This page gives some advice on disinfection procedures and products that can be used on mollusc aquaculture sites.
While direct disease transmission by moving diseased shellfish into a previously uninfected shellfish growing area is the greatest threat of infection, inadvertent transfer of disease through the contamination of equipment, clothing or footwear also poses a threat. Disinfection procedures should be used alongside other biosecurity measures to minimise this risk of disease transfer.
Any items that are to be used between different water bodies or sites in a separate part of the same bay should be disinfected between uses on each of the sites. However, farmers working at multiple sites or bays on a frequent basis ideally should use separate equipment for each. Typical items that would need to be disinfected are boots, oilskins, gloves, boats, nets & bags, ropes, trestles etc
The efficacy of disinfectants is severely decreased by the presence of organic matter, it is therefore extremely important to precede disinfection with thorough cleaning. The process below is recommended:
a) Remove all visible debris or organic material
b) Apply detergent/degreasing agent and leave for 15 minutes (or longer according to label instructions)
c) Rinse off
d) Apply appropriate disinfectant at recommended concentration and leave to penetrate for the period recommended by the manufacturer.
e) Rinse with clean water.
Disinfectant solutions need to be replaced before they lose efficacy - to avoid this happening, the date of its disposal should be clearly displayed.
While there is no published information regarding disinfectants suitable for use specifically against the Oyster Herpes Virus (OsHV1-uvar), the combination of a heavy duty detergent such as Biosolve and a broad spectrum disinfectant such as Virkon would probably be the best option. Virkon has been shown to be effective against many aquatic viruses including IPNv - a virus which is known to be robust and very difficult to kill.
The table below contains information on the range of disinfectants suitable for use in finfish aquaculture sites in Ireland. Given the knowledge gap which currently exists in relation to which products are suitable for use against mollusc pathogens, it should be used for guidance only.
| Disinfectant/Cleaner |
Example* |
Dose |
Comments |
| Chloramine T |
Halamid |
1% (w/v), 5 mins |
Reported effective against ISAc (1% for 30 minutes vs. IPNv) www.halamid.com |
| Iodophor |
FAM30, Virudine
Vandoline |
100ppm, 10 mins |
Reported effective against ISAv and IPNv. Loss of brown colour indicates loss of efficacy. Iodine requires neutralisation before discharge. Stains and is corrosive. |
| Peroxy Compounds |
Virkon Aquatic
Virasure |
1% (w/v), 10 mins (IPNv)0.5% (w/v), 30 mins (ISAv) |
Reported effective against fish pathogenic bacteria and viruses (BKD, furunculosis, ERM, ISA, IPN, rhabdoviruses). www.antecint.co.uk |
| Calcium oxide (quicklime) |
|
0.5kg/m(sq) for 4 weeks |
For earth ponds (dried). Dangerous substance. |
| Chlorine Dioxide |
Cidox |
1-1.5ppm CIO2 |
Water treatment for processing plants |
| Citric Acid |
|
2g/l (0.2%) (w/v) for 30 mins |
Clothing |
| Hydrogen peroxide |
Hyperox |
1:100 (1%), 30 min |
Reported effective vs ISAv. |
| Sodium hypochlorite |
|
100ppm, 10 mins (a)
1000ppm, 10 mins (b)
1000ppm, 6 hours (c) |
(a) Boats, Cages, tanks, hand nets, harvest equipment
(b) Processing plant effluent
(c) Cage nets
Leave to inactivate for a few days or neutralise with sodium thiosulphate after three hours. Not effective if organic material present. |
| Sodium hydroxide |
Biosolve Plus Shift |
1:100 (1%), 500mls/m(sq)
1:250, 15 mins |
Degreasing and cleaning of well boats, work boats, equipment, processing equipment & utensils. |
| UV |
|
122mj/cm(sq)/sec (IPNv)
290mj/cm(sq)/sec (noda) |
Freshwater intake.
Efficacy compromised by organic loading.
May be combined with ozone for treating processing effluent. |
| Heat |
|
70 (deg) C, 2 hrs - IPNv
60 (deg) C, 2 mins - ISAv
37 (deg)C, 4 days - noda |
Cage nets, diving gear |
| Formic acid |
|
|
Ensiling |
| Ozone |
|
8mg/l/min, 3 mins (redox 600-750mV) |
Water intake & effluent.
Costly and toxic to fish and humans |
| Peracetic acid, hydrogen peroxide and acetic acid mix |
Proxitane, Kickstart |
0.4% (v/v), 5 mins |
Reported effective against ISAv. |
*The inclusion or exclusion of a particular brand on this list does not indicate an endorsement or a rejection of its use by the Marine Institute
All products used for disinfection must be used and disposed of in accordance with the manufacturers’ recommendations and likewise any health and safety guidelines should also be closely adhered to. If a Material Safety Data Sheet (MSDS) has not been supplied with the product we strongly recommend that a MSDS be obtained from the manufacturers’ website or from the suppliers of the product.
If you have a particular query relating to disinfectants, please contact the Fish Health Unit at the Marine Institute on 091 387200 or email notification@marine.ie