Lecture 5 - Part 1. FMD, ASFV & CSFV Flashcards
Diseases are divided into categories:
A, B, C, D, E
Disease category A
Diseases that do not normally occur in the EU and for which immediate eradicaton measures must be taken as soon as they are detetcted.
Disease category B
Diseases which must be controlled in all member states with the goal of eradicating them throughout the EU
Disease category C
DIseases which are of relevance to some Member States and for which measures are needed to prevent them from spreading to parts of the Union that are officially disease-free or that have eradication programs for the listed disease concerned.
Disease category D
Diseases for which measures are needed to prevent them from spreading on account of their movements between member states or entry into the EU.
Disease category E
Diseases for which there is a need for surveillance within the EU.
Notifiable animal diseases, so Highly contagious animal diseases, first half (6)
Foot and mouth disease
African swine fever
Classical swine fever
Rinderpest
Lumpy skin disease
Contagious bovine pleuropneumonia
Notifiable animal diseases, so Highly contagious animal diseases, 2nd half (7)
Sheep pox and goat pox
Peste des Petits Ruminants
Contagious caprine pleuropneumonia
African horse sickness
Glanders
(Highly pathogenic) Avian influenza
Newcastle disease
Name 3 Vesicular animal diseases
Foot and mouth disease
Vesicular stomatitis
Swine vesicular disease
(Vesicular exanthema of swine virus)
What species are susceptible to foot and mouth disease?
all cloven-hoofed animals
Domestic: cattle, pigs, sheep, goats, llamas, alpacas, camels, buffalos
Wild: African buffalos, deer, moose, wild pigs, giraffes, elephants etc.
What species are susceptible to vesicular stomatitis disease? (4)
bovine
swine
goats
horses
FOOT AND MOUTH DISEASE (FMD) is
a highly infectious viral disease of cloven-hoofed species characterized by fever and vesicles in the mouth and on the muzzle, teats, and feet.
FOOT AND MOUTH DISEASE (FMD) is rarely fatal except for - who and why?
young animals due to dystrophy of the heart and skeletal muscles.
How many serotypes of FMDV?
foot and mouth disease virus
7 serotypes exist: A, O, C, SAT1, SAT2, SAT3, Asia1
Serotypes do not confer cross immunity —> vaccination!
FMDV belongs to what viral family?
foot and mouth disease virus
family Picornaviridae,
genus Aphthovirus,
is an RNA-virus
FMDV can be inactivated by pH of?
Virus can be inactivated by pH <6.5 and pH >11.
Survives in milk and milk products, bone marrow and lymph nodes.
Can persist in contaminated fodder and the environment for up to 1 month!
Morbidity & mortality & recovery of FMDV
High morbidity (100%) in all age groups
Mortality <1%
Higher in young animals (myocarditis)
Recovery in 2 weeks.
World distribution of FMDV?
Endemic: Asia, Africa, Middle-East ja South-America
FMDV endemic where?
Asia, Africa, Middle-East ja South-America
Transmission of FMDV.
Virus is excreted with all body fluids.
So if e.g. you were not to find it in the fluid of a vesicle, then you can rule out FMD.
Incubation period of FMDV:
2-14 days
Can be as little as 24h!
Depends on the viral load - the smaller the dose, the longer the incubation period.
FMDV viral replication occurs where (typically)?
inthe oropharynx (tonsils!) and/or skin
Epithelial cells lyse, formation of blisters.
Which species are considered maintenance hosts for FMDV?
Sheep and goats are considered maintenance hosts for FMD; they have mild signs which delay diagnosis and allow for aerosol, contact spread, and environmental contamination.
Sheep can carry the virus in their pharyngeal tissue for 4-6 months.
What is meant by indicator host?
indicator host because they are often the first species to demonstrate clinical signs. Lesions quickly progress and become severe.
For FMD this is cows.
What is meant as amplifier host?
Pigs are amplifying hosts of FMD; they produce large quantities of aerosolized virus, but shed for a short time and are not long-term carriers
Which species are considered indicator hosts for FMDV?
Cows because they are often the first species to demonstrate clinical signs.
Cattle can carry the virus in their pharyngeal tissue for 6-24 months once infected with FMD.
Vaccination can protect from clinical signs but does not prevent development of the carrier state.
Which species are considered amplifier hosts for FMDV?
Pigs are amplifying hosts; they produce large quantities of aerosolized virus, but shed for a short time and are not long-term carriers
Course of FMD disease in cows:
acute, because cows are indicator hosts for FMD.
Clinical signs of FMD in cattle.
Pyrexia, anorexia, shivering, reduction in milk production (2-3 days), then:
smacking of the lips, grinding of the teeth, drooling, lameness, stamping or kicking of the feet.
vesicles in the mouth and on the muzzle, teats and feet
after 24h: rupture of vesicles —> erosions
Recovery time for FMD in cattle?
