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Why hasn’t the US eradicated the plague?

Why hasn’t the US eradicated the plague?

  • 15 October 2015
Dry gangrene, caused by the plagueImage copyrightScience Photo Library

It’s nearly 50 years since the US landed men on the moon, but Americans are still dying from a disease that ravaged Europe in the Middle Ages. Why hasn’t the US eradicated the plague?

The Black Death caused about 50 million deaths across Africa, Asia and Europe in the 14th Century. It wiped out up to half of Europe’s population.

Its last terrifying outbreak in London was the Great Plague of 1665, which killed about a fifth of the city’s inhabitants. Then there was a 19th Century pandemic in China and India, which killed more than 12 million.

But the disease has not been consigned to the dustbin of history. It is endemic in Madagascar, the Democratic Republic of Congo and Peru. What’s perhaps more surprising is that it is still killing people in the US.

There have been 15 cases in the US so far this year – compared to an average of seven, according to the Centers for Disease Control and Prevention (CDC) – and the figure of four deaths is higher than in any year this century.

Bar charts showing US plague cases and deaths from 2000 to 2015

The bacterium responsible – Yersinia pestis – was introduced to the US by rat-infested steamships in 1900, according to Daniel Epstein of the World Health Organization (WHO).

“Plague was pretty prevalent, with epidemics in Western port cities. But the last urban plague was in Los Angeles in 1925. It spread to rural rats and mice, and that’s how it became entrenched in parts of the US,” he says.

The disease – typically transmitted from animals to humans by fleas – has a 30-to- 60% fatality rate if left untreated, however, antibiotics are effective if patients are diagnosed early.


The plague

Plague bacteria, Yersinia pestisImage copyrightScience Photo Library
  • More than 80% of US cases have been bubonic plague, the most common form, which affects the lymph nodes and causes gangrene (see picture at top of page)
  • There are two other types, septicaemic, an infection of the blood, and pneumonic, which infects the lungs
  • It can be hard to identify the disease in its early stages because symptoms, which usually develop after three to seven days, are flu-like – 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 plague-endemic areas,” says Epstein.

The areas in question 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, which Dr Amesh Adalja, an infectious-disease specialist at the University of Pittsburgh’s Center for Health Security, refers to as “the plague line”.

“Prairie dogs are the main reservoir for plague, and they tend to be west of the 100th meridian,” he says. The geography and climate of the Western US suits them, he explains, and the fact that they are “social animals” helps the infected fleas to spread.

Prairie dog in CaliforniaImage copyrightGetty Images
Image captionYersinia pestis thrives in prairie dogs’ fleas

Black-footed ferrets and the Canada lynx are other particularly susceptible species, says Dr Danielle Buttke, an epidemiologist at the US National Park Service.

It’s the existence of this “animal reservoir” that makes the plague hard, if not impossible, to eradicate, experts say.

The only human disease eradicated so far, smallpox, does not exist in animals. It’s the same with polio, which remains endemic in two countries – Afghanistan and Pakistan. The WHO is working towards to eradicating polio and last month announced that it is no longer endemic in Nigeria. (It has, however, returned to Syria, since the civil war.)

“Unless we exterminate rodents, [the plague] is always going to be around,” Epstein argues.

California Department of Public Heath workers treat the ground to ward off fleas at the Crane Flat campground in Yosemite National Park, California, on 10 AugustImage copyrightReuters
Image captionPublic health workers treat the ground in Yosemite National Park to get rid of fleas

On the other hand, scientists at the National Wildlife Health Center have been working with parks to develop oral vaccines to protect black-footed ferrets and prairie dog – prairie dogs seem to prefer peanut butter-flavoured baits, research shows.

An injectable vaccine for black-footed ferrets has also been created. So maybe it will be possible to rid animals of the disease, at least in the most popular national parks.

Generally, research into the disease is in a “vibrant” state, according to Adalja, with scientists trying to improve ways of diagnosing it, and to develop an effective human vaccine.

The reason? The plague has been classified as a “category A bioweapon”, he says. An average of seven cases of plague per year is one thing, but the risk of biological warfare, even if it’s a remote one, is quite another.

Permanent link to this article: https://animatedscience.co.uk/2015/why-hasnt-the-us-eradicated-the-plague

Caffeinated plants give bees a buzz

Caffeinated plants give bees a buzz

Permanent link to this article: https://animatedscience.co.uk/2015/caffeinated-plants-give-bees-a-buzz

Pluto in a higher definition..

New Horizons: Tension mounts over Pluto signal – http://www.bbc.co.uk/news/science-environment-33531751

Permanent link to this article: https://animatedscience.co.uk/2015/pluto-in-a-higher-definition

Pentaquarks…

Large Hadron Collider discovers new pentaquark particle – http://www.bbc.co.uk/news/science-environment-33517492

Permanent link to this article: https://animatedscience.co.uk/2015/pentaquarks

Harnessing the sun with the blackest paint in the world

Harnessing the sun with the blackest paint in the world –

http://www.bbc.co.uk/news/business-32931928Spray paintingImage captionBack to black: This might just look like black paint – but it’s probably the blackest black paint in the world

 

In a cramped laboratory on the campus of the University of California San Diego (UCSD), graduate student Lizzie Caldwell is hard at work, painting tiny squares of metal with a fine mist of black paint.

