Foot and Mouth Disease

1. FOOT AND MOUTH DISEASE
APHTHOUS FEVER
Dr. Joice P. Joseph

3. ETIOLOGY
• Aphthous virus
• Family: Picorna viridae
• 7 major serotypes: O, A, C, Asia 1, SAT1, SAT2 & SAT3 (SAT=
Southern African Territories)
• Three serotypes of FMD virus (O, A and Asia1) are prevalent.
• Serotype O is responsible for 80 % of the confirmed cases.
• Serotype C has not been encountered in India since 1995.
• Each serotype has multiple subtype with varying antigenicity and
degrees of virulence
• No cross immunity between serotypes
• Change in antigenicity in developing serotypes
• Capsid protein (VP1, VP2 & VP3) determines ability of virus.

4. EPIDEMIOLOGY
• Highly contagious disease
• Asia is endemic
• Disease free : Newzealand, Australia, USA, UK etc.
• Affect cattle, pig, sheep, goat and all cloven hoofed ruminants
• Transmission: Inhalation/ingestion
• Disinfectant: Sodium hydroxide (2%) / sodium carbonate (4%)/ citric
acid (0.2%)/ acetic acid (2%)/ sodium hypochlorite (3%)/ potassium
peroxymonosulfate / sodium chloride (1%)/ chlorine dioxide.
• Spread by direct contact
• Virus can in atmosphere in aerosol form for long periods in
temperate & subtropical condition
• Spread more in dawn or dusk
• Wind can transmit disease to 250 kms
• Amplifying host: Pig (more potent excretor of virus)
• Reservoir host: Wild fauna
• Reservoir host in Africa: Wild Buffalo (Syncerus caffer)

5. EPIDEMIOLOGY
• Virus is transmitted by animal transport, inanimate objects &
equipment
• Human is also a vehicle of transmission
• After 12 hrs of contact, if attending person changes dress,
transmission can be reduced
• Virus remain for 1 yr in infected premise
• Uncooked food is infective
• Sunlight and boiling destroy virus
• Damage economy
• Mild zoonotic importance also
• Morbidity ---- 100 %
• CFR (Case fatality rate) ---- 2 %
• Fatal in young ones (CFR --- 20 %)
• Causes severe production loss (after recovering also, animal
becomes weak & debilitated)

6. ECONOMIC LOSS

7. PATHOGENESIS
Stages:
(i) Pre‐viraemic phase: characterized by infection and
replication at the primary replication site
(ii) Viremic phase: with generalization and vesiculation at
secondary infection sites
(iii)Post‐viraemia/convalescet stage: including resolution of
clinical disease that may result in long‐term persistent
infection
First site of infection & rapid multiplication (nasal mucosa) ----
---Pharynx-----------blood-----------Different body region----------
Different epidermal site-----------virus appears in milk & saliva-
---------Vesicle in mouth

8. PATHOGENESIS
• Young animal develops myocarditis
• FMD virus shows cellular tropism for infecting prickle cells in
the stratum spinosum.
• Vesiculation in the tongue originated from the necrosis of
individual prickle cells in the middle to bottom layer of the
stratum spinosum along the midline of the dorsal epithelium.
• Dysregulated metabolic functions of thyroid gland will be
exhibited as heat intolerance (HI) (panting) in recovered
animals.

9. CLINICAL SIGNS
• I.P---1-7 days
• Reduced milk production
• Fever (104-1060F)
• Acute painful stomatitis
• Salivation
• Ropy salivation (hanging in long, ropelike string)
• Smacking of lip
• Vesicle & Bulla on Buccal mucosa, dental pad, tongue------
may rupture after 24 hrs
• Vesicles or blisters can be on the tongue, dental pad, gums,
cheek, hard and soft palate, lips, nostrils, muzzle, coronary
bands, teats, udder, snout of pigs, corium of dewclaws and
interdigital spaces.

