Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Ester doai
Patent
1997-03-11
1998-06-23
Henley, III, Raymond
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Ester doai
A61K 31275
Patent
active
057706212
DESCRIPTION:
BRIEF SUMMARY
This is a 371 of PCT/GB95/02153 filed Sep. 8, 1995.
This invention relates to the control of sea lice in fish, such as salmon.
Infestation of salmon with sea lice is a recognised problem. Salmon are infected by free swimming immature sea lice in the copeopodid phase of development, which attach themselves to the body of the fish by hooked antennas. Once attached to the fish, the lice develop through four immature chalimus phases before becoming pre-adults about 2-3 weeks after the initial infestation. During the chalimus phases, the lice attach themselves to the fish by frontal filaments, and though they feed on the fish, they do not cause extensive damage. During their final pre-adult and adult phases of development, the lice attach themselves to the body of the fish by suction and graze over its surface, especially the head, back and peri-anal areas, causing extensive damage and ultimately death.
A number of treatments have been used to control sea lice in the past, most notably dichlorvos, azamethiphos and hydrogen peroxide treatment baths. A common feature of these known treatments is that they are effective only against mature lice (i.e. lice in the pre-adult and adult phases), and are ineffective against lice in immature phases of development. Hydrogen peroxide has been suggested by some workers to have a limited effect against immature lice, but this effect is slight compared to its effect on mature lice.
The reason for this selective activity is not known but it is thought likely to be due in some way to the substantial differences in anatomy and metabolism between the immature (copeopodid and chalimus) and mature (pre-adult and adult) lice. One theory is that differences in respiration are responsible, but this has not been fully substantiated. Whatever the underlying reasons for the selectivity, it remains an empirical rule that the conventional topical treatments are effective only against mature lice, with the resultant drawback that infested fish require repeated and frequent treatments in order to kill the lice as and when they mature.
We have now identified a group of compounds that are effective for controlling immature as well as mature sea lice. The compounds concerned are the pyrethroids, for example Cypermethrin (3-(2,2-Dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylic acid cyano (3-phenoxyphenyl)-methyl ester). We have already suggested the use of these compounds for the control of sea lice in our international patent application, published as WO 92/16106, but it was previously thought that the compounds were effective only for mature lice, and the tests described in our earlier application utilised mature lice exclusively. Because of the known resistance of immature lice to all known conventional bath treatments for mature lice, the identification of a group of compounds which is effective when used topically against both mature and immature lice is surprising. It is also of significant practical importance, in that a single treatment will affect substantially all of the lice present on the fish, whether mature or immature, thereby reducing the frequency with which treatments need to be made. This in turn leads to a saving in labour, a decrease in environmental contamination, and the minimising of stress to the fish.
The present invention therefore provides the use of a pyrethroid compound for the manufacture of a composition for the treatment of the immature phases of sea lice infestation of fish.
Alternatively, the invention provides the use of a pyrethroid compound for the manufacture of a composition for the prophylaxis of pre-adult and adult sea lice infestation of fish.
The invention is hereinafter described by way of example only, with reference to the following experimental trials and the accompanying figures which illustrate the results of the trials.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1, 2A, 2B, and 3 show the effectiveness of pyrethroids against the immature stages of sea lice.
TRIAL 1
Trial 1 was carried out at the Marine Harvest International research establ
REFERENCES:
G.A. Boxhall et al. (EDS.), "Pathogens of wild and farmed fish. Sea Lice.", Ch. 17, pp. 219-252, 1994.
G.A. Boxhall et al. (EDS.), "Pathogens of wild and farmed fish. Sea Lice", Ch 20, pp. 275-289, 1994.
Braidwood Julian Charles
Hart Jayne Laura
Grampian Pharmaceuticals Limited
Henley III Raymond
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