Biosecurity practices in livestock farms for prevention and control of Foot and Mouth Disease

Biosecurity practices in livestock farms for prevention and control of Foot and Mouth Disease

Aditya Prasad Sahoo, Basavaraj Sajjanar, Sabarinath Thankappan, Gnanavel Venkatesan

Introduction:

Foot-and-mouth disease (FMD) is one of the most serious and highly contagious viral animal disease that affects animals with divided hooves like cattle, sheep, buffalo, goat, pig, deer and camelids. In India, FMD is one of the most common disease of livestock which hamper livestock production leading to huge economic loss. There are several economic losses due to FMD such as value of milk lost, loss of draught power, costs of treatment and death in young calves. In addition, there are indirect losses due to the non-acceptance of milk and milk products, meat and skin of affected animals. FMD spreads rapidly and often, entire herds can get infected within 2-3 days. Cattle is the most susceptible host while pigs spread the disease fastest. FMD is not transmitted to humans by eating milk or meat of infected animals. FMDV pose negligible threat to human health. Although few animals die from FMD, it has significant effects on animal welfare and production.

How to identify FMD affected animals

Animals infected with FMD initially show fever, drooling of saliva and reluctance to move. Fluid filled blisters (vesicle) appear on the lips, tongue, palate, between and above the hooves on the feet and teats. These blisters eventually burst exposing raw, painful ulcers.

FMD in cattle: Fever (up to 41°C), difficulty while eating, drastic reduction in milk yield. Vesicles develop in mouth, claws and coronary band lead to smacking of lips, drooling of saliva, lameness and stamping or kicking of feet.

FMD in sheep and goats: Fever, lameness, mouth and foot lesions are usually mild and mostly goes unnoticed. Death of young animal without any visible clinical signs.

FMD in pigs: Fever, severe foot lesions and lameness, with detachment of the claw horn, vesicles on snout, pressure points of limbs and abortion.

How FMD spreads

FMD virus is excreted in breath, saliva, mucus, milk and faeces of infected animals. FMD spreads rapidly from one animal to another, through inhalation, ingestion and direct contact with infected animals. Infected animal begins excreting virus even before clinical signs appear, making the disease difficult to control. When animals are housed closely together, FMD might have already infected most of the animals in a herd by the time it is detected. Hence, animals should be checked regularly for appearance of clinical signs. The disease spreads between farms most commonly through the movement of infected animals especially in cool, damp climates. The movement of infected sheep and goat can be an important source of infection since in these animals’ symptoms can be absent or very mild, and mostly goes unnoticed. FMD virus can also be spread on wool, hair, meat, milk, grass or straw, by the wind, by mud or manure sticking to footwear, clothing, vehicles tyres and equipment used with infected animals. It can also be carried on people’s clothing and footwear. Pigs are highly susceptible to oral infection if they are fed contaminated meat or meat products. Pigs act as ‘amplifying hosts’ because they can excrete very large quantities of the virus in their exhaled air. Cattle are highly susceptible to infection by inhalation of the virus. Farms with mixed-husbandry practices of rearing cattle, buffaloes, sheep, goats and pigs together provides a favourable condition for FMD spread.

Prevention and control of FMD

Management is a key factor in the prevention and control of disease to minimize the introduction and spread of FMD in the farm. Animal contact (within and between species), animal products, manure, water, feed and environmental sources are among the several risk factors related to spread of the disease. A better understanding the means by which FMD spread on the farm is critical for disease prevention. Strong biosecurity practices on farm are crucial to protect animals from infectious diseases like FMD. A biosecurity plan should be always ready to control the movement of animals, people, equipment and vehicle onto farm premises. The FMD control measures include strict biosecurity practices, vaccination, segregation of infected and in-contact animals, restriction on animal movement, cleaning and spraying of disinfectant in affected premises equipment and vehicles.

Biosecurity practices in farms for FMD prevention and control 

Biosecurity is a set of practices that are implemented to stop the spread or introduction of harmful pathogen or disease onto farm premises. Biocontainment practices are critical in preventing spread of disease among animals already present in the farm apart from preventing large scale loss when biosecurity is breached. Almost anything moved onto farm can be a potential source of infection hence strict monitoring is crucial. While designing the biosecurity protocol actual plan should be designed based on the existing available facilities. Principles of biosecurity measures primarily involve three steps such as segregation, cleaning and disinfection.

