ diarrhea
secretory
54
Transmission of Rotavirus in foals
fecal-oral
-- via feces in environment and fomites
-- overcrowding is a risk factor
55
Rotavirus is the most common cause of diarrhea in foals at what age?
2 days - 3 months of age (incubation period is short - 24hrs)
--> may shed virus for up to 10 days
56
T/F: Adult horses have subclinical infection of Rotavirus
True
-- may shed virus asymptomatically for up to 8 months
57
Rotavirus in foals causes
necrosis of enterocytes at the tips of villi in the small intestine (duodenum and jejunum)
58
How to diagnose Rotavirus in foals
ELISA, PCR, on fecal sample
59
What type of vaccine is the Equine Rotavirus Vaccine
A killed virus vaccine
60
Are pregnant mares allowed to receive the Equine Rotavirus Vaccine?
An inactivated equine rotavirus vaccine for vaccination of pregnant mares has conditional approval from the USDA
--> Vaccination of pregnant mares is to provide passive transfer of antibodies to foals against equine rotavirus
61
Neonatal diarrhea occurs at what age in bovine?
Diarrhea in calves <1 month and rotavirus is the most common viral agent detected
--> Rotavirus usually occurs as a mixed infection with other pathogens
62
What does rotavirus infect?
Enterocytes leading to villous atrophy (malabsorption osmotic diarrhea)
63
What protein does rotavirus have that can cause secretory diarrhea?
NSP4
64
All of the following are true about coronavirus EXCEPT
a) they have envelopes with spike protein
b) they have large RNA genomes that constantly mutate
c) they can be transmitted via feed/water
d) they replicate in the lymphoid tissue to cause leukopenia
e) they have receptors on enterocytes
d
65
A positive result from which of the following tests provides a definitive diagnosis of feline infectious peritonits?
a) Rivalta test
b) Serum chemistry
c) PCR of feces
d) A higher titer of antibodies against feline enteric coronavirus
e) None of the above
e
66
An 8-week-old puppy presented at your clinic with a history of diarrhea and vomiting. CBC showed mild to moderate anemia, marked leukopenia referable to marked lymphopenia. A PCR test is mostly likely to return a positive test result for
a) rotavirus A
b) canine coronavirus
c) canine adenovirus
d) canine parvovirus-2
e) canine metapneumovirus
67
Pathogen factors that promote neonatal calf diarrhea
Rotavirus-crypt is most common
--> Rate of co-infection in healthy calves = 3%
--> Rate of co-infection in calves with diarrhea = 55%
68
Host factors that promote neonatal calf diarrhea
- Failure of passive transfer
- Age; calves that die do so within 7-14 days of life
- 7 to 14 days = highest fecal shedding of diarrhea pathogens
- Age of dam; calves born to heifers are more susceptible
69
Environmental factors that promote neonatal calf diarrhea
Initial exposure is from adults to newborn calves
- calves born earlier in calving season shed a lot of virus
- calves born later are exposed to more of the virus
- diarrhea may be more common later in season
70
Prevention of neonatal calf diarrhea
Sandhills Calving System
- Segregate calves by age
- Move pregnant cows to clean calving pasture to reduce environmental factors
71
Merk GUARDIAN vaccine
Killed viruses
-- Rotavirus
-- Bovine Coronavirus
Bacterin-toxoid
-- Clostridium perfinges types C and D
-- Escherichia coli K99
**Vaccinate pregnant cows with this***
72
Zoeitis - Bovine Rota-Coronavirus Vaccine
Live attenuated strains of bovine rotavirus (serotypes G6 & G10) bovine coronavirus
--> Used to vaccinate newborn calves or healthy pregnant cows
--> Contains penicillin and streptomycin as preservatives
73
Management of neonatal diarrhea of calves
Reduce exposure of newborns to infectious agents
-- larger pasture or lot to reduce overcrowding
-- separate healthy from sick immediately
74
Rotavirus diarrhea in swine
10-15% of diarrhea in pigs
-- high morbidity and low mortality
-- 100% sero-conversion in adult stock
75
Rotavirus diarrhea in piglets
7-10 days of age
-- progressively less important with age
76
There are at least ____ antigenically distinct serogroups of rotavirus of which ___ affect swine
7
4
77
What is the most common group of rotavirus in swine?
