Diphtheria

Diphtheria is treated with an antitoxin that can only neutralize the toxin that has not yet bound to a cell membranes; it cannot neutralize the toxin that has already bound to and penetrated a cell. For this reason, antitoxin must be administered early in infection. In fact, some experts recommend giving doses of antitoxin if diphtheria is even suspected, since the additional time spent waiting for confirming lab results allows for more of the toxin to spread and penetrate the cells.