WO2018062246A1 - Therapeutic agent for diseases mediated by microsporidia and myxosporea both parasitic in marine fishes - Google Patents

Abstract

Provided is a method for controlling microsporidia or myxosporea in marine fishes (particularly cultured fishes) with an oral administration agent. A control agent for "Beko" disease or a myxosporean disease mediated by microsporidia parasitic in marine fishes, said controlling agent containing, as an active ingredient, any one of albendazole, febantel, flubendazole, fenbendazole, oxfendazole and mebendazole.

Description

Therapeutic agents for diseases caused by microsporidia and myxospores parasitic on marine fish

The present invention relates to a parasite-controlling agent and a parasite-controlling method for marine fish. In detail, it is related with the chemical | medical agent and extermination method by which oral infection administrates the downy mildew which develops by the microsporidia parasitic on marine fish.

The causative parasite of yellowtail downy mildew is Microsporidium seriolae. In the case of microsporidia, if it is clear that it is a new species and it is difficult to identify the taxonomic position above the genus level, it can be placed in a collective genus called Microsporidium, which is a causative parasite of yellowtail This is also the case. Parasitism of this worm was reported in 1982, after which parasites were also found in hiramasa and amberjack. The feature of this disease is that a small cyst conglomerate of parasites of several mm to 1 cm in white irregular shape is formed in the side muscles of the affected fish. Sporulation is completed in the cyst, and when the cyst collapses, the surrounding muscles melt, so the body surface of the site appears to be depressed. For this reason, the appearance of irregularities on the body surface is the reason why it is called downy mildew. Parasitic sites cover a large area of the trunk, and sometimes fish are very thin and die. If the affected area is limited and there is no infection with secondary bacteria, the wound will naturally heal after the cyst melts and the microsporeworm escapes from the body. However, not all cysts melt and the worms escape from the body, and it is known that cysts exist in the trunk even after a long period until shipment, which is one of the causes of reducing the value of the product ing. Currently, no treatment for this disease has been developed, and the damage continues.

Also in fish species other than yellowtail, downy mildew caused by microsporidia is known in red sea bream and bluefin tuna.

The causative parasite of yellowtail myxosporeosis is Kudoa yasunagai. This worm was found in 1980 in the brains of diseased fish with abnormal swimming in cultured sea bass and cultured sea bream in Nagasaki Prefecture. Because the spore usually has 7 spore shells and a polar sac, it was described as a new species of Septemcapsula yasunagai. However, subsequent molecular phylogenetic analysis eliminated the Septemcapsulidae and Septemcapsula genera, and the species was transferred to the Kudoa genus. Affected fish exhibit characteristic swimming that bends and turns. In the case of yellowtail, the body may be curved. Small spherical white cysts are seen around the brain. There are no effective measures to control this disease.

In fish species other than yellowtail, tuna, flounder, etc. are known to be myxosporeosis, also known as kuduosis due to genus Mycosporea, and in pufferfish, it is caused by myxospores of the genus Enteromixum or Leptoseca Intestinal myxosporesis (also known as pufferfish disease) is known.

Benzimidazoles are known as antiparasitic drugs. In Japan, mebendazole is used as an helminthic agent, albendazole is used as a helminthic agent, and flubendazole is used as an animal for roundworms and roundworms. Febantel and fenbendazole are approved as veterinary drugs for nematodes and tapeworms. For fisheries, fevantel is approved for puffer fish.

There has been a report of testing the effect of albendazole on Loma salmonae, a microspore parasite of rainbow trout (Non-patent Document 1). There is a report that examined the effects of Flubendazole, Mebendazole, Oxibendazole, Parbendazole, Triclabendazole on the monocytic parasite Gyrodactylus sp. Parasitic on rainbow trout (Non-patent Document 2). There is a report in which the effects of Flubendazole, Mebendazole, Oxibendazole, Parbendazole, and Triclabendazole on Philasterides dicentrarchi, which is a ciliate parasitic on turbot and seabass, were tested in vitro (Non-patent Document 3). There is a report which tested the effect of Albendazole, Mebendazole, and Fenbendazole on Glugea anomala which is a microspore insect parasitizing Itoyo (non-patent document 4). There is a report that a benzimidazole-type drug is effective against heterobotulium okamotoi, which is a single insect that parasitizes trough (Patent Document 1).

WO02 / 005649

An object of the present invention is to provide a drug for oral administration of downy mildew or myxosporesis in marine fish (particularly, cultured fish), a method for extermination with the drug, and the like.

The inventors searched for existing various antiparasitic drugs for animals and substances derived from natural products in search of an orally-administered drug effective against downy mildew, which is an important problem in the cultivation of yellowtails. As a result, they found that some of the benzimidazole drugs sold as antiparasitic drugs for animals were effective, and completed the present invention.

