Model Answer
0 min readIntroduction
Foot and Mouth Disease (FMD) is a highly contagious viral disease affecting cloven-hoofed animals, including cattle, sheep, goats, and pigs. It poses a significant threat to global livestock industries, causing substantial economic losses due to decreased productivity, trade restrictions, and control measures. The disease is characterized by the development of characteristic vesicles (blisters) on the feet and mouth, and is transmitted primarily through direct contact and aerosol spread. Recent outbreaks in several countries underscore the continued importance of understanding and mitigating this disease. This answer will detail the various facets of FMD, focusing on its impact on cattle.
Etiology
FMD is caused by the Foot and Mouth Disease Virus (FMDV), belonging to the Aphthovirus genus within the Picornaviridae family. There are seven serotypes (O, A, B, C, D, E, and SAT) and numerous topotypes (variants within each serotype). The virus is non-enveloped, single-stranded RNA virus.
Epidemiology
FMD is endemic in many parts of the world, particularly in Africa, Asia, and South America. It is notifiable under the World Organisation for Animal Health (OIE) regulations. The virus spreads rapidly through animal movement, contaminated feed and water, and even through the air over considerable distances (up to 100 km under favorable conditions). The seasonal patterns of FMD outbreaks are often linked to weather conditions that favor virus survival and transmission. STATISTIC: According to the FAO, FMD causes an estimated annual economic loss of US$20 billion globally (Knowledge cutoff - May 2023).
Pathogenesis
Following infection, the virus replicates rapidly in the oropharynx and hoof tissues. This replication damages epithelial cells, leading to vesicle formation. The vesicles rupture, releasing the virus and contributing to its spread. The host's immune response is relatively weak, allowing for persistent viral shedding. The pathogenesis is primarily localized but can lead to systemic infection in young or immunocompromised animals.
Symptoms
Symptoms in cattle vary depending on age, serotype, and immune status. Common signs include:
- Fever (39.5-42°C)
- Depression
- Loss of appetite
- Salivation (foaming at the mouth)
- Vesicles on the tongue, gums, palate, feet, and udder. These vesicles rupture easily, leaving painful ulcers.
- Lameness due to foot lesions
- Reduced milk production
Postmortem Lesions
Gross postmortem lesions in cattle with FMD typically include:
- Erosions and ulcers in the oral cavity
- Raised, healed vesicles on the feet (often appearing as "clotted blood")
- Enlarged, congested lymph nodes
- Pulmonary edema (in severe cases)
Histologically, there is epithelial necrosis and viral replication within the affected tissues.
Diagnosis
Diagnosis relies on a combination of clinical signs, epidemiological history, and laboratory testing. Common diagnostic techniques include:
| Method | Advantages | Disadvantages |
|---|---|---|
| Virus Isolation | High sensitivity | Time-consuming (requires specialized facilities) |
| RT-PCR | Rapid, sensitive, and specific | Requires trained personnel and expensive equipment |
| Serological Tests (ELISA, VN) | Detects antibodies, indicating past or present infection | Cannot differentiate between active infection and past exposure |
Control
Control strategies focus on preventing introduction and spread, and reducing the severity of outbreaks.
- Movement Controls: Strict restrictions on animal movement are crucial.
- Quarantine: Infected farms and animals must be quarantined.
- Culling: In some cases, culling of infected and in-contact animals may be necessary.
- Vaccination: Vaccination is the primary preventative measure. Inactivated vaccines are commonly used. Booster vaccinations are required. Vaccination strategies need to consider the circulating serotypes and topotypes.
- Biosecurity: Strict biosecurity measures on farms, including disinfection of vehicles and equipment, and limiting contact with other animals.
- Surveillance: Active surveillance programs to detect outbreaks early.
- Public Awareness: Educating farmers and the public about FMD and its prevention.
SCHEME: The Department of Animal Husbandry and Dairying, Government of India, implements various schemes like the National Animal Disease Control Programme (NADCP) to control FMD and other diseases. The NADCP aims to eradicate FMD and Brucellosis in India by 2030.
EXAMPLE: The FMD Control Programme in India utilizes a combination of vaccination and surveillance to minimize outbreaks.CASE STUDY: The 2001 FMD outbreak in the UK resulted in the culling of millions of livestock, costing the UK economy billions of pounds. This highlighted the devastating economic consequences of FMD and the importance of rapid and effective control measures.
Conclusion
Foot and Mouth Disease remains a significant global challenge, demanding constant vigilance and robust control measures. Understanding the etiology, epidemiology, pathogenesis, and diagnostic techniques is paramount for effective management. A multi-pronged approach encompassing movement controls, quarantine, vaccination, and biosecurity, supported by government initiatives and public awareness, is crucial to mitigate the impact of FMD on livestock industries and economies. Continued research into improved diagnostics and vaccines is essential for long-term control.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.