Un petit extrait d'un article à venir sur les Camallanus (en anglais pour l'instant). L'auteur étant Tapan (dit le scotish ), un véto français expatrié :Camallanus spp :
A previous study from up to five different exporting companies’ showed uniformly hiGH parasite prevalence and suggested that prior to release, fish transported internationally should be checked for hiGH risk pathogens such as Camallanus cotti.
Picture 1: Camallanus spp. under a binocular :
These are nematodes, also called roundworms or th
readworms. They are elongated with a round cross-section and usually less than 3 cm long. It is an intestinal parasite of fresh-water tropical fish. Related species can be found in temperate and tropical fish worldwide.
Its wide geographical distribution seems mainly to be the result of dissemination due to extensive ornamental fish trade.Pathogeny:
Attachment to the wall of the posterior intestine and blood feeding behaviour cause considerable damage:
-Ischemia of the intestine wall resulting in emaciation (Loss of muscle mass along the back),
- anaemia, and lethargic.
- secondary infection: internal bacterial infection which consequently give death.Diagnostic :
The early signs of the parasite's presence are typically unnoticed. The infestation is characterised by the presence of tiny red thread structures protruding few millimetres from the anus of the infected host fish (cf.pict.2).
The parasites are only visible when protruding from the anus to release their live larvae. Close inspection of the victim shows a swollen and irritated vent area. It must be decided whether or not destruction or treatment of infected fish is more appropriate.
picture2: Xyphos with protruding Camallanus cotti :Host species :
The parasitic fish nematode Camallanus has been reported from a number of freshwater fish species around the world. Camallanus cotti infestations occur most often in livebearer fish such as : Poecilia reticulata (guppy
); Xiphophorus maculatus (platy
). Other species of Camallanus infected american cichlids like Pterophyllum scalare
(angel fish), Apistograma sp…and Anabantidae species. But Camallanus is able to infect directly a variety of different families of fish.
: cf fig1
Microscopic larvae from this parasite are constantly being produced and dumped into the water when the fish are stationary. Like most of the fish nematodes, Camallanus use an intermediate host, a copepode (a cyclope), but can complete their life cycle without intervention of secondary host. The life cycle is about 6 month at 24-26 C. Moreover the infective free-living stage larvae may survive for more than three weeks in the host-external environment and several months in copepods. Control and treatment :Introduction of fish species:
-Quarantine and regular inspections are important (the worms are not visible all the time)
-Separation in individual tanks of each differents species, origins and age.
-Livebearer species require particular attention.Control of copepods:
-Avoid feeding your fish with copepods or freezing them before the passing of at least a week.
-Disinfection of plants before introduction in the tank (may contain copepods)
-Each tank must have its own materiel and both must be disinfected after each use.Treatment:
Any treatment for Camallanus under aquaculture or aquarium conditions should be directed towards all fish, including those not yet showing visible clinical signs in the same tank, as well as the free-living larvae on the substrate: fish should be isolated in a naked and disinfected tank with the system cleaned and sterilised.
Several anthelmintics can be used in different ways:
- Bath treatment: with levamisole, febendazole
- Oral treatment: with piperazine, febendazole
An aquaculture veterinarian should be approached regarding appropriate molecule, dose, and use in any one of the particular case.