The gist of the present invention is the following (1) to (24) therapeutic agents for diseases caused by microsporidia or myxospores parasitic on fish.
(1) A therapeutic agent for downy mildew or myxosporesis of marine fish, comprising any one of albendazole, fevantel, fenbendazole, oxfendazole, mebendazole, and fulbendazole as an active ingredient.
(2) The therapeutic agent for downy mildew of (1), wherein the causative parasite of downy mildew is a microsporeworm belonging to the genus Microsporidium or Spraguera.
(3) Myxospores of (1), wherein the causative parasite of myxosporesis is a myxospore that belongs to any of the genus Kudoa, Enteromyxum, and Leptotheca Insect treatment.
(4) The therapeutic agent according to any one of (1) to (3), wherein the marine fish is a fish of the order Perch, flounder or puffer.
(5) Perch fishes are fish belonging to the genus Buri, Thai family or Tuna genus, flounder fishes are fish belonging to the flatfish family, and fishes belonging to the puffer fish are fish belonging to the puffer family, ( 4) Therapeutic agent.
(6) Fishes belonging to the genus Buri include yellowtail (Seriola quinqueradiata), amberjack (Seriola dumerili), white-spotted (Seriola lalandi), white-necked amberjack (Seriola rivoliana), Seriola carpenteri, Seriola fasciata, Seriola hipposana, Seriola peruana, And Seriola zonata, the fish belonging to the Thai family include the southern sea bream (Acanthopagrus sivicolus), the scallop (Argyrops bleekeri Oshima), the red sea bream (Dentex tumifrons), the red sea bream (Evynnis tumifrons), the red sea bream (Pagrus major), and the black sea bream. (Acanthopagrus schlegelii) and red sea bream (Rhabdosargus sarba, Sparus sarba). obesus), albacore tuna (Thunnus alalunga), yellowfin tuna (Thunnus albacares), It is one of the bluefin tuna (Thunnus tonggol) and Atlantic bluefin tuna (Thunnus atlanticus). pentophthalmus), elegans flounder (Pseudorhombus cinnamoneus), megaray (Pseudorhombus dupliciocellatus), sage flounder (Pseudorhombus arsius), and aramegarei (Tarphops oligolepis). The therapeutic agent according to (5), which is porphyreus).
(7) The therapeutic agent according to any one of (1) to (6), wherein the active ingredient is orally administered in an amount of 5 to 100 mg / kg body weight per day.
(8) A therapeutic agent for downy mildew of marine fish, comprising any one of albendazole, fevantel, fenbendazole, oxfendazole, and mebendazole as an active ingredient.
(9) A therapeutic agent for downy mildew or myxosporesis of marine fish, comprising albendazole as an active ingredient.
(10) A therapeutic agent for myxosporesis, comprising albendazole or fulbendazole as an active ingredient.
(11) A method for treating downy mildew or myxosporesis of marine fish, wherein an effective amount of albendazole, fevantel, fenbendazole, oxfendazole, mebendazole, or fulbendazole is orally administered to marine fish Administering said method.
(12) The method of treating a downy mildew according to (11), wherein the causative parasite of the downy mildew is a microsporeworm belonging to the genus Microsporidium or Spraguera.
(13) The myxospores of (11), wherein the causative parasite of myxosporesis is a myxospore that belongs to any of the genus Kudoa, Enteromyxum, and Leptotheca How to treat worms.
(14) The method according to any one of (11) to (13), wherein the marine fish is a perch, flounder, or puffer fish.
(15) The perch fish is a fish belonging to the genus Buri, the Thai family or the tuna genus, the flatfish is a fish belonging to the flatfish family, and the fish belonging to the puffer fish is a fish belonging to the puffer fish family, Method (14).
(16) Fishes belonging to the genus Buri are yellowtail (Seriola quinqueradiata), amberjack (Seriola dumerili), white-spotted (Seriola lalandi), white-necked amberjack (Seriola rivoliana), Seriola carpenteri, Seriola fasciata, Seriola hipposana, Seriola peruana, And Seriola zonata, the fish belonging to the Thai family include the southern sea bream (Acanthopagrus sivicolus), the scallop (Argyrops bleekeri Oshima), the red sea bream (Dentex tumifrons), the red sea bream (Evynnis tumifrons), the red sea bream (Pagrus major), and the black sea bream. (Acanthopagrus schlegelii) and red sea bream (Rhabdosargus sarba, Sparus sarba). obesus), albacore tuna (Thunnus alalunga), yellowfin tuna (Thunnus albacares) The fishes belonging to the flounder family are Tuna (Thunnus tonggol) and Atlantic tuna (Thunnus atlanticus). pentophthalmus), elegans flounder (Pseudorhombus cinnamoneus), megaray (Pseudorhombus dupliciocellatus), sage flounder (Pseudorhombus arsius), and aramegarei (Tarphops oligolepis). porphyreus), the method of (15).
(17) The method according to any one of (11) to (16), wherein any one of albendazole, fevantel, fenbendazole, oxfendazole, mebendazole, and fulbendazole is orally administered at 5 to 100 mg / kg fish body weight per day.
(18) Use of any of albendazole, fevantel, fenbendazole, oxfendazole, mebendazole, and fulbendazole in the manufacture of a medicament for the treatment of downy mildew or myxosporeosis of marine fish.
(19) The use of (18), wherein the causative parasite of downy mildew is a microsporidia belonging to the genus Microsporidium or Spraguera.
(20) Use of (18), wherein the causative parasite of myxosporesis is a myxospore that belongs to any of the genus Kudoa, Enteromyxum, and Leptotheca.
(21) Use of (18) to (20), wherein the marine fish is a perch, flounder or puffer fish.
(22) The perch fish is a fish belonging to the genus Buri, the Thai family or the tuna genus, the flatfish is a fish belonging to the flatfish family, and the fish belonging to the puffer fish is a fish belonging to the puffer fish family, Use of (21).
(23) Fishes belonging to the genus Buri are yellowtail (Seriola quinqueradiata), amberjack (Seriola dumerili), white-spotted (Seriola lalandi), white-necked amberjack (Seriola rivoliana), Seriola carpenteri, Seriola fasciata, Seriola hipposana, Seriola peruana, And Seriola zonata, the fish belonging to the Thai family include the southern sea bream (Acanthopagrus sivicolus), the scallop (Argyrops bleekeri Oshima), the red sea bream (Dentex tumifrons), the red sea bream (Evynnis tumifrons), the red sea bream (Pagrus major), and the black sea bream. (Acanthopagrus schlegelii) and red sea bream (Rhabdosargus sarba, Sparus sarba). obesus), albacore tuna (Thunnus alalunga), yellowfin tuna (Thunnus albacares) The fishes belonging to the flounder family are Tuna (Thunnus tonggol) and Atlantic tuna (Thunnus atlanticus). pentophthalmus), elegans flounder (Pseudorhombus cinnamoneus), megaray (Pseudorhombus dupliciocellatus), sage flounder (Pseudorhombus arsius), and aramegarei (Tarphops oligolepis). porphyreus), the use of (22).
(24) The medicament is used for oral administration of any one of albendazole, fevantel, fenbendazole, oxfendazole, mebendazole, and fulbendazole at 5 to 100 mg / kg fish body weight per day, (18) to (23) Use of either.

