* The phrase appears to date from 1821 when France sent 30,000 troops into the Pyrenees to stop a lethal fever raging in Spain from crossing the border. Centuries ago, in its most extreme form, everyone within the boundaries of a cordon sanitaire was left to die or survive, until the outbreak ended.
* The most famous voluntary cordon, according to Joseph P Byrne, a historian at Belmont University in Nashville, was of the English village of Eyam. In 1665, the plague reached it from London, probably in fleas on cloth shipped to a local tailor, the first to die. The village, which had about 350 people, voluntarily cordoned itself off from the spring until November to prevent the plague from spreading to the rest of Derbyshire. Grateful people from other villages left food outside a circle of stones around Eyam. Only a quarter of the village survived, but the plague did not spread.
* Cordons have not been seen since the border between Poland and Russia was closed in 1918 to stop typhus, a disease spread by lice or fleas, from moving West. Delousing stations were established for troops on the Western Front during WWI, but the disease ravaged the armies of the Eastern Front. Travellers wanting to cross had to be interned, bathed, shaved and deloused, and their clothes had to be treated with chemicals.
* The US has seen cordons with racial overtones. In 1899, a 35-acre area of Honolulu housing its Chinese and Japanese residents was sealed off because of the plague. Ultimately, a blaze started by the Fire Department to burn flea-infested buildings got out of control and destroyed much of the district.
* Plans for the new cordon were announced on August 1, isolating a triangular area where worst-affected Guinea, Sierra Leone and Liberia meet, separated only by porous borders. Seventy per cent of known Ebola cases are here.
* Inside the cordoned areas, residents have told reporters they fear starving because food prices are rising. Many farmers have died, and traders who cannot travel cannot earn money.
* It is not clear whether plans to deliver food, water and care are underway.
* Officials, including at the Centers for Disease Control and Prevention, which advises the countries, say the tactic could help contain the outbreak but want to see it used humanely. WHO has not opposed the cordon either.
* There have been nearly 20 Ebola outbreaks in Africa, and all previous ones were beaten by the same tactics: Teams of outside health experts flew in, recruited local health workers and set up field hospitals to treat victims. The teams also took over burials, disinfecting and bagging bodies. They traced all contacts of known victims and hospitalised any who fell ill. Health workers protected themselves with gloves, coveralls, masks, bleach spray and the burning of used gear.
* The disease is named after the Ebola river in the Democratic Republic of Congo, where the first outbreak, in 1976, started.