local names, definition, etiology,epidemiology lifecycle, pathogenesis, clinical findings, necropsy finding, diagnosis,treatment, control and prevention

1. Faculty of Veterinary Science
Infectious Diseases II
(Viral Diseases)
FOOT AND MOUTH DISEASE
(FMD)
23th ,Mar ,2016SHAFI’I. A. M. SHEIKH

2. FMD is an acute febrile, highly contagious
disease of cloven-footed animals
characterized by:
Vesicle formation in the mouth, muzzle, and
their surroundings,
on the feet, coronary band, and interdigital
space,
on the teats and in the rumen

3. Muscular lesions may be observed in young
animals.
Man is very occasionally infected.
The disease is characterized by low mortality,
but high morbidity rates.
Mortality is high in young animals but low in
adults

4. Bovine, gingiva. There is an elongate erosion (ruptured vesicle) ventral to the incisors.

5. Goat, oral mucosa. There is a large erosion (ruptured vesicle) on the rostral
mandibular buccal mucosa.

6. Bovine, lip. The buccal mucosa contains an erosion (rupturedvesicle).

7. Tongue. There are multiple large mucosal erosions and ulcers.

8. Bovine, tongue. A large area of undermined epithelium (bulla) is centrally eroded; this
lesion probably resulted from coalescence of several smaller lesions.

9. Rumen mucosa, higher magnification. There are several irregularly shaped erosions
(ruptured vesicles) on the pillar.

10. Teat. There is a ruptured vesicle on the end of the teat.

12. Foot and Mouth Disease
Foot and Mouth Disease is one of the most serious
diseases of livestock because of economic loss due
to:
–Restricted trade with FMD Free countries
–Animal deaths and poor performance
–Eradication requires destruction of
thousands of exposed animals

13. Importance
However, the disturbance of the growth or milk
production in affected animals results in a great
reduction in productivity, causing serious
damage to the livestock industry
Moreover, as the countries and regions where
FMD outbreaks occur are subjected to the
movement restriction of animals and animal
products, FMD is a major constraint to
international trade in animal and animal
products

14. Since the establishment of the WTO it was
aiming to advocate international harmonization
and to accelerate international trade
FMD has become more important year by year
according to the principle of the Agreement on
the Application of Sanitary and Phytosanitary
Measures of the WTO (SPS principle) because it
greatly hinders the trade of animals and
livestock products

15. Etiology
FMD virus is RNA virus classified under the
family Picornaviridae, genus Aphthovirus
No envelope with 21-25 nm in diameter, single
stranded, positive polarity.
FMDV has seven serotypes: O, A, C, Asia1,
SAT1, SAT2 and SAT3

16.  Strains O, A, C, SAT-1, 2, and 3 occur in
Africa;
 0, A, C, Asia-1 in Asia.
 Types 0, A, C, occur in South America, and
Europe.

17. Within each serotype there are subtypes
which may be sufficiently different to give very
poor protection against other viruses of the
same serotype. This is an important factor in
the epidemiology of the disease and vaccine
production, since there appears to be a
continual antigenic drift in endemic situations.

18. There is no cross-immunity between these
serotypes, i.e., immunity against one does
not confer immunity to any of the others.

19. The disinfectants commonly used for
sterilization of FMDV contaminated objects
are caustic soda, formaldehyde, iodophores
and acid. Visible and UV light have an
inactivating effect. In common with other
picornaviruses FMDV is resistance to phenolic
and quaternary ammonium disinfectants,
alcohol, and lipid solvents.

20. Species affected
Cattle, pigs and sheep are the domestic animals
most commonly affected; goats are also
susceptible. The disease has been reported in
many wild species, ruminants and swine being
important as reservoirs of the disease in
Africa.

21. Transmission of FMD
Infected animals generate large volumes of infective
aerosols
Infective aerosols spread by wind and air currents for
considerable distances, possibly up to 100
kilometers, given conditions where the relative
humidity is above 60-70 per cent.
The exhaled air from infected animals, particularly
swine, is highly infective.

22. Spread by direct contact with an infected
animal is the most important method of spread.
Animals contaminate their surroundings(Food
& water) and the ability of the virus to survive
on dried materials such as hay and straw can
lead to the spread of the disease by ingestion.
The presence of virus in the milk of infected
cows at titers up to 100,000 particles per ml
provides another source of indirect infection.