In addition, the gist of the present invention is a microsporeworm or myxospores control agent parasitic on the following (A1) to (A5) fish of the genus Seriola.
(A1) A microsporeworm or myxospores control agent parasitic on fish of the genus Seriola, containing a benzimidazole drug as an active ingredient.
(A2) Microsporidia or myxospores are microsporidium seriolae, microsporidia belonging to the genus Spraguera, Kudoa yasunagai, Myxobolus acanthogobii, Kudoa The pesticide of (A1), which is any one of Kudoa shiomitsui, Kudoa pericardialis, and Kudoa amamiensis.
(A3) The disinfectant according to (A1) or (A2), wherein the benzimidazole-based agent is any one of albendazole, fevantel, flubendazole, triclabendazole, fenbendazole, oxfendazole, and thiabendazole.
(A4) The fishes of the genus Buri are yellowtail (Seriola quinqueradiata), amberjack (Seriola dumerili), white-spotted (Seriola lalandi), white-necked amberjack (Seriola rivoliana), Seriola carpenteri, Seriola fasciata, Seriola hippos, Seriola peruana, Seriola peruana A pesticidal agent of any one of (A1) to (A3), which is any of zonata.
(A5) The disinfectant according to any one of (A1) to (A4), which is for oral administration of 0.5 to 500 mg / kg of fish body weight per day.

The gist of the present invention is the method for controlling parasites (A6) to (A10).
(A6) A method for controlling microsporidia or myxospores parasitic on fish of the genus Seriola, which comprises administering a benzimidazole-based drug.
(A7) Microsporidia or myxospores are Microsporidium seriolae, Spraguera microsporidia, Kudoa yasunagai, Myxobolus acanthogobii, Kudo Shiomitsu The method of (A6) which is any one of Kudoa shiomitsui), Kudoa pericardialis, and Kudoa amamiensis.
(A8) The method of (A6) or (A7), wherein the benzimidazole drug is any one of albendazole, fevantel, flubendazole, triclabendazole, fenbendazole, oxfendazole, and thiabendazole.
(A9) The fishes of the genus Buri are yellowtail (Seriola quinqueradiata), amberjack (Seriola dumerili), white-spotted (Seriola lalandi), white-spotted amberjack (Seriola rivoliana), Seriola carpenteri, Seriola fasciata, Seriola hippos, Seriola peruana, Seriola peruana The method according to any one of (A6) to (A8), which is any of zonata.
(A10) The method according to any one of (A6) to (A9), wherein the benzimidazole drug is orally administered at a dose of 0.5 to 500 mg / kg body weight per day.

According to the present invention, vegetation is a parasitic disease that is an important problem infesting widely cultivated marine fish, particularly fish belonging to the genus Buri, Thai, Tuna, Flounder, or Fuguidae. Disease or myxosporesis can be effectively treated by oral administration.

It is a figure which shows the test schedule which made the test feed administration in the breeding period in Example 7 into 2 cycles.

The active ingredient of the therapeutic agent or parasite-controlling agent of the present invention is effective for downy mildew or myxosporesis among drugs classified as benzimidazole drugs. The benzimidazole-based drug is a drug having benzimidazole as a basic skeleton and is known as a parasite-controlling agent or a bactericidal agent. Benzimidazoles (Albendazole: methyl N- (5-propylsulfanyl-1H-benzimidazol-2-yl) carbamate), febantel (Febantel; methyl (NE) -N-[[ 2-[(2-methoxyacetyl) amino] -4-phenylsulfanylanilino]-(methoxycarbonylamino) methylidene] carbamate), fenbendazole (methyl N- (5-phenylsulfanyl-1H-benzimidazol-2-yl) carbamate), ox Examples thereof include Fendazole (Oxfendazole; methyl-N- [5- (benzenesulfinyl) -1H-benzimidazol-2-yl] carbamate), Mebendazole (methyl [5- (Benzoyl) benzimidazol-2-yl] carbamate), and the like. Fevantel is known to be a prodrug, and its active ingredients are fenbendazole and oxfendazole. Examples of benzimidazole drugs effective for myxosporesis include albendazole, flubendazole (methyl N- [5- (4-fluorobenzoyl) -1H-benzimidazol-2-yl] carbamate), and the like.