10. CLINICAL SIGNS
• Ulcer heals by 1 week
• Vesicle on Feet, cleft & coronet
• Secondary bacterial infection in FMD results non-healing
ulcer
• Pregnant may abort
• Young animal may die
• Endocrine damage can cause: Dyspnea, anemia,
overgrowth of hair, lack of heat intolerance (“Hairy
panter”)
• Vesicular lesions on the snout and dry lesions on the tongue
may occur in pigs
• Sheep and goats: Less lesions compared to cattle

17. DIAGNOSIS
• Sample to be collected: Fresh vesicular fluid & surrounding
epithelial tissue. Transport in phosphate buffered saline.
• Virus Isolation
• Immunology – ELISA, CFT, Virus neutralization
• Experimental transmission – White mice & intradermal
inoculation to Guinea pig plantar pad
• Electron microscopic examination of lesion material

18. D.D
• Vesicular stomatitis
• Vesicular exanthema
• Swine vesicular disease
• Blue tongue
• BVD/MD
• Rinder pest
• Malignant cattarhal fever
• Lumpy skin disease
• Pox
• Ingestion of caustic material

19. NECROPSY FINDINGS
• Erosions on rumen pillars
• Tiger heart appearance: Gray or yellow streaking in the heart
due to degeneration and necrosis of the myocardium in young
animals of all species

20. PREVENTION
• Stamping out (slaughter of all infected and in contact animals)
• Vaccination
• Movement restriction
• Public awareness campaign
• Isolation and containment of affected animals
• If outbreak, it should be reported to state animal husbandry
(as per the act ‘Prevention and control of infectious &
contagious diseases in animals’)
• Each and every outbreak should be investigated to know the
epidemiology of the disease with forward and backward linkage.
• Ring vaccination (5-10 Km) radius around the affected
village/area to cover all the susceptible animals including sheep,
goats, pigs etc.
• Disinfection and implementation of bio-security measures

21. VACCINATION
• Since 2003, a trivalent vaccine incorporating only three strains
(O, A, and Asia 1 serotypes) is used in India.
• Better to produce vaccine from locally isolated strains.
• Vaccination‐based FMD Control Programme (FMDCP) was
launched in India in 2003–2004 (10th 5yr plan)
• Ring Vaccination: To contain out break - The vaccination of all
susceptible animals in a prescribed area around an outbreak of
an infectious disease. It forms a buffer of immune individuals to
prevent the spread of the disease.
• Frontier vaccination: To produce a buffer area between infected
and free countries - Vaccination of susceptible animals along a
country's frontier (border) to a given depth. This is practiced in
countries which doesn’t have a natural barrier. One type of it is
practiced around forests also to control FMD spread.
• Some vaccinated animals can be carriers for 6 month
• Some vaccinated animals show anaphylaxis

22. Killed vaccine
• Inactivation of virus is done with formalin/Binary ethylene
immine
• Immunity: 6 to 8 months
Oil adjuvant vaccine:
 It has long immunity (1Yr)
 Annual revaccination in adult cattle
 Biannual revaccination in young stock
 Revaccination at 4 to 6 months interval in pig
 Immunity occurs 7 to 20 days after vaccination
 Calves should be vaccinated as :
If dam is vaccinated, 6 months followed by 10 month age
 If dam is not vaccinated, 4 months followed by 8 month age

23. Attenuated live virus vaccine
• More potent
• Narrow margin between loss of virulence and
loss of immunogenicity

24. COMMON VACCINE
• Raksha - Ovac Trivalent (FMD Oil Adjuvant vaccine)
contains tissue culture virus strains, O, A, Asia-1, and
inactivated with Aziridine compound. Mineral oil is added
as an adjuvant
Dosage:
• Cattle, Buffaloes, Calves and Pigs : 2 ml
• Sheep and Goats : 1 ml
Vaccination Schedule:
• Primary vaccination : 4 months of age (Cattle, Buffaloes,
Sheep and Goats).
• Primary vaccination : 2 months of age (Pigs).
• Booster : 9 months after primary vaccination
(Cattle/buffaloes/Sheep and Goats).
• Revaccination : Every 12 months thereafter (Cattle,
Buffaloes, Sheep and Goats).
• Revaccination : Every 6 months thereafter (Pigs).

25. OTHER VACCINES

26. THANK YOU