Following recent news that Zika virus can lurk in semen for months, a pair of infectious-disease researchers got to wondering: how many other viruses can hang out down there?

With the intriguing question dangling, the ballsy researchers decided to do a study to figure it out—because, you know, why not?

The answer: 26.

With Zika, a total of 27 viremia-causing viruses are known semen squatters, including some not typically considered sexually transmitted, the pair reported in Emerging Infectious Diseases. The startling finding whips out a load of questions about men’s health, sexual transmission of viruses, and risks to offspring.

To come up with the titillating total, the two researchers— Peter Horby of Oxford and Alex Salam of NHS Foundation Trust—did a full pat-down of scientific literature, going over more than 3,800 studies. They looked for those that mentioned detecting viruses in semen by viral DNA or RNA, antigens, or replication. To keep their search most relevant to health, they only sought viruses known to get into the blood, causing viremia.

The full list of 27 is shown to the right. Some may cause chronic or latent infections, such as HIV or cytomegalovirus. Others can cause acute infections, such as chikungunya and Lassa fever. The researchers note that previous studies have picked out at least 11 viruses that are testes tenants and can cause inflammation there. These include SARS, influenza, and dengue.

The 27 viruses come from diverse families of viruses, suggesting that they may all be using different means for spunky sojourns. In fact, it might be rather easy for viruses to penetrate the male reproductive tract; the southern blood-brain barriers are often patchy, especially if there’s inflammation anywhere along the line. And the area is “immunologically privileged,” that is, immune responses are restricted there to protect sperm.

With finding so many—and so many different—viruses that can seed male seeds, Horby and Salam were bursting with questions. The ones they say should be answered first and foremost include: “Which viruses are shed and remain viable in semen, for how long, and at what concentrations?”

And they spewed a daunting set of scenarios and potential risks, including that hidden splooge-dwellers could: boost risks of sexually transmitted infections, reduce fertility, and spread to subsequent generations and elevate their risks of cancers and other disorders. The pair also pondered the potential for viruses to hide in the male reproductive tract, unreachable by drugs or treatments.

Following the eruption of possibilities, the researchers calmly concluded:

The presence of viruses in semen is probably more widespread than currently appreciated, and the absence of virus in genital secretions should not be assumed for traditionally non–sexually transmitted viruses.

Emerging Infectious Diseases, 2017. DOI: 10.3201/eid2311.171049 (About DOIs).