Infectious Disease Flashcards
1
Q
what is calf scours
A
undiffirentiateed diarrhea in new born calves
2
Q
calf scours
A
- causes diarrhea in newborn calves (>28-30d)
-one of the most common maladies of production animals
3
Q
calf scours economic losses
A
- USDA estimates btwn 4 and 25% of calves will die from scours each year in the US
- btwn 50% beef and 100% dairy calves in herd will be ill
- ALberta: 36% of all death losses btwn birth and 30d
-significant costs
-losses: cost of dead calves, stunted calves, labour and medication
4
Q
pathogens that cause calf scours
A
- rotavirus
- K99 e.coli
- coronavirus
- clostridium perfringens type c
- cryptosporidium
- coccidia
- salmonella spp.
5
Q
rotavirus age of onset and signs
A
possible: 0-28d
-most common: 1-6d
-watery brown to light and green feces, blood and mucus
6
Q
k99 e coli bacteria age of onset and signs
A
- most common: 1-7d
- effortless passing of yellow to white feces
7
Q
coronavirus age of onset and signs
A
-possible: 0-28d
-most common:7-10d
-watery, yellow feces
8
Q
clostridium perfringens type c age of onset and signs
A
-most common: 7-28d
-sudden death, blood tinged diarrhea
9
Q
cryptosporidium age of onset and signs
A
-most common: 7-21d
-watery brow nto light green feces, blood and mucus
10
Q
-coccidia age of onset and signs
A
-most common: 7+ days
-blood tinged diarrhea
11
Q
salmonella spp. onset and signs
A
-most common: 1-7d
- similar to e coli: yellow to white feces and possible blood
12
Q
most common pathogenic cause of calf scours
A
1.e coli
2. coronavirus
3. salmonella
13
Q
salmonella
A
- affects gut villi: less SA for absorption and lots of bleeding bc of barrier breach
-zoonotic
14
Q
coccidia
A
-common in western canada
-drills holes into epithelium= hemorrhage and diarrhea
15
Q
cryptosporidium spp.
A
- zoonotic
-sits on epithelium brush border = dehydration
16
Q
contributing factors of calf scours
A
-cold, wet weather
- bad sanitation: crowded housing= allows organism to increase in numbers and enhance exposure to neonates
- nutrition for calf and dam: good nutrition ensures adequate amnts of good quality colostrum: 10% of calf body weight in 12 hr
17
Q
calf scour treatment and prevention
A
- provide stress free clean enviro
- treat w antimcrbls: to protect against secondary infections
- fluid and electrolyte therapy (oral or iv)
- colostrum
18
Q
calf scour management to prevent
A
- spearate healthy cow/calf from sick cow/calf pairs
- move healthy animals to clean pasture and removed soiled bedding in calving area
- good sanitation: clean equipment and animal andlers
-vaccinate cows prior to calving: rotavirus coronavirus, cl.. prefringens type c, ecoli k99
19
Q
how are cows healthy
A
-good body scores, better calvings, less diarrhea
20
Q
bovine respiratory disease
A
shipping fever
21
Q
shipping fever cause
A
assembly of calves into feedlots from diverse geographic, nutritional and genetic backgrounds
-stress and bacteria mixing
22
Q
shipping fever onset
A
- seen in feeder calves 7-10d after assembly in a feedlot
- morbidity: 35%
- mortality: 5-10%
23
Q
shipping fever primary infection causes
A
- primary: insult w viral pathogen
- insult with mycoplasma sp.
24
Q
shipping fever primary pathogens
A
-bovine herpes virus-1: infectious bovine rhinotracheitis (IBR)
-bovine viral diarrhea virus (BVDV): togavirus
-bovine respiratory syncytial virus (BRSV): paramyxovirus
-bovine parainfluenza virus (PI-3): paramyxovirus
25
shipping fever secondary infectious agents
1. manheimia (pasteurella) hemolytica
2. histophilus (hemophilus) somni
3. pasteurella multocida
26
shipping fever causes in canada
- manheimia (pasteurella) hemolytica
-histophilus (hemophilus) somni
27
fibrinoplueropneumonia
- caused by manheimia and histophilus
-increased fibrin in between lungs and ribcage and leaves behind scar tissue post recovery
28
hallmark of bacterial infection
- cranial-ventral presentation
29
histophilus somni effects
-fibrinous pericarditis
-myocarditis
-fibrinopleuropneumonia
30
strategies that induce disease
1. evasion of innate immunity
2. evasion of adaptive immunity
31
strategies that evade innate immunity (5)
1. interference of physical barrier (lung)
2. interference of phagocytosis
3. interference w intracell killing
4. interference w INF (interferons)
5. regulation of apoptosis
32
interference of physical barrier (lung)
- respiratory epithelial cells: mechanical, chemical, mcrb barriers
-ex. mucous allows cillai to move upwards t oropharynx to be coughed out
-mucous makes pathogen more susceptible to phagocytosis bc of less mvmnt
33
pathogen that interferes w physical barrier
bovine herpes 1
34
bovine herpes 1 barrier mechs
-infects repsiratoy epithelium
-infects goblet cells
= injusry to epithelial barrier and assoc. lymphoid tissue = erosion/necrosis = nonfunctioning respiratory elevator
