Published Date: 2022-03-30 11:40:14 BST
Subject: PRO/AH/EDR> Foot & mouth disease - Tunisia (03): cattle, goat, st O, topotype EA-3
Archive Number: 20220330.8702296
FOOT & MOUTH DISEASE - TUNISIA (03): CATTLE, GOAT, SEROTYPE O, TOPOTYPE EA-3
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Date: Thu 24 Mar 2022
Source: International Atomic Energy Agency (IAEA) [abridged, edited]
Earlier this year , a virology laboratory in Tunisia received the oral samples of cows suspected by veterinarians of having foot-and-mouth disease (FMD). Within days of submitting the samples to a genetic sequencing service, Soufien Sghaier, a virologist at the Virology Laboratory at the Institute of Veterinary Research of Tunisia (IRVT), received results that helped confirm the circulating strain of FMD. Sghaier was able to notify veterinary authorities to implement control measures to prevent the disease from spreading. The timely confirmation was made possible by the IAEA, in partnership with the Food and Agriculture Organization of the United Nations (FAO), which facilitates the sequencing service and provides the training needed to process the results.
"We received the sequencing results from an FMD suspicion very quickly. Samples were sent to a laboratory in Berlin on Friday, and we received the sequencing results on Monday afternoon," Sghaier explained. "This allowed us to perform an analysis to identify the specific strain of FMD in a record time: less than a week from receipt of samples. By Tuesday, we sent the report on the FMD strain to the veterinary authorities." The strain of FMD needs to be identified to select or develop an effective vaccine.
Genetic sequencing is important to determine if a circulating disease is endemic -- or typically found in a certain area -- or transferred from another region. "Genetic sequencing can help to understand which cluster a pathogen -- an organism that causes disease -- belongs to and which vaccine is effective against the pathogen," said Ivancho Naletoski, animal health officer at the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture. "Sequencing is also important in helping to identify the patterns of mutation of the pathogens." Based on genetic sequencing, a phylogenetic tree can be created, which maps the lineage of a species.
"With our phylogenetic analysis, we determined that we already had a vaccine that could protect our cattle. The veterinary authorities implemented perifocal vaccination to reduce the risk of FMD spreading," Sghaier said. Perifocal vaccination, or buffer vaccination, is implemented within a zone around the affected area to prevent spillover of the virus to other regions.
[Byline: Joanne Liou]
[Cattle and goats have been reported as affected during the current epizootic (see PRO/MENA archives 20220124.8701028 and 20220202.8701207).
According to the Tunisia page on the website of the World Reference Laboratory FMD (WRLFMD), FMDV serotype O has been reported for the following years: 1970, 1975, 1989-1990, 1994, 1999, 2014, 2018, and 2019 (https://www.wrlfmd.org/north-africa/tunisia).
Genotyping, performed by WRLFMD since 2014, revealed that the 2014 FMD-O epizootic was caused by topotype ME-SA, lineage Ind-2001, sublineage d. The FMD-O samples collected during December 2018 and January 2019 were identified as topotype EA-3 (East African). Detailed genotyping results, as well as vaccine-matching test results pertaining to the said topotype, are conveniently available at https://www.wrlfmd.org/sites/world/files/quick_media/WRLMEG-2019-00020-TUN-GTR-O-O_001.pdf.
Recent complementary information for the 2022 event can be derived from the presentation "Update on the FMD situation representing a major risk for the EU" dated 20 Feb 2022, published by EuFMD (European Commission for the Control of Foot-and-Mouth Disease). The presentation is available at https://ec.europa.eu/food/system/files/2022-02/reg-com_ahw_20220210_fmd_eur.pdf. According to the map on slide 7, the FMDV serotype O strain, causing the 2018/2019 and the 2022 outbreaks, have been genotyped EA-3. It would be helpful to obtain additional information on the 2022 strain, including its vaccine-matching data and phylogenetic tree (dendogram). - Mod.AS
ProMED map of Tunisia: https://promedmail.org/promed-post?place=8702296,71]