There are a handful of rare diseases out there that are known as “neglected tropical diseases,” or NTDs. Leishmaniasis is one of them. While many of these are only found in remote, tropical, or unsanitary places in the world, it turns out that leishmaniasis — which is caused by protozoan parasites from 20 different Leishmania species and transmitted to humans through sandflies — is beginning to appear in the U.S.

Like the other diseases on the NTD list, leishmaniasis is nearly impossible to treat. It’s come into the spotlight recently because some 20 people on a Honduran rainforest expedition fell ill after returning to the U.S.. There’s still a lot about the disease that scientists don’t understand, however.

Most leishmaniasis cases that have popped up in the U.S. involved individuals who had contracted the disease while traveling. The risk of an average American falling ill with it is very low. However, in 2012 researchers pinpointed 13 cases of cutaneous leishmaniasis — a form of the disease that causes skin sores and isn’t as severe as visceral leishmaniasis — in Texas and Oklahoma. The patients hadn’t traveled outside their area, so their cases were considered “autochthonous,” meaning they contracted the disease in the U.S.

The researchers aren’t sure what’s causing the parasite to spread north, but they outline a few reasons in their study. “Urban sprawl, climatologic variability, or natural expansion of Leishmania Mexicana are possible explanations for the apparent spread to the north and east,” the authors wrote.

But for now, the risk of the average American getting leishmaniasis is extremely low. People in tropical regions of North Africa, southern Europe, Central America, and South America, are more likely to be exposed to infected sandflies or dogs. Humans typically can’t spread it to one another unless they share blood transfusions or infected needles.

“It’s a disease that tends to occur in conditions of extreme poverty, where there are breakdowns in garbage collection and the sand flies that carry it proliferate, and where people live in poor-quality dwellings,” Dr. Peter Jay Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, told National Geographic. “It has not been a priority for drug development.”

If we can learn anything from the Ebola outbreak, it’s never too soon to boost research for relatively rare, tropical diseases that can spread quickly. There are some treatments that have been approved, such as drugs like meglumine antiomiate and Amphotericin B, but they often come with debilitating, toxic side effects. Leishmaniasis can be treated, but only if it’s early enough. Most of the time, patients end up living with scars, disfigurations, or unhealed lesions for years.

Currently, there has been an outbreak of leishmaniasis in conflict-ridden countries like Syria. The faster we can get a vaccine available, the better we’ll be able to prevent another Ebola-like outbreak in countries that aren't equipped to treat scores of people.