It is poorly understood, though, what ultimately connects these emotional experiences to sexual gratification, or how that connection initially forms. Dr. Joseph Merlino, author and psychiatry adviser to the New York Daily News, said in an interview that a sadomasochistic relationship, as long as it is consensual, is not a psychological problem:

Its a problem only if it is getting that individual into difficulties, if he or she is not happy with it, or its causing problems in their personal or professional lives. If its not, Im not seeing that as a problem. But assuming that it did, what I would wonder about is what is his or her biology that would cause a tendency toward a problem, and dynamically, what were the experiences this individual had that led him or her toward one of the ends of the spectrum. It is usually agreed on by psychologists that experiences during early sexual development can have a profound effect on the character of sexuality later in life. Sadomasochistic desires, however, seem to form at a variety of ages. Some individuals report having had them before puberty, while others do not discover them until well into adulthood. According to one study, the majority of male sadomasochists (53%) developed their interest before the age of 15, while the majority of females (78%) developed their interest afterwards (Breslow, Evans, and Langley 1985). The prevalence of sadomasochism within the general population is unknown.
The provisional representation of species addressed by the resource has been indicated in the TaxBox on this page by a superscript yb beside the species name. Development of YersiniaBase was funded by the University of Malaya and the Ministry of Education, Malaysia. Pathogenesis
Y. pestis is the causative agent of plague. The disease caused by Y. enterocolitica is called yersiniosis. Yersinia may be associated with Crohns disease, an inflammatory autoimmune condition of the gut. Iranian sufferers of Crohns disease were more likely to have had earlier exposure to refrigerators at home, consistent with its unusual ability to thrive at low temperatures. Yersinia is implicated as one of the causes of reactive arthritis worldwide.Also, the genus is associated with pseudoappendicitis, which is an incorrect diagnosis of appendicitis due to a similar presentation. History
Y. pestis, the first known species, was identified in 1894 by A.E.J. Yersin, a Swiss bacteriologist, and Kitasato Shibasaburō, a Japanese bacteriologist. It was formerly described as Pasteurella pestis (known trivially as the plague-bacillus) by Lehmann and Neumann in 1896. In 1944, van Loghem reclassified the species P. pestis and P. rondentium into a new genus, Yersinia. Following the introduction of the bacteriological code, it was accepted as valid in 1980. References
External links
Yersinia Enterocolitis Mimicking Crohns Disease in a Toddler
Sweden: Pork warnings over new stomach illness
Yersinia genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
YersiniaBase