Undated circular handstamp for the pharmaceutical firm of H.K. Mulford Co., an antecedent company to the current Merck Corporation. H. K. Mulford developed diptheria anti-toxin in the United States in the late 1890s soon after its initial discovery and use in Germany. They also developed an early small pox vaccine and kept its own cattle to do so. Unlike many of the snake-oil firms of the time, H.K. Mulford developed some effective vaccines and medications, and is considered by many authorities to be one of the first firms in the United States to use scientific methods to develop and create medicines.
H.K. Mulford developed the drug to combat the toxin secreted by the diptheria bacillus. Diptheria's damaging effects come from that toxin. Prior to the development of an effective vaccine against diptheria which would have promoted human immune response to diptheria and prevented a case of the disease, scientists discovered anti-toxin in the blood of animals exposed to diptheria and developed methods to extract effective doses of the anti-toxin. In the early 20th century a vaccine would be developed against diptheria. Antibiotics are used against active diptheria infections. Diptheria anti-toxin is still made today but is rare.
H.K. Mulford would eventually be acquired by the firm of Sharpe and Dohme, which would in turn merge with Merk. Mulford's early history would presage Merck's later success as a developer and manufacturer of vaccines.