Swine Disease Impacts and Diagnostics and PRRS Flashcards
Disease Impacts
- Mortality
- Decreased weight gain over time (ADG)
- Sort loss
- Increased lights and culls
- Increased feed:gain ratio (decreased feed efficiency)
- Increased vet costs (drugs, biologicals, vet services)
- Increased labor (tx, culling, disposal)
- Decreased animal welfare (concern about animals themselves, not just profitability)
What disease contributes the most to the total cost of disease per pig?
- Pneumonia (28%)
- Stillbirths coming in 2nd (11%)
- Overlaying (8%)
- Scours (diarrheal diseases) - (8%)
- Starvation, death, cold exposure
- Mastitis (2%)
What are the pathogenic causes of pneumonia?
- >90% due to combination of pathogens:
- Porcine Reprodctive and Respriatory Syndrome (PRRS)
- Mycoplasma hyopenumonia
- Swine influenza
- Porcine circovirus type 2
High Impact Swine Gastrointestinal Disease (today - in 2015)
- Porcine epidemic diarrhea (PED)
- First case occurred in 2013 in the US
- Transmissible gastroenteritis (TGE)
- Colibacillosis (neonatal, postweaning)
Culture, virus isolation (VI), PCR, Immunologic tools (fluorescent antibody, immunochemistry, ELISA) are diagnostic methods that demonstrate _______
The presence of a pathogen
ELISA, SN, and HI are all diagnostic methods that demonstrate….
Host response to pathogen (antibody)
Some definitive daignosis can be made upon clinical signs, pathology or clinical pathology. True or False.
True
In a PCR, you are trying to identify ______ acids of the pathogen. PCR identifies both ____ and ____.
Nucleic; RNA and DNA
The most common site for blood samples in the pig
Neck - jugular vein, and cranial vena cava
Is the ear a good place to take a blood sample? Why or why not?
No, becuase often times the vein collapses easily, and you only end up with a very small sample of blood.
When collecting oral fluids, make sure tubes do not contain _____ and ____.
EDTA and heparin
When collecting oral fluid samples, and using glass tubes, only use the ____ tops.
Red
How thick should the rope be for oral fluid collection in adults?
1/2 inch wide
A single rope for oral fluid collections can provide a sufficient sample within ____ minutes.
20-30 minutes
Several methods of extracting oral fluids from the rope:
- Use plastic bag to cover wet parts of rope and squeeze fluid out by squeezing over the outside of the plastic bag
- You can also use a ringer to collect larger fluid samples
When do you send oral fluid samples to the lab?
On the same day they were collected
Samples for PCR or Ab detection may be frozen. True or False.
True
What time of day is it best to sample for oral fluids?
In the morning b/c pigs are more active.
If you have already tried to sample oral fluids in the morning, and the pigs are still not chewing on the rope, what else can you do?
Trying placing the ropes in different pens
Porcine Respriatory Disease Complex (PRDC) - often we have co-infections, and often one agent will ______ the adverse effects of another.
Intensify
Etiology of PRRS
arterivirus (RNA virus)
PRRS was first recognized in the USA in 1987 as a _____ swine disease.
Mystery
Clinical signs of PRRS vary from _____ to quite ____.
unnoticed, severe
PRRS is highly ____ in the US and most of the pig-producing countries of the world.
endemic
Coinfection of PRRS and ________ was the likely cause of massive sow and pig mortality in China in 2007.
Classical Swine Fever (Hog cholera)
General clinical signs of PRRS include: ____ and ____
Fever and inappetance
Reproductive syndrome of PRRS include:
- Abortion/premature farrowings
- Stillbirths
- Fetal mummies
- Weak/poorly viable piglets
Clinical signs of Respriatory syndrome of PRRS include:
- Labored breathing
- Increased incidence of other respiratory infections
- Decreased growth performance and increased mortality in nursery and grow/finish
In a naive herd, reproductive syndrome of PRRS usually resolves spontaneously in __-__ months. And is associated with _____ immunity.
2-4 months; natural immunity
In a niave herd, respriatory syndrome associated with PRRS may persist _____, usually in ___ or ___ pigs.
Indefinitely; nuresry or grower pigs
Respriatory syndrome in PRRS is associated with susceptible pigs that are waning ____ immunity, in the presence of actively infected pigs that are _____ the virus.
Passive; shedding
Continuous circulation of virus can occur with the introduction of ____ pigs to the herd.
naive
If you can wean naive piglets in an environment that doesn’t have PRRS virus, you can ____ cycle of infection.
break
PRRS typically effects neonatal pigs that are still on colustrum. True or False.
