ASFV and CSFV Flashcards
1
Q
What is Classical Swine Fever Virus (CSFV)?
A
- Flaviviridae
- Flavi = yellow
- ssRNA: 12.3kb
- Single-stranded, positive-sense RNA virus, enveloped
- Genus Pestivirus:
- BVDV, BDV, CSFV
2
Q
What is the history of CSFV?
A
- 1833 - 1st reported in US “Hog cholera”
- 1960 - cost %50mil / year
- 1978 - US declared “hog cholera” free
- 17 year Federal-state eradication program
- 1997- Netherlands outbreak 12mill pigs dead
3
Q
What is the epidemiologic information for CSFV?
A
- Natural host - swine
- Highly contagious - high morbidity and mortality
- 3 genotype (1, 2, 3) and subgenotypes
- high, moderate, and low virulence strains
- Severity of illness varies with viral isolate, age of pig, immune status, dose, health status
4
Q
How is CSFV transmitted?
A
- Primarily oronasal transmission (direct or indirect contact)
- virus shed in oronasal and ocular seretions, urine, feces, blood
- genital and transplacental transmission also possible
- Spread readily by feeding uncooked swill from infected pigs
- transmissible through contaminated fomites
5
Q
how does the virulence of CSFV differ?
A
- Acute and severe disease in naive herds
- highly virulent strains
- high mortality - can approach 100%
- death typically within 1-3 weeks
- Rapid recognition/diagnosis
- Subacute
- clinical signs less severe, prolonged time course, lower mortality
- Chronic disease:
- Seen with moderate or low virulence strains
- May be difficult to recognize/diagnose
- May only affect a few animals
- Clinical sings wax and wane for weeks to months
6
Q
What are the clinical signs of Acute CSFV in a naive herd?
A
- High fever
- huddling
- weakness
- lethargy
- decreased appetite
- conjunctivitis
- constipation or diarrhea
- incoordination
- posterior paresis
- convulsions
- vomiting
- respiratory signs
- skin hyperemia, hemorrhage or cyanosis
- sever leukopenia
7
Q
What are the clinical signs of Chronic CSFV?
A
- Decreased appetite
- depression
- fever
- leukopenia
- constipation or diarrhea
- wasting or poor growth
- skin lesions
8
Q
What are the overall Clinical signs of CSFV?
A
-
Poor reproductive performance
- may be only sign in herds infected with less virulent strains
- Abortion, stillbirths, mummified, malformed, weak piglets
- Piglets may be born with congenital tremor
-
Piglets may be born persistently infected
- Nonclinical at birth
- late-onset C/S - inappetence, depression, poor growth, dermatitis, diarrhea, conjunctivitis, ataxia, posterior paresis
9
Q
What lesions are associated with CSFV?
A
- Highly variable
- Acute disease:
- Hemorrhage most common
- skin discolored purple, cyanosis of extremities
- lymph nodes swollen and hemorrhagic
- Petechial or ecchymotic hemorrhages on serosal and mucosal surface
- GI- hemorrhage, enteritis, button ulcers
- Fluid in peritoneum, thorax or pericardial sac
- Tonsilitis (+/- necrotic foci)
- Splenic infarcts
- Lungs - congestion and hemorrhage
- Encephalitis
- Kidney - Cortical petechiae and pale infarcts surrounded by hemorrhage
10
Q
How is CSFV diagnosed?
A
- Virus detection
- PCR, sequencing, FA, ELISA, VI
- blood, tonsil or nasal swabs (live)
- Tonsils, lymph nodes, brain, spleen, kidneys, ileum (necropsy)
- Serology: FAVN, ELISA
- Ab develop 2-3 weeks post-infection, usually lifelong
- persistently infected piglets with be negative fo Ab
- Consider Cross-reactivity with ruminant pestiviruses
- BVDV and BDV occasionally infect pigs
11
Q
What are some differentials for suspected CSFV?
A
- PDNS
- ASFV
- septicemic bacterial diseases (Salmonellosis, Erysipelas, acute Pasteurella
- Severe PRRSV
12
Q
How is CSFV controlled?
