AMNA NAWAZ: Health officials are on high alert because of the rapid spread of mpox in several African nations.

The World Health Organization has declared the outbreak a global health emergency.

And experts warn the virus could spread further internationally.

In fact, today, Sweden reported the first case outside of Africa in an individual who had recently returned to Sweden from Africa.

Ali Rogin has the details.

ALI ROGIN: The Africa Centers for Disease Control reports that mpox, originally known as monkeypox, has been detected in 13 African nations, including Kenya, Rwanda and Uganda.

More than 96 percent of all cases and deaths have occurred in one country, the Democratic Republic of Congo.

So far there have been more than 14,000 cases registered and 524 deaths in the continent this year alone, surpassing last year's numbers.

Experts are asking for more funding, vaccines and a concerted effort to slow the transmission of this virus, which can be spread through infected individuals, sex and contaminated meat.

For more, I'm joined by Anne Rimoin, an epidemiologist at the University of California at Los Angeles who has studied mpox in the Democratic Republic of Congo for two decades.

Anne, thank you so much for being here with us.

What populations are the most vulnerable to mpox?

DR. ANNE RIMOIN, UCLA Epidemiologist: Well, thanks for having me here.

What we're seeing is, we're seeing two different populations at great risk.

We're seeing people in remote rural areas in DRC who are traditionally hunting wild animals for food source.

And then we're seeing from -- a spillover from an animal to a human, some human-to-human transmission within households.

The other thing that we're seeing in more urban areas is sexual transmission, primarily happening in sexual and gender minorities and also in sex workers as well.

ALI ROGIN: And why are we seeing such a rise in reported cases and deaths this year, as compared to last year?

DR. ANNE RIMOIN: Well, there are a number of reasons that this could be happening.

And nobody knows for sure, because we just haven't had terrific disease surveillance on the ground, given all of the logistical barriers that are in place, given the vastness of a place like DRC and the limited resources available.

So we don't have excellent surveillance on the ground.

We don't have enough diagnostics.

So many of these cases are reported.

They don't go with big case investigations that give us the data that we need to really know what's happening on the ground.

We don't have the tests available to be able to determine, is this monkeypox or is this something else?

So, right now, situational on the -- awareness on the ground is less than optimal.

And that's why it's not possible to say with certainty anything about what's happening on the ground.

ALI ROGIN: And that underscores again how little we know about the specifics of how this disease, how this virus is spreading.

But I do wonder, does the declaration of a global emergency have any impact on that?

And what other effects might come from this declaration?

DR. ANNE RIMOIN: Well, seeing these global declarations, first from Africa's CDC calling this a global health emergency of regional concern, and then from WHO, the public health emergency of international concern, should be very important in terms of unlocking funds and resources to be able to really better understand the mechanisms of spread, provide information through better surveillance, better testing, and then also being able to get vaccines on the ground to be able to better control the outbreaks that are occurring.

ALI ROGIN: And tell us about the scarcity of vaccines.

I know that's a big issue.

DR. ANNE RIMOIN: Africa CDC suggested that they should -- that there is a need for approximately 10 million doses of vaccine to be able to control the outbreak on the ground.

And, right now, there is actually very limited supply of vaccine available.

The DRC is working closely with their partners on the ground to be able to identify groups that are at greatest risk, where they can deploy the vaccine most effectively first to be able to control the outbreak on the ground.

But, by and large, we should be getting maximum number of doses of vaccine available to places like the Democratic Republic of Congo, where this virus has originated, so that we can control it at its source.

That's going to be critically important.

And these countries where -- that are most affected by this virus are countries that have the least amount of resources available traditionally and currently.

So, hopefully, these declarations will make a very big difference in terms of being able to get resources to the places that are needed.

ALI ROGIN: That's UCLA epidemiologist Anne Rimoin.

Thank you so much for joining us.

DR. ANNE RIMOIN: My pleasure.