Emergence of Foot-and-Mouth Disease Virus SAT2 Topotype XIV in Western Asia

 

Dr. Majed Hamed Al Saegh / poultry pathologist / Australia

 

Overview : A recent study has revealed the emergence of the SAT2 Topotype XIV strain of Foot-and-Mouth Disease Virus (FMDV) in Western Asia during 2022–2023. This strain was previously confined to Eastern Africa, but its detection in several countries indicates a potential risk of spreading to new regions. The emergence of this strain is linked to the importation of animals from Africa, along with the absence of appropriate preventive vaccination for this type of virus.

 

Outbreak and Spread:  The first cases of the SAT2/XIV virus were reported in buffalo in Baghdad, Iraq, in December 2022. Genetic analysis conducted in Turkey confirmed that this strain was not native to Western Asia but originated from Eastern Africa. With increased surveillance efforts, the virus’s spread was tracked, and by January 2023, new cases were recorded in Bahrain, Jordan, and Oman. The virus continued to spread, reaching Eastern Anatolia in Turkey in March 2023, before later moving to Central Anatolia and the Adana provinces, indicating a possibility of this strain becoming endemic in the region if precautionary measures are not taken.

 

Genetic Analysis and Origins To verify the origins and spread of the SAT2/XIV strain, whole-genome sequencing was conducted on 49 samples collected from Ethiopia, Iraq, Jordan, Bahrain, Turkey, and Oman. The analysis confirmed that the virus likely originated from Eastern Africa, particularly Ethiopia, and was introduced to Western Asia multiple times. A significant genetic match was found between Ethiopian and Iraqi samples, suggesting that livestock trade may have played a key role in the outbreak.

 

A time-scaled phylogenetic analysis indicated that the most recent common ancestor (MRCA) of the SAT2/XIV strain dates back to April 1991, suggesting that the virus had been circulating undetected in Africa before its recent emergence. The study also found genetic similarities between Iraqi and Turkish samples, indicating that the virus spread from Iraq to Turkey. Interestingly, the Jordanian cases were genetically distinct, suggesting a separate introduction event.

 

Potential Contributing Factors to Spread:  The study identified several factors that may have contributed to the spread of the SAT2/XIV virus in Western Asia:

• Trade and livestock movement: Informal livestock trade between Eastern Africa and Western Asia, especially during Eid al-Adha, may have played a role in introducing infected animals.
• Grazing practices: Shared grazing areas and the absence of effective quarantine measures may have facilitated virus transmission, as infected animals can remain carriers for extended periods.
• Natural virus reservoirs: The virus may have been maintained in African buffalo populations, serving as a long-term source of transmission before emerging in livestock.
• Weak veterinary quarantine systems: In some of the affected countries, there were no strict measures in place to monitor imported animals, leading to increased risks of spread.

 

Diagnosis and Vaccine Response Researchers developed a real-time reverse transcription PCR (RT-PCR) assay to detect the SAT2/XIV strain and distinguish it from other circulating FMDV serotypes. In vaccine compatibility studies, FMD vaccines (SAT2 Eritrea 98 and SAT2 ZIM 83) provided partial protection against SAT2/XIV. However, there is limited data on vaccine efficacy against this strain, underscoring the need for further research.

 

Study results indicated that immune responses were not strong enough to completely prevent virus transmission, necessitating further trials to develop more effective vaccines tailored to this emerging strain.

 

Biological Challenges and Control Measures:  The incursion of SAT2/XIV into Western Asia presents a significant biosecurity challenge. If the virus continues to spread, it could become endemic, affecting livestock production and regional trade. The study recommended the following measures:

• Enhanced surveillance and monitoring: Strengthening genetic surveillance to track new outbreaks and ensuring prompt reporting of new infections.
• Improved biosecurity measures: Implementing stricter livestock import regulations and quarantine protocols to prevent the entry of new virus strains.
• Vaccination strategies: Developing specific vaccines to protect against SAT2/XIV and conducting trials to assess their effectiveness in controlling transmission.
• International cooperation: Strengthening partnerships between veterinary authorities in Eastern Africa and Western Asia to improve disease control efforts and exchange information on prevention and response strategies.
• Veterinary and agricultural awareness: Increasing awareness campaigns for farmers and livestock breeders on the importance of early detection and reporting of suspicious symptoms.

 

Conclusion : The detection of SAT2/XIV in Western Asia represents a significant epidemiological event, emphasizing the need for proactive surveillance, targeted vaccination, and improved trade regulations. Through continued monitoring and effective intervention, the spread of this foreign FMD strain can be mitigated, preventing further economic and agricultural disruptions in the region. Additionally, coordination between affected countries and the implementation of strict veterinary policies could be key to controlling future outbreaks.