As experiments go, it doesn’t look terribly impressive.

Yet the paint she is using is highly sophisticated – the result of intensive research. It is also probably one of the blackest materials ever created.

What the research team at UCSD are trying to do is make large-scale solar power generation more viable, by creating a material which can absorb a greater quantity of sunlight than existing coatings, and last longer.

Heart of darkness

The paint is being developed for a new generation of so-called concentrating solar power plants (CSP).

These use thousands of mirrors to focus sunlight on a central tower, which is coated with a dark, light-absorbing material. The light is converted into intense heat, which is used to make steam. The steam can then be used to drive turbines, in order to produce electricity.

It is a very clean form of power generation, and existing plants which use coal or other fossil fuels can be converted to use the technology. In addition, heat can be stored so that power generation can continue even when the sun isn’t shining.

Concentrating solar power plant
Image captionConcentrating solar power plants – like this one in California – use mirrors to reflect the sun’s rays at a central tower

However, there’s a catch. The light-absorbing coatings which are currently used aren’t really up to the job.

They aren’t efficient enough, can’t withstand the highest temperatures and, out in the elements, bombarded with intense sunlight, they don’t last very long either.

According to Professor Renkun Chen, who is helping to lead the research, the new material will be very different.

“First of all, it can absorb the light at a very high efficiency. And secondly, it can withstand very high temperatures in air, above 700 degrees Celsius. That isn’t possible with existing materials”, he says.

Spray painted plates
Image captionThe blacker the material, the more of the sun’s energy it will absorb

Small things

The secret of the new paint lies in nanotechnology – creating a surface made up of layers of microscopic particles. It is designed to minimise reflection.

The research team claims that it can convert up to 90% of the sunlight it captures into heat.

“The size of these particles matches the wavelengths of light, which is in the order of a few nanometres”, Prof Chen says.

“So when light gets in, it will get trapped. It’s as though it gets lost in a miniature forest, and never comes out”.

That is the theory, at any rate. But the mosaic of small metal tiles lined up in the lab for testing is testament to how challenging it is to put that theory into practice.

Each one represents a slightly different technique or chemical formula, as the team searches for the right balance of light absorption and durability.

Fifty shades of black, if you like.

“Right now we’re just playing with a lot of different ideas that we’ve been talking about for the last few months and years” says Lizzie Caldwell.

“We want to make sure we get the perfect, blackest colour”.

Under a microscope, the structure of the nanoparticles that make up the paint can be seen
Image captionUnder a microscope, the structure of the nanoparticles that make up the paint can be seen

Run for the sun

The research has been funded by the US government’s SunShot initiative, which hopes to make solar energy as financially competitive as other forms of power generation by the end of the decade.

There is clearly a very long way to go. Solar energy still accounts for less than 1% of all mass electricity generation in the US, according to the US Energy Information Administration.

But that figure doesn’t tell the whole story.

Solar capacity is growing rapidly, particularly in energy-hungry California. Moreover, the number of homes and businesses using solar panels to generate their own power has risen dramatically over the past five years.

It isn’t just happening in the United States. In China, generous subsidies have led to a very rapid growth of solar power generation over the past few years.

This has come partly in response to the country’s voracious appetite for power and the need to curb severe urban pollution. But China has also become a major exporter of cheap solar technology, which has brought prices down worldwide.

And according to Professor Chen, CSP in particular has the potential to become a major source of clean energy in developing countries, reducing their reliance on burning fossil fuels such as coal.

Renowned environmentalist Denis Hayes, who now leads the Seattle-based Bullitt Foundation, thinks that we could be heading for a golden age of solar power.

Environmentalist Denis Hayes
Image captionEnvironmentalist Denis Hayes is optimistic about the future of solar power

“With solar, if you take a unit of area, there’s only so much sun that is going to strike it,” he says.

“So if you can get twice as much electricity out of that sunshine, and it costs no more or even less than before then suddenly you’ve transformed the market”.

He thinks that one day, entire cities could be powered by the energy of the sun, with the fabric of the buildings themselves being used to trap solar energy.

It’s fair to say that such a sunny utopia remains a very long way off. However, research such as that being carried out at UCSD just might bring it a little bit closer.

So if there is a golden age approaching, it may owe a debt to some very, very black paint.

Permanent link to this article: https://animatedscience.co.uk/2015/black-paint

Black Hole Matter Ejection

Black hole glimpsed playing cosmic billiards – http://www.bbc.co.uk/news/science-environment-32915126

Permanent link to this article: https://animatedscience.co.uk/2015/black-hole-matter-ejection

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