An Open-label, Nonrandomized Study to Evaluate the Safety and Immunogenicity of Raxibacumab With Reinjection

Inclusion Criteria: * Enrolled and treated with raxibacumab in another HGS protocol, \>= 4 months ago. * Male or female \>= 18 and \<= 64 years of age. * Laboratory values that are Grade 0 by the modified Division of Microbiology and Infectious Diseases (DMID) toxicity tables. Subjects with laboratory values that are Grade 1 and are not considered clinically significant by the Principal Investigator may be enrolled following consultation with the Medical Monitor. * A female subject is eligible to enter the study if she is: Not pregnant or nursing, Post menopausal, has had a hysterectomy, or documentation of sterility, Of child bearing potential (ie, woman with an intact uterus and ovaries and no documentation of oviductal or uterine dysfunction that would cause sterility). * These women must have a negative blood pregnancy test at screening and on Day -1 prior to dosing and agree to 1 of the following: a)Complete abstinence from intercourse from the date of screening through the duration of follow-up, b)Consistent and correct use of 1 of the following medically accepted methods of birth control, in addition to a male partner who correctly uses a condom or is sterile prior to the female subject's entry into the study and is the sole sexual partner for the female subject from the date of screening through the duration of follow-up, implants of levonorgestrel; injectable progesterone; any intrauterine device (IUD) with a documented failure rate of less than 1% per year; oral co…