False - usually piglets are protected with colustrum, and become susceptible with weaning off of colustrum.
Gold standard of PRRS diagnosis
Demonstration of virus via virus isolation
Virus isolation of PRRS may be used in acute cases. True or False.
True
Why are there many false negatives with virus isolation of PRRS?
- Virus eliminated due to immune response
- Virus degrades in tissues over time
What are the appropriate samples for virus isolation with PRRS diagnosis?
Serum, BAL, buffy coat, lymph node, tonsil
Gene sequencing remains fairly constant among various field and vaccine strains of virus. True or False.
False - gene sequencing differentiates among field and vaccine strains
Other diagnostic methods of PRRS that demonsrate viral components other than isolating the virus, which prove to be more sensitive, include:
- Immunoflourescence (IF) - in ____ tissue
- Immunohistochemistry (IHC) - in ___ tissue
- Polymerase chain reaction (PCR)
- IF - fresh tissue
- IHC - fixed tissue
Is PRRS a reportable disease?
No
Limitations of serological tests when diagnosing PRRS:
- Positive serology does not necessarily mean that PRRS is the problem
- Seroprevalence is high (>50% of US herds)
- Serology does not differentiate between vaccination and natural infection
- Antibodies take 10-14 days to develop after exposure to the virus
The most common transmission of PRRS is:
Oral/nasal secretion from infected to susceptible pig; requires close contact
The most common route of farm to farm transmission of PRRS:
aerosols
Can semen, urine/feces, and fomites (transport vehicles, boots and clothing) transmitt PRRS?
Yes, but less common
PRRS may be transmissible via aerosols for as far as __ miles or more.
2
Likelihood of aerosol transmission of PRRS may be __ dependent.
Strain
PRRS spreads quickly throughout a barn. True or False.
False, the virus spreads somewhat slowly within a barn. Not highly contagious within barn (however, can transmit farm to farm via aerosols when the conditions like wind are right).
Shedding in acutely infected pigs is usually complete by _____ post-infection.
6
Acutely infected pigs include more commonly ____/____ pigs; and are often the result of sero-_____ breeding females introdued into sero-______ herds.
nuresry/grower pigs; seronegative; seropositive
Chronically infected pigs result from pigs infected in utero or early in life and shed for life. Is this significant in PRRS?
No
Shedding PRRS pigs may be difficult to identify. What is the best diagnostic sample to take to determine if the pig is shedding the virus?
Tonsillar scrape
Pros of PRRS Vaccination
- Reduces severity of clinical signs
- Reduces viral shedding post-infection
- Stabilizes herd immunity
Cons of PRRS Vaccination
- may cause reproductive failure in pregnant sows (especailly last trimester)
- MLV virus may circulate and infect non-vaccinated animals
- MLV virus may recombine with field strains of virus
- Complicates interpretations of serology
- Incomplete immunity (heterologous strians, decoy epitopes)
PRRS Management for seronegative herds invovles herd additions from other seronegative herds. Outside pigs need to be quarantined for ___ days, and have a negative test on ____ and before ____ from quarantine.
60 days; on arrival and before release
Other PRRS managmenet besides controlling herd additions from other seronegative herds:
- Semen from negative boar studs
- Control people traffic
- Air filters in swine-dense areas
Can air filters in swine-dense areas reduce risk of reinfection via aerosoles post eradication?
Yes - as long as it is well managed
PRRS Managemnet for seropositive stable herds includes:
- herd additions from sero-______ or other stable sero-_____ herds
- Acclimatization - development of ____ to PRRS
- Vaccination
- Exposure to pigs _____ virus (ex - nursery pigs)
- Avoid introdction of sero-____ breeding stock into sero-_____ herd. Need some level of immunity to avoid ______ of virus load in the environment.
- seronegative; seropositive
- shedding
- seronegative; seropositive
- Amplification
To minimize respriatory syndrome in grow/finish pigs, what can you do to manage PRRS?
- All-in, all-out pig flow
- Partial depopulation
- Segregated off-site weaning
- Vaccination
PRRS Eradication - May be able to produce virus-_____ subpopulations via ______ off-site weaning.
negative; segregated
PRRS virus may naturally die out in a sow herd totally ______ to new additions for __ months and _____ from grow/finish pigs. This eradication process can be known as “___, ___, ___”
closed; 6 months; isolated;
load, close, expose
In the load, close, expose eradication method, the time to virus negative status may be reduced by:
- Live virus (serum) inoculation
- MLV vaccine
