(AKA Seal Finger, Spaek Finger, Speck Finger, Spekk Finger, and Blubber Finger)
Fish finger is an infection that develops after handling fish, fish products, seal, or walrus. It is considered an occupational hazard for wildlife and marine workers and aquarium personnel. It may also occur from handling items exposed to the above such as slime covered nets, knives, etc. In the Delta, the infection may be noted on any extremity that comes into contact with aquatic creatures. Patients may describe both arm and leg exposure to animals such as walruses, ie when kneeling on a carcass while butchering. Fingers, however, are the primary area involved. A complete history is warranted when investigating the presentation of a painful, red, swollen digit. Patients may insist they have used intact gloves with butchering, yet on later history they reveal gutting lake trout without gloves.
The infection is characterized by an incubation time ranging from hours to 3 – 4 days. Infection may occur in initially intact tissue, although history of seal or fish bite, knife cut, etc may precede infection onset. Fish finger develops rapidly, with severe pain, intense swelling, and often adjacent joint involvement. Ascending lymphangitis and adenopathy may be seen. Without treatment, the joint symptoms may progress for months or years, leading to cellulitis, tenosynovitis, and/or arthritis. Pathological examination has revealed neither necrosis nor abscess formation. Prior to antibiotics, sealers were known to opt for amputation because of the pain and disability resulting from infection.
The causative organism is unknown. Three different types of mycoplasm are suspect. Unfortunately these cannot be appreciated on routine culture. Other organisms that may cause similar infection from saltwater organism exposure include erysipelothris rhusiopathiae and vibrio vulnificus. This differential is important because while vibrio and mycoplasm infection are treatable with tetracyclines, erysipeloid infection is treated with penicillins.
With a straightforward presentation of a dull red. hot, swollen, very painful finger with a rapid onset and clear history of fish/walrus/seal exposure, fish finger is suspect and doxycycline is the drug of choice. This will cover the common sources of infection. Erysipelothris is suspect, however, is there is not a good response to doxycycline, if the erythema is intense, and if the infection spreads peripherally with violaceous color and distinct raised borders. Erisipelothris is a serious infection with risk of bacteremia and endocarditis, thus is important to keep in the differential. Erisipeloid may be cultured as well.
It is wise to keep village patients with fish finger in town for a recheck the following day, in order to observe response to doxycycline. If they return to the village without a recheck, there is the possibility that they will be “weathered in” and be unable to promptly return to Bethel should treatment failure occur. This places them at risk of bacteremia and endocardititis should they be infected with the more serious erysipeloid.