(NEXSTAR) – Monkeypox cases have been confirmed in all but one state, but there’s still a lot we don’t understand about the virus, health leaders admit.

How the virus spreads is actively being studied, even as the number of U.S. cases nears 10,000.

In a late July update from the Centers for Disease Control and Prevention, the agency admits there are several aspects of monkeypox transmission that require more scientific research.

The first thing – a major one – is whether or not the virus can be spread by someone who has no symptoms. The best-known monkeypox symptom is bumping on the skin, but the virus can also cause fever, headaches, aches, chills, and fatigue.

Secondly, it’s not clear how often the virus is being spread through “respiratory secretions,” like coughing or sneezing, the CDC says. Scientists agree respiratory spread is technically possible with monkeypox, but it’s not yet established how often it is driving the transmission.

Finally, the CDC writes, that more research is needed on whether the virus can spread through “semen, vaginal fluids, urine, or feces.”

We do know the virus appears to mainly be spreading through sexual and intimate activity. However, the virus could be transmitted as a result of close skin-to-skin contact that happens during sex – not through bodily fluids. The CDC says more research is needed to understand the role bodily fluids play in transmitting the virus if any.

The CDC also acknowledges the virus can spread through contact with surfaces, though infectious disease experts don’t believe this form of spread is a major threat.

“I don’t think I would worry too much about these very casual encounters with inanimate objects,” said Dr. David Wohl, a professor in UNC School of Medicine’s Division of Infectious Diseases, in an interview with WTVD. “You’re not going to catch this at a restaurant. You’re not going to catch this off of a park bench. Trying on clothes, I would say that’s pretty unlikely. You would have to have somebody who right before you tried on clothes, had lesions with monkeypox virus.”

There are a few other ways monkeypox can spread, the CDC says. Pregnant people can transmit the virus to a fetus through the placenta, for example.

Animal-to-human transmission is also possible, “either by being scratched or bitten by the animal or by preparing or eating meat or using products from an infected animal,” the CDC writes.