What Is SAT-2 Type Foot and Mouth Virus and How Is It Detected?
Affecting cattle, pigs, sheep, and various cloven-hoofed wildlife species, foot-and-mouth disease (FMD) is one of the most economically important viral infections of livestock in the world. With the recent outbreak caused by the SAT-2 serotype of the foot and mouth disease virus (FMDV) in Turkey, national and global authorities are once again urging caution against the symptoms of foot-and-mouth disease (FMD) with an emphasis on the importance of early detection, efficient surveillance, vaccination, and infection management measures. Read along to learn more about the foot and mouth disease virus (FMDV), its symptoms, and its detection.
What Is Foot and Mouth Disease (FMD)?
Foot and mouth disease (FMD) is a highly contagious vesicular disease caused by the foot and mouth disease virus (FMDV). Foot and mouth disease virus (FMDV) is a non-enveloped positive-sense RNA virus of the genus Aphthovirus in the family Picornaviridae. The virus has seven major serotypes with significant genetic and epidemiological differences: O, A, C, SAT-1, SAT-2, SAT-3, and Asia-1. These serotypes are endemic in different countries around the world, and each requires a specific vaccine. Once it enters the body, foot and mouth disease virus (FMDV) quickly becomes present in all excretions and secretions of the infected animal, including saliva, milk, and semen. The virus can easily spread through various routes within the herd or the flock. Transmission may involve contact with an infected animal’s secretions, meat, and products. Notably, infected animals can also breathe out significant amounts of aerosolized virus, which can infect other animals via air currents. Finally, the virus can transmit through contaminated pens, buildings, vehicles, materials, clothing, and equipment.
Foot and mouth disease (FMD) is common across Asia, Africa, the Middle East, and certain regions of South America. Altogether, the infection is estimated to circulate in around 77% of the global livestock population. While foot and mouth disease (FMD) is not readily transmissible to humans and does not pose a public health risk, it has become the first disease for which the World Organization for Animal Health (WOAH) established official status recognition due to its grave impact on the production and trade of animals and animal products.
What Are the Symptoms of Foot and Mouth Disease (FMD)?
Clinical signs of foot and mouth disease (FMD) may range from mild or inapparent to severe depending on the infected species, the exposure dose, the health and immunity status of the host, or the responsible serotype. While the morbidity rate can reach 100% in susceptible populations, it is generally limited to around 1 to 5% in adult animals. In younger animals, on the other hand, the disease may lead to a morbidity rate of 20% or above. Following an incubation period of 2 to 14 days, the disease often presents with blisters on the nose, tongue, and lips, inside the oral cavity, between the toes, above the hooves, on the teats, and at pressure points on the skin. The rupture of these blisters can lead to lameness and reluctance to move or eat. Although these blisters typically heal within a week, complications such as secondary infections can prolong the process. In addition to the development of blisters, the infected animals can present with fever, depression, hypersalivation, loss of appetite, weight loss, growth retardation, and a drop in milk production. In fact, chronically infected animals have been reported to have a reduction of around 80% in milk yield.
How Is Foot and Mouth Disease Virus (FMDV) Detected?
Early detection, efficient surveillance, and warning systems are critical for preventing and managing foot and mouth disease (FMD). Moreover, as foot and mouth disease (FMD) cannot be clinically differentiated from other vesicular diseases such as swine vesicular disease, vesicular stomatitis, and vesicular exanthema, diagnostic devices are often used for the determination of the infection status through the detection of the pathogen-specific antigens or nucleic acids. Enzyme-linked immunosorbent assays (ELISA), lateral flow devices (LFD), reverse transcription polymerase chain reaction (RT-PCR) assays, and virus isolation are currently among the most common methods for the detection of foot and mouth disease virus (FMDV). In addition, serological assays based on antibody detection are also used to detect prior or past infection with the foot and mouth disease virus (FMDV) in non-vaccinated animals.
What Are the Main Precautions Against Foot and Mouth Disease Virus (FMDV)?
The traditional method of infection prevention and management against foot and mouth disease (FMD) in the affected areas often involves the inhibition of the travel and trade of animals or animal products. In addition, the infected and contact animals are slaughtered, carcasses are safely disposed of, and the environment is disinfected to prevent further transmission. Ring vaccination can also be performed to create a buffer zone. In regions where vaccination is performed, it should be ensured that the vaccine contains the serotype circulating in the affected area. As foot and mouth disease virus (FMDV) often changes during transmission among various species, the serotype should be checked frequently to enable maximum vaccine efficacy throughout an outbreak.