Foot and Mouth

Question:
There has been a lot of news coverage on the Foot and Mouth Disease outbreak in England and Europe. What exactly is Foot & Mouth Disease and how concerned do we need to be with our llama and alpacas?

Answer:
You have asked a question that is out of my league. This is really a medical issue more appropriately directed to a veterinarian. I contacted Dr. David Anderson at The Ohio State University, College of Veterinary Medicine, and he graciously gave me permission to reproduce his recent work on the subject.

FOOT AND MOUTH DISEASE:
ARE LLAMAS AND ALPACAS AT RISK?

Based on the inquiries I have gotten over the past few weeks, I feel it
would be timely to mention a few words about the current scare in Europe
with Foot and Mouth Disease (FMD). As many of you know, I have been
preaching bio security as an issue for the future for the industry. You have
only to talk to the llama and alpaca owners in the United Kingdom to see
how this can effect you whether you like it or not!

Are llamas and alpacas at risk? Unfortunately, the answer is both yes and
no. Yes, llamas and alpacas have been infected with FMD. No they do not
appear to be very susceptible to it. FMD infection in alpacas in Peru was
confirmed in the 1970's. FMD risk in llamas and alpacas was researched in
the USA and Argentina. Routes of infection included tongue scarification,
intra-muscular injection, intra-dermal injection, intravenous injection,
and cohabitation. Llamas and alpacas appear to be fairly resistant of
infection by natural exposure (cohabitation) but can and do succumb to
infection when any of the other exposure methods were used. Infected llamas
developed mild clinical signs including fever, anorexia, lesions to the
footpads, and lameness. Virus did not persist in any llamas beyond 14 days
after infection. Certainly, the risk of llamas or alpacas becoming infected
seems extremely low.

Fondevila et al studied the susceptibility of llamas to FMD natural
exposure in a bio containment facility in Argentina. This was a
collaborative study between CICV and INTA in Argentina and the USDA and
APHIS in the United States. In that study, llamas were exposed by
cohabitation to FMD strains A-79, C-3, and O-1. Of 30 llamas exposed to FMD
virus infected pigs, only 3 showed any evidence of infection and only 2
llamas (exposed to the O-1 strain) showed any clinical signs of infection.
No llamas exposed to A-79 or C-3 strains of FMD showed signs of infection.
Clinical signs were extremely mild. More importantly, FMD virus could not
be recovered from any specimen obtained from the infected llamas beyond 14
days post-exposure. Ten cattle, 10 sheep, 10 goats, 10 pigs, and 30 other
llamas were exposed to the 30 llamas that had been exposed to the FMD virus
infected pigs. None of these animals showed any clinical signs of disease.

Lubroth et al studied the susceptibility of llamas to FMD by cohabitation
and by inoculation. This was a study conducted by the USDA in a
bio containment facility. In this study, 3 swine, 1 bull, and 6 llamas were
used. FMD virus strain A-24 was used. In-Group I, 1 llama was inoculated
with FMD A-24 by giving 2 ml intra-lingually, 2 ml intranasal, and 1 ml in
the footpad. After 24 hours, 3 swine were introduced to the room for 7
days. All 3 swine showed clinical signs of FMD after 3 to 4 days of
exposure. The llama showed fever, excessive salivation, lameness, and
anorexia. In Group II, one calf was inoculated with FMD A-24 by
intra-lingual and intranasal routes. After 24 hours, 2 llamas were
introduced to the room. One of the two llamas developed mild clinical signs
of FMD as evidenced by fever on day 2, and oral lesions noted on day 4. In
Group III, one llama was inoculated with FMD A-24 intranasal. After 24
hours, 2 llamas were introduced to the room for 7 days. One of the 2 llamas
developed mild foot lesions only. FMD virus could not be detected in any
llama beyond 8 days post-inoculation or post-exposure.

These two studies lead us to believe that llamas are much more resistant
to "natural" FMD virus infection compared with cattle, sheep, goats, and
pigs where the morbidity of disease is expected to approach 100 %. Further
and most importantly, llamas do not appear to "carry" the virus for
prolonged periods of time as is seen with cattle, sheep, goats, and pigs.
What we do not know is whether or not low-level cycling of the virus, as
has been documented in sheep flocks, occurs in llamas and alpacas because
there may be some difficulty in identifying the virus if intermittent
shedding takes place. Based on these studies, a policy of livestock
separation (to diminish high concentration cohabitation exposure risk) and
quarantine of all camelids with no movement or visitation would seem
reasonable and prudent.