Group A
78
Rotavirus transmission in swine
Fecal-oral is primary
79
Rotavirus lesions in swine
Villous atrophy in jejunum and ileum
80
Diagnosis of rotavirus in swine
PCR on feces and small intestine
Immunohistochemistry on tissue (small intestine)
ELISA (rotaviral antigens) in feces
81
Control of rotavirus in swine
Modified live virus and killed rotavirus vaccines
**Dams can be vaccinated prior to farrowing to produce antibody in colostrum/milk to protect piglets
--> Alternative: expose dam to wild type indigenous rotaviruses
-->Most rotavirus vaccines are for type A and are combination vectors
82
Infection and necrosis of crypt epithelial cells and lymphocytes in Peyer's patches are essential in the pathogenesis of the disease caused by all of the following EXCEPT
a) Feline panleukopenia virus
b) Canine parvovirus-2
c) Canine parvovirus-1
d) Bovine virus diarrhea virus
83
Concerning neonatal diarrhea of farm animals, all of the following statements are false EXCEPT
a) both rotavirus A and bovine coronavirus cause infection and necrosis of crypt epithelial cells in small intestine
b) profuse diarrhea in an 8-month-old 350lb Jersey calf is most likely to be cause by rotavirus A
c) malabsorption and osmotic diarrhea can be caused by both rotavirus A and bovine coronavirus
d) rotavirus can be transferred from the dam to the developing calf through the placenta
84
FELOCELL FIP (ZOETIS) is an intranasal modified vaccine for FIP in cats. This vaccine is preferred to a killed injectable vaccine because
a) Felocell induces IgA
b) Felocell induces IgG
c) Injectable vaccines induce IgG
d) IgG may predispose cats to the immune-enhanced disease
e) A, C and D
85
Up to ____% of uveitis have associated systemic disease
70
86
Non-effusive FIP: "mutton fat" precipitate in the anterior chamber
Cryptococcosis
Histoplasmosis
Blastomycosis
Coccidioidomycosis
87
In dogs what are the 2 antigenically-distinct parvoviruses?
Canine parvovirus-2 (this is the most important one that causes enteritis and myocarditis)
Canine parvovirus-1 (CPV-1) -- AKA "minute viruses of canines" not considered to be a significant pathogen.
88
CPV-2 causes ..
enteritis in young dogs and is the major cause of viral diarrhea in dogs.
-->This disease is highly contagious and often fatal
89
What are the different variants of CPV-2
CPV-2, CPV-2a, CPV-2b, and CPV-2c
90
What is the standard variant of parvovirus that caused enteritis in dogs in the USA?
CPV-2b
91
T/F: The three different antigenic variants of parvovirus, 2a, 2b, 2c are currently circling worldwide
True
--> data is not conclusive that either of the 3 variants is more virulent in dogs
92
T/F: Commercially available tests are not able to detect all variants of CPV-2
False
--> They are able to detect all variants of CPV-2 including CPV-2c
93
CPV-2 is the result of a mutation in what virus?
Feline panleukopenia virus
94
Hosts of CPV-2
All canidae are susceptible (dogs, foxes, wild dogs, coyotes, wolves)
95
T/F: CPV-2 (strains 2a, 2b, 2c) can infect domestic cats as well as dogs
True
--> Infection with CPV-2 can cause disease in cats, similar to feline panleukopenia. It may also cause in-apparent infection and result in shedding of the virus
96
T/F: A modified live vaccine for feline panleukopenia virus provides cross-protection against CPV infection in cats
True
97
Epidemiology of CPV-2
Occurs worldwide
--> Infection in dogs is very common, many dogs developing subclinical disease from which they recover.
--> When clinical disease occurs, it is most severe in young, rapidly growing puppies
98
CPV-2 routes of transmission
Highly contagious, and most infections occur as a result of oral contact with contaminated feces in the environment.
--> People, instruments, insects and rodents can act as fomites
--> Stable in the environment and can survive for up to 5 months on surfaces
--> Resistant to many common disinfectants
99
CPV-2 age predilection
Pups between 6 weeks and 6 months of age are the most susceptible
100
Where does CPV replicate?
