Gucci_b
Well-Known Member
How will you take precautions to safe guard your horse's!!
Some facts below.....
2. The FAQ.
2.1 What is Foot and Mouth Disease?
FMD is a highly contagious disease of cloven-hoofed animals such as sheep, goats, pigs, cattle and deer. Rarely, other animals including humans can catch FMD. (See 'Can other animals catch FMD?' for more information about this.)
The cattle plague described by Aristotle in 350BC might have been FMD or rinderpest, but the first detailed description is from Venice in 1546 by the Italian physician Fracastorius. FMD was first recorded in Britain in 1839. It's caused by a virus (of the family Picornaviridae, genus Apthovirus) with seven different strains or serotypes: A, O, C, SAT1, SAT2, SAT3 and Asia1. FMD virus is very adaptable and very variable; each of these seven serotypes has evolved sub-types that may be more or less infective, or affect different species in different ways, and may require slightly different vaccines.
The current outbreak (began early spring of 2001) in Britain is caused by the Pan-Asian type O strain. This strain first appeared in India in 1990 and is now the most widely distributed of the seven. It is endemic in many South American, African and Asian countries. It has several sub-types each of which is associated with a particular areas and species; for example, the strain prevalent in the Middle East affects primarily sheep and cattle (perhaps because there are few pigs in the area), whereas the Far East type O is responsible for major outbreaks in pigs. Nucleotide sequencing can distinguish between sub-types causing outbreaks in areas with both cattle and pigs such as Vietnam.
2.1.1 How do animals catch FMD?
The most frequent mode of transmission is by inhalation of virus particles. FMD is very infectious: as few as 1-10 virus particles can produce the disease.
Infections are also transmitted by direct contact with fluids from blisters and open wounds containing the virus. Laboratory workers on FMD often infect subjects by injecting the virus into the skin (intradermal) or into the body cavity (intraperitoneal).
Animals may catch FMD by eating contaminated feed (a higher dose is required); drinking contaminated water or milk (a higher dose is required unless the animal actually inhales liquid and virus particles while drinking), or through exposure to contaminated semen or vaccine (some vaccines are prepared using live virus, which may cause infections).
Active virus particles may be carried on inanimate objects such as vehicles, clothing, or in mud attached to boots.
In 'Foot-and-Mouth Disease: Sources of Outbreaks and Hazard Categorisation of Modes of Virus Transmission' (1994), the USDA assessed the risk of carrying FMD virus on various items/substances (virus survival is longest time reported in the literature they surveyed):
bedding (straw, woodshavings): high hazard. Virus survived 4 weeks, transmission to livestock demonstrated.
clothing: high hazard. Virus survived up to 100 days, transmission demonstrated.
buckets, tools: moderate hazard. Virus not shown to survive, but transmission demonstrated.
feed/fodder: high hazard. Virus survived up to 200 days, transmission to livestock demonstrated.
garbage/rubbish containing animal products or by-products: high hazard. Virus not shown to survive, but transmission demonstrated. (Imported animals and infected meat products are the two main causes of FMD outbreaks in most countries.)
packing materials: high hazard. virus survived 46 days at room temperature, transmission demonstrated.
shoes/boots: high hazard. Virus survived 9 weeks summer, 14 weeks winter, transmission demonstrated.
soil: summer (drier) moderate hazard, survival 3-7 days. Autumn/winter high hazard, survival 4 weeks/21 weeks. Transmission to livestock not demonstrated.
vehicles: moderate hazard. Virus not shown to survive, but transmission demonstrated.
The OIE recommendations at
<http://www.oie.int/eng/normes/MCode/A_00028.htm> are a useful summary of some treatments used to ensure products such as straw are FMD-free before export.
2.1.2 What are the symptoms and when do they appear?
After infection there is an incubation period of 2-14 (OIE) 1-21(USDA) days during which the virus multiplies. It's important to note that the speed with which the symptoms appear and the severity of the symptoms depend on:
the strain of FMD
the initial dose and route of infection: if only a few particles are inhaled as an aerosol, then the infection will incubate for longer than if the animal was in direct contact with the larger quantities of virus found in the feces, urine, saliva, and lesions of an infected animal. So aerosol infections between farms take longer to incubate than those within a single herd. Once FMD has begun to spread within a herd or flock the incubation period is about 2-4 days in cattle and sheep and 3-6 days in pigs.
