The influence of pollution of Bulgarian section of the river Danube on the occurrence of helminthiases in fish.
D000818:Animals; D002031:Bulgaria; D005393:Fish Diseases / Q000469:parasitology*; D005399:Fishes / Q000469:parasitology; D005618:Fresh Water; D006373:Helminthiasis / Q000469:parasitology; D006374:Helminthiasis, Animal