Ten days after quarantining a town of 10,000 people after three deaths from the pneumonic plague, Chinese officials announced at the beginning of this week that the quarantine had ended.
On Saturday night, according to wire reports, the quarantine on Ziketan, in the ethnically Tibetan Chinese province of Qinghai, ended when no new deaths from the plague were reported. Three people died and nine people were sickened during the course of the plague.
The bacteria responsible, Yersinia pestis, is the same bacteria blamed for the bubonic plague, which wiped out, millions of people in Europe in the fourteenth century.
While this form of the disease, known as pneumonic plague, spreads from human to human, without needing rats or fleas for transmission, it does not present the grave threat to humans that it did in medieval times.
"In this form, the organism gets in the lung -- that allows it to be transmitted by coughing," explained Philip Alcabes, associate professor in the program in urban public health at Hunter College's School of Health Sciences and author of Dread: How Fear And Fantasy Have Fueled Epidemics From The Black Death To Avian Flu. "The problem with that is that it allows it to be transmitted directly from person to person."
Fleas will spread the bubonic plague when they bite rats, injecting the bacteria into the animal's bloodstream, but will bite humans when a rat is not available. In some cases, those bacteria will find a way into the lung, turning bubonic plague into the more contagious pneumonic plague.
"If it's in the person's bloodstream, that's called bacteremia. That goes to the lungs, and it could potentially seed the lung tissue, and the bacteria could set up shop there," said Dr. Howard Markel, professor of the history of medicine and of pediatrics and communicable diseases at the University of Michigan Medical School in Ann Arbor, who noted that the disease could also become pneumonic if aerosolized bacteria are inhaled.
"Pneumonic is the kind where you really get scared," he said. "You can spread it even more quickly?breathing on people in close, crowded areas."
While China quickly moved to quarantine the village, Markel and Alcabes questioned the appropriateness of that response.
"Quarantines were invented historically for bubonic plague," said Markel, noting that the port in Venice was closed because of the Black Death.
He said, however, that a quarantine needed to be more targeted when it is used.
"You certainly want to isolate those who are ill with it, and the people who are taking care of those people are going to have to take 'universal precautions' - gloves, mask, etc," he said.
He said that people who interact with these patients may need to be placed under a "voluntary quarantine."
Markel said controled quarantines may be effective in cases where a disease is spread person to person in the manner of pneumonic plague.
"There may be some benefit, but we haven't measured that," he said.
He noted that the response may be the result of criticism after a lax response by the Chinese government during the SARS outbreak several years ago.
Alcabes agreed that the quarantine of the entire town was unnecessary.