In one embodiment, the therapeutic agent or parasite-controlling agent of the present invention comprises any one of albendazole, fevantel, fenbendazole, oxfendazole, and mebendazole as an active ingredient, and is intended to treat downy mildew of marine fish. . In a preferred embodiment, the therapeutic agent or parasite-controlling agent of the present invention contains albendazole as an active ingredient and is intended for treatment of downy mildew of marine fish.

In yet another embodiment, the therapeutic agent or parasite-controlling agent of the present invention comprises albendazole or fulbendazole as an active ingredient, and is intended for treatment of myxosporeosis.

Benzimidazole drugs effective against downy mildew, especially albendazole, combats downy mildew-causing parasites before cyst formation, not only has a cyst formation-inhibiting effect, but also treats diseased fish that have caused cyst formation Has an effect.

Parasites in which the antiparasitic effect of the therapeutic agent or parasite-controlling agent of the present invention is recognized cause microsporidia or mycosporesis causing mycotic diseases parasitic to fish belonging to marine fish It is a myxospore. Examples of microsporidia that cause downy mildew include microsporidium belonging to the genus Microsporidium sp. Or Spraguera. Specific examples include microsporidium seriolae parasitic on yellowtail and microsporidia of the genus Spraguera that cause microsporidian cerebrospinal inflammation. In addition, myxospores causing myxosporesis include myxospores belonging to the genus Kudoa, which causes quadrosis, and Enteromyxum, which is the cause of intestinal myxosporesis, or Examples include myxospores belonging to the genus Leptotheca. Specifically, Kudoa yasunagai, the cause of cerebral myxosporesis, Myxobolus buri, the cause of myxosporeous scoliosis, Kudo Shiomitsui, the cause of cardiac quadrosis (Kudoa shiomitsui), Kudoa pericardialis, Kudoa amamiensis, the cause of amami-kudoosis, and Kudoa hexapunctata, known to infest tuna Kudoa septempunctata, known to infest flounder, Enteromyxum leei, enteromyxum fugu, known to infest puffers Leptotheca fugu.

The marine fish that is the subject of the present invention is a fish infested with the above-mentioned parasites. Examples of such marine fish include fish belonging to the order of Perch, for example, fish belonging to the genus Periphyceae, Periphyceae, Thai, or Persidaceae.

The fish species belonging to the genus Buri include yellowtail (Seriola quinqueradiata), amberjack (Seriola dumerili), white-spotted (Seriola lalandi), white-spotted amberjack (Seriola rivoliana), Seriola carpenteri, Seriola fasciata, Samiola hipposu, Seriola hipposu, Seriola hippos Seriola zonata is exemplified. In a preferred embodiment, the therapeutic agent or parasite control agent of the present invention is used for aquaculture fish such as yellowtail, amberjack, hiramasa, and longleaf amberjack, which are particularly cultivated.

The fish species belonging to the Thai family include minami micro dai (Acanthopagrus sivicolus), taiwan dai (Argyrops bleekeri shima Oshima), red sea bream (Dentex tumifrons), red sea bream (Evynnis tumifrons), red sea bream (Pagrus major), black sea bream (Acanthopagrus schlegelii) (Rhabdosargus sarba, Sparus sarba).

Fish species belonging to the genus Tuna include bluefin tuna (Thunnus orientalis), Atlantic bluefin tuna (Thunnus thynnus), southern bluefin tuna (Thunnus maccoyii), bigeye tuna (Thunnus obesus), bluefin tuna (Thunnus alalunga), yellowfin tuna (Thunnus alcare) tonggol) and Atlantic tuna (Thunnus atlanticus).

The fishes belonging to the flounder family include flounder (Paralichthys olivaceus), California halibut (Paralichthys californicus), jujube (Paralichthys dentatus), lobster (Pseudorhombus pentophthalmus), Pseudorhombuscio Pseudorhombus arsius) and aramega lei (Tarphops oligolepis).

Examples of fishes belonging to the pufferfish family include tiger puffer (Takifugu マ rubripes) and pufferfish (Takifugu porphyreus).

The therapeutic agent or parasite control agent of the present invention can exert an effect by oral administration. In addition, administration by a medicine bath in which a fish is immersed in a solution in which a drug is dissolved, or administration by injection is also possible.

The dosage of the therapeutic agent or parasite-controlling agent of the present invention is, for example, 5 mg to 100 mg per kg body weight per day for any fish, preferably 10 to 50 mg or 10 to 40 mg orally. To do. The administration period is 1 to 20 days, preferably 3 to 10 days.

The therapeutic agent or parasite control agent of the present invention uses the above-mentioned compound, which is an active ingredient, alone or, if necessary, other substances such as carriers, stabilizers, solvents, excipients, diluents and the like. It can be used in combination with ingredients. Further, the form may be any form normally used for these compounds such as powder, granule, tablet, capsule and the like. In the case of fish sensitive to the taste and odor of the compound, a method such as coating can be used to prevent a decrease in the palatability of the feed and make it difficult for the compound to leak out.

