TOX and Fever: Here, we showed that C. diphtheriae is a contributor; of note, six other cases of tox-negative C. diphtheriae endocarditis were previously reported in New Caledonia, five of them between 2005 and 2011, and one in 2021 (CHT laboratory data, unpublished), for a total of 8 cases, and with a history of acute rheumatoid fever for 6 patients.