the species of the animals infected. For example, when cattle are infected they normally show symptoms more quickly and more severely than pigs, sheep or goats (possibly because their pulmonary volume is greater, so they inhale larger quantities of virus). But in the 1997 FMD epidemic in Taiwan cattle appeared to be resistant - only pigs contracted that strain of FMD in the field. So FMD has very different effects on different animals: some may catch it and develop symptoms, some may catch it without developing noticeable symptoms, and others may not be affected by the same strain of virus.
the breed of animal involved: breeds originating in areas where FMD is endemic tend to be less susceptible to the disease than different breeds of the same species brought into the area for the first time. African breeds of cattle are more resistant (but not immune!) than European breeds.
the health of the individual animal. Physiological stress leaves animals more vulnerable to infection, so cows in heavy lactation are more likely to succumb than low-yielding individuals. Shipping stress and social stress are also likely to increase vulnerability.
Classic symptoms are that after the incubation period, in addition to a fever (103-105°F, 39.4-40.6°C) and loss of appetite, FMD causes vesicles (blisters) to develop on various parts of the body of infected animals. The virus affects the throat first, where it multiplies in the primary vesicles. Eventually virus particles enter the blood stream and are carried to different parts of the body where they cause secondary vesicles. Affected animals have nasal discharges and salivate excessively. As the name suggests, the most obvious secondary vesicles are on the feet and in/on the nose, mouth and tongue, but others may appear on/in the mammary gland or udder and internal organs such as the rumen. A high death rate in young animals is associated with vesicles or lesions on the myocardium (heart muscle).
These vesicles often rupture after about 24 hours, leaving large, painful open wounds that bleed easily. Vesicles on the coronary band (where the hoof joins the ankle) may result in sloughing of the hooves, leaving animals unable to stand.
http://www.aphis.usda.gov/vs/ep/fad_training/VESVOL7/page22_7.htm and subsequent pages illustrate the symptoms of FMD.
Pregnant animals often abort their young, or the young are born dead; lactating females lose 50-60% of their milk for that lactation. Draught animals such as oxen lose 60-70% of their draught power in the first month of an outbreak: the Vietnamese authorities have estimated that each case of FMD in working cattle or buffalo results in the loss of 3 tons of rice.
2.1.3 How long does the illness last? Does FMD inflict permanent damage?
The acute phase (when the symptoms are obvious) lasts about 8-15 days. Afterwards those animals that can recover will do so, gradually. Sheep and goats tend to be less badly affected than cattle, which may be left with scarring on their tongues and in their mouths that makes it difficult or painful to eat; deformed feet; mastitis or other permanent drop in milk production and damaged heart muscle. Some lose the ability to regulate their body temperature. Animals that have recovered from FMD gain weight more slowly and (as a result of secondary infections and mastitis) produce less milk than uninfected animals, a overall decrease of 10-25% in productivity for both beef and dairy cattle.
2.1.4 Virus 'factories'.
It's very important to remember that infected animals are also virus 'factories', producing large quantities of virus particles and shedding them into the environment where they can infect other animals. The most important route is through the lungs: infected animals exhale virus particles that can be inhaled by other animals. In the acute phase and during convalescence there are virus particles in all fluids secreted by the animals, such as blood, saliva, tears, faeces, urine, milk, and semen.
<http://aleffgroup.com/avisfmd/A010-fmd/tools/3-chrt-virus-production.html> shows virus levels in different fluids from different species, but note there is no information about the conditions (temperature, for example) in which survival was determined.
Some virus may be shed even after the animal recovers (see 'The Carrier State' below).
Different species produce differing amounts of virus: sheep, goats and cattle produce moderate amounts but pigs breathe out between 30 and 100 times as much, up to a hundred million infectious doses per day. It is said that in an outbreak sheep act as maintenance hosts, pigs act as amplifiers, and cattle act as indicators because they tend to be more susceptible to illness.
Different species appear to produce the virus at different stages in the development of the disease: according to the MAFF, virus production in sheep and goats peaks 7-10 days after infection. According to AVIS <http://aleffgroup.com/avisfmd/> virus production in cattle peaks around the onset of clinical signs, but milk and semen may be contaminated up to 4 days before clinical signs develop. Ferguson assumed constant infectiousness from 3 days after infection in his model of the current UK epidemic; I don't know enough about it to explain this discrepancy.
