Hitch-hiking viruses.
D000818:Animals; D005393:Fish Diseases / Q000382:microbiology* / Q000635:transmission; D005399:Fishes; D008297:Male; D013094:Spermatozoa / Q000382:microbiology*; D014777:Virus Diseases / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*