23. Survival in the tissues of animals slaughtered
for meat also contributes to the spread of
disease, sometimes on an international scale,
since the virus will survive in many of the
tissues (such as lymph node, offals and bone
marrow).
Transferred mechanically on clothing, shoes,
and other objects

24. Foot-and-mouth disease virus may persist in
the pharynx of some animals for a prolonged
period after recovery. In cattle, virus may be
detectable for periods up to 2 years after
exposure to infection, in sheep for about 6
months.

25. The international transmission of FMD is
mainly caused by the trade of affected
animals or contaminated agricultural and
animal products with the virus, contaminated
garbage from ships and airplanes of the
international lines, insufficiently inactivated
vaccine and physical transmission by wind
People or birds are also reported as the causes
of international disease transmission

26. Since once affected animals show viremia, all of
their carcasses, including skin organs, muscle,
blood, lymph nodes and bones, contain the
infectious viruses
FMDV survives for long period in uncooked
meat
Transmission of FMD is still a big risk as a result
of illegal movement (smuggling) of domestic
animals and animal products in Africa.

27. FMDV infects the epithelium of the upper
respiratory tract or alimentary tract by
inhalation or ingestion. The virus multiplies at
the site of infection where primary vesicles
are formed.
Primary vesicle virus initiates a viremia which
is associated with pyrexia..
Pathogenesis:

28. The virus localizes in distant epithelia where
such cells are growing and being replaced and
secondary vesicles then appear 2 days later.

29. Clinical Signs
After an incubation period of 2-8 days, there is fever,
loss of appetite, depression, and a marked drop in
milk production.
Within 24 hours, drooling of saliva commences, and
vesicles develop on the tongue and gums

30. The animal may open and close its mouth
with a characteristic smacking sound. Vesicles
may also be found in the interdigital skin and
coronary band of the feet and on the teats.
The vesicles soon rupture, producing large
denuded ulcerative lesions.

31. Those on the tongue often heal within a few
days, but those on the feet and within the nasal
cavities often become secondarily infected with
bacteria, resulting in prolonged lameness and a
mucopurulent nasal discharge.
In calves up to 6 months of age, foot-and-
mouth disease virus can cause death through
myocarditis.

32. P.m Lesions:
Vesicles or blisters on the tongue, dental pad,
gums, cheek, hard and soft palate, lips,
nostrils, muzzle, coronary bands, teats, udder,
and interdigital spaces. Post-mortem lesions
on rumen pillars, in the myocardium,
particularly of young animals (Tiger heart)

33. Differential diagnosis
The clinical signs of FMD can be similar to
vesicular stomatitis, swine vesicular disease,
vesicular exanthema of swine, foot rot,
traumatic stomatitis induced by poor quality
feed, and chemical and thermal burns.

34. In cattle, oral lesions seen later in the
progression of FMD (erosions, ulcers) can
resemble rinderpest, infectious bovine
rhinotracheitis (IBR), bovine viral diarrhea
(BVD), malignant catarrhal fever (MCF), and
epizootic hemorrhagic disease. In sheep, these
later lesions can resemble bluetongue,
contagious ecthyma, and lip and leg ulceration.

35. Epidemiology
Countries Free of Endemic Foot-and-Mouth
Disease: In countries where foot-and-mouth
disease either has not previously existed or has
been eliminated, a "virgin soil" epidemic can
rapidly develop from introduction of virus on
one farm.

36. Within a short period, often measured in days
rather than weeks, the outbreak can extend to
so many farms that veterinary authorities
have difficulty in controlling its spread.

37. The reasons for the rapidity of spread are the
highly infectious nature of the virus, the
production of high-titer virus in respiratory
secretions and the large volumes of droplets
and aerosols of virus shed by infected animals,
the stability of virus in such droplets, the rapid
replication cycle with very high virus yields, and
the short incubation period.

38. The international movement of domestic food
animals and their products is also an
important way of transmission. Nowadays,
most introductions of foot-and-mouth disease
virus to nonendemic countries can be traced
either to meat on the bone being fed to swine
or, rarely, to long-distance spread of virus by
aerosols.

39. Endemic Countries: The introduction of a type not
previously present in a country may cause a virgin-
soil epidemic because livestock will not have
acquired immunity either through natural infection
or through vaccination.

