Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Reexamination Certificate
2001-08-03
2003-01-14
Cook, Rebecca (Department: 1614)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
C604S020000
Reexamination Certificate
active
06506791
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of aquaculture. More particularly, the present invention relates to the field of the therapeutic treatment of parasitic infections in fish. More particularly to the use of photoactive dyes such as Phloxine B as a method of controlling protozoan infections in fish populations. More particularly, the invention relates to the use of photoactive dyes such as Phloxine B for the treatment and/or prevention and of parasitic diseases in fish populations such as the disease Ick which is caused by the infection of fish with the external protozoan,
Ichthyophthirius multifiliis.
BACKGROUND OF THE INVENTION
Aquaculture in the United States represents a relatively small segment of agricultural production, however the industry is relatively young and growing rapidly. Per capita consumption of fish food products in the United States has increased more than 50 percent since 1970. Furthermore, ornamental fish distribution has more than doubled since 1986. Food fish and ornamental fish markets combined contribute nearly $2 billion per year to the retail United-States economy. It has been estimated that these trends will continue in the new millenium.
Although the demand for food fish and ornamental fish products has increased, natural fish harvest populations have not increased and, in many cases, have declined. As such, aquaculture of fish species has increased to meet consumer demand. Among food fish, catfish, salmonid, and cichlid species dominate commercial aquaculture in the US. Catfish aquaculture, estimated at nearly $770 million in farm sales for 1999, accounts for about half of total annual US production. Among ornamental species, guppies, swordtails, and mollies dominate the ornamental fish market in the US. Ornamental aquaculture in Florida alone is valued at over $52 million.
Aquaculture of fish has been plagued by disease since its inception. Disease outbreaks are particularly prevalent when culturing large numbers of fish in crowded conditions. Many parasites and diseases can spread and quickly kill entire fish populations. Although the economic impact of infectious diseases is difficult to determine, it is estimated that annual losses in the US catfish industry may exceed $20 million.
A majority of fish losses in the aquaculture industry can be attributed to protozoan infections. Protozoans can infect both external and internal portions of the fish including the gills, fins, skin, and digestive organs. External protozoa of major concern to aquaculturists include members of the genus Costia, Chilodon, Scyphidia, Trichodina, Epistylis, Carchesium, and Trichophrya. The external ciliate,
Ichthyophthirius multifiliis
, causes white spot disease known as Ick or Ich. Ick is difficult to control and is often observed in crowded cultures of catfish and warm-water aquarium fish. Characteristic signs of Ick infection include the presence of grayish-white warts on the external surfaces of the fish and behavior changes such as flashing, jumping, or thrashing erratically in the water.
The life cycle of
I. multifiliis
is indirect. An adult stage called a trophozoite invades the skin or gills of fish and feeds directly on tissue fluids. Trophozoites, the form of Ick found on fish, are large protozoans and can easily be distinguished by light microscopy. Trophozoites are identified by a clearly visible C-shaped nucleus. After several days, depending on water temperature, the trophozoite releases from the fish, encysts, and undergoes fission to produce the next stage of its life cycle. After the cyst ruptures, an infective form called a tomite is released. As many as 2,000 tomites can be produced from a single cyst. Tomites are highly ciliated, pear-shaped (30-45 nm diameter), and are actively mobile in seeking out a new host. Prior therapeutic efforts to control Ick infections have focused on treating free-swimming tomites and unattached trophozoites. These therapeutic treatments are ineffective in controlling Ick trophozoites once they have attached to the fish.
As of 1999, only five drugs have been approved by the FDA for use in the aquaculture industry. Use of these drugs for particular disease conditions is highly regulated particularly regarding the use of these drugs with food fish. Formalin, oxytetracycline, and sulfadimethoxine have been approved to treat catfish diseases. Although not approved for food fish, potassium permanganate and copper sulfate are also used to treat Ick infections of ornamental fish. Other non-approved drugs, including malachite green and quinine, have been demonstrated effective against Ick. Toxicity and safety concerns have hindered FDA approval of many of these treatments. Malachite green, for example, is both mutagenic and teratogenic, and its use is restricted in many countries. Formalin, although approved, has also been demonstrated as a potential carcinogen to fish. Other drugs, such as potassium permanganate, have been demonstrated to cause gill injury at effective concentrations.
There are arguably no effective long-term treatments for fish infected with the protozoan parasite,
Ichthyophthirus multifiliis
. Prior treatments are ineffective in controlling the complete life cycle of Ick and have the potential to be harmful to fish or other animals, including humans. Current chemical treatments are costly and may also be labor intensive due to clean-up procedures required both before and after treatment. Last, available treatments are not practical for treating large numbers of infected fish such as those cultured in indoor hatcheries or in ponds. Phloxine B, by contrast, is non-toxic to most animal species, does not accumulate or pose an environmental threat, and is relatively inexpensive compared to other drug treatments.
The limited number of approved treatments for protozoan infections results in large production losses each year. Ick alone is responsible for nearly 50% all catfish losses reported during the Spring and Summer months of pond farm production and as mush as 80% of ornamental industry losses annually. The use of Phloxine B for treating Ick infections in fish may dramatically reduce these annual losses. Furthermore, the innovative use of a chemical currently approved by the FDA may reduce the need for extensive environmental and human safety testing before approval.
The limited number of approved and/or effective treatments for Ick infections presents a problem for the aquaculture industry. Costs, however, for approving a single therapeutic by the FDA can typically exceed $50 million. As such, pharmacological suppliers are reluctant to sponsor expensive research and testing campaigns for new drug therapy. Currently, researchers are examining alternative uses for chemicals that have already been FDA approved. For example, oxytetracycline was marketed as a human medicinal and then later approved for use in the aquaculture industry to control certain bacterial infections. Alternative uses for FDA approved chemicals can provide not only an alternative treatment for fish diseases but also reduce the costs associated with extensive FDA research and testing.
Research examining the effectiveness of photodynamic (or photoactive) dyes as pesticides has been conducted since the early seventies. The USDA's Agricultural Research Service (USDA-ARS) have identified at least twenty photodynamic dyes that are toxic to insects, many of which are used in the human cosmetic industry. The pesticide SureDye™ was discovered through a joint effort conducted by the USDA's Animal and Plant Health Inspection Service (USDA-APHIS) and Photodye International, Inc. Specifically, studies demonstrated that Phloxine B, as the active ingredient in SureDye™, was effective in the control of various Diptera species. Other photoactivated dyes such as rose Bengal and acridine orange have been shown to be toxic to fire ants and
E. coli
, respectively. It has been suggested that dye-light therapy may also be effective against the herpes simplex virus.
Phloxine B, is FDA approved and has been used in hum
Alston & Bird LLP
Cook Rebecca
Jacksonville State University
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