Managing common viral infections in poultry Flashcards
1
Q
Describe the problem-solving approach to ommon presentations?
A
- Problem identification
- Data collection
- Hypothesis formation
- Diagnosis Testing
- Data analysis and interpretation
- Evidence based intervention
- Monitoring and Evaluation
- Prevention Strategies
2
Q
How to PE poultry
A
- Capture & restraint
- BCS
- HEad & neck
- Oral cavity
- FFeathers and skin
- Breathing and Respiration
- Abdomen
- Vent
- Legs and Feet
- Feeding and drinking bhvr
3
Q
Describe Newcastle disease virus
A
- Varies in severity
- NOTIFIABLE - VACCINATED against
- Variable STRAINS
4
Q
What type of transmission for NDV?
A
HORIZONTAL
5
Q
What factors influencing SPREAD of NDV?
A
- Virus characteristics
- Host Factors
- Environmental conditions
- Management practices
- Transmission vectors
- Geographical factors
6
Q
What are the 5 forms of NDV?
A
- Doyle’s form
- Beach’s Form
- Beaudette’s form
- Hitchner’s form
- ASYMMPTOMATIC
7
Q
What CLS vary depending on ?
A
depending on strain of virus
8
Q
Describe Doyle’s form
A
GIT - viscerotropic velogenic Newcastle dx (VVND)
9
Q
Describe BEach’s form ?
A
Respiratory and neurological signs - neutropic velogenic (NVND)
10
Q
Beaudette’s form - describe
A
less pathogenic form = mesogenic pathotype = live vaccine
11
Q
Hitchner’s form - describe
A
mild or inapparent respiratory infections : lentogenic pathotype = live vaccines
12
Q
Describe asymptomatic form
A
= enteric form = lentogenic viruses = no obvious CS= some live commercial vaccines
13
Q
What CLs for Doyle’s form ?
A
- May appear suddenly, with high mortality
- CS begins with Listlessness, weakness, unusual quietness, prostration, death
- May cause oedema around eyes and head. Green D+, muscular tremors, torticollis, paralysis of legs and wings and opisthonous
14
Q
What CLS for Beach’s Form?
A
- Chickens -> sudden onset resp dx followed 1/2 d by neuro signs
- Resp signs == sneeing, coughing etc
- Egg prod dec
15
Q
Morbidity/ Mortality for Beach’s form?
A
Morbidity 100% Mortality considerably lower up to 50% in adults and 90% in young
16
Q
Describe CLS for BEaudette’s form
A
- Mesogenic strains of NDV usually cause respiratory dx in field infections
- In adult birds drop in prod several weeks
- Nervous signs sometimes
17
Q
Mortality for Beaudette’s form?
A
Mortality in fowl low exept in susceptible/ v young birds
18
Q
T/F Beaudette’s form used as vaccine virus?
A
TRUE
19
Q
Describe CLS from Hitchner’s form
A
- Lentogenic viruses do not usually cause dx in adults
- YOung birds -> serious resp dx & mortality with coinfection with LaSota
20
Q
Production consieration with Hitchner’s form?
A
Vaccination or infection of broilers close to slaughter -> colisepticaemia or airsacculitis with resulting condemnation
21
Q
Are there any pathognomic lesions for NDV?
A
Not really - gross lesions may be absent
22
Q
What gross lesions may we see with NDV? (PME)
A
- haemorrhagic lesions in the intestine distinguishing VVND viruses from NVND
- Lesions prominent in mucosa and proventriculus, ceca, SI
- Haemorrhage in Resp tract
23
Q
Overall what CLS may ring bells for NDX in your history?
A
- Resp: coughing, sneezing, nasal disC & resp distress
- Neuro: tremors, twisted necks, paralysis, incoordination
- Digestive: D+ & greenish watery faeces
- General: reduced egg prod, misshapen eggs, lethargy, SD
24
Q
How do we do Virus isolation to diagnose NDV
A
- Swab from trachea, cloaca, & oropharynx as well as tissue samples from spleen, lungs and brain
- Samples incoulated into emryonated chicken eggs. NDV causes embryonic death and characteristic leisons in the eggs
25
How do we do serological tests for diagnosis of NDV
- Haemagglutination test (HA)
- Haemagluttination Inhibition (HI)
- ELISA
26
Describe HA test
NDV can cause agglutination of red blood cells, which can be detected using the HA test
27
Describe HI test
Detects specific antibodies against NDV in the serum of infected birds. A positive HI test indicated exposure to the virus
28
What molecular techniques for diagnosis?
- RT- PCR (Reverse- Transcription Polymerase Chain reaction)
- Real-Time PCR
29
Detail RT-PCR?
Detects NDV RNA in clinical samples - highly Se & Sp allows differentiation of strains!
