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Tilapia Farming In England And Wales And The Occurrence Of Francisella Sp

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By Keith Jeffery, Cefas.

By Keith Jeffery, Cefas.


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  • 1. Tilapia farming in England and Wales and the occurrence of Francisella sp. Keith Jeffery 18th June 2009 Tilapia workshop Barnsdale, Rutland.
  • 2. Early development in the 1990s •Early farms (1990s) < 10 tonnes •Recirculation / warm water discharge sites •Research institutes & Colleges
  • 3. Recent development since 2002 •One major player building systems •On-growing & supplying fry •Purchasing fish back for processing •Sites built for 50 – 400 tonnes production •Approximately 12 sites built
  • 4. Current status •13 farms mostly Independents •Several mothballed systems •Potential 1000 tonnes plus production ? •Stirling University initiative •Most fry still imported •UK hatchery now exists
  • 5. Disease Investigation Early 2008 Fry losses (0.5g to 5g) @ approx 20% External • Flashing, fungal patches, exophthalmia, pale gills petechial haemorrhaging around pectoral fins, lethargy. Internal • Empty intestines, enlarged gall bladder, some enlarged granular spleens and one or two enlarged kidneys. Water quality readings provided appeared OK. 23.9 C Fibreglass tanks > Concrete tanks >suspended hapas in raceways. Bead filters, (No UV or Ozone)
  • 6. Sampling - January 2008 • Live fish for Parasitology • Bacteriology - TSA – RIVAOA • Virology – Spleen, Kidney & Brain > Transport medium – FH’s, CHSE’s, SSN, BF & EP’s & 20 & 25C • Histology – Kidney, spleen, gill, liver, intestine, heart, eye, skin, muscle & Whole fish > NBF.
  • 7. Results January 2008 • Negative for Parasitology,Bacteriology, Virology Granuloma Histology • Lesions present in most tissues of all fish. • Host response was Granuloma formation of granulomas. • Parasites and other pathologies not seen Images from spleen tissues
  • 8. Results January 2008 (cont) • Reminiscent of mycobacterium Bacteria • Re-cuts & ZN staining = no acid fast bacteria Granuloma • Some gram –ve bacteria associated with granulomas. • Necrotic material and macrophage aggregates (melanin) visible. Presumptive positive for Francisella sp.
  • 9. Further Sampling ? Literature search • Francisella topical in Cod farming (Cefas north sea wild cod ) • Some papers on Tilapia + other species • Google F. tularensis = Human pathogen ? Bio-weapons? Second sample • Bacteriology – CHA & SKDMs • Histology – Kidney, spleen, gill, liver, intestine, heart, eye, skin, muscle & Whole fish (NBF) • Molecular biology - Spleen, Liver, Heart & whole fry (Ethanol) and onto ice. • Additional samples for Health Protection Agency
  • 10. Results – Second sample • Additional sample = no evidence of Francisella tularensis • Bacteriology –culture of the organism unsuccessful. • Histology – Granulomas in the spleens of affected fish • Newly imported fry showed N.A.D. Molecular biology • Products obtained from several fish
  • 11. Results – Second sample • 406 base Sequence obtained • BLAST at NCBI • 100% nucleotide identity with a Francisella species previously described in tilapia. Positive for Francisella sp.
  • 12. Unrooted phylogenetic tree, (Neighbor-Joining method) Francisella sp.DQ007456 Tilapia, Taiwan Francisella sp. AY928389 Tilapia, Taiwan Asian Francisella sp. Tilapia, Taiwan Francisella sp AY928393Tilapia, Taiwan subgroup 100 Francisella sp. AB194068 three-line grunt ,Japan Francisella sp. AF385857 Tilapia, C. America 91 Francisella sp. AY928388 Tilapia, Taiwan F. piscicida AM403242 Chile salmon F. piscicida EF685350wild cod 99 F. piscicida GM2212T farmed cod DQ309246 100 F. piscicida cod EF685349 European cod F. philomiragia subsp.noatensis DQ295795 subgroup F.piscicida EF685351wild cod F. philomiragia ATCC 25015 AY928394 73 F. philomiragia AY243027 F. philomiragia DQ314206 F. philomiragia AY496933 F. endosymbiont AY805306 100 F. endosymbiont AY805305 Ornithodoros moubata symbiote B AB001522 F.tularensis subsp. novicida AY968238 94 F.tularensis subsp. holoarctic AY968228 F. tularensis subsp. tularensis AY968225 F. tularensis subsp. novicida AY968237 F.tularensis subsp. holoarctica AY968229 F.Tularensis subsp novicida AY928396 F. tularensis subsp mediasiatica AY968236 F. tularensis subsp. mediasiatica AY968235 0.001
  • 13. Consequences for farmer and industry sector Voluntary cull & disinfection by farmer Site now sourcing from a single European hatchery site Two further +ve samples A problem in re-circs (Heish, pers comm) But not maintained above 26.5 C Increased morts after moving and increasing temperatures
  • 14. Further information • Article published in Fish news • Note at final draft for journal article • Further culture work ongoing at Cefas • Taxonomy complicated F. orientalis ? • FHI contact with another country who has experienced similar problems in recirculation systems FHI need to notified of any abnormal mortalities. Feed back from farmers would be very valued
  • 15. Acknowledgements David Stone and Cefas Molecular biology team Stephen Feist and Histopathology Team Research on emerging diseases funded by Defra through contracts F1166 and FA001 Thank You