40. In subtropical and tropical countries, with
predominantly local breeds of cattle, the endemic
strains produce only mild disease in indigenous cattle
but cause severe disease in introduced European
breeds.
Cattle that have recovered from foot-and-mouth
disease are usually immune to infection with the
same virus type for 1 year or more, but immunity is
not considered lifelong.

41. Recovered animals, however, can be
immediately infected with one of the other
types of foot-and-mouth disease virus and
develop clinical disease.

42. Laboratory Diagnosis
Rapid diagnosis of foot-and-mouth disease is
of extreme importance, especially in
countries that are usually free of infection, so
that eradication can proceed as quickly as
possible.

43. Foot-and-mouth disease is a notifiable disease
in most countries; thus, whenever a vesicular
disease of domestic animals is seen, it must be
reported immediately to the appropriate
government authority.
Usually, samples include:

44. From live animals:
vesicular fluid,
epithelial tissue from the edge of ruptured
vesicles,
blood in anticoagulant,
serum, and
esophageal/pharyngeal fluids.

45. Diagnosis
2) Antigen Detection
–Indirect sandwich ELISA
–Complement Fixation test
–Virus isolation on cell cultures
–RT-PCR

46. Diagnosis
3) Serological tests
–Serum neutralization test
–ELISA
–OIE member countries are obliged to report
promptly if FMD is diagnosed

47. OIE and FAO have formed two centers for FMD
diagnosis:
– World Reference Laboratory for FMD (WRL/FMD) in
the Institute for Animal Health at the Pirbright
Laboratory, United Kingdom. WRL/FMD is in charge
of the analyses of both antigenic and genetic
properties of the isolates
– Regional Reference Laboratories for FMD (RRL/FMD)
located in Russia, Botswana, and Brazil.

48. Control
Vaccination establishes an immunity protective for a
period not greater than four to six months but
repeated vaccination enhances the duration of
immunity and tends to widen the spectrum of
immunity within the type range. The marked
specificity of infective types of virus requires that
vaccines should be specific but polyvalent vaccines
covering several types are available.

49. Foot-and-mouth disease, more than any other
disease, has influenced the development of
international regulations designed to minimize
the risk of introducing animal diseases into a
country. Some countries have successfully
avoided the introduction of foot-and-mouth
disease by prohibiting the importation of all
animals and animal products from countries
where the disease exists.

50. For many countries such as Australia, Canada,
United Kingdom, and the United States that
have a recent history of freedom from foot-and
mouth disease, cost-benefit analyses justify a
"stamping out" policy whenever disease occurs
or is suspected. This is based on slaughter of
affected animals and exposed animals, along
with rigid enforcement of quarantine and
restrictions on movement.

51. Vaccination:
Vaccination establishes an immunity
protective for a period not greater than four
to six months but repeated vaccination
enhances the duration of immunity and tends
to widen the spectrum of immunity within
the type range. Current vaccines, except in a
few countries, are inactivated vaccines which
include adjuvants such as aluminium
hydroxide, saponin or oil.

52. In countries where the disease is endemic,
vaccination as a method of control is most
effective if strategic vaccination programs
covering a relatively well defined area is
established and maintained. Decisions on the
establishment of vaccine control campaigns
must be based on sound economic principles.
Two types of vaccination programs can be
adopted:

53. A. Systematic vaccination: In this program,
vaccination should involve all animals in the
national herd and should be
compulsory.Animals should be re-vaccinated
every 4-6 months depending upon the
economic situation of the country.

54. B. Ring vaccination: This type of vaccination
program is practiced if an outbreak occurs in a
neighboring area. Animals in the vicinity of the
area of the outbreak should be vaccinated
first, and then the vaccination campaign
moves in-wards. The purpose of this
procedure is to create a barrier of immune
stock around the infected areas.

55. Other measures should include: restriction of
movement of animals out of the affected area,
newly introduced animals should be
quarantined for one month period and then
vaccinated with appropriate vaccine, besides
carrying-out emergency vaccination in case of
an outbreak.

56. In some regions steps have been taken
towards the production of disease-free zones,
which are of particular value in protecting
highly productive exotic cattle in livestock
improvement schemes. For such animals,
vaccination at regular short intervals against
prevalent types is now an economically
justifiable measure