Foot-and-Mouth Disease
Overview
Foot-and-Mouth Disease (FMD, 구제역) is an acute viral infectious disease that occurs in cloven-hoofed animals (우제류) such as cattle, pigs, sheep, and goats. It is caused by the Foot-and-Mouth Disease Virus (FMDV) of the family Picornaviridae, characterized by fever and the formation of vesicles (blisters) on the mouth, tongue, hooves, and teats. The disease is highly contagious, capable of spreading to an entire herd within hours after a single infection, and is designated by the World Organisation for Animal Health (WOAH) as one of the most important livestock diseases. An outbreak can lead to a complete halt in international trade of livestock and livestock products, causing enormous economic losses.
Main Content
1. Pathogen and Characteristics
The FMD virus has 7 serotypes (O, A, C, Asia 1, SAT 1, SAT 2, SAT 3) and over 60 subtypes. There is almost no cross-immunity between serotypes, so an animal infected once can be reinfected with a different serotype. The virus survives relatively long in the external environment, especially in low temperatures and humid conditions. It is sensitive to pH changes and is easily inactivated in acidic (pH 6.0 or below) or alkaline (pH 9.0 or above) environments.
2. Transmission Routes
Transmission of FMD is very rapid and diverse. Direct contact through respiratory transmission is the most common route, and the virus is present in all secretions and excretions of infected animals, including saliva, urine, feces, and milk. Airborne droplet transmission is also possible, allowing the virus to spread several kilometers via wind. Indirect transmission through contaminated feed, water, farm equipment, vehicles, and human clothing or shoes is significant. Humans can act as mechanical vectors, posing major challenges for disease control.
3. Clinical Symptoms
The incubation period is typically 2 to 14 days. Main symptoms include high fever (40–41°C), loss of appetite, drooling, and lameness. Vesicles form on the mouth, tongue, gums, between the hooves, and on the teats, which rupture to form ulcers. In cattle, excessive drooling and lameness due to hoof pain occur, while dairy cows show mastitis and a sharp drop in milk production. Pigs may exhibit severe symptoms such as hoof detachment. Young animals show high mortality rates (over 50%) due to myocarditis. Adult animals mostly recover but may suffer sequelae such as weight loss, reduced milk production, and chronic lameness.
4. Diagnosis and Testing
Clinical symptoms alone are difficult to distinguish from similar diseases (e.g., vesicular stomatitis, swine vesicular disease), so laboratory diagnosis is essential. Methods include virus isolation, RT-PCR, ELISA antigen detection, and virus neutralization antibody tests. Internationally, WOAH standard diagnostic methods are followed, and rapid diagnostic kits for field use have been developed for quick diagnosis.
5. Control and Prevention
Control measures during an FMD outbreak are very strict. First, all infected animals on the affected farm are culled and buried or incinerated. Second, a protection zone (3 km radius) and surveillance zone (10 km radius) are established around the outbreak area, with movement restrictions and disinfection. Third, thorough disinfection of all livestock facilities, vehicles, and people is carried out. Fourth, emergency vaccination may be implemented, with vaccinated and non-vaccinated areas managed separately. Culling methods are controversial due to animal welfare and environmental concerns.
6. Vaccines and Prevention
Inactivated vaccines are mainly used for FMD, manufactured as multivalent vaccines targeting the circulating serotypes. Vaccination does not completely prevent infection but reduces clinical symptoms and virus shedding, thereby suppressing spread. Many countries, including South Korea, conduct regular vaccination programs, and vaccination status affects international trade conditions. For prevention, biosecurity measures such as controlling farm access, installing disinfection facilities, and prohibiting entry of overseas travelers and livestock products are most important.
Recent Trends
As of 2024–2025, FMD remains a major global livestock disease. In 2024, serotypes O and A FMD continued to occur in Southeast Asian regions such as Indonesia, Malaysia, and Thailand. Indonesia, in particular, has experienced ongoing outbreaks since 2022 and is expanding vaccination efforts. In early 2025, SAT-type FMD was reported in North African regions like Libya and Egypt, requiring international attention. Meanwhile, South Korea has had no additional outbreaks since 2023, but a suspected case in Chungcheongbuk-do in May 2024 tested negative, maintaining vigilance. Recent research trends include the development of mRNA vaccines, elucidation of virus survival mechanisms in the environment, and rapid field diagnostic technologies (e.g., CRISPR-based diagnostics). Additionally, an increasing number of countries are shifting from culling to vaccination-based management strategies, and discussions on improving disease control policies in terms of animal welfare and environmental protection are ongoing.
Related Topics
- [[African Swine Fever]]
- [[Avian Influenza]]
- [[Livestock Infectious Diseases]]
- [[World Organisation for Animal Health]]
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