A person in Arizona has died from the plague, local health officials reported on Friday.

This marks the first such death in this region in 18 years. But it’s a stark reminder that this historic disease, though rare nowadays, is not just a disease of the past.

So what actually is “plague”? And is it any cause for concern in Australia?

There are 3 types of ‘plague’

The word “plague” is often used to refer to any major disease epidemic or pandemic, or even to other undesirable events, such as a mouse plague. Naturally, the word can evoke fear.

But scientifically speaking, plague is a disease caused by the bacterium Yersinia pestis.

Plague has three main forms: bubonic, septicemic and pneumonic.

Bubonic is the most common and is named after “buboes”, which are the painful, swollen lymph nodes the infection causes. Other symptoms include fever, headache, chills and weakness.

Bubonic plague is typically spread by fleas living on animals such as rats, prairie dogs and marmots. If an infected flea moves from their animal host to bite a human, this can cause an infection.

People can also become infected through handling an animal infected with the disease.

Septicemic plague occurs if bubonic plague is left untreated, or it can occur directly if the disease enters the bloodstream. Septicemic plague causes bleeding into the organs. The name comes from septicemia, which refers to a serious blood infection.

The recent death in the United States was due to a case of pneumonic plague, which is the most severe form. Bubonic plague can in some cases spread to the lungs, where it becomes pneumonic plague. However, pneumonic plague can also spread from person to person via tiny respiratory droplets, in a similar way to COVID. Symptoms are similar to the other forms but also include severe pneumonia.

Some 30–60% of people who contract bubonic plague will die, while the fatality rate can be up to 100% for pneumonic plague if left untreated.

Plague: a potted history

This disease is one of the most important in history. The Plague of Justinian (541–750CE) killed tens of millions of people in the western Mediterranean, heavily impacting the expansion of the Byzantine Empire.

The medieval Black Death (1346–53) was also seismic, killing tens of millions of people and up to half of Europe’s population.

Spread by the growing trade networks of the British empire, the third and most recent plague pandemic spanned the years 1855 until roughly 1960, peaking in the early 1900s. It was responsible for 12 million deaths, primarily in India, and even reached Australia.

It’s believed the bubonic plague was largely behind these pandemics.

Plague in the modern day

First introduced into the US during the third pandemic, plague infects an average of seven people a year in the west of the country, due to being endemic in groundhog and prairie dog populations there. The last major outbreak was 100 years ago.

Deaths are very rare, with 14 deaths in the past 25 years in the US.

Globally, there have been a few thousand cases of plague over the past decade.

The countries with the most cases currently include the Democratic Republic of the Congo, Madagascar and Peru, with cases also occurring in India, central Asia and the US. Cases usually occur in rural and agricultural areas.

Plague can be treated

Plague can easily be treated with common antibiotics, typically a course of 10–14 days, which can include both oral and intravenous antibiotics. But it must be treated quickly.

The recent death is concerning, as it involves the airborne pneumonic form of the disease, the only form that spreads easily from person to person. But there’s no evidence of further spread of the disease within the US at this stage.

As Y. pestis is not found in Australian animals, there is little risk here. Plague has not been reported in Australia in more than a century.

But plague, like many diseases, is influenced by environmental conditions. The risk of climate change causing an expansion in the habitat of animal hosts means public health experts around the world should continue to monitor it closely.

The plague, though often perceived as a disease of history, is still with us and can pose a major health threat if not treated early.

Thomas Jeffries, Senior Lecturer in Microbiology, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Robert F. Kennedy Jr, who oversees the health of more than 340 million Americans, says vitamin A can prevent the worst effects of measles rather than urging more people to get vaccinated.

In an opinion piece for Fox News, the US health secretary said he was “deeply concerned” about the current measles outbreak in Texas. However, he said the decision to vaccinate was a “personal one” and something for parents to discuss with their health-care provider.