1. Segregation is a practice of keeping the diseased animal in a separate and isolated place to prevent spreading of the disease to healthy animals. It is often the first and one of the most effective biosecurity steps after animal infected with FMD because virus cannot be spread unless it come into contact with healthy animals.
2. Cleaning is the removal of dirt with soap or detergent from floor, footwear, equipment and vehicle. It is crucial to clean all the visible dirt before disinfection because inorganic and organic materials that remain on the surfaces interfere with the efficacy of disinfectant.
3. Disinfection kills all the virus on the surface hence prevent the spreading. Before disinfection, all surfaces must be cleaned. Disinfectant cannot kill virus hide under the layers of dirty surface. The effectiveness of disinfection can be improved by ensuring sufficient contact time with the surface and using the recommended concentration of disinfectant. A number of commercial disinfectants like citric acid (0.2%), FAM (30%), Virkon (1%) are effective to kill FMD virus. Disinfectants mixed with water are easily get evaporated in direct sunlight, hot and windy conditions thus will not be completely effective unless disinfected for a second time. Care must be taken while choosing appropriate disinfectant as many disinfectants are corrosive and damage equipment.

Disinfectants recommended to sanitize FMDV infected premises

(Source: United States Department of Agriculture)

Biosecurity guidelines
  In order to ensure the biosecurity of a farm, a protocol must be developed and followed strictly.

1. Segregate/quarantine sick animals from the healthy animals to minimize spread of disease. It can take as long as 14 days to appear clinical signs of disease in FMD exposed animals. Hence, segregation should be up to 28-30 days (which equals two incubation periods for FMD).
2. Animal movement between farm and within farmmust be carefully controlled.
3. Visitors should be restricted to access the critical areas where animals are housed, feed is stored and handled. They should be aware of the importance of good sanitation and biosecurity.
4. Do not allow farm workers to handle animals if they come from a foot-and-mouth disease (FMD) infected village.
5. Biosecurity signage with clear instructions should be placed at farm entry and exit point.
6. Arrange facilities for washing and disinfecting shoes, clothing, equipment and vehicles that enter farm premises.
7. Foot baths are a useful and inexpensive method to clean footwear before entering and exiting a farm. Set up a foot bath at entry point of farm and provision to clean footwear at entry point of farm.
8. Record movements, vaccination status and disease status of animals.
9. All new animals should be isolated for up to two weeks before allowed to house with existing animals.
10. Farm workers and animal handlers should be encouraged to wear gun boot which are easy to clean and helpful in muddy conditions of farm.
11. Educate and train farm staff about FMD for any signs of disease like blister or ulcers on the mouth, tongue, feet or teats, profuse salivation, refusal to eat and move etc. Contact local veterinarian if any sign of sickness is noticed.
12. Record all vehicle movements onto farm and ensure vehicle tires are free from mud, soil and manure. Clean and disinfect the vehicle before entry and exit, particularly the tyres and wheel. Ensure all vehicles are parked in a designated area.
13. To prevent the spread of disease spray 4% sodium carbonate solution (400gm sodium carbonate in 10 liters of water), lime, bleaching powder in animal shed and the surrounding of the infected shed.
14. If possible, use separate facilities, equipment and staff to handle sick animals. It is recommended to visit the sick animals last.
15. The young animal should always be attended first, followed by the older animal.
16. Clean and disinfect all equipment, clothing, boots, etc. that come into contact with sick animals.
17. Clear demarcation to be made for of the clean and dirty area inside farm.

Reference:

1. World Organisation for Animal Health (2022). Terrestrial Animal Health Code. OIE, Paris.
2. OIE Terrestrial Manual Chapter 2.1.5. Foot and Mouth Disease
3. Alexandersen, S., Quan, M., Murphy, C., Knight, J., Zhang, Z. (2003). Studies of quantitative parameters of virus excretion and transmission in pigs and cattle experimentally infected with foot-and-mouth disease virus. J. Comp. Pathol. 129, 268–82.
4. Harada, Y., Lekcharoensuk, P., Furuta, T., Taniguchi, T. (2015). Inactivation of Foot-and-Mouth Disease Virus by Commercially Available Disinfectants and Cleaners. Biocontrol Sci. 20, 205–8. doi:10.4265/bio.20.205.
5. Jamal SM, Belsham GJ. (2013). Foot-and-mouth disease: past, present and future. Veterinary Research, 44:116.
6. Paton DJ, Gubbins S, King DP. (2018). Understanding the transmission of foot-and-mouth disease virus at different scales. Current Opinions in Virology 28:85-Department of Agriculture, Forestry and Fisheries, and CSIRO (2019). Emergency animal diseases: A field guide for Australian veterinarians, Canberra, August.

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