Summary about Disease
Foot-and-mouth disease (FMD) is a highly contagious viral disease that affects cloven-hoofed animals, including cattle, pigs, sheep, goats, and deer. It is characterized by fever, blisters (vesicles) in the mouth and on the feet, and weight loss. FMD is a significant concern for animal agriculture due to its rapid spread and potential for causing substantial economic losses. While it is not typically a human health risk, its impact on livestock industries is profound.
Symptoms
Fever
Blisters (vesicles) on the tongue, lips, inside the mouth, and between the claws and on the coronary band of the feet.
Excessive salivation (drooling).
Lameness.
Reluctance to move or eat.
Depression.
Reduced milk production in dairy animals.
Weight loss.
Snout lesions are typical in pigs.
Causes
FMD is caused by the foot-and-mouth disease virus (FMDV), which belongs to the Aphthovirus genus of the *Picornaviridae* family. There are seven distinct serotypes of FMDV (A, O, C, SAT 1, SAT 2, SAT 3, and Asia 1), and infection with one serotype does not confer immunity against other serotypes. The virus spreads through:
Direct contact with infected animals.
Indirect contact with contaminated materials (e.g., vehicles, clothing, equipment).
Airborne transmission over short distances.
Ingestion of contaminated feed or water.
Semen and other animal products.
Medicine Used
There is no specific "medicine" to cure FMD. Treatment focuses on supportive care to manage symptoms and prevent secondary infections.
Symptomatic Treatment: Cleaning and dressing of foot lesions to prevent secondary infections. Soft bedding and readily accessible food and water.
Vaccination: Vaccination is a key preventative measure in endemic areas. Vaccines are serotype-specific, and the choice of vaccine depends on the circulating serotype.
Antimicrobials: Antibiotics are not effective against the virus, but may be used to treat secondary bacterial infections in lesions.
Is Communicable
Yes, FMD is highly communicable. It spreads rapidly among susceptible animals. The virus can survive for extended periods in the environment and on contaminated materials, facilitating its transmission.
Precautions
Strict Biosecurity Measures: Implementing strict biosecurity practices on farms and at livestock markets is crucial. This includes controlling access to farms, disinfecting vehicles and equipment, and providing protective clothing and footwear for visitors.
Quarantine: Isolating newly acquired animals and animals suspected of being infected.
Movement Restrictions: Imposing movement restrictions on animals and animal products in affected areas to prevent the spread of the disease.
Vaccination: Vaccinating susceptible animals in high-risk areas.
Surveillance: Conducting regular surveillance to detect and control outbreaks early.
Proper Disposal: Ensuring proper disposal of carcasses and contaminated materials.
Reporting: Promptly reporting any suspected cases of FMD to veterinary authorities.
How long does an outbreak last?
The duration of an FMD outbreak can vary depending on factors such as the speed of detection, the effectiveness of control measures, and the density of susceptible animals in the affected area. Outbreaks can last from a few weeks to several months. Control measures such as stamping out (culling infected and susceptible animals), movement restrictions, and vaccination can help to shorten the duration of the outbreak.
How is it diagnosed?
Diagnosis of FMD involves a combination of clinical examination and laboratory testing.
Clinical Examination: Observing clinical signs such as fever, blisters, and lameness.
Laboratory Testing:
Virus Isolation: Isolating the FMDV from vesicular fluid or tissue samples.
Real-Time Reverse Transcription Polymerase Chain Reaction (rRT-PCR): Detecting the viral RNA in samples.
Enzyme-Linked Immunosorbent Assay (ELISA): Detecting antibodies against FMDV in serum samples.
Virus Neutralization Test (VNT): Measuring the ability of serum antibodies to neutralize the virus.
Lateral Flow Assay: Rapid diagnostic test for use in the field.
Timeline of Symptoms
Incubation Period: Typically 2-14 days (the time between exposure and the appearance of symptoms).
Initial Symptoms: Fever, depression, and anorexia.
Vesicle Formation: Blisters appear in the mouth, on the feet, and sometimes on the teats. Vesicles rupture within 24 hours, leaving painful erosions.
Salivation and Lameness: Excessive salivation and lameness become prominent as the vesicles develop.
Recovery: Animals may recover within 2-3 weeks, but complications such as secondary infections, mastitis, and permanent damage to the hooves can occur.
Important Considerations
Economic Impact: FMD can have devastating economic consequences for livestock industries due to production losses, trade restrictions, and the cost of control measures.
Trade Restrictions: Countries free from FMD often impose strict trade restrictions on animals and animal products from affected countries to prevent the introduction of the disease.
Differential Diagnosis: It is important to differentiate FMD from other diseases that cause similar symptoms, such as vesicular stomatitis, bluetongue, and swine vesicular disease.
Strain Variation: The high mutation rate of FMDV leads to the emergence of new strains, which can pose challenges for vaccine development and control efforts.
Role of Wildlife: In some regions, wildlife species can serve as reservoirs for FMDV, making control more difficult.