Kennedy mentioned updated advice from the Centers for Disease Control (CDC) to treat measles with vitamin A. He also cited a study he said shows vitamin A can reduce the risk of dying from measles.

Here’s what the vitamin A study actually says and why public health officials are so concerned about Kennedy’s latest statement.

Why is a measles outbreak so worrying?

Measles is a highly contagious disease caused by a virus. It spreads easily including when an infected person breathes, coughs or sneezes.

Measles initially infects the respiratory tract and then the virus spreads throughout the body. Symptoms include a high fever, cough, red eyes, runny nose and a rash all over the body.

Measles can also be severe, can cause complications including blindness and swelling of the brain, and can be fatal. Measles can affect anyone but is most common in children.

The Texan health department has confirmed 150-plus cases of measles and one death of an unvaccinated child during the current outbreak. While this is by far the largest measles outbreak in the US in 2025, the CDC has reported smaller outbreaks in several other states so far this year.

Why vitamin A?

Vitamin A is essential for our overall health. It has many roles in the body, from supporting our growth and reproduction, to making sure we have healthy vision, skin and immune function.

Foods rich in vitamin A or related molecules include orange, yellow and red coloured fruits and vegetables, green leafy vegetables, as well as dairy, egg, fish and meat. You can take it as a supplement.

Vitamin A can also be used therapeutically. In other words, doctors may prescribe vitamin A to treat a deficiency. Vitamin A deficiency has long been associated with more severe cases of infectious disease, including measles. Vitamin A boosts immune cells and strengthens the respiratory tract lining, which is the body’s first defence against infections.

Because of this, the CDC has recently said vitamin A can also be prescribed as part of treatment for children with severe measles – such as those in hospital – under doctor supervision.

One key message from the CDC’s advice is that people are already sick enough with measles to be in hospital. They’re not taking vitamin A to prevent catching measles in the first place.

The other key message is vitamin A is taken under medical supervision, under specific circumstances, where patients can be closely monitored to prevent toxicity from high doses.

Vitamin A toxicity can cause birth defects and increase the risk of fractures in elderly people. Vitamin A and beta-carotene (which the body turns into vitamin A) from supplements may also increase your risk of cancer, especially if you smoke.

How about the study Kennedy cites?

Kennedy cites and links to a 2010 study, a type known as a systematic review and meta-analysis. Researchers reviewed and analysed existing studies, which included ones that looked at the effectiveness of vitamin A in preventing measles deaths.

They found three studies that looked at vitamin A treatment by specific dose. There were different doses depending on the age of the children, measured in IU (international units). Having two doses of vitamin A (200,000IU for children over one year of age or 100,000IU for infants below one year) reduced mortality by 62% compared to children who did not have vitamin A.

The 2010 study did not show vitamin A reduced your risk of getting measles from another infected person. To my knowledge no study has shown this.

To be fair, Kennedy did not say that vitamin A stops you from catching measles from another infected person. Instead, he used the following vague statement:

Studies have found that vitamin A can dramatically reduce measles mortality.

It’s easy to see how a reader could misinterpret this as “take vitamin A if you want to avoid dying from measles”.

We know what works – vaccines

The World Health Organization recommends all children receive two doses of measles vaccine.

The CDC states two doses of the measles vaccine (measles-mumps-rubella or MMR vaccine) is 97% effective against getting measles. This means out of every 100 people who are vaccinated only three will get it, and this will be a milder form.

But these facts were missing from Kennedy’s statement. Should we be surprised? Kennedy is well known for his vaccine sceptism and for undermining vaccination efforts, including for the measles vaccine.

As Sue Kressly, president of the American Academy of Pediatrics, told the Washington Post:

relying on vitamin A instead of the vaccine is not only dangerous and ineffective […] it puts children at serious risk.

Evangeline Mantzioris, Program Director of Nutrition and Food Sciences, Accredited Practising Dietitian, University of South Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.