A
- MLV vaccines
- reduce clinical signs, limit transmission
- Employed to reduce infections during eradication program
- Widely used in CSF-endemic countries
- Prohibited in CSF-free areas
- Not DIVA
- Biosecurity, movement restrictions, quarantine, surveillance
- CSFV generally labile in environment
- inactivated by disinfectants, drying, heat, UV
- remains infectious for months in meat
- inactivated by disinfectants, drying, heat, UV
13
Q
What are the characteristics of the African Swine Fever Virus (ASFV)?
A
- Asfarviridae
- Genus Asfivirus (only member)
-
Large complex dsDNA virus, enveloped
- 170-190 kb, >150 proteins
-
Environmentally stable - resistant to pH and temperature
- can survive at room temp and in meat for months
-
Large complex dsDNA virus, enveloped
- Soft ticks of the genus Ornithodoros can be involved n the infection cycle
- Only DNA virus classified as arthropod borne virus
14
Q
What is the history of ASFV?
A
- Never been documented in the US
- Economically important
- Trade restrictions
- Reportable
- Since 2007- outbreaks in Caucus region, russia, and eastern Europe
- increased risk of spread
- August 2018 -
- China +12 Asian Countries
- Belgium, Slovakia, Serbia
- Sept 2020 - Germany
15
Q
What is ASFV?
A
- Contagious hemorrhagic disease
- clinically indistinguishable from CSFV
- Occurs in domestic pigs and European wild boar
- all ages susceptible
16
Q
How is ASFV transmitted?
A
- Oronasal route by direct or indirect contact
- Bite of an infected soft tick
- Ingestion of uncooked pork in food waste
- Ingestion of contaminated feed
17
Q
What is the Pathogenesis of ASFV?
A
- Primary route of infection is oral or upper respiratory tract
- Virus replicates in the tonsil and regional lymph nodes
- predominately in monocytes and macrophages
- Generalized infection follows rapidly via the blood stream
- high concentration of virus found in the spleen
18
Q
What is the cellular pathogenesis of ASFV?
A
- Causes severe disruption to blood clotting mechanism
- Destruction of macrophages
- impaired hemostasis
- release of cytokines nd complement
- Thrombocytopenia
- Lymphopenia
19
Q
what is the incubation period of ASFV?
A
- Incubation period: 4-19 days
- Peracute, acute, subacute, chronic, and subclinical forms
20
Q
What are the clinical signs of ASFV?
A
- Sudden death
- high fever
- skin hyperemia or cyanosis (ears abdomen legs)
- depression
- decreased appetite
- recumbency
- conjunctivitis
- vomiting
- watery to bloody diarrhea
- tachypnea
- tachycardia
- abortion
- incoordination
21
Q
What are additional clinical signs in the Acute and lethal forms of ASFV?
A
- Hemorrhagic lesions (petechiae, epistaxis, hematochezia)
- DIC
- Thrombocytopenia
- increased vascular permeability
- death within 5-10 days
22
Q
What are additional clinical signs of the less acute form of ASFV?
A
- Respiratory signs
- coughing
- sneezing
- dyspnea
- GI signs
- diarrhea
- constipation
23
Q
What are the additional clinical signs of the chronic form of ASFV?
A
- emaciation
- swollen joints
- respiratory disease
24
Q
What is the mortality rate of ASFV?
A
- ranges from 0-100%
- depends on strain virulence
25
Q
What lesions are associated with ASFV?
A
- Hyperemia and hemorrhage on skin
- Extensive hemorrhages in: LN, kidneys, heart, other organs
- Straw-colored or blood-stained fluid in pleural, pericardial, or peritoneal cavities
- Lung hemorrhages
- pulmonary edema
- splenic enlargement
26
Q
How is ASFV diagnosed?
A
- Reportable to federal authorities
- Differentials same as A+CSFV
- Virus detection:
- Whole blood, spleen, tonsil, LN
- VI, PCR, ELISA, FA, ISH
-
Serology:
- ELISA, IFA
27
Q
How is ASFV controlled?
A
- No treatment NO VACCINE
- Eliminate risk factors for viral introduction
- prevent infected live pigs, contaminated pig meat or feed from being introduced
- Reduce exposure to soft tick vector
- Biosecurity of personnel and farm supplies
- Eradication - depends on rapid diagnosis, slaughter, and disposal of infected animals
- Controlled or stopped pig movement
- Treatment of food waste or ban of swell feeding
- Biosecurity and reducing exposure to wild suids
