Foot and Mouth Disease (FMD) is a highly contagious viral disease affecting cloven-hoofed animals including cattle, sheep, goats and pigs. While mortality rates are low, the disease has severe economic impacts on the livestock industry worldwide. In this article, we discuss the available FMD vaccines and their importance in preventing outbreaks of this disease.

 

What is Foot and Mouth Disease?

 

Foot and mouth disease (FMD) is caused by an RNA virus from the Aphthovirus genus. It mainly affects cattle, sheep, goats, pigs and other cloven-hoofed animals. The disease is characterized by fever and vesicles (blisters) in and around the mouth and on the feet. While mortality rates are low, infected animals stop eating and lose weight rapidly. In acute cases, weight loss of up to 10% of the live weight of the animal within a week has been reported. This leads to severe economic losses for farmers.

 

FMD is endemic in parts of Africa, Middle East and Asia. Even though vaccination programs are in place, sporadic outbreaks continue to occur. Countries like the UK and Argentina had to face devastating epidemics in 2001 and 2001 respectively despite being FMD free for decades. The disease spreads rapidly through direct contact between infected and susceptible animals as well as contact with contaminatedenclosures, vehicles, clothing and equipment.

 

Available Foot and Mouth Disease Vaccines

 

There are two main types of vaccines used globally – the chemically-inactivated vaccines and the live-attenuated vaccines.

 

Chemically-inactivated vaccines: These are the most widely used vaccines globally. They contain inactivated or killed Foot and Mouth Disease Vaccine virus grown in cell culture. Popular brands include Polyvalent FMD oil-adjuvanted and water-based vaccines from multiple manufacturers. These provide solid protection for up to a year against circulating strains when given as per schedule. However, they require good cold chain maintenance.

 

Live-attenuated vaccines: These vaccines contain a live but weakened strain of the virus. Popular brands are the TAD vaccine from Merial and Apollo vaccine from Indian Immunologicals. They provide lifelong immunity after one or two doses. However, handling requires good biosafety practices to prevent transmission from vaccinated animals.

 

Both vaccine types are trivalent or hexavalent, protecting against three or six prevalent serotypes in a region. Anti-sera tests help monitor antibody response and determine next booster schedule individually or for a herd. Factors like animal species, age, immune status, strain circulation influence vaccine selection in different geographies.

 

Importance of Foot and Mouth Disease Vaccines

 

FMD vaccines play a vital role at multiple levels:

 

- Protection of livestock: Regular vaccination builds up herd immunity and protects susceptible animals from the severe effects of the disease. This saves livelihoods of smallholder farmers.

 

- Control of outbreaks: Strategic mass vaccination programs around infected zones help contain andlocalize outbreaks. countries often vaccinate all susceptible animals country-wide during epidemics.

 

- International trade: Many countries demand proof of regular vaccination to allow import of livestock and their products from endemic areas. This is a non-tariff barrier affecting billions in trade.

 

- Disease eradication: Long-term vaccination in combination with movement controls and zoning has helped some regions like South America and large parts of Europe become FMD free. However, sporadic outbreaks necessitate continued vigilance.

 

- Food security: Protecting cattle, goats and pigs from FMD impacts milk and meat production. Over 175 million livestock depend on vaccines globally each year. This indirectly supports food and nutrition security.

 

- Poverty alleviation: Livestock keeping is an important livelihood for millions of small farmers worldwide. FMD vaccines safeguard these assets which are key to their socioeconomic development.

 

In summary, FMD vaccination programs underpin progressive control of the disease at national and international levels. Continued innovation to further develop new generation vaccines is essential to combat this challenging pathogen.

 

Challenges in Foot and Mouth Disease Control

 

While FMD vaccines provide solid protection when used appropriately, breaking transmission chains of the virus completely remains challenging due to factors like:

 

- Antigenic variation: The virus has seven distinct serotypes with multiple subtypes circulating worldwide. Cross-protection between types is limited requiring frequent vaccine composition updates.

 

- Resource constraints: In developing countries, funding constraints often limit optimum vaccine coverage and cold chain maintenance impacting program efficacy.

 

- Poor implementation: Logistical issues in remote rural settings where majority livestock reside affect timely administration of recommended booster doses.

 

- Reservoir hosts: Wildlife like buffalo and warthog act as virus reservoirs in Africa complicating eradication efforts even in vaccinated populations.

 

- Globalization: International/regional trade and movement of animals/people spread the virus over long distances, offsetting control in previously free areas.

 

- Diagnostic challenges: Atypical clinical signs in vaccinated herds and presence of carrier animals require highly sensitive modern tests for early outbreak detection.

 

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