Black Spot
Uvulifer ambloplitis, a trematode also known as black spot, infects a large number of Northern pike. Uvulifer ambloplitis is not known to be transferable to humans. External signs of this parasite are black spots on the fins, gills and scales of the Northern pike. Fortunately, adequately cooking, cleaning and skinning of the fish kills the parasite. As northern pike secrete a mucus coating to prevent illness, fishers can help to slow the spread of this disease to non-infected, undersized fish by removing the hook underwater or wetting your hands before handling the fish.
Red Sore
Pseudomonas hydrophila is another parasite that lives within the northern pike and causes red sore in them. This bacterium is not known to be transferable to humans, however it significantly reduces the appeal of the fish. Symptoms of this parasite include red lesions on the flesh and muscle of the fish, and these can lead to cancerous tumors. While not infectious to humans, this disease renders the fish nearly inedible because of damage to the meat and can easily spread to other fish.
Broad Fish Tape Worm
Broad fish tape worms are to humans the most potentially dangerous infection from which a northern pike can suffer. These parasites are well adapted to life within the gut of an adult fish, and often do not display obvious signs of infection. To ensure no transferal of broad fish tape worm occurs when eating northern pike, cook your catch very thoroughly. Inadequately cooked fish is the primary cause of infection in human hosts.
Blue Spot
Esocid herpesvirus-1, also known as EHV-1 occurs in northern pike and causes small blueish lesions. Most often these lesions occur on the dorsal fin and flesh, and like most northern pike diseases is not known to be transferable to humans. This infection is highly contagious to fish, and if an infected fish is caught, fishing equipment should be sterilized to avoid further infection spread. Adult fish seem relatively unaffected by this disease, however it is thought to cause death in younger fish. The disease seems to be dormant in warmer water, but outbreaks occur when water temperature is between 35 and 55 degrees Fahrenheit.
