Published Date: 2023-04-10 19:55:06 BST
Subject: PRO/AH> Foot & mouth disease - Libya (03): livestock, st O, tt EA-3, RFI
Archive Number: 20230410.8709432
FOOT & MOUTH DISEASE - LIBYA (03): LIVESTOCK, SEROTYPE O, TOPOTYPE EA-3, REQUEST FOR INFORMATION
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Date: Sun 9 Apr 2023
Source: National Centre for Animal Health - Libya [in Arabic, trans. Mod.SF, abridged, edited]
https://www.facebook.com/photo/?fbid=550021877277834&set=a.270452858568072
Spread of FMDV serotype O
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Number of infected farms recorded since the start of 2023: Tobruk (1); Tripoli (1); Bayda (2); Al Marj (01); Misrata (03); Djeffara (05); Al Swani (02); An-Najila (01); Darnah (01); Sabratha (01)
Quantitative data summary
Species / Susceptible / Cases / Deaths
Cattle / 871 / 160 / 27
Sheep / 12 908 / 570 / 112
The serotype has been identified (O) and samples were sent to the FMDV reference laboratory -- Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna (IZSLER) -- for topotyping. Results were received. The sequencing analysis followed by phylogenetic analysis confirmed the presence of serotype O which belongs to the EA-3 topotype. This topotype was previously detected in Libya in 2019.
Cattle were vaccinated in 2021. The evaluation of the vaccine was done and it gave a positive result.
The BLAST analysis showed that the most closely related viruses are O/EGY/21/2017 (OM221225.1) and O/EGY/33/2017 (OM221221.1), with 94.8% identity.
Measures in progress:
- Initiation of procedures to import a vaccine
- Ban on animal movements and strengthening of controls
- Capacity building of veterinary services through continuing education
--
Communicated by:
ProMED-MENA
[Between 8 Mar and 4 Apr 2023, 13 FMDV outbreaks (serotype O) have been officially reported to WOAH as follows:
7 outbreaks in the eastern region (see https://wahis.woah.org/#/in-review/3835?reportId=160279) and 6 outbreaks in the western region (https://wahis.woah.org/#/in-event/4990/dashboard). Clinical signs have been observed in sheep, goats, and cattle.
Serotype O causes more than 60% of outbreaks worldwide. It includes 11 topotypes: East Africa 1 to 4 (EA-1 to -4); Southeast Asia (SEA); Europe-South America (EURO-SA); Indonesia-1 and -2 (ISA-1 and -2); CATHAY; South Asia and Middle East (ME-SA); and West Africa (WA). These topotypes are further divided into different genotypes (https://www.foot-and-mouth.org/FMDV-nomenclature-working-group/prototype-strains).
The antigenic diversity of the FMD virus is a major concern. Regular vaccine matching and strain selection studies are indispensable for disease control. The information regarding the topotype provided in the report above is crucial for the adaptation of the vaccination strategy in Libya and its neighboring countries.
An FMD vaccine matching strain differentiation report for 2017 and 2016 Egyptian field isolates is available at https://www.wrlfmd.org/sites/world/files/WRLFMD-2017-00014-EGY-VMR-O-multiple_001.pdf). - Mod.SF
The FMD event in Libya's eastern region (event ID 3835), had started, according to WAHIS reports, in June 2021; 3 outbreaks were reported during 2021; their diagnosis was followed by vaccinations, likely applying vaccines targeting FMDV serotype O, topotype ME-SA (known to be involved in the 2019 event). No outbreaks were recorded during 2022 when mass vaccinations were applied. On 20 Feb 2023, new cases of FMD were suspected, causing the sudden death of young calves kept in dairy farms in the regions of Al-Bayda - Tobruk - Al-Marj. They were initially considered a continuation of the 2021 event and reported as such to WOAH. Blood samples, collected from the affected herds, were tested by the National Veterinary Laboratory in Tripoli. ELISA tests for the detection of antibodies against non-structural proteins (NSP ELISA) were found positive, indicative of infection, irrespective of vaccination status. On 4 Apr 2023, the Brescia reference laboratory published the topotyping results.
"Historically, Libya encountered numerous FMDV incursions. Overall, 3 different serotypes have circulated: O, A, and SAT2. Type O is the most prevalent serotype, followed by serotype A. In 2012 FMDV O/EA-3 topotype was found to co-circulate with ME-SA topotype PanAsia-2 lineage ANT-10 sublineage. Those EA-3 strains were more closely related with eastern Africa strains (that is, Ethiopia and Sudan) while the 2019 incursion was more correlated with strains circulating in the Maghreb from a western Africa route."
(https://doi.org/10.3390/ani12223198)
Notably, Tunisia suffered an incursion of FMDV st O, topotype EA-3 in 2022 (20220330.8702296).
The possibility of current co-circulation of FMDV topotypes ME-SA and EA-3 in Libya warrants confirmation or otherwise. This relates to both events - ID 3835 in the east and ID 4990, the new event in the West. Information from knowledgeable sources in the area will be appreciated. - Mod.AS
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Libya: https://promedmail.org/promed-post?place=8709432,68]