A mysterious skin disease has infected dozens in Vietnam's central Quang Ngai province and has claimed the lives of 19 people. Residents are frightened, the country's doctors are stumped, and officials are asking for the World Health Organization (WHO) to intervene. "Since we don't know what caused the disease, we will have to rely on our rituals and prayers," said one worried resident. Here, a brief guide to the perplexing contagion that has the country rattled:

What does the disease do?
It starts with a rash on the palms of the hands and soles of the feet, says the BBC, before it "progresses to liver problems and multiple organ failure." Other symptoms include a loss of appetite, high fever, and potential eye and respiratory problems. The disease was first reported in 2011, but doctors have not been able to stop it from spreading. Now, it has re-emerged in the mountainous district of Quang Ngai province, says Reuters, and no one's sure why. 

How many people have been infected?
Within the past year the mysterious ailment has afflicted 171 people. And those who have had it once don't become immune to it; 29 patients contracted the illness twice. Doctors suspect that the infection "travels by touch," says Digital Journal

Is it curable?
"Once the infection has set in, it is extremely difficult to treat effectively," says Christian Nordqvist at Health News Today. But if symptoms are caught early on, the infection is very treatable. 

What's causing it?
Doctors still aren't entirely sure, but "Vietnamese health authorities believe that the victims are suffering from poisoning from chemical herbicides," notes Digital Journal. The symptoms are consistent with the harmful effects of one brand of spray used on cassava fields, an "American product named Kanup 480 SL." In the meantime, the government has asked the WHO and the U.S. Centers for Disease Control and Prevention to help determine the mysterious killer.

Sources: ABC News, BBC, Digital Journal, Medical News Today, Reuters