What is it? FMD is a viral infection of cloven-footed animals (virus is
family Picronaviridae, genus Aphthovirus, 7 serotypes: A, O, C, SAT1, SAT2,
SAT3, ASIA1, and at least 60 subtypes - a very adaptable virus!). It most
seriously effects cattle but swine, sheep, and goats can be severely
affected at times. !). FMD has been referred to as the most contagious
disease of livestock. Infection with some strains of FMD appears to be
restricted to a specific species. The virus does not appear to infect
horses or people but there is a concern that any animal may act as a
vehicle to spread the virus. The plethora of serotypes and subtypes makes
effective vaccination extremely difficult because little cross-protection
exists between serotypes. This is one reason why slaughter, where
practical, has been used to control and eradicate the disease. People do
not appear to be susceptible to the disease unless severely immunocompromised.

Where is it? FMD has been enzootic to Africa, Europe, Asia, Japan,
Philippines, and South America. The spread of FMD is a critical concern to
countries that do not have it (e.g. North America, Australia, and New
Zealand). A good example of why FMD vigilance is critical: FMD was
successfully eradicated from Canada after it had been introduced in the
baggage of a European immigrant. Britain suffered a massive outbreak in
1967-68 possibly as a result of feeding infected Argentine lamb to swine.
That outbreak was controlled and the disease eradicated as was a smaller
outbreak in 1980. The British survived that outbreak, you can be sure they
will survive this one! The last reported case in the USA was in 1929. FMD
was eradicated from Mexico in 1954. Thus, all of North America is currently
free of FMD. Apparently the Darien Gap (between Columbia and Panama) and
prevented northern spread of diseased cattle from South America. With the
completion of the Pan American highway the risk of northern spread today
may be much different than several years ago. New Zealand has never had a
case of FMD and Australia has only suffered one small outbreak that was
immediately confined and successfully eradicated.

What does it do? FMD is most severe in cattle and causes fever and
vesicles in the mouth and on the feet. These cause lameness and decreased
feed intake because of pain. The virus takes from 1 to 7 days from the time
of infection to the development of clinical signs but the animal may be
shedding the virus in milk or saliva for up to 24 hours before vesicles
appear. At this time, high fever (104-106 F), low milk production, poor
appetite, and depression are noted. Excessive salivation is present and
vesicles (fluid filled pockets) are noted on the buccal mucosa, dental pad,
and tongue. The vesicles rupture within 24 hours leaving a painful lesion.
Vesicles also occur around the coronary band causing lameness. As vesicles
heal, animals return to eating over several days, but may take up to 6
months to fully recover. Occasionally, the heart muscle is damaged and
acute deaths ensue. Diarrhea, sometimes including blood may be seen. In
sheep, goats and swine, the disease is usually much less severe. As few as
5% of affected sheep in infected flocks show any clinical signs of disease.
Fever, anorexia, and general lassitude may be observed along with
lameness, with or without foot lesions. Foot lesions are usually in the
interdigital space, along the coronary band, and on the bulb of the heel.
Oral lesions are less common and may disappear by the time foot lesions
appear. When they do occur, they are likely to be on the back of the
dorsal surface of the tongue rather than the tip and may be more necrotic
than vesicular. Lesions may also occur on the dental pad and lips (usually
small), teats, vulva, prepuce, and rumenal mucosa. Sudden death in
apparently healthy lambs may be the most obvious sign of infection in the
flock and is generally the result of myocardial lesions.

How deadly is it? FMD rapidly spreads within a herd and essentially 100% of
susceptible animals become infected and show clinical signs of the disease.
FMD is not considered a particularly lethal disease. Death rates rarely
exceed 2% in adults and 20 % in young stock. There have been outbreaks with
up to 50% mortality. However, prolonged convalescence causes severe losses
in production and health, cripples animal industries, and severely inhibits
travel and tourism.

Where does it come from? There are a variety of species that allow the
virus to persist or serve to spread the infection. Some include elephants,
capybara, hedgehogs, coypu, rodents, birds, and wild ruminants (Roe deer,
muntjac, sika deer, fallow and red deer, water buffalo). These animals may
not show clinical signs, but may harbor the virus to allow later spread of
the infection to susceptible species. These species are not likely to play
a major role in transmission because of lack of contact with susceptible
species. Several reports indicate that, among sheep, the virus may persist
at a low-level in the absence of clinical disease with cycling between
infected and susceptible animals. Although sheep may be carriers of the
virus for up to 5 to 9 months, they tend to excrete it at relatively low
levels and perhaps intermittently. The risk of transmission to other
species appears to be highest during the early stages of either clinical or
subclinical infection. Virulence varies with the infecting strain, and
those strains adapted to sheep and goats may exhibit variable virulence for
other species. African buffalo may harbor the virus for up to 28 months!
Goats may also serve as carriers of the disease. One study in Kenya showed
that goats served a minor role in transmission to cattle and that sheep
were not significant carriers. In other outbreaks, sheep meat imported from
infected areas appear to have been the origin of infection. Swine are
considered an "amplifier host" because of the tremendous number of viral
particles they release into the air (estimated at 1500 times greater than
that produced by cattle).

