Understanding Foot-and-Mouth Disease: A Comprehensive Guide

I. Overview: What is Foot-and-Mouth Disease?

Foot-and-Mouth Disease is an acute, highly contagious animal infectious disease caused by the Foot-and-Mouth Disease virus. It primarily affects cloven-hoofed animals such as cattle, sheep, and pigs, including both domesticated and wild ones. The disease is notorious for its fast transmission speed, wide transmission routes, and strong pathogenicity. Once an outbreak occurs, it can deal a devastating blow to a country or region's livestock industry, leading to huge direct economic losses and trade restrictions.

II. Epidemiology and Transmission

• Source of Infection: Mainly sick animals and infected animals during the incubation period. The virus is present in vesicular fluid, vesicular epithelium, milk, saliva, urine, feces, and semen.
• Transmission Routes:
• Direct Contact: Direct contact between healthy animals and sick animals.
• Indirect Contact: Transmission through contaminated vehicles, farming tools, feed, water sources, personnel (soles of shoes, clothing), air (aerosols, especially transmission from pigs to cattle in temperate regions), etc.
• Long-Distance Transmission: The introduction of animal products containing the virus (such as frozen meat, bones, offal) through international trade and personnel movement is a major risk for cross-border transmission of the epidemic.

III. Clinical Symptoms and Pathological Changes

Incubation Period: Usually 2-14 days.

Typical Symptoms:

• High Fever: Body temperature rises to 40-41°C.
• Vesicles and Ulceration in the Mouth and Hooves: Vesicles of varying sizes appear in the mouth (tongue, gums, cheeks), coronary band, interdigital space, and teats/udder. These vesicles rupture, forming erosions and ulcers.
• Salivation: Due to oral pain, affected animals salivate excessively, often forming strings of saliva.
• Lameness: Due to foot pain, animals are reluctant to stand or walk; in severe cases, the hoof horn may detach.
• Loss of Appetite: Due to oral pain, animals stop eating and rapidly lose body condition.

Mortality Rate and Impact: The mortality rate in adult animals is usually low (2%-5%), but young animals often suffer mortality rates as high as over 50% due to myocarditis ("tiger heart"). Surviving animals experience severely reduced productivity (sharp drop in milk yield, extended fattening periods, loss of draught ability), causing long-term economic losses.

IV. Economic Impact and Industry Shock

The outbreak of FMD has a comprehensive and devastating impact on the livestock industry:

Direct Losses:

• Animal deaths (especially young stock).
• Culling costs: To control the outbreak, large-scale culling of animals in infected zones and threatened zones is usually necessary.
• Decreased production performance: Losses in milk and meat production, reduced reproductive performance.

Indirect Losses and Trade Restrictions:

• International Trade Disruption: The World Organisation for Animal Health classifies member countries into different statuses such as "FMD-free country/zone" (with or without vaccination). Once an outbreak occurs, the export of all cloven-hoofed animals and their products (e.g., beef, pork, dairy products) from that country is immediately banned, resulting in enormous losses.
• Stagnation of Domestic Circulation: The movement of live animals and products between domestic regions is blocked, paralyzing the market.
• Industrial Chain Disruption: Affects a series of upstream and downstream industries such as feed industry, slaughtering and processing, dairy products, and the leather industry.
• Surge in Control Costs: Vaccination, quarantine, disinfection, surveillance, etc., require huge financial investment.

V. Prevention and Control Strategies

Global control strategies are mainly divided into two paths:

• Stamping-Out Policy:

Core: Rapidly cull all infected animals and exposed at-risk animals after an outbreak occurs, and carry out safe disposal.

Applicable Targets: Typically countries or regions that were originally disease-free, aiming to quickly eradicate the outbreak and restore disease-free status.

Key Measures: "Early, Fast, Strict, Small" (Early detection, Rapid response, Strict disposal, Minimal loss). Includes movement controls, epidemiological investigation, traceability, and strict disinfection. JG's rapid diagnostic solutions aid in the early identification of the FMD virus.

• Vaccination Policy:

Core: Establish immune protection within the animal population through large-scale, compulsory vaccination to reduce virus transmission and prevalence.

Applicable Targets: Widely used in FMD-endemic regions or countries with high risk.

The best practice often involves a combination of both: adopting a "Stamping-Out + Emergency Vaccination" strategy in high-risk areas or during the initial stages of an outbreak.

VI. Global Status and Industry Challenges

Global Distribution: FMD is endemic in most parts of Africa, Asia, the Middle East, and South America. Regions such as North America, Western Europe, and Australia are disease-free.

Major Challenges:

• Virus Variation: The continuous evolution of the virus requires timely updates of vaccine strains, posing extremely high demands on vaccine R&D and production.
• Cross-Border Transmission Risk: With deepening globalization, illegal smuggling of animal products and wildlife migration increase the risk of the disease being introduced into disease-free areas.
• Significant Economic Burden: For developing countries, sustained vaccination and surveillance systems represent a heavy financial burden.
• Biosecurity Gaps: Insufficient biosecurity awareness at the farm level is a weak link in epidemic prevention and control.