Recovery in 8-15 days
Complications of FMD in cattle?
tongue erosions,
superinfection of lesions,
hoof deformation,
mastitis and permanent impairment of milk production,
myocarditis,
abortions,
permanent weight loss,
loss of heat control (‘panters’)
Death of young animals from myocarditis.
Clinical signs of FMD in goats and sheep.
Are not as clear as in e.g. cattle, signs can be very mild which is why these are maintenance hosts.
Pyrexia
Lameness and oral lesions are often mild - complicates diagnosis
Agalactia
Death of young stock may occur without clinical signs.
Foot lesions along the coronary band or interdigital spaces may go unrecognised, as may lesions on the dental pad.
Clinical signs of FMD in pigs.
Pyrexia
foot lesions with lameness
(even detachment of the claw horn)
Vesicles at pressure points of the limbs, especially along the carpus (‘knuckling’)
Vesicular lesions on snout and dry lesions on the tongue
High mortality of piglets
Cardiac change in FMD cases.
Gray or yellow streaking in the heart from myocarditis, degeneration and necrosis of the myocardium in young animals of all species (‘tiger heart’).
Humans can catch FMD how?
milk, or droplet transmission from ppl with it
in very rare cases from animals, but disease is mild.
ddx for FMDV (3)
Vesicular diseases are clinically indistinguishable so they’re your main ddx!
vesicular stomatitis
swine vesicular disease
vesicular exanthema of swine
other ddx for FMDV other than the vesicular diseases (5)
burns - e.g. chemical, thermal
rinderpest
bovine viral diarrhoea and mucosal disease
infectious bovine rhinotracheitis
bluetongue disease
Material needed for Diagnosis of FMDV.(4)
an unruptured vesicle’s fluid (1ml),
or recently ruptured vesicle’s tissue (1g)
oesophageal-pharyngeal fluid
blood
Laboratory Diagnosis of FMDV.(3)
Virus isolation in cell-culture which is slow (4 days), but has high sensitivity and specificity.
Antigen ELISA - fast (hours), but may produce false positives.
RT-PCR
CLASSICAL SWINE FEVER (CSF) is a
highly contagious disease of pigs,
caused by a Pestivirus,
characterised by high fever, lethargy, diarrhoea, vomiting and purple skin discolouration of the ears, lower abdomen and legs.
Clinical signs of CSFV acute dz
Clinical signs are similar to other swine diseases (e.g. ASF)
Pyrexia (>40⁰C), huddling, weakness, anorexia, Conjunctivitis, Diarrhea, staggering, cyanosis, skin hemorrhages, death.
Clinical signs of chronic CSFV dz
anorexia, depression, fever, diarrhoea
abortions, stillbirths, deformities
persistently infected pigs
almost always fatal
Post mortem: CSFV acute dz
Highly variable
Haemorrhages
Necrotic foci in tonsils
Petechiae/ecchymoses on serosal and mucosal surfaces - kidneys, larynx, trachea, intestines, spleen, lungs
What type of post mortem ulcer is typical to chronic CSFV
necrotic foci called button ulcers, found in the: intestinal mucosa
epiglottis
larynx
ASFV stability
Inactivation pH <3.9 and >11.5
Serum increases the resistance of the virus
(pH 13.4 - 21h vs 7 days with serum)
Remains viable for long periods in blood, faeces and tissues (pork products!)
ASFV can survive for how long in;
4*C blood
room temp. feces
putrefied blood
contaminated pig pens
frozen meat
4’C blood 18 months
room temp. feces 11 days
putrefied blood 15 weeks
contaminated pig pens 1 month
frozen meat 1000 days
Forms of ASF disease:
peracute, acute, subacute and chronic
Clinical form of ASFV disease depends on (4)
virus strain virulence
exposure dose
exposure route
host
Clinical signs: subacute ASFV
caused by moderately virulent strains
similar clinical signs than in acute dz, just less severe
mortality is low in adults
very high in young animals
fever, thrombocytopenia and leukopenia may be transient - affected pigs die or recover within 3-4 weeks
Clinical signs: chronic ASFV
caused by strain with low virulence.
intermittent low fever, appetite loss, weight loss, depression, respiratory signs, necrosis in areas of skin, chronic skin ulcers, arthritis
pericarditis, adhesions of lungs, swelling over joints.
can go on for months (2-15 months)
can be fatal, though low mortality
Review this table on African swine fever disease forms.
Post mortem changes in acute ASFV
haemorrhages in LNs
petechial haemorrhages of the kidneys
congestive splenomegaly
oedematous areas of cyanosis in hairless parts
cutaneous ecchymoses on the legs and abdomen
excess of pleural, pericardial and/or peritoneal fluid
Post mortem changes in chronic ASFV
focal caseous necrosis and mineralisation of the lungs
enlarged LN
