Eskimos are very susceptible to upper respiratory infections on contact with the outside world. Ordinary bacterial infections rarely occur. Diphtheria and scarlet fever are unknown clinically and in a group of about fifty subjects all were negative to the Dick test and all the adults were also Schick negative. Children up to the age of twelve years were invariably Schick positive.
Three serums were found to contain antitoxin both for diphtheria and scarlet fever. It is therefore concluded that the immunity to the disease and the negative skin tests depend on the presence of antitoxin. This is interpreted as being due to a natural hereditary immunity dependent upon some non-specific antitoxic mechanism. Skin reactions with filtrates of streptococci isolated from cases of rheumatic fever were mildly positive in a small percentage of cases. Neutralizing antitoxin was demonstrated in all three sera but it was not invariably present for all three toxins. The Eskimos showed a high percentage of positive reactions when tested with a staphylococcus aureus filtrate.