2.1.5 What happens after the animal recovers?
2.1.5.1 The carrier state.
Although the animals that survive the acute phase may not show any symptoms, they still have virus particles circulating in their bodies. The concentration of these particles normally decreases over time as the animals' immune systems fight the infection, but while there are virus particles present any animal that has FMD will be shedding virus. The amount and duration varies according to the species involved (see above). Some animals become carriers: they continue to shed virus from the pharynx, and may infect other animals although they themselves display no symptoms. Sheep and goats may continue to shed virus for about 9 months after infection, cattle for up to 2.5-3 years. Pigs do not become carriers.
Transmission from 'true' carrier cattle (those that have had the disease and recovered, but show virus in pharyngeal fluid) to susceptible cattle has not been demonstrated under experimental conditions (Salt, 1994) and it sounds as though they've tried really hard. Nonetheless, there's a lot of anecdotal evidence that such transmission occurs.
There is some experimental evidence that over time in the carrier animal the virus becomes less virulent to other members of the same spp as the carrier, but retains its virulence towards other spp. Virus isolated from carrier cattle was less cytopathic in culture than wild-type virus, and was less virulent towards susceptible cattle. But it retained its virulence for pigs and guinea pigs, regaining its virulence for cattle after a single passage in pigs.
Vaccination doesn't prevent animals becoming carriers: please see section 2.2.4 on Vaccination for more information.
2.1.5.2 Immunity.
<http://aleffgroup.com/avisfmd/A010-fmd/mod4/4411-infection.html> Animals that have recovered from FMD are immune to that strain for some time; the strength of the immunity normally decreases with time after infection. Cattle have been demonstrated to retain immunity against the original virus for up to 5.5 years - this is thought to be related to the carrier state that lasts up to 30 months. Both may be a function of continuing challenge from trace amounts of virus. AVIS state that little is known about the immune response/duration of immunity for sheep and goats. Pigs appear to retain immunity for a much shorter period than cattle, perhaps 3-6 months.
2.2 Isn't there a treatment, a drug or vaccination that will prevent or cure this disease?
2.2.1 Antibiotics.
Antibiotics have no effect on viral diseases such as FMD, although they can be used to treat secondary infections.
2.2.2 Other remedies.
Other publicised remedies, such as Jeyes fluid (a phenolic compound), may act as disinfectants to prevent or treat secondary infections in wounds but according to the OIE [1] have no effect on the virus: 'Resistant to iodophores, quaternary ammonium compounds, hypoclorite and phenol, especially in the presence of organic matter'.
Some facts below.....
2. The FAQ.
2.1 What is Foot and Mouth Disease?
FMD is a highly contagious disease of cloven-hoofed animals such as sheep, goats, pigs, cattle and deer. Rarely, other animals including humans can catch FMD. (See 'Can other animals catch FMD?' for more information about this.)
The cattle plague described by Aristotle in 350BC might have been FMD or rinderpest, but the first detailed description is from Venice in 1546 by the Italian physician Fracastorius. FMD was first recorded in Britain in 1839. It's caused by a virus (of the family Picornaviridae, genus Apthovirus) with seven different strains or serotypes: A, O, C, SAT1, SAT2, SAT3 and Asia1. FMD virus is very adaptable and very variable; each of these seven serotypes has evolved sub-types that may be more or less infective, or affect different species in different ways, and may require slightly different vaccines.
The current outbreak (began early spring of 2001) in Britain is caused by the Pan-Asian type O strain. This strain first appeared in India in 1990 and is now the most widely distributed of the seven. It is endemic in many South American, African and Asian countries. It has several sub-types each of which is associated with a particular areas and species; for example, the strain prevalent in the Middle East affects primarily sheep and cattle (perhaps because there are few pigs in the area), whereas the Far East type O is responsible for major outbreaks in pigs. Nucleotide sequencing can distinguish between sub-types causing outbreaks in areas with both cattle and pigs such as Vietnam.
2.1.1 How do animals catch FMD?
The most frequent mode of transmission is by inhalation of virus particles. FMD is very infectious: as few as 1-10 virus particles can produce the disease.
Infections are also transmitted by direct contact with fluids from blisters and open wounds containing the virus. Laboratory workers on FMD often infect subjects by injecting the virus into the skin (intradermal) or into the body cavity (intraperitoneal).
Animals may catch FMD by eating contaminated feed (a higher dose is required); drinking contaminated water or milk (a higher dose is required unless the animal actually inhales liquid and virus particles while drinking), or through exposure to contaminated semen or vaccine (some vaccines are prepared using live virus, which may cause infections).
Active virus particles may be carried on inanimate objects such as vehicles, clothing, or in mud attached to boots.