In the nucleus of the host cell and they require host cell functions of dividing cells (S phase of the cell division cycle)
101
In dogs 6 weeks and older, what is the predominant clinical manifestation of CPV
Enteritis and leukopenia due to infection and loss of lymphocytes and crypt epithelial cells which divide at a high mitotic rate throughout life
102
What is the incubation period of CPV-2
7-14 days
--> Viral replication begins in the lymphoid tissue of the oropharynx
--> After 1-5 days primary viremia occurs and the virus disseminates primarily to the epithelium of the small intestine, lymphoid tissue and bone marrow
103
CPV-2 infects ..
germinal epithelium of the crypts in the small intestine resulting in necrosis of crypt epithelium and atrophy and blunting of the villi (diarrhea)
--> CPV-2 also destroys mitotically active precursor cells of circulating leukocytes and lymphoid cells, causing leukopenia and lymphopenia
104
CPV-2 is shed extensively in the ..
feces for 7-10 days, and active excretion beings to prior onset of diarrhea (shedding of virus has been documented in some cases for weeks)
105
What are the 2 major clinical syndromes of CPV-2
1. Enteritis (6 weeks +) manifested as a rapidly-progressing GI disease. Affected dogs have fever, vomiting, and rapid onset of severe diarrhea. Leukopenia is present. Death can occur as early as 2 days after onset of illness
2. Myocarditis (young puppies - that do not have sufficient levels of maternal Ab are infected at approx 3 weeks) All pups in a litter are usually infected and death from cardiac failure is the usual outcome. Cardiac failure may not occur for weeks or a few months.
106
Gross lesions of enteritis in CPV-2
***NO GROSS LESIONS COMMON***
--> Lesions may be segmental, so TAKE MULTIPLE SAMPLES of the small intestine
107
Gross lesions of myocarditis in CPV-2
Pale streaks in the heart muscle
--> Microscopically these areas are non-suppurative myocarditis with infiltration of lymphocytes and macrophages. Intranuclear inclusions may be observed
108
Diagnosis of CPV-2
Clinical signs are suggestive
--> ELISA test for the CPV-2 antigen (detects 2a, 2b, 2c), however, the virus is usually shed in the feces at detectable levels for only 10 days and by 5-7 when clinical illness occurs the virus may no longer be detected in the feces.
--> Immunohistochemistry on tissues, electron microscopy on feces
--> PCR (detects 2a, 2b, 2c and vaccine virus) in feces or tissues
109
T/F: dogs vaccinated with the modified live vaccines will shed live vaccine virus in their feces and can have a positive ELISA test for 5-12 days
True
110
T/F: SNAP Parvo Test does not detect vaccine CPV-2 in canine feces
True
111
T/F: PCR tests can distinguish wild type virus from vaccine virus
True
112
Puppies with diarrhea, dead, negative on viral ab test for CPV (diagnosis=canine parvovirus enteritis) are not uncommon. Thus, diagnosis by ...
Histopathological lesions
113
How to kill CPV on surfaces
Diluted bleach (1:30) for ten minute exposure
114
Vaccine for CPV
MLV (attenuated) effective in preventing disease
115
What is the most common cause of vaccination failure in puppies
interfering levels of maternal antibody to CPV-2 blocks the development of an immune response in the puppy
116
T/F: CPV vaccines protect against all CPV-2 strains
True
117
Where does canine coronavirus replicate?
In the cytoplasm of the cell
118
CCV epidemiology
Highly contagious and spreads rapidly among groups of dogs.
--> Uncommon cause of enteritis and diarrhea in dogs
--> Non-core vaccine; may be important for puppies in kennels
119
Incubation of CCV
1-4 days
120
What does CCV infect?
mature epithelial cells of the intestinal villus. The virus replicates in the enterocytes and is released by budding from the apical surface of the cell.
--> Crypt cells undergo hyperplasia
121
What is CCV characterized clinically?
Sudden onset of diarrhea in puppies
--> Vomiting and fever are variable
--> Anorexia and lethargy are common
122
Diagnosis of CCV
RT-PCR test detects viral RNA
123
Prevention/Control of CCV
Inactivated and modified-live vaccines
*Not a core vaccines but may be recommended in situations like kennels
124
Canine Rotavirus
Rare cause of diarrhea in puppies less than 12 weeks of age
--> No vaccine