In the case of fish, orally administered drugs are usually added to the feed. When the therapeutic agent or parasite control agent of the present invention is added to the feed, it is preferable to use a feed that takes into consideration the nutritional components and physical properties required for each fish species. Usually, fish meal, salmon, starch, minerals, vitamins, fish oil, etc. are mixed into pellets, or frozen fish such as sardines and powdered feed (mash) with fish supplemented with vitamins are mixed. The pellets are used. Since the daily food intake is almost determined by the type and size of the fish, the amount of the therapeutic agent or parasite control agent of the present invention converted to the above-mentioned dosage is added to the feed. The therapeutic agent or parasite control agent of the present invention may be administered in a single daily dose or in several divided doses. Since the therapeutic agent of the present invention is used by adding it to fish feed, it is preferable to prepare a preparation suitable for adding an appropriate concentration to the feed taken by fish per day. Specifically, it is preferable to formulate and use the active ingredient in an amount of 1 to 50% by weight, preferably 5 to 30% by weight, more preferably 10 to 20% by weight.

Examples of the present invention will be described below, but the present invention is not limited to these.

<Anthelmintic effect of albendazole against downy mildew>
In an onshore breeding facility, fry was produced from fertilized eggs using sand filtration and UV sterilized seawater. The produced fry offshore to the sea surface ginger, reared for several days and brought back into the land facility. This sea surface ginger rearing caused the yellowtail to be naturally infected with causative parasites of downy mildew. The juvenile yellowtail that was brought into the land facility again was divided into two groups, the control group and the albendazole oral administration group, and each was housed in a 200 liter aquarium. Sand filtration / ultraviolet sterilized seawater was poured into the water tanks of each section under conditions of 2.4 liters / minute. The fish weight was measured on the last day of acclimatization. The test diet was fed for 10 consecutive days after habituation. The albendazole administration condition was 40 mg / kg fish body weight / day, and administration was once a day. For the preparation of albendazole-added feed, a predetermined amount of commercial feed and albendazole are placed in a polyethylene bag, and the spreading agent S30 (low saccharified reduced starch syrup, product Food Science Co., Ltd.) diluted to 2 times is added to the feed weight. % Amount was added and stirred. The control feed was prepared by adding only 4% of the diluted 30S and stirring. After administration of the test feed for 10 days, a commercial feed was fed, and the amount fed was 2% of the fish body weight. The test was conducted 4 times, each sea surface ginger breeding days, water temperature at the time of ginger breeding, acclimation period after facility introduction, test body weight at the start of the test, feeding rate at oral administration of the drug, period of the breeding test, test Table 1 shows the water temperature and the number of test specimens. Only the 4th control zone was housed in a 500 liter water tank, and sand filtration / ultraviolet sterilized seawater was poured under conditions of 4.8 liter / min.

At the end of the breeding test, all fish were picked up from both sections, and the presence or absence of cysts on the side muscles was observed by necropsy. The evaluation was performed by comparing the incidence of the control group and the albendazole oral administration group (number of developing fish tails / number of test fishes × 100).

Results and Discussion In the control plot, affected fish were observed in all four tests. On the other hand, in the albendazole oral administration group, no cyst-forming fish was observed in all the tests, and the incidence of downy mildew was 0% (Table 2). Therefore, it was confirmed that oral administration of albendazole deworms the worms that have entered the fish body and inhibits cyst formation of the worms.

<Anthelmintic effect of benzimidazole drugs against downy mildew-1>
In Example 1, it has been found that albendazole is effective for anthelmintic bugs. Therefore, we investigated the anthelmintic effect of benzimidazole drugs against downy mildew causative insects. The fry produced in the same manner as in Example 1 was offshore to sea surface ginger, reared for 10 days, and again transported to the land facility. This sea surface ginger rearing caused the yellowtail to be naturally infected with causative parasites of downy mildew. The red sea bream fry brought back to the land facility was divided into 10 groups with 40 fish each (2 groups in the control group, 2 groups in the albendazole administration group, 2 groups in the fevantel administration group, 2 groups in the triclabendazole group, 2 groups in the fulbendazole group), Each was housed in a 200 liter aquarium. Water injection into the water tank was performed under the same conditions as in Example 1. The fish weight was measured on the last day of acclimatization, and the fish weight of the test fish was about 10 g. The test diet was fed for 10 consecutive days after habituation. The administration condition of the benzimidazole drug was 40 mg / kg fish weight / day, and the administration was once a day. Preparation of the benzimidazole-based drug-added feed and the control group feed was carried out in the same manner as in Example 1. After administration of the test feed for 10 days, a commercial feed was fed, and the amount fed was 2% of the fish body weight. The test was conducted twice. The breeding period was 37 days for the first test and 40 days for the second test. The water temperature during the breeding period was about 20.5 ° C.

At the end of the breeding test, all fish were picked up from all sections, and the presence or absence of cysts in the body side muscles was observed by necropsy. The evaluation was performed by comparing the incidence of the control group and the benzimidazole drug administration group (number of developed fish tails / number of test fishes × 100), the number of cysts of the affected fish, and the cyst length.