30
Detail PCR
quantifies RNA in real time - VIRAL LOAD measured
31
What differentials list other than NDV
- Avian Influenza
- Infectious bronchitis
- Fowl Cholera
32
What intervention strategies can be put into place?
- International control policies (import/export & border control)
- National Control Policies
- Control and prevention at FARM level
33
What national contorl policies can we have?
- Regular health checks: routine monitoring and testing to detect early signs of dx
- Reporting: Implement systems for rapid reporting and response to suspected cases of Newcastle dx
- Slaughter policy
34
What control and prevention on FARM level?
1. Biosecurity -> isolation, Sanitation, Controlled access
2. Management Practices -> Nutrition, Stress Reduction
3. Antiviral tx (none for NDV, supportive care )
4. Vaccination (Live vs Inactivated)
35
Describe Live vaccines
Drinking water, eye drops, or aerosols. They provide quick immunity but may cause
mild reactions in birds.
36
Describe Inactivated Vaccines
Injected and offer longer-lasting immunity. They are often used in
combination with live vaccines for a comprehensive vaccination program.
37
What CONSIDERATIONS with Vaccination?
- seromonitoring before vaccination
- Cross protection
- ROA
- Age of vaccination
38
What is Infectious Brconhitis
Acute, highly contagious viral respiratory dx in chickens characterised by **tracheal rales, coughing, and sneezing**
39
What Virus-related factors influence spread of IBV ?
- Virus strain
- Mutation and Recombination
40
What host-related factors influence spread of IBV?
* Age and Immune status of birds (all ages susceptible but chicks more severe) -> As age inc >* more resistant to nephritogenic effects, oviduct lesions and mortality *
* Genetic Susceptibility
* Vaccination Status
41
What Environmental Factors to IBV spread?
- Housing and Management Practices
- Biosecurity measures
42
What is the transmission mode of IBV?
HORINZONTAL
43
# Describe the transmission of IBV
Describe the transmission of IBV
1. Direct Contact -> via res secretions and faeces
2. Indirect contact (euipment, feed, water)
3. Airorne Transmission (INHALATION) (Vaccine route)
44
What is the incubation period of IBV?
18-36 hrs
45
What CLS in chicks of IBV?
Gasping, coughing, sneezing, tracheal rales, and nasal discharge. The chicks appear depressed
and may be seen huddled under a heat source.
46
What signs of IBV in Layers?
* Decline in egg production and quality + respiratory signs.
* Number of eggs unacceptable for setting is increased; hatchability is reduced; and soft-shelled,
misshapen, rough-shelled eggs are produced and cystic ovary.
47
Is INTERNAL OR EXTERNAL OR BOTH aspects of eggs affeted by IBV ?
## Footnote
Al
BOTH
| Albumin may be thin and watery without definite demarcation between the
## Footnote
Soft shelled eggs & egg deformation
48
What Gross lesions will we see with IBV?
* Serous, catarrhal, or caseous exudate in the trachea, nasal passages and sinuses
* air sacs clougy or yellow caseous exudate
* Caseous plug in lower trachea or bronchi of chicks that die
* Small areas of pneumonia around large bronchi
* KIDNEY LESIONS
49
DESCRIBE THE KIDNEY LESIONS WITH IBV
- Nephropathic infections produce swollenba nd pale kidneys with the tubules and ureters often distended with urates
50
DIAGNOSIS of IBV?
- History & Observation
- Lab testing -> virus isolation, molecular or serology
- Necropsy & histopath
| Histopath changes -> epithelial damage, inflammation and presence of lyp
51
Describe all Symptoms of IBV
* Resp signs (coughing, cneezing tracheal rales etc)
* Reduced feed & water intake
* Poor weight gain an stunted growth
* Drop in egg production and quality in laying hens
52
Describe Lab testing for diangosis of IBV
1. Virus isolation
2. Molecular Methods
3. Serology
53
Describe Virus Isolation for IBV testing
Tracheal swabs, kidney tissues, or cloacal swabs
Isolation in embryonated chicken eggs and tissue culture
54
Describe Molecular Methods for for IBV testing
* RT-PCR: specific strains & genotypes of virus
* Real Time PCR: quantitiative data
55
Describe Seorlogy for IBV testing
- ELISA: quantitative and qualitative
- Virus Neutralization Test: Detects presence of neutralisation antibodies that inhibit virus replication
- HI test
56
Diagnosis on Gross exam of IBV?
- Mucus in trachea,s wollen kidneys, egg peritonitis in layers
- Cystic oviducts or haemorrhagic follicles
57
Differentials for IBV?
- NDV
- Avian Influenza
- Mycoplasmosis
- Infectius laryngotracheitis
58
What intervention strategies for IBV?
