Brighton microbiologist shares advice as reported plague death puts disease back in spotlight

The reported death of a scientist working in a microbiology research department in Russia has raised questions about plague, how it is transmitted and the safety procedures used when working with dangerous organisms.

Dr Pitt, Principal Lecturer at the University of Brighton and President of the Institute of Biomedical Science, says that while the circumstances surrounding the reported death are concerning, people should not assume that the incident will lead to a wider outbreak.

Why are people being isolated?

Reports that people have been placed in isolation following the death have prompted questions about whether an outbreak is underway.

Dr Sarah Pitt

Dr Pitt says isolation is a precautionary measure and does not necessarily mean that someone has plague or that an outbreak is taking place.

“The person involved may simply have contracted pneumonia from another source or from a different bacterium, but because of the nature of her job and the possibility that she had pneumonic plague, it is appropriate to take precautions.

“People who have been exposed should be monitored. Plague is treatable with standard antibiotics and, where appropriate, people who may have been exposed can be given antibiotics as a precaution.”

What does the reported death mean for laboratory safety?

The reported case has also raised questions about how dangerous organisms such as the plague bacterium are handled in laboratories.

Yersinia pestis, the bacterium that causes plague, is classified as a Hazard Group 3 biological agent. This means it can cause serious disease and presents a significant risk to people who work with it, but effective treatments are available. Other Hazard Group 3 biological agents include the bacteria that cause tuberculosis. Working with organisms in this group requires specialist containment procedures, restricted access and protective equipment, as well as measures to prevent the organism escaping into the wider environment.

Dr Pitt said: “From my perspective as a microbiologist, I genuinely want to know exactly what happened and how the exposure occurred. If someone is working with a dangerous organism, there should be appropriate safety procedures in place, and anyone who may have been exposed should be identified, monitored and considered for appropriate treatment.”

What is plague?

Plague is caused by the bacterium Yersinia pestis and is the same disease historically associated with the Black Death.

While plague is often thought of as a disease from history, it has never completely disappeared. Outbreaks still occur in parts of the world, including Madagascar and the Democratic Republic of the Congo, as well as other regions.

Dr Pitt said: “Plague has never completely gone away. It is a bacterium that has been known about for thousands of years and there are still outbreaks in parts of the world today. Unlike COVID, this is not a newly emerging infection. We understand the bacterium, we know how it spreads and, importantly, we have effective antibiotics to treat it.”

The disease was devastating during historical outbreaks partly because people did not understand how it spread and there were no effective treatments. Today, there is much greater understanding of the bacterium and how to diagnose and treat infection.

How do humans get plague?

The bacterium normally circulates among certain species of rodents rather than humans. The animal host varies depending on where the disease is found.

Dr Pitt said: “The most common way for humans to become infected is through the bite of a flea carrying the bacteria. People can also become infected by handling an infected rodent.

“People with plague are not infectious to others unless they develop pneumonic plague, the form of the disease that affects the lungs. In this case, the infection can be passed to others through coughing. Respiratory transmission is not the usual route of plague infection. While pneumonic plague can result in some transmission to people nearby, it is not normally a situation where the disease would infect huge numbers of people.”

What are the symptoms?

People infected with Yersinia pestis can develop a high temperature, headache, tiredness, nausea and sometimes vomiting.

A characteristic sign of bubonic plague is swollen, painful lymph glands, known as buboes, usually in the neck, armpits or groin.

Bubonic plague is the most commonly seen form of the disease. If the bacteria spread into the bloodstream, it can cause septicaemic plague, a serious bloodstream infection. In others, the infection can spread to the lungs, causing pneumonic plague.

Dr Pitt said: “People with this form can experience difficulty breathing, chest pain and coughing, sometimes coughing up blood.

“It is this pneumonic form that can spread directly between people through close contact and coughing.”

Is plague treatable?

The time between picking up the bacterium and developing symptoms is usually less than a week, although symptoms can develop within 24 hours. This means early treatment is important.

Laboratory tests can be used to look for Yersinia pestis in samples from a bubo, blood or the lungs.

Patients are treated with standard antibiotics, while people who have been in close contact with someone diagnosed with plague can also be given antibiotics as a precaution.

Dr Pitt said: “Given that we have experience of dealing with outbreaks, good diagnostic tests and effective antibiotics, it should be possible to stop the bacteria spreading too far.”

Should people in the UK be worried?

Dr Pitt says the reports should not cause undue alarm among the UK public.

“There is no reason for people in Britain to assume that this reported case means plague poses an immediate risk to the wider public.”