Results and Discussion In the albendazole administration group and the fevantel administration group, fish that formed cysts were not observed in the two tests, and the incidence of mildew was 0% (Tables 3 and 4). Therefore, it has been reproduced that albendazole deworms the worms and inhibits cyst formation of the worms, and fevantel also has an anthelmintic action on the worms. On the other hand, in the triclabendazole administration group and the fulbendazole group, onset fish were observed in both tests, and the incidence was slightly higher than the control group. In addition, the number of cysts and the cyst length of the affected fish were similar to the control group. From these results, it was considered that these two agents did not deworm the worms and conversely promoted the onset. It was found that not all benzimidazole drugs exert an anthelmintic effect on this worm.

<Anthelmintic effect of benzimidazole drugs against downy mildew-2>
Following Example 2, the anthelmintic effect of mebendazole, a benzimidazole drug, on the downy mildew causative insect was examined. The fry produced in the same manner as in Example 1 was offshore to the sea surface ginger, reared for 11 days, and again transported to the land facility. This sea surface ginger rearing caused the yellowtail to be naturally infected with causative parasites of downy mildew. The juvenile yellowtail that was brought into the land facility again was divided into 6 groups of 40 fish each (control group 2 groups, albendazole administration group 2 groups, mebendazole group 2 groups), and each was housed in a 200 liter aquarium. Water injection into the water tank was performed under the same conditions as in Example 1. The fish weight was measured on the last day of acclimatization, and the fish weight of the test fish was about 10 g. The test diet was fed for 10 consecutive days after habituation. The administration condition of the benzimidazole drug was 40 mg / kg fish weight / day, and the administration was once a day. Preparation of the benzimidazole-based drug-added feed and the control group feed was carried out in the same manner as in Example 1. After administration of the test feed for 10 days, a commercial feed was fed, and the amount fed was 2% of the fish body weight. The breeding period was 40 days. The water temperature during the breeding period was about 20.1 ° C.

At the end of the breeding test, all fish were picked up from all sections, and the presence or absence of cysts in the body side muscles was observed by necropsy. Evaluation was performed in the same manner as in Example 2.

Results and Discussion In the albendazole administration group, no fish that formed cysts were observed, and the incidence of mildew was 0% (Table 5). Therefore, it was reproduced that albendazole deworms the worm and inhibits the cyst formation of the worm. The incidence rate, the number of onset fish cysts, and the cyst length in the mebendazole administration group were all lower than those in the control group, and an anthelmintic effect was exerted against this worm. However, the effect was considered to be low compared to albendazole.

It has been found that the anthelmintic effect varies depending on the drug even with benzimidazole drugs.

<Effects of albendazole and fevantel on feeding of yellowtail>
From the results of Examples 1 to 4, it has become clear that the benzimidazole drugs albendazole and fevantel exert a high anthelmintic effect against microsporidium seriole, which causes downy mildew. It was. For use in yellowtail culture, it is desirable that administration of these drugs has no or low side effects that adversely affect feeding. In previous tests, the test was conducted at a water temperature of 20 ° C or higher, and no adverse effects on feeding were observed. Therefore, we investigated whether albendazole and fevantel administration adversely affected food intake at a water temperature of about 18 ° C. The juvenile yellowtail was divided into 6 groups of 10 fish each (2 groups in the control group, 2 groups in the albendazole administration group, 2 groups in the fevantel administration group), and each was housed in a 200 liter aquarium. Water injection into the water tank was performed under the same conditions as in Example 1. The fish weight was measured on the last day of acclimatization, and the fish weight of the test fish was about 73 g. After the acclimatization, the drug-added feed was fed for 10 days continuously, and then the breeding was continued with the commercial feed for 20 days. The drug-added feed was further fed for 10 consecutive days, and then the commercial feed was again fed for 29 days. The administration conditions for albendazole and fevantel were 40 mg / kg fish body weight / day, and administration was once a day. Preparation of the drug-added feed and preparation of the control feed were in accordance with Example 1. Feeding amount was 1.5% of fish weight. The water temperature during the breeding period was about 18.3 ℃.

At the end of the breeding test, all fish were taken from all wards, and the fish weight and body length were measured.

Results and Discussion In the albendazole administration group, the feeding activity decreased slightly during the first drug administration, and it took longer to eat than the control group. However, no decrease in feeding activity was observed during subsequent feeding or drug administration, and the fish weight and body length at the end of the study were comparable to the control group (Table 6). On the other hand, the fevantel administration group did not eat all the prescribed amount of drug-added feed at the time of the first drug administration, and about 20% of the remaining food came. About 20% of the remaining food was observed for 10 days even after switching to the commercial feed after drug administration. No decrease in feeding activity was observed during the second drug-added feed administration, but a decrease in feeding activity was observed for 10 days after switching to a commercial feed after drug administration, and all of the prescribed amount of feed was eaten. I gave it twice a day to make it happen. At the end of the study, the weight and length of the fish in this area were clearly lower than those in the control and albendazole administration groups. Therefore, it was clarified that fevantel decreases the feeding activity of yellowtail at low water temperature. From these results, it was speculated that fevantel had higher side effects on fish than albendazole.