In 'Foot-and-Mouth Disease: Sources of Outbreaks and Hazard Categorisation of Modes of Virus Transmission' (1994), the USDA assessed the risk of carrying FMD virus on various items/substances (virus survival is longest time reported in the literature they surveyed):
bedding (straw, woodshavings): high hazard. Virus survived 4 weeks, transmission to livestock demonstrated.
clothing: high hazard. Virus survived up to 100 days, transmission demonstrated.
buckets, tools: moderate hazard. Virus not shown to survive, but transmission demonstrated.
feed/fodder: high hazard. Virus survived up to 200 days, transmission to livestock demonstrated.
garbage/rubbish containing animal products or by-products: high hazard. Virus not shown to survive, but transmission demonstrated. (Imported animals and infected meat products are the two main causes of FMD outbreaks in most countries.)
packing materials: high hazard. virus survived 46 days at room temperature, transmission demonstrated.
shoes/boots: high hazard. Virus survived 9 weeks summer, 14 weeks winter, transmission demonstrated.
soil: summer (drier) moderate hazard, survival 3-7 days. Autumn/winter high hazard, survival 4 weeks/21 weeks. Transmission to livestock not demonstrated.
vehicles: moderate hazard. Virus not shown to survive, but transmission demonstrated.
The OIE recommendations at
<http://www.oie.int/eng/normes/MCode/A_00028.htm> are a useful summary of some treatments used to ensure products such as straw are FMD-free before export.
2.1.2 What are the symptoms and when do they appear?
After infection there is an incubation period of 2-14 (OIE) 1-21(USDA) days during which the virus multiplies. It's important to note that the speed with which the symptoms appear and the severity of the symptoms depend on:
the strain of FMD
the initial dose and route of infection: if only a few particles are inhaled as an aerosol, then the infection will incubate for longer than if the animal was in direct contact with the larger quantities of virus found in the feces, urine, saliva, and lesions of an infected animal. So aerosol infections between farms take longer to incubate than those within a single herd. Once FMD has begun to spread within a herd or flock the incubation period is about 2-4 days in cattle and sheep and 3-6 days in pigs.
the species of the animals infected. For example, when cattle are infected they normally show symptoms more quickly and more severely than pigs, sheep or goats (possibly because their pulmonary volume is greater, so they inhale larger quantities of virus). But in the 1997 FMD epidemic in Taiwan cattle appeared to be resistant - only pigs contracted that strain of FMD in the field. So FMD has very different effects on different animals: some may catch it and develop symptoms, some may catch it without developing noticeable symptoms, and others may not be affected by the same strain of virus.
the breed of animal involved: breeds originating in areas where FMD is endemic tend to be less susceptible to the disease than different breeds of the same species brought into the area for the first time. African breeds of cattle are more resistant (but not immune!) than European breeds.
the health of the individual animal. Physiological stress leaves animals more vulnerable to infection, so cows in heavy lactation are more likely to succumb than low-yielding individuals. Shipping stress and social stress are also likely to increase vulnerability.
Classic symptoms are that after the incubation period, in addition to a fever (103-105°F, 39.4-40.6°C) and loss of appetite, FMD causes vesicles (blisters) to develop on various parts of the body of infected animals. The virus affects the throat first, where it multiplies in the primary vesicles. Eventually virus particles enter the blood stream and are carried to different parts of the body where they cause secondary vesicles. Affected animals have nasal discharges and salivate excessively. As the name suggests, the most obvious secondary vesicles are on the feet and in/on the nose, mouth and tongue, but others may appear on/in the mammary gland or udder and internal organs such as the rumen. A high death rate in young animals is associated with vesicles or lesions on the myocardium (heart muscle).
These vesicles often rupture after about 24 hours, leaving large, painful open wounds that bleed easily. Vesicles on the coronary band (where the hoof joins the ankle) may result in sloughing of the hooves, leaving animals unable to stand.
http://www.aphis.usda.gov/vs/ep/fad_training/VESVOL7/page22_7.htm and subsequent pages illustrate the symptoms of FMD.
Pregnant animals often abort their young, or the young are born dead; lactating females lose 50-60% of their milk for that lactation. Draught animals such as oxen lose 60-70% of their draught power in the first month of an outbreak: the Vietnamese authorities have estimated that each case of FMD in working cattle or buffalo results in the loss of 3 tons of rice.