No specific Tx
- Provisoo of additional heat to eliminate cold stress, eliminate overcrowding, and attempt to maintain feed consumption to prevent weigth loss are flock management factors that help reduce losses from IB
59
What management procedures (IBV)
- Hygiene and biosecurity
- Repopulation with only day-old chicks, following the cleaning and disinfection of the poultry
house.
- Temperature, Ventilation to avoid secondary bacteria infection
60
What is Marek's Disease ?
Common **lymphoproliferative dx** of chickens characterised by mononuclear cellular infiltrates in peripheral nerves and various other organs and tissues including itis and skin
Dx is caused by **herpesvirus**, is transmissible and cna be distinguished etiologically from other lymphoid neoplasms in birds
61
What serotypes of MArek's are there ?
Serotype 1 - Divided into pathotypes - PATHOGENIC
mild (m) MDV
virulent (v) MDV
very virulent (v v)
very virulent plus (v v+)
Serotype 2. Apathogenic
Serotype 3. HVT
62
What Host Factors to spread of MDV
1. Age - younger birds (2-16 wks)
2. Genetics - some predisposed some resistant
3. Immune status - compromised or not vaccinated more susc
| While vaccination reduces severity, does not prevent infection/shedding
63
What environment factors to MDV spread
1. biosecurity Practices: poor biosecurity measures, such as inadequate cleaning and disinfection
2. Housing Conditions: high density housing and poor
3. Hygiene: Contaminated litter can harbour the virus and facilitate its transmission
64
What Viral Factors to spread of MDV.
1. **Virulence of Virus** : different strains fo Marek's vary in virulence. More virulent strains can cause more severe dx and spread more efficiently within a flock
2. **Shedding and Transmission** - Shed through feather follicle dander whioch can remain infectious in environment for long time. Virus hoighly contagious - spread via dust, feathers and fomites
65
Describe Transmission fo MDV
Direct or indirect contact of chicks (Horizontal)
**Airborne route** virus associated with feathers and dander is infectious, contaminaye poultry house ust remains infectious for several months at 20-25°C and years at 4°C
66
When do we get outbreaks fo MDV?
Under field conditions, MD
outbreaks sometimes occur
in unvaccinated layer
chickens as young as 3—4
weeks. Most of the serious
cases begin after week 8 or
9 but also sometimes
commence well after the
onset of egg production.
67
CLS (and progression) for MDV
Related to PEripheral nerve dysfunction signs associated with asymmetric progressive paresis and later compelte spastic paralysis and dilation of the crop and/ or gasping
Bc locomotory disturbances easily recognised, incoordination or stilted gait first obsserved signs
A particularly characteristic clinical presentation is a bird with **one leg stretched forward** and the other back as a result of *unilateral paresis* or paralysis of the leg
68
What other CLS of MDV?
- Nonsp -> weight lsos, paleness, anorexia, D+
- Death from starvation & dehydration
- Ocular invovlement -> blindness uni or bilat ; lose abilit to accomodate to light intensity
- Depression & comatose prior to death
69
What Two forms of Marek's exist?
- Classical form -> chickens with ataxia and flaccid paralsysis 8-12 d after exposure to virus by inocculationn
- Acute (fatal) form -> death 24-72hrs following paralytic signs -> formation of lymphomas in visceral organs
70
Example of Ocular lesion with MDV
71
What Integument Gross Pathology lesions with MDV?
SKin lesions usually associated with feather follicles
Nodular leisons f
72
What Gross pathology lesions in visceral organs with MDV?
- Lymphomatous lesions can be found in gonad, lung, heart, mesentery, kidney, liver, spleen ,bursa, thymus , adrenal gland, pancreas, proventriculus, intestine, iris, skeletal muscle and skin
73
Overall gross pathology findings for MDV?
NErve lesions and visceral lymphomas
Enlarged peripheral nerves (cross striations, gray or yellow discoloratio)
74
Gross changes to the eye?
Loss of pigmentation in iris an dirregularity of pupil, -> resul in mononuclear infiltration of iris
75
CLS Overall of MDV?
* Paralysis
* Weight loss
* Ocular changes
* Cutaneous tumours
76
Diagnosis of MDV (LAb) ?
- **Virus culture** : from tissue samples using embrypo fibroblasts
- **Molecular Techniques**: Advanced real-time PCR quantify load - differentiation vaccinated vs infected
- **PCR**
77
What other DDX for MDV?
- Avian leukosis
- Reticuloendotheliosis
- Lymphoid leukosis
78
What intervention strategies for MDV?
- Genetic Resistane (breeding selectively)
- Biosecurity: sanitation & controlled access
- Vaccination & prevention (most effective)
79
Describe Vaccination of birds against MDV?
Live Vaccines: HVT, RISPENS, RECOMBINANT VACCINES
Vaccine administered at day old OR in ovo to embryos at 18th day of incubation: for
commercial birds to decrease labour cost and greater precision of vaccine administration
80
What is Avian Influenza?