<Examination of albendazole dosage for downy mildew>
The fry produced in the same manner as in Example 1 was offshore to the sea surface ginger, reared for 11 days, and again transported to the land facility. This sea surface ginger rearing caused the yellowtail to be naturally infected with causative parasites of downy mildew. The red sea bream fry brought into the land facility was divided into 12 groups with 40 fish each (control group 0 mg / kg fish body weight 2 groups, 5 mg / kg fish body weight administration group 2 groups, 10 mg / kg fish body weight administration group 2 groups, 20 mg / kg fish body weight administration group 2 group, 30 mg / kg fish body weight administration group 2 group, 40 mg / kg fish body weight administration group 2 group), and each was housed in a 200 liter water tank. Water injection into the water tank was performed under the same conditions as in Example 1. The fish weight was measured on the last day of acclimatization, and the fish weight of the test fish was about 10 g. The test diet was fed for 10 consecutive days after habituation. Administration was once a day. Preparation of the albendazole-added feed and the control group feed was carried out in the same manner as in Example 1. After administration of the test feed for 10 days, a commercial feed was fed, and the amount fed was 2% of the fish body weight. The breeding period was 40 days. The water temperature during the breeding period was about 20.1 ° C.

At the end of the breeding test, all fish were picked up from all sections, and the presence or absence of cysts in the body side muscles was observed by necropsy. Evaluation was performed in the same manner as in Example 2.

Results and Discussion In the albendazole 5mg / kg fish body weight group, less cysts of downy mildew were observed compared to the control group (Table 7). On the other hand, in the group administered with a body weight of 10 mg / kg or more, no fish having a downy mildew cyst was observed. Therefore, it was considered that the minimum effective dose for the downy mildew was about 10 mg / kg fish body weight.

<Examination of the number of days of albendazole administration for downy mildew>
Naturally captured fry were introduced into the ginger of the fishing ground and bred for 21 days. This sea surface ginger rearing caused the yellowtail to be naturally infected with causative parasites of downy mildew. The juvenile yellowtail brought into the land facility was divided into 4 groups (control group 0 mg / kg body weight, 90 fish for 10 days, 40 mg / kg fish body weight, for 3 days, 70 fish groups, 40 mg / kg fish weight, for 6 days 70 fish, 40 mg / kg body weight, 70 fish for 10 days). Each group was housed in a 200 liter aquarium. Water injection into the water tank was performed under the same conditions as in Example 1. The test diet was fed after 2 days of habituation. Administration was once a day. The fish weight of the test fish at the start was about 8 g. Preparation of the albendazole-added feed and the control group feed was carried out in the same manner as in Example 1. After administration of the test feed, commercial feed was fed, and the amount fed was 3% of the fish body weight. The breeding period was 22 days. The water temperature during the breeding period was 20 ° C. for the first 10 days, and then 22 ° C. until the end of the breeding.

At the end of the breeding test, all fish were picked up from all sections, and the presence or absence of cysts in the body side muscles was observed by necropsy. Evaluation was performed in the same manner as in Example 2.

Results and Discussion In the group treated with albendazole 40 mg / kg for 10 days, no affected fish were observed. Onsets were observed in the 3 and 6 day treatment groups, but the incidence, number of cysts and cyst length were clearly lower than those in the control group, and the administration period was 3 or 6 days. However, it exerted an anthelmintic effect against the worm. It should be noted that in the albendazole 3-day and 10-day treatment groups, each one died of fat by feeding away. These fish did not eat from the time of grouping. It was inferred that transportation and environmental changes were affected.

<Therapeutic effect of albendazole on fish with onset of downy mildew>
Naturally caught larvae were introduced into the fishing grounds and raised for 50 days. This sea surface ginger rearing caused the yellowtail to be naturally infected with causative parasites of downy mildew. The larvae brought to land facilities were divided into 10 groups with 28 fish each (control group 0 mg / kg fish weight, 2 groups for 10 days, 10 mg / kg fish body weight, 3 days administration group, 2 groups, 10 mg / kg fish body weight, 10-day administration group 2 groups, 40 mg / kg fish body weight 3 days administration group 2 group, 40 mg / kg fish body weight 10-day administration group 2 groups). Each group was housed in a 200 liter aquarium. Water injection into the water tank was performed under the same conditions as in Example 1. In addition, in order to grasp the onset of downy mildew at the start of the study, 29 fish were necropsied to examine the number of cysts and length of cysts on the body side. The test diet was fed after acclimatization for 3 days. Administration was once a day. The fish weight of the test fish at the start of the test was about 21 g. Preparation of the albendazole-added feed and the control group feed was carried out in the same manner as in Example 1. After administration of the test feed, a commercial feed was fed, and the amount fed was 2% of the fish body weight. In this test, the test feed administration during the breeding period was made into 2 cycles, and the test schedule is shown in FIG. The water temperature during the breeding period was 22 ° C.

At the end of the breeding test, all fish were picked up from all sections, and the presence or absence of cysts in the body side muscles was observed by necropsy. Evaluation was performed in the same manner as in Example 2.