-nonfucntioning elevator allows for viral pathogens (manheimia nad hemolytica) to invade from nasopharynx bc no coughing
35
interference w phagocytosis
-phagocytosis links innate and adaptive immunity ex. macrophage engulf cells
- activate/ control adaptive immune responses
36
pathogen that interferes w phagocytosis
histophilus somni
37
histophilus somni phagocytosis mechs
-when engulfed by phagocytic cells it induces apoptosis which reduces capacity of phagocytosis
-releases exopolysacc that may impair intracell phagocytic mechs
38
interference w intracell killing mechs
-phagocytytic cells produce toxin compunds to destroy bacteria ex:
superoxide anions
hydrogen peroxide
nitric oxide
hypochlorous acid
myeloperoxidase
39
pathogen that interfeeres w intra cell killing
bovine parainfluenza 3 (Pi-3)
40
bovine parainfluenza 3 intra cell killing mechs
-inhibits superoxide anion production in alveolar macrophages but doesn't destroy macrophages = propagation of pathogenic bacteria in secret
41
interferons (inf)
INFs= antivirals
-induce and enhance immune fxn
=activates JAK/STAT signal
=reduces viral replication and cell-cell transmission
42
pathogen that interferes w interferons
bovine viral diarrhea virus-1 (BVDV)
43
bovine viral diarrhea virus interferon mechs
amino terminal (IRF3) of BVDV virus inhibitsfrom binding to INF promoter
44
regulation of apoptosis
-viral induced cell death prevents viral proliferation and cell- cell transmission
45
pathogen that regulates apoptosis
-bovine herpes virus-1 (IBR)
46
bovine herpes virus-1 (IBR) apoptosis mechs
-induce apoptosis at end of viral replication= increases numbers of viral particles
=decreases apoptotic signal in viral host cell
47
strategies to evade adaptive immunity (7)
1. suppression of lyphocyte proliferation
2. induction of humoral and cellular immune tolerance
3. down regulation of MHC-II mlcls
4.inhibition of antibody production and antibody effectiveness
5. loss of CD4T cell function
6. interference w cytotoxic t cell fxn
7. shut down protein syn.
48
lymphocyte proliferation suppression
interrupts clonal expansion of B and T cells
49
pathogen that suppresses lymphocyte proliferation
bovine viral diarrhea virus (BVDV)
50
bovine viral diarrhea virus (BVDV) lymphocyte mechs
-infects antigen presenting cells and reduces clonal expansion of CD4-T cells = reduced cognate interaction
51
pathogen that induces humoral and cellular immune tolerance
-bovine viral diarrhea virus
52
bovine viral diarrhea virus (bvdv) immune tolerance mechs
-mucosal disease: noncytopathic form that infects fetus (d60 of gestation)
= decrease in INF production = unrestricted viral replication in tissues
=induses immunotolerance to virus (tolerized CD4T cells) so when the calf is exposed to the cytopathic form there's no immune response
53
mucosal disease
-identical lesions as FMD (epithelial erosions and ulcers)
- NOT WANTED IN CANADA
54
MHC-II mlcl fxns
activates CD4 Tcells and helps B cells
55
down regulation of MHC-II mlcs
antigen presentation
-exogenous protein (pathogen protein) degraded by cellular process in antigen presenting cells and expressed as MHC-II restricted antigens
56
pathogen that down regulates MHC-II mlcl
leukotoxin of manheimia (pasteurella) hemolytica
57
leukotoxin of manheimia hemolytica mechs
decrease expression of MHC-II mlcl on antigen presenting cells which allows organism to grow in tissue
58
pathogen that inhibit antibody production and effectiveness
-histophilus somni
59
histophilus somni antibody mechs
secretes proteins that bind to IgG2 antibodies in nonspecific manner
=renders antibody useless
60
pathogen that affects CD4 T cell fxn
bovine herpes virus -1
61
bovine herpes virus -1 CD4T cell mech
-induce loss of CD4T cells on lymphocytes
- CD4 lympholysis in peripheral blood and lymph nodes
62
Interference w cytotoxic T cells
MHC-I mlcs needed for CD8T cells (CTL) to eliminate virally infected cells
-CD8T recognize viral peptides (antigens) presented in MHC-I mlcls
-no MHC-I means no CTL elimination of pathogens
63
shut down of protein syn
-protein syn needed to generate mlcls used in immune fxn
-MHC I and II
-cytokines
-chemokines
64
pathogen that shut down protein syn
bovine herpes virus -1
65
bovine herpes virus 1 protein syn mehcs
produces "virion host shut off protein" (UL41)
-reduces protein syn by degrading mRNA of cell protein
-stea protein mech for pathogen to use
66
strategegy that induces disease changes in pathogen
antigenic variation
67
antigenic variation
-organisms change sturcture of sruface memranes to avoid immune system recognition (chameleon)
68
pathogen for antigenic variation
histophilus somni
69
histophilus somni antigenic shift mech
-glycoses and phosphoryl choline of LPS randomly vary
=occurence at multiple sites = can evade antibody immune responses
