Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Nitrogen containing other than solely as a nitrogen in an...
Reexamination Certificate
2000-11-20
2003-03-25
Weddington, Kevin E. (Department: 1614)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Nitrogen containing other than solely as a nitrogen in an...
C514S596000
Reexamination Certificate
active
06538031
ABSTRACT:
This application claims foreign priority benefit of European Patent Application No. 99811084.5 filed Nov. 25, 1999.
The present invention in the field of commercial fish farming for meat production relates to the control of parasites, which attach themselves to the skin of fish. To be more precise, it relates to the control thereof using the active substances named in claim
1
, preferably by injection.
Fish farming, particularly when used to produce meat, operates nowadays on a large scale in so-called fish farms, where numerous fish are farmed in a confined area until they are ready for slaughter or for sale. As with any intensive livestock farming, in this case also, diseases and parasite infestation can lead to substantial losses and thus to drastic financial losses. As well as diseases caused by microorganisms such as Protozoa or by fungi, ecto-parasites that are customarily called sea lice, play a particularly decisive role.
Sea lice have absolutely nothing to do with insects, but as described in more detail below, belong to the fish-parasitic crustacea. There are in particular two members of the class of Copepodae [hoppers], which lead to substantial losses in yield, namely Lepeophtheirus [
Lepeophtheirus salmonis
] and Caligus [
Caligus elongatus
]. Primarily, they are popularly known as sea lice. They are easily recognised by their brown horseshoe-shaped shell, with Lepeophtheirus being considerably larger than Caligus.
These sea lice bite the fish firmly and damage it by eating the scales, the cell tissue and the mucous membrane. In the case of severe infestation, these parasites even penetrate into deeper layers of tissue. The immune system of the fish is weakened, leading to secondary infections and an excessive accumulation of water in the tissue. Frequently, the excessive parasite infestation leads to increasing tissue damage and, due to natural or artificial ultraviolet radiation or due to osmotic shock or the secondary infection, finally leads to death of the fish. Even with a light infestation, the fish lose body weight and only reach the right size for slaughter very slowly, if at all. In addition, infested fish have an unpleasant appearance and are not accepted by bulk buyers and end consumers.
By now, the sea louse can be found on almost all fish farms. Mortality rates based on infestation by sea lice of more than 50% have been reported by Norwegian fish farms. The extent of damage depends on the season and environmental influences, such as the salt content of the water and the average water temperature. In an initial phase, the sea louse infestation is observed by the parasites attached to the fish, and later on—more significantly—by the damage to the skin and the tissue. The greatest damage is observed on smolts which are in that period of life in which they migrate from fresh water to sea water. The whole situation is made worse by the specific conditions in the fish-breeding farms, where often salmon of different years, but the same class of weight, are kept together; soiled nets or cages are used; high salt concentrations are found; little running water flows through the nets and cages, and the fish are kept in a very small area.
Fish farmers who are confronted with these parasite problems have to accept substantial financial losses and additional costs. On the one hand, their fish are weakened and damaged by the lice, which leads to lower rates of weight increase; and on the other hand secondary infections have to be kept in check with expensive medicines and labour-intensive measures. In many cases, the goods can no longer be sold, as the damaged fish deter the consumers. For salmon breeders, this problem of lice infestation may threaten their existence.
The greatest damage is produced by Lepeophtheirus, since even a few parasites cause vast tissue damage. The life cycle of Lepeophtheirus consists basically of two larval stages living freely in water [Naupilus and Copepodia stages], four Chalimus stages, one pre-adult and the actual adult stage. The Chalimus and adult stages are host-dependent.
The most dangerous, since they produce the greatest damage, are all the fish-parasitic stages of sea louse, in particular the actual adult stages.
In the meantime, a series of chemical substances have been used against these sea lice with more or less success, e.g. trichlorfon [dimethyl-2,2,2-trichloro-1-hydroxyethyl-phosphonate], which requires concentrations of 300 ppm in salt water, and dichlorvos [2,2-dichloroethenyl-dimethylphosphate], which is effective from 1 ppm. A disadvantage of these preparations is the relatively high application rates, and the environmental contamination associated therewith, which also applies all the more because of the relatively high half-life periods. Other more selective substances that are used successfully are described e.g. in EP-497,343, EP-590,425, EP-781,095 and WO 97/21350. The fish are usually treated orally, e.g. through the food, or topically, i.e. externally by means of bath treatment, for example in a “medicinal bath” into which the fish are placed and kept for a period [minutes to several hours], e.g. transferring from one breeding tank to another. If there is no possibility of transferring the fish into a special tank, normally temporary or long-lasting treatment of the habitat of the fish takes place, e.g. in net cages, whole ponds, aquariums, tanks or basins, in which the fish are kept. In individual cases, treatment also takes place parenterally, e.g. by injection, especially if this is a hand-picked specimen for further breeding or ornamental fish as part of a hobby.
Although there are substances that show good efficacy against fish parasites, there is a need for further active substances that are more effective, can be tolerated by the underwater flora and fauna, or can be handled without problems by the breeder. Of course, the shelf life and stability in feed mixtures are also important. In addition, practicable application methods are desired, which save time and energy or further reduce environmental contamination. In this rapidly expanding industry, the above factors play an ever increasing role and can be crucial to commercial success.
WO 92/06599 describes the administration of oral compositions to fish and depicts this as an especially advantageous method compared with the labour-intensive and complex injection of individual fish. An injection is described as a particular stress factor, which at the very least leads to a temporary reduction in growth.
In contrast to this, it has now surprisingly been established that, with appropriate handling, the injection can have significant advantages over the other types of administration, if it is used in mass breeding using suitable apparative measures. It was established that the injection nowadays does not have to be restricted to specific cases, e.g. for especially expensive breeding and ornamental fish or for individually selected sick fish, but can be carried out with relatively little manual effort and using little time, even for whole schools of fish, without exposing the fish to exceptional stress. As will be shown in the following, whole schools of hundreds or thousands of fish may be treated in an almost stress-free manner, giving rise to quite significant advantages. The present invention accordingly relates also to the treatment of whole schools of fish, i.e. to commercial fish breeding for meat production, which is also known by the name “fish-farming”. Under no circumstances should this be confused with the known occasional treatment of individual sick fish or with individual experiments to establish the efficacy of a potential active ingredient.
The conventional treatment processes that are successful per se of course also have their down side. The serious disadvantages of the current water treatment method are that the active substance and the remaining formulation excipients are not specifically targeted to the fish or the parasites, but extend inevitably over the whole h
Lee Michael U.
Novartis Animal Health US Inc.
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