Results and Discussion In all albendazole administration groups, the incidence, number of cysts and cyst length decreased compared to the beginning of the study, and it was found that the anthelmintic effect was exhibited even in symptomatic fish in which cysts were already observed. did. The increase in the number of onset fish in the control group at the end of the test was thought to be due to the formation of cysts by the worms that had not reached cyst formation, and the effect of albendazole on cyst formation was recognized again. Further, it was found that albendazole 10 mg / kg body weight of fish and administration for 3 days exerted a therapeutic effect and a cyst formation inhibitory effect. In each test area, several dead fish were observed. The dead fish was thin and, like Example 6, it was speculated that it died due to anorexia.

<Anthelmintic effect of benzimidazole drugs against myxospores Kdoa Yasunaga>
We investigated the anthelmintic effect of benzimidazole drugs against Kudoa Yasunagai. The fry produced in the same manner as in Example 1 was offshore to sea surface ginger, reared for 10 days, and again transported to the land facility. The sea bream rearing caused the yellowtail to be naturally infected by Kudo Yasunagai. The red sea bream fry brought back to the land facility was divided into 10 groups with 40 fish each (2 groups in the control group, 2 groups in the albendazole administration group, 2 groups in the fevantel administration group, 2 groups in the triclabendazole group, 2 groups in the fulbendazole group), Each was housed in a 200 liter aquarium. Water injection into the water tank was performed under the same conditions as in Example 1. The fish weight was measured on the last day of acclimatization, and the fish weight of the test fish was about 10 g. The test diet was fed for 10 consecutive days after habituation. The administration condition of the benzimidazole drug was 40 mg / kg fish weight / day, and the administration was once a day. Preparation of the benzimidazole-based drug-added feed and the control group feed was carried out in the same manner as in Example 1. After administration of the test feed for 10 days, a commercial feed was fed, and the amount fed was 2% of the fish body weight. The breeding period was 40 days. The water temperature during the breeding period was about 20.5 ° C.

At the end of the breeding test, whole fish were picked up from all sections, a brain smear was prepared, and Difquick dyed. 40 fields of view were observed with an optical microscope 400 times, and the presence of spore and the number of spores were examined. Evaluation was performed by comparing the detection rate (number of detected fish tails / number of test fishes × 100) between the control group and the benzimidazole-based drug-administered group, and the number of spores of the detected fish.

Results and Discussion In the albendazole administration group and the fulbendazole administration group, the detection rate and the number of spores were clearly lower than those in the control group. On the other hand, the number of spores was higher in the fevantel administration group than in the control group. Accordingly, it has been found that albendazole and fulbendazole exert an anthelmintic effect on the worm, and fevantel promotes the growth of the worm.

It was found that not all benzimidazole drugs exert an anthelmintic effect on the worm, and even if they have an anthelmintic effect on the downy mildew, they do not necessarily have an effect on the quadrature yasnagai .

Seven dead fish were observed in the control plot and one in the albendazole plot. The dead fish was thin, and it was assumed that it died from the same cause as in Example 6.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an antiparasitic agent capable of combating downy mildew or myxosporeosis caused by microsporidia parasitic on marine fish by oral administration.

Claims (7)

1. An agent for the treatment of downy mildew or myxosporesis of marine fish containing any one of albendazole, fevantel, fenbendazole, oxfendazole, mebendazole, and fulbendazole as an active ingredient.
2. 2. The therapeutic agent for downy mildew according to claim 1, wherein the causative parasite of downy mildew is a microsporeworm belonging to the genus Microsporidium or the genus Spraguera.
3. 2. The mycosporeworm of claim 1 wherein the causative parasite of myxosporesis is a myxosporeworm belonging to any of the genera Kudoa, Enteromyxum, or Leptotheca. Therapeutic agent.
4. The therapeutic agent according to any one of claims 1 to 3, wherein the marine fish is perch, flounder, or puffer fish.
5. The perch fish is a fish belonging to the genus Buri, Thai or Tuna, the flounder fish is a fish belonging to the flatfish family, and the fish belonging to the puffer fish is a fish belonging to the pufferfish family. Therapeutic agent.
6. The fishes belonging to the genus Buri include yellowtail (Seriola One of the zonata fishes belonging to the Thai family is the southern microdai (Acanthopagrus sivicolus), taiwan daidai (Argyrops bleekeri Oshima), red sea bream (Dentex tumifrons), chidai (Evynnis tumifrons), red sea bream (Pagrus major), black sea bream (Acanthopagrus) schlegelii) and red sea bream (Rhabdosargus sarba, Sparus sarba), and the fish belonging to the genus Tuna are bluefin tuna (Thunnus orientalis), Atlantic bluefin tuna (Thunnus thynnus), southern bluefin tuna (Thunnus maccoyii), bigeye tuna (Thunnus obes) , Albacore tuna (Thunnus alalunga), yellowfin tuna (Thun) nus albacares), Copinus tuna (Thunnus tonggol), and Atlantic bluefin tuna (Thunnus atlanticus). There are rips that belong to the family of rubs belonging to the genus gulp (Pseudorhombus pentophthalmus), Pseudodorhombus cinnamoneus, flounder (Pseudorhombus dupliciocellatus), squirrel flounder (Pseudorhombus arsius), and rubs belonging to the rub (Trphops oligolepis) Or the therapeutic agent of Claim 5 which is a mahugu (Takifugu porphyreus).
7. The therapeutic agent according to any one of claims 1 to 6, wherein the active ingredient is orally administered in an amount of 5 to 100 mg / kg body weight per day.
   

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