On April 19, sick animals were detected in Rafah —
a town on the border between the coastal Palestinian territory of the Gaza
Strip and Egypt. As reported by the Food and Agriculture Organization of the
United Nations, these cases were diagnosed as an outbreak of foot-and-mouth
disease, caused by a new strain, SAT2, which had been detected in February in
Egypt and Libya.
Highly contagious among animals
Foot-and-mouth disease (FMD) is not considered to be a
public health problem. Foot-and-mouth disease virus (FMDV) infections in humans
are very rare, with approximately 40 cases diagnosed since 1921. Vesicular
lesions and influenza-like symptoms can be seen; the disease is generally mild,
short-lived and self-limiting. Please note that FMD is not related to
hand-foot-and-mouth disease, a condition seen only in humans.
FMD is the most contagious disease of mammals and has a
great potential for causing severe economic loss in susceptible cloven-hoofed
animals. It is caused by a virus of the genus Aphthovirus and family
Picornaviridae. There are seven serotypes of FMDV, namely O, A, C, Asia1
and South African Territories (SAT) serotypes SAT1, SAT2, SAT3. Infection with
any one serotype does not confer immunity against another. Within serotypes,
many strains can be identified by biochemical and immunological tests.
Indeed, the introduction of the African FMDV serotype
SAT2 into Egypt and Libya in February caused grave concern because the target
animal species in both countries, primarily cattle, buffalo, sheep and goats,
had never been in contact nor vaccinated against this exotic virus strain and
were fully vulnerable.
Although the Libyan outbreak remained localized, the
virus spread rapidly in Egypt, severely affecting the densely populated delta
region and eventually infecting livestock in all of Egypt’s governorates.
The disease was characterized by severe signs, primarily in cattle and buffalo,
despite their earlier vaccination against serotypes A and O. The clinically
affected animals were counted in six-digit figures. High mortality was observed
in young animals, and by late April, the death toll topped 20,000.
After peaking, the disease continued during May, albeit
in a slower pace; mass SAT2 vaccination has been applied. The issue became
subject to public debates; the media showed pictures of dead animals thrown in
front of government offices by protesting farmers. Meat prices soared, with FMD
becoming one of the main factors blamed as the cause of the current economic
Movements of animals from the Nile Delta eastward
through the Sinai Peninsula and north into the Gaza Strip have been deemed the
highest risk for the spread of the disease into the wider Middle East region.
The Food and Agriculture Organization of the United Nations (FAO) has recently
indicated that if FMD SAT2 reaches deeper into the Middle East, it could spread
throughout vast areas, threatening the Gulf countries — even southern and
eastern Europe, and perhaps beyond.
Of the domesticated species, cattle, pigs, sheep, goats
and water buffalo are susceptible to FMD. Infection of susceptible animals with
FMDV can lead to the appearance of vesicles on the feet, in and around the oral
cavity, and on the mammary glands of females. The vesicles rupture and then
One of the first signs of disease in milking cows is a
sudden drop in milk yield. Mastitis is a common sequel of FMD in dairy cattle.
Vesicles can also occur at other sites, such as inside the nostrils and at
pressure points on the limbs — especially in pigs. FMDV is exhaled by the
sick animal and discharged in saliva, milk and excretions.
Besides direct contact and aerosols, it spreads easily
and indirectly via contaminated hay, stalls, trucks and clothing. The rapid
spread into large proportions of the animal population is behind the serious
economic implications. Suspected cases are notifiable and may cause trade
restrictions on national and international levels.
Identification and control measures
The severity of clinical signs varies with the strain of
virus, the exposure dose, the age and breed of animal, the host species and the
immunity of the animal. The signs can range from a mild or unapparent infection
to one that is severe. Death may result in some cases. Mortality from a
multifocal myocarditis is most commonly seen in young animals and may exceed
50% in severe outbreaks. The convalescence period is extended, which
contributes to serious economic loss.
FMD is present throughout Asia, Africa and South
America. However, Europe, North America, Australia and New Zealand are free of
disease. In case FMD is suspected in such a country, the suspected animals and
their contacts are culled, with no vaccination applied.
Countries that are officially recognized as FMD-free,
prohibit imports of live animals and unprocessed animal products (such as meat
and dairy products) from infected countries. On their part, many infected
countries apply preventive mass vaccinations.
FMD vaccines are inactivated; the protection conferred
by such vaccines is relatively short-lived and will protect only against the
homologous virus strain. After the primary vaccination, which should be
repeated after several weeks, the animals undergo at least one annual
vaccination throughout their life. If more than one serotype circulates within
the country or region, multivalent vaccines are used.
Early and accurate diagnosis of FMD in samples from
suspected cases is of the highest importance to enable the timely application
of control measures. In vaccinating countries, the earliest identification of
exotic types, not covered by the vaccine strains in use, is of the utmost
The world reference laboratory for FMD (WRLFMD) in
Pirbright, United Kingdom, provides the needed support to identify virus
strains in samples from suspected cases and confirm results of national
laboratories. WRLFMD carries out vaccine matching tests and genotyping of the
Gaza Strip outbreak
During 2012, samples from the FMD outbreak in Egypt,
Libya and the Palestinian Autonomous Territories were received by the WRLFMD.
Serotype SAT2 was isolated from each set of samples and subjected to reverse
transcription polymerase chain reaction and sequencing of the VP1 gene.
Genotyping revealed that the virus belonged to topotype
VII (there are 14 SAT2 topotypes), known to circulate in sub-Saharan Africa. It
was found that there were either two independent introductions or a single
introduction of two lineages into Egypt, all presumably from one or more
sub-Saharan African countries; there was one independent introduction into
Libya. The strain in the Gaza Strip was identical to one of the Egyptian
Besides these recent cases due to serotype SAT2, a new
FMDV serotype A lineage was also detected in Egypt in 2012. The FMD situation
in Egypt has become extremely complex with the presence of at least five
distinct FMDV lineages between 2010 and 2012, requiring at least three
different vaccine virus strains.
The spread of SAT2 into the Middle East is of great
concern to countries in the region and to European nations because further
spread may be possible. For example, in January 1962, FMDV SAT1 was introduced
into Bahrain from East Africa. Within a few months, it had spread to Iran,
Iraq, Israel, Jordan, Lebanon, Syria, Turkey and Greece. The virus persisted in
Iran until 1964 and Turkey until 1965.
So far, the undertaken steps in the Gaza Strip and in
neighboring Israel have prevented a further spread of the SAT2 virus strain. In
Gaza, all cattle were vaccinated with an emergency SAT2 vaccine supplied by the
FAO. Israel created a buffer zone along its borders with the Gaza Strip and
Egypt, in which all susceptible animals were vaccinated and severe restrictions
on animal movements were applied.
The situation is still rather precarious and high
alertness is maintained.
Clearly, close monitoring of the FMD situation in the
region is now needed to define risks of future outbreaks, as well as to ensure
that control measures (vaccines and diagnostic tests) are appropriate for the
virus strains that are circulating. Countries in the region are encouraged to
submit samples to the WRLFMD for genetic and antigenic characterization.
Arnon Shimshony, DVM, is Associate Professor at the Koret School of Veterinary Medicine Hebrew University of Jerusalem, Rehovot, and is the ProMED-mail Animal Diseases Zoonoses Moderator. Dr. Shimshony is a member of the Infectious Disease News Editorial Board. Dr. Shimshony was Chief Veterinary Officer, State of Israel, from 1974 to 1999.