Human case of bubonic plague confirmed in US | US News
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Human case of bubonic plague confirmed in US | US News

Purple cells of plague bacteria (Yersinia pestis) in a computer illustration.

Bubonic plague is still present and deadly, but it is rare and can be cured (Photo: Kateryna Kon/Science Photo Library/Getty Images)

A case of bubonic plague, which causes the Black Death, has been detected in a human in the US state of Colorado.

Health officials are urging people to seek medical attention if they have symptoms of the disease that killed up to 50 million people between 1346 and 1353.

“We advise all individuals to protect themselves and their pets from the plague,” said Alicia Solis of the Pueblo County Office of Communicable Diseases and Emergency Preparedness.

The county health department launched an investigation into a possible human case last Friday after preliminary tests indicated the presence of the Yersinia pestis bacteria that causes it.

A positive case was confirmed on Monday. But what are the symptoms to watch for, how is the plague transmitted and is there a cure?

How is bubonic plague spread?

Bubonic plague is caused by a bacterium called Yersinia pestis, which is commonly found in rodents, small mammals, and their fleas.

According to the World Health Organization (WHO), human-to-human transmission of bubonic plague is rare. But cases do occur from time to time.

People can become infected through flea bites, direct contact with infected bodily fluids, and by inhaling droplets exhaled by an infected person or animal.

Human-to-human transmission is only possible when the infected person develops pneumonic plague, the most severe form of the disease.

This is how the virus is said to have wreaked havoc in the Middle Ages, when a pandemic known as the Black Death wiped out up to half of Europe’s population, making it one of the deadliest in history.

However, according to a recent study, body lice may be just as responsible for the spread of the plague as rats and fleas.

A laboratory study suggests that human body lice are more efficient at transmitting Yersinia pestis than previously thought.

The findings, published in the journal PLoS Biology, support the possibility that parasites contributed to previous pandemics.

Two brown rats

Rats have long been thought to help spread the plague (Photo: Getty/iStockphoto)

Dr. David Bland conducted the research with colleagues at the U.S. National Institute of Allergy and Infectious Diseases, based in Maryland.

“Y. pestis has been the cause of many pandemics, including the Black Death of the Middle Ages that killed millions of people in Europe,” he said.

“Transmission occurs naturally between rodents and fleas, and fleas sometimes infect humans through bites. Fleas and rats are therefore thought to be the primary vectors of plague pandemics.

“Body lice, which feed on human blood, can also carry Y. pestis, but they are widely considered too inefficient to spread it and contribute substantially to outbreaks.

“However, the few studies that have addressed the efficiency of lice transmission are very divergent.”

Dr. Bland and his team conducted a series of laboratory experiments in which body lice fed on blood samples containing Y. pestis.

A black and white image of Yersinia pestis bacteria in a sample taken from an infected person.

Human cases of bubonic plague are rare, but they are appearing in countries around the world (Photo: Centers for Disease Control and Prevention/Getty Images)

The experiments involved the use of membrane feeding devices, which simulate warm human skin, allowing the team to study the potential for transmission in the laboratory.

They found that body lice were infected with Y. pestis and were able to routinely transmit it after feeding on blood containing levels of the pathogen similar to those found in real-world cases of human plague.

The team also discovered that Y. pestis can infect a pair of salivary glands found in body lice, called Pawlowsky’s glands.

Lice with infected Pawlowsky glands transmitted the pathogen more consistently than lice whose infection was limited to their digestive tract.

Pawlowsky’s glands are thought to secrete lubricant onto the mouthparts of lice.

This led the research team to hypothesize that in infected lice, these secretions can contaminate the mouthparts with Y. pestis, which can in turn spread to humans if bitten.

Dr Bland said: “These results suggest that body lice may be more efficient spreaders of Y. pestis than previously thought, and they may have played a role in past plague outbreaks.”

Where have cases of plague been found in the United States?

A chest x-ray.

Bubonic plague can cause breathing difficulties if it spreads to the lungs and becomes pneumonic plague (Photo: Smith Collection/Gado/Getty Images)

The plague has been detected in animals and caused human epidemics on every continent except Oceania.

According to BBC News, 3,248 cases and 584 deaths were reported worldwide between 2010 and 2015.

But according to the WHO, it is in Africa that this phenomenon has been most frequent since the 1990s.

Currently, Madagascar, which reports up to 700 cases each year, is one of the three most endemic countries, along with the Democratic Republic of Congo and Peru.

This does not mean, however, that countries like the United States are completely plague-free.

According to the country’s Centers for Disease Control and Prevention (CDC), there are an average of seven cases each year.

Most are located in rural areas of the western United States.

Oregon confirmed its first case of bubonic plague in nearly a decade this year in February, after a man caught it from his pet cat.

A month later, a man died of the disease in Lincoln County, New Mexico.

Northern Oregon and southern Oregon are two of six areas responsible for the most human cases in the United States, according to the CDC.

Northern Arizona, southern Colorado, California and far western Nevada are also on the list.

The last urban plague pandemic in the United States occurred in Los Angeles, California, and ended in 1925, some 25 years after its introduction by rat-infested steamships.

What are the symptoms of the plague?

The skin and tissues on the fingertips of one hand turn black and die.

Skin and tissues can turn black and die in the later stages of bubonic plague (Photo: Smith Collection/Gado/Getty Images)

Symptoms can appear between one and eight days after infection.

The first sign is one or more swollen, tender, painful lymph nodes – called “buboes” – usually closest to the bite through which the bacteria entered the body.

According to the WHO, swollen lymph nodes can turn into open, pus-filled sores as the disease progresses.

Patients with bubonic plague may also experience symptoms such as fever, headache, chills, and weakness.

If the disease spreads to the lungs, it can cause shortness of breath, chest pain, coughing, and sometimes bloody or watery mucous membranes. This is called pneumonic plague.

If left untreated, bubonic plague can cause tissue necrosis, which is when the skin and other tissues of the fingers, toes, nose, and other areas turn black and die.

Is there a cure for bubonic plague?

Gone are the days of bleeding patients with leeches or encouraging children to smoke to ward off the “bad air” believed to cause the plague.

Today, the disease can be treated relatively easily with antibiotics, meaning it is no longer a near-total death sentence as it was in the 14th century.

The key to survival lies in early diagnosis and treatment, which is much less likely if people do not know what to look out for or do not have access to adequate health facilities.

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