Chikunganya, a disease which emerged in Africa is sweeping through South America, causing devastating illness, although only few fatalities.

SANTO DOMINGO, AP - An excruciating mosquito-borne illness that arrived less than a year ago in the Americas is raging across the region, leaping from the Caribbean to the Central and South American mainland and infecting more than one million people.

Some cases have already emerged in the United States.

While the disease, called Chikungunya, is usually not fatal, the epidemic has overwhelmed hospitals, cut economic productivity and caused its sufferers days of pain and misery. And the count of victims is soaring.

It's spread has not gained much media attention, since the world's focus has been on Ebola.

Chikungunya is transmitted when a mosquito bites an infected person and then feeds on someone else.

Chikungunya is a word that comes from the Makonde language of Tanzania in eastern Africa and translates roughly as "that which bends up," in reference to the severe arthritis-like ache in joints that causes sufferers to contort with pain.

It's usually accompanied by a spiking fever and headache. There have been only 113 deaths linked to the region's outbreak, according to the most recent data.

In El Salvador, health officials report nearly 30,000 suspected cases, up from 2300 at the beginning of August and hospitals are filled with people with the telltale signs of the illness, including joint pain so severe it can be hard to walk.

"The pain is unbelievable," said Catalino Castillo, a 39-year-old seeking treatment at a San Salvador hospital.

"It's been 10 days and it won't let up."

Venezuelan officials reported at least 1700 cases as of Friday and the number is expected to rise. Neighbouring Colombia has around 4800 cases but the health ministry projects there will be nearly 700,000 by early 2015.

Brazil has now recorded its first locally transmitted cases, which are distinct from those involving people who contracted the virus while travelling in an infected area.

Hardest hit has been the Dominican Republic, with half the cases reported in the Americas. According to the Pan American Health Organisation, Chikungunya has spread to at least two dozen countries and territories across the Western Hemisphere since the first case was registered in French St Martin in late 2013.

There have been a few locally transmitted cases in the US, all in Florida, and it has the potential to spread farther, experts say.

But Central and South America are particularly vulnerable.

It may have found fertile ground in Latin America and the Caribbean because many people are outside in the daytime, when aedes aegypti bite, or lack adequate screens on their windows.

Conditions vary widely in the region. Haiti, where many people live in flimsy shacks with little protection from mosquitoes, has been hit hard. In Venezuela, air conditioning is widespread but the country has a shortage of insect repellent and pesticide sprayers due to the country's economic problems.

The chief factors are the prevalence of the main vector for the virus, the aedes aegypti mosquito, and the lack of immunity in a population that hasn't been hit with chikungunya in modern medical history, said Scott Weaver, director of the Institute for Human Infections and Immunity at the University of Texas Medical Branch.

"There are going to be some very large populations at risk down there, much larger than the Caribbean," Weaver said.

Authorities throughout the region have been spraying pesticide and encouraging people to remove water containers where mosquitoes can breed.

Copyright AAP 2014.