“influenza” originally
referred to epidemics of acute,
rapidly spreading catarrhal
fevers of humans caused by
viruses in the family
Orthomyxoviridae
81
Transmission & carriers of AI?
- Excreted from nares, mouth, conjunctiva, cloaca of infected birds into environment bc of virus replication in resp, intestinal, renal and/ or reprod organs
- Transmission by direct contact between infected and susceptible or indirect contact through aerosol droplets or fomites
82
Environmental Factors for sprea of AI ?
- Climate and Weather Conditions -> cold wet enhances survival of virus & seasonal migration of birds
- Biosecurity Practices: poor biosecurity
83
What Host Factors to spread of AI
WILD BIRDS -> waterfowl = natural reservoirs spreading to domestic chickens
VACCINATION -> inconsistent or inadequate vaccination programs can fail to control the spread
84
What Virus -related factors to AI ?
1. Certain strains more virulent & transmsisibel than others
2. Segmented virus capabale of reassortement
85
What strains fo HPAI?
AI viruses are further
divided into 16
hemagglutinin (H1–
H16) and 9
neuraminidase (N1–
N9) subtypes.
## Footnote
From 1959 through
May 2024, 46 distinct
virus lineages caused
HPAI outbreaks or
events.
86
What 4 clinical groups of AI infection?
1. Highly virulent
2. Moderately virulent
3. Mildly virulent
4. Avirulent
87
DO we get distinct CLS with AI?
VERY variable -> msot infections by MP AI viruses in wild birds produce no CLS
88
Domestic Chickens & turkeys CLS of AI?
- abnormalities in the respiratory,
digestive, urinary, and
reproductive organs.
- The most frequent signs are
coughing, sneezing, rales, rattles,
and excessive lacrimation.
- In layers and breeders, hens
* Increased broodiness
* Decreased egg production.
89
Which infections have highly virulent groups ?
HP H5 or H7 AI viruses usually in chickens or closely related gallinaceous birds
Expressed as a severe, highly fatal systemic disease that affects most organ systems including the nervous
and cardiovascular systems.
Morbidity and mortality approach 100%.
90
What other findings with higly pahtogenic AI viruses ?
Poultry houses unusually quiet
Haemorrhage, cyanosis of nonfeathered skin esp wattles, combs and shank
Depression is common as are significant declines in feed and water consumption, drops in egg production to
cessation of egg production
91
What gross pathology with mildly pathogenic AI viruses ?
| thogenic AI viruses ?
- Cattarrhal, fibrinous, mucopurulent or fibrinopurulent inflammation
- Tracheal mucosa can be oedematous with congestion with occasionally haemorrhages
92
What gross lesions on PME with HP AI?
Variety of oedematousn haemorrhagic and necrtotic leisons in visceral organs and skin
If death peracute - may be no lesions
93
Diagnosis of AI ?
1) Direct detection of AI viral proteins or genes in specimens such as tissues, swabs, cell cultures, or
embryonating eggs
2) Isolation and identification of AI virus. A presumptive diagnosis can be made by detecting antibodies to
AI virus.
94
Other DDX for AI Virus ?
- NDV
- Infectious laryngotracheitis
- Infectious bronchitis
- Fowl cholera
95
What intervention strategies against AI virus?
1. Regulatory and Policy Measures
2. Biosecurity Measures
3. Disinfection and Sanitation
4. Surveillance and Monitoring
5. Culling and Depopulation
6. Vaccination
96
Describe Regulatory and Policy measures?
Trade Restrictions: Imposing restrictions on the import and export of birds and bird products from
affected regions.
* Legislation: Developing and enforcing laws related to avian influenza control and prevention.
97
Describe Biosecurity measures for AI?
Farm Management: Ensuring strict biosecurity measures on poultry farms to prevent the
introduction and spread of the virus.
Movement Control: Regulating the movement of birds and bird products between regions and
countries.
98
Discribve the Disinfection and Sanitation for AI?
Cleaning Procedures: Thorough cleaning and disinfection of farms and equipment.
Waste Management: Proper disposal of bird carcasses and waste materials to prevent
environmental contamination.
99
Describe Surveillance and Monitoring for AI?
Early Detection: Regular monitoring of bird populations, especially in high-risk areas, to detect
the virus early.
Reporting Systems: Implementing systems for reporting outbreaks quickly and accurately.
100
Describe Culling and Depopulaiton for AI?
Infected Flocks: Immediate culling of infected birds to prevent the spread of the virus.
At-risk Flocks: Sometimes, culling of birds in proximity to infected flocks may be necessary.
101
Describe Vaccination for AI ?
Vaccination Programs: Implementing vaccination programs for poultry, where appropriate, to
protect birds from infection.
Selective Vaccination: Vaccinating only high-risk populations or in areas with recurrent
outbreaks.