2.1.3 How long does the illness last? Does FMD inflict permanent damage?
The acute phase (when the symptoms are obvious) lasts about 8-15 days. Afterwards those animals that can recover will do so, gradually. Sheep and goats tend to be less badly affected than cattle, which may be left with scarring on their tongues and in their mouths that makes it difficult or painful to eat; deformed feet; mastitis or other permanent drop in milk production and damaged heart muscle. Some lose the ability to regulate their body temperature. Animals that have recovered from FMD gain weight more slowly and (as a result of secondary infections and mastitis) produce less milk than uninfected animals, a overall decrease of 10-25% in productivity for both beef and dairy cattle.
2.1.4 Virus 'factories'.
It's very important to remember that infected animals are also virus 'factories', producing large quantities of virus particles and shedding them into the environment where they can infect other animals. The most important route is through the lungs: infected animals exhale virus particles that can be inhaled by other animals. In the acute phase and during convalescence there are virus particles in all fluids secreted by the animals, such as blood, saliva, tears, faeces, urine, milk, and semen.
<http://aleffgroup.com/avisfmd/A010-fmd/tools/3-chrt-virus-production.html> shows virus levels in different fluids from different species, but note there is no information about the conditions (temperature, for example) in which survival was determined.
Some virus may be shed even after the animal recovers (see 'The Carrier State' below).
Different species produce differing amounts of virus: sheep, goats and cattle produce moderate amounts but pigs breathe out between 30 and 100 times as much, up to a hundred million infectious doses per day. It is said that in an outbreak sheep act as maintenance hosts, pigs act as amplifiers, and cattle act as indicators because they tend to be more susceptible to illness.
Different species appear to produce the virus at different stages in the development of the disease: according to the MAFF, virus production in sheep and goats peaks 7-10 days after infection. According to AVIS <http://aleffgroup.com/avisfmd/> virus production in cattle peaks around the onset of clinical signs, but milk and semen may be contaminated up to 4 days before clinical signs develop. Ferguson assumed constant infectiousness from 3 days after infection in his model of the current UK epidemic; I don't know enough about it to explain this discrepancy.
2.1.5 What happens after the animal recovers?
2.1.5.1 The carrier state.
Although the animals that survive the acute phase may not show any symptoms, they still have virus particles circulating in their bodies. The concentration of these particles normally decreases over time as the animals' immune systems fight the infection, but while there are virus particles present any animal that has FMD will be shedding virus. The amount and duration varies according to the species involved (see above). Some animals become carriers: they continue to shed virus from the pharynx, and may infect other animals although they themselves display no symptoms. Sheep and goats may continue to shed virus for about 9 months after infection, cattle for up to 2.5-3 years. Pigs do not become carriers.
Transmission from 'true' carrier cattle (those that have had the disease and recovered, but show virus in pharyngeal fluid) to susceptible cattle has not been demonstrated under experimental conditions (Salt, 1994) and it sounds as though they've tried really hard. Nonetheless, there's a lot of anecdotal evidence that such transmission occurs.
There is some experimental evidence that over time in the carrier animal the virus becomes less virulent to other members of the same spp as the carrier, but retains its virulence towards other spp. Virus isolated from carrier cattle was less cytopathic in culture than wild-type virus, and was less virulent towards susceptible cattle. But it retained its virulence for pigs and guinea pigs, regaining its virulence for cattle after a single passage in pigs.
Vaccination doesn't prevent animals becoming carriers: please see section 2.2.4 on Vaccination for more information.
2.1.5.2 Immunity.
<http://aleffgroup.com/avisfmd/A010-fmd/mod4/4411-infection.html> Animals that have recovered from FMD are immune to that strain for some time; the strength of the immunity normally decreases with time after infection. Cattle have been demonstrated to retain immunity against the original virus for up to 5.5 years - this is thought to be related to the carrier state that lasts up to 30 months. Both may be a function of continuing challenge from trace amounts of virus. AVIS state that little is known about the immune response/duration of immunity for sheep and goats. Pigs appear to retain immunity for a much shorter period than cattle, perhaps 3-6 months.
2.2 Isn't there a treatment, a drug or vaccination that will prevent or cure this disease?
2.2.1 Antibiotics.
Antibiotics have no effect on viral diseases such as FMD, although they can be used to treat secondary infections.
2.2.2 Other remedies.
Other publicised remedies, such as Jeyes fluid (a phenolic compound), may act as disinfectants to prevent or treat secondary infections in wounds but according to the OIE [1] have no effect on the virus: 'Resistant to iodophores, quaternary ammonium compounds, hypoclorite and phenol, especially in the presence of organic matter'.