How is it spread? The virus may be spread by inhalation or ingestion.
Initial outbreaks are most commonly caused by ingestion (e.g. infected
meat), but rapid spread within a herd is likely via inhalation (airborne
virus). Moderate temperatures, overcast skies and high humidity appear to
facilitate wind-borne spread. Virus spread has been estimated to be as far
as 62 miles (100 kilometers)! Up to 50 % of infected animals may remain as
carriers of the disease for at least 6 months. The virus can be spread by
contaminated semen, meat and milk products. Virus could be recovered from
nasal secretion of PEOPLE for up to 28 hours after working with infected
cattle. In England, one estimate of how the disease was spread included
birds (16%), meat products in pig food (40%), meat and bones (7%), unknown
(7%), and obscure (28%).

Can we kill the virus? FMD is a very stable virus. It can survive up to 1
year in the environment, 10 to 12 weeks on clothing and feed, and 30 days
on hair! Sunlight, boiling, and autoclaving rapidly destroy the virus. The
virus can survive flash pasteurization of dairy products. Most
disinfectants and meat packing industry techniques do not destroy the
virus. Disinfectants seem to have little effect on this virus. However,
sodium hydroxide (1-2%), formalin (1-2%), or sodium carbonate (4%) will
destroy the virus within a few minutes. If you travel in an area that has
and active outbreak of FMD, you should use disposable shoes and clothing
(e.g. coveralls), shower extensively after the visit and before traveling,
and preferably stay away from any farm for at least 30 days upon returning.
Currently, the USDA recommends a 5-day waiting period before entering a
farm or having contact with other livestock. The best bet is to stay clear
of infected areas during active outbreaks of disease.

Do animals become immune? Cattle mount an effective immune response to FMD
that lasts up to 4 years. Swine immunity persists for only 7 to 8 months.
Immunity is relatively specific to the serotype involved in the exposure.
New outbreaks with different serotypes can occur at any time.

How is it diagnosed? There are multiple tests that have been used including
tissue culture, virus neutralization, compliment fixation tests,
experimental infection, PCR techniques, and ELISA tests. A
government-approved laboratory must perform these tests. FMD is a federally
reportable disease in the USA. FMD must be differentiated from other
vesicular diseases including vesicular stomatitis, vesicular exanthema of
swine, swine vesicular disease, and bluetongue.

Is there a vaccine? Yes, but success of vaccination programs has been
highly variable because of the multitude of serotypes and subtypes.
Vaccination may or may not prevent infection or the establishment of
carriers. The most common types are killed virus trivalent forms.
Vaccination in the USA is not permitted. Suspected cases of FMD are
required to be reported to federal authorities for investigation and
immediate responses to control spread.

Reading:

Fowler ME. Medicine and Surgery of South American Camelids. Iowa State
University Press. 1998, pp153-155

Blood DC, Radostits OM. Foot and Mouth Disease. In: Blood DC, Radostits OM
(eds), Veterinary Medicine (7th Edition). Bailliere and Tindall, 1989,
pp824-831.

Lubroth J, Yedloutschnig RJ, Culhane VK, Mikiciuk PE. Foot-and-mouth
disease virus in the llama (Lama glama): diagnosis, transmission, and
susceptibility. J Vet Diagn Invest 1990;2:197-203.

Fondevila NA, Marcoveccio FJ, Viera JB, O'Donnell VK, Carrillo BJ, Schudel
AA, David M, Torres A, Mebus CA. Susceptibility of Llamas (Lama glama) to
infection with foot-and-mouth disease virus. J Vet Med 1995;B42:595-599.

Barnett, BV, Cox SJ. The role of small ruminants in the epidemiology and
transmission of foot-and-mouth disease. The Veterinary Journal 1999;158:6-13.

Callens M., De Clercq K, Gruia M. and Danes M. Detection of foot-and-mouth
disease by reverse tanscription polymerase chain reaction and virus
isolation in contact sheep without clinical signs of foot-and-mouth
disease. Veterinary Quarterly 1998;20(Suppl 2):S37-40.

Radostits OM, Gay CC, Blood DC, Hinchcliff KW. Veterinary Medicine (9th
ed.). WB Saunders.

House JA, House CA. Vesicular Diseases. In: Straw BE, D'Allaire S,
Mengeling WL, Taylor DJ (eds). Diseases of Swine (8th ed.) Iowa State
University Press. 1999, pp. 327-340.

David E Anderson, DVM, MS, Diplomate ACVS
Associate Professor, Food Animals
Department of Veterinary Clinical Sciences
College of Veterinary Medicine
The Ohio State University
Columbus, Ohio 43210
Phone: 614-292-6661; Fax: 614-292-0895
E-mail: Anderson.670@osu.edu