Cutis masculinus virus and cutis femininus virus are the two members of the cutisvirus family known to infect humans. It is estimated that >90% of the world's population has been infected with a cutisvirus at one point or another. While the viruses may also be contracted through exchange of bodily fluids, they are still primarily spread by skin-to-skin contact, hence the name cutisvirus from the Latin word for "skin". Early-stage cutis masculinus infection may cause uterine hyperplasia, and early-stage cutis femininus infection may cause prostatic hyperplasia, both resulting in abdominal pain and urinary incontinence colloquially known as "cooties" (a corruption of "cutis"). Early-stage infections are most common among prepubescent children. Cutis m. infection in a male and cutis f. infection in a female have no clear symptoms, although these are still capable of spreading the infection — this is why schoolyard children tend not to fraternize with the opposite sex, declaring that they all "have cooties". By the onset of puberty most children have developed an immunity to early-stage cutisviruses and are no longer infectious.
Symptoms of cooties typically resolve within a week of infection, thereafter cutis m. migrates to and lies dormant in the ovarian cells, and cutis f. migrates to and lies dormant in the testicular cells. In about 1 in 75 cases, cutisviruses will reactivate after years or even decades of dormancy, resulting in gonad transformation syndrome (GTS, colloquially known as "the trans"), where the viruses in their replication end up modifying the gonad cell genes in such a way that the granulosa and theca cells spontaneously become Sertoli and Leydig cells (cutis m. infection), resulting in infertility and masculinization; and likewise Sertoli cells become granulosa cells (cutis f. infection), resulting in infertility and feminization.
Those with immunity to the early stage of cutisviruses that causes "cooties", will in all likelihood not have immunity to the late stage that causes "the trans" — the two stages are so different that they are for all intents and purposes different viruses, setting the cutisviruses apart from other latent viruses like VZV. Therefore cutisvirus infection from someone with GTS may result in GTS in the infected, or may make the infected a carrier of GTS.
This is why persons with GTS, colloquially termed "trans people", are ostracized from society — lest women be masculinized, men feminized, and children sterilized. Although prophylaxes have been developed, it is still a good idea for the sake of public health to screen potential sexual partners for GTS.
In summary: trans people have an advanced form of cooties capable of infecting adults.