Even the technologically advanced U.S. is not able to eradicate the plague that haunted Africa, Asia, and Europe killing about 50 million people in the 14th Century. Europe’s population was reduced to half.
In London, the Great Plague of 1665, killed about a fifth of its citizens. In the 19th Century, more than 12 million died in China and India.
The disease had not been totally eradicated. It is endemic in Madagascar, the Democratic Republic of Congo and Peru. It is still killing people in the US. So far, 15 cases were reported in the U.S. according to the Centers for Disease Control and Prevention (CDC). The four deaths is higher than in any other year in this century. Daniel Epstein of the World Health Organization (WHO) says that the bacterium Yersinia pestis responsible for the plague was introduced to the U.S. by rat-infested steamships in 1900. The plague that was an epidemic in Western port cities moved to Los Angeles in 1925. It spread to rural rats and mice and that’s how it became entrenched in parts of the US.
The plague is transmitted from animals to humans by fleas with a mortality rate of 30% to 60% if left untreated. But, with antibiotics, patients can be saved if diagnosed early.
- More than 80% of US cases have been bubonic plague, which affects the lymph nodes and causes gangrene
- The disease can affect the blood (septicaemic) or the lungs (pneumonic)
- The disease develops after three to seven days.
- A laboratory test can confirm diagnosis
Most cases occur in summer when people spend more time outdoors. “The advice is, take precautions against flea bites and don’t handle animal carcasses in,” says Epstein. The plague-endemic areas are New Mexico, Arizona, California and Colorado, according to the CDC. All of this year’s cases originated in those states or in other states west of the 100th meridian causing a ‘plague line’. Prairie dogs which are believed to live west of the 100th meridian help the infected fleas to spread. Black-footed ferrets and the Canada lynx are other particularly susceptible species. It’s the existence of this “animal reservoir” that makes the plague hard, if not impossible, to eradicate, experts say.
The plague can’t be eradicated unless the animals are vaccinated. The scientists at the National Wildlife Health Center have been working with Parks to develop oral vaccines to protect black-footed ferrets and prairie dogs. The plan is to vaccinate all animals, at least in the most popular national parks. The researchers are trying to improve ways of diagnosing it, and to develop an effective human vaccine because the plague has been classified as a “category A bioweapon”. An average of seven cases of plague per year is different from the peril of biological warfare that can’t be ignored.
