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Atishoo atishoo we all fall down!

Atishoo atishoo we all fall down!

The deadliest of diseases: the Black Death

The effects of black death

The most famous and deadliest pandemic in human history is the Black Death (bubonic plague). It spread through the Western world in the Middle Ages in the 14th century and killed millions of people.


It was called the Black Death because it caused bleeding under the skin, and this caused the skin to turn a dark red, almost black colour.

Most people think the Black Death came from Europe, but it actually came from the Gobi desert which lies between Mongolia and China. That’s a very long way from Europe!

How did it get to Europe?

China was the first country to be affected by the Black Death. In 1328, over a quarter of its population (about 35 million people) died of the disease. That’s about 15 times the population of Wales!

By 1346 the disease had spread to Istanbul, the Capital of Turkey. Within weeks thousands of people were dying in the city. Within six months it had spread 1300Km (800 miles) to Cairo in Egypt. Two months later nearly 8000 people a day were dying in the city.

By 1348 it had reached Britain. Within two years it had killed over two million people. This was a massive amount as the total population of the Britain at the time was only about six million. The effect was worst in the cities. In London 30,000 of the city’s 70,000 population died of the disease.

The passage of the black death

What would happen if the Black Death struck today?

In comparison, it would be like about 20 million British people being killed today.

  • The hospitals would be overwhelmed within weeks
  • Most of the country’s medical personnel would be dead within months
  • There may not even be enough key people left to run power stations, grow food or transport fuel
  • Virtually every aspect of modern life would be under threat
Empty Streets

Could such a catastrophe really happen today?

Yes, it could! What’s more, a disease like that would spread much faster than back in the Middle Ages. Today modern transport like cars, trains and planes would spread the disease thousands of times faster. The world population is much higher today; high populations increase the potential for a disease to establish itself and spread even faster. This is why planning for a possible pandemic is REALLY important.

How germs get about

The oldest cold in the world!

Human Influenza, or the flu, has been around for about six thousand years. The name influenza comes from the Latin word influential. The word describes something bad you got because of the position of the planets. Not a very scientific idea, but this is the way people thought in the Middle Ages. In fact, it wasn’t until the early 20th century that the first flu virus was isolated.

Symptoms include: fever, sore throat, muscle pains, headache and weakness. The symptoms are similar to the common cold, but much more severe. In serious cases it can cause pneumonia which can be fatal in the young and old.

The £20 note test…

One of the ways you can tell if you have flu is to imagine that a £20 note has just blown into your garden. If you went out to pick it up you have a cold, but if you couldn’t be bothered then you definitely have flu!

How do viruses mutate?

All organisms contain cells with a nucleus. Bacteria and viruses also have a nucleus. Many viruses have a reproductive process based on Deoxyribonucleic acid (DNA). Flu viruses do not. They use a reproductive method based on Ribonucleic Acid (RNA). The problem with this is that RNA-based viruses can mutate about 1,000,000 times quicker than DNA-based ones. This is a bit of a pain if you are trying to produce a vaccine: the virus changes faster than you can keep up with it.

H2 N1, H3 N2: what’s with all the numbers?

Microbes

There are three types of Flu virus: A, B and C. Type A influenza is the one that causes pandemics, types B and C rarely trouble human beings and mostly infect animals. Type A viruses have 15 subtypes known as H1, H2, H3 etc up to H15. Only H1, 2 and 3 can infect humans. H1 and 3 can also infect pigs (swine), H3 and H7 infect Horses, and they all infect birds.

Helix

What about the Mexican flu?

The latest Mexican flu is an H1N1 type. The bird flu panics that happen from time to time involve the H5N1 virus. This is not one of the viruses that can infect humans; the problem is that it could mutate into human flu…with the help of a little piggy.

Clever little piggy!

Pigs can be infected by both bird and human flu viruses. This means that pigs can carry both kinds of virus. The virus can exchange genetic information creating a completely new strain of flu virus. The problem is that this new strain is capable of infecting humans. Pigs act as a kind of genetic mixing pot allowing new strains of human flu to be cooked up continuously. The latest form of flu found first in Mexico has come to be known as Swine flu. In fact, almost all human flu is Swine flu!

How is flu spread?

People with flu are most infectious about three days after infection and stay infectious for about ten days. It is spread in three main ways:

  • By direct transmission when an infected person sneezes mucus into the eyes, nose or mouth of another person
  • Inhaling people’s coughs, and liquid from their sneezing and spitting
  • Through hand-to-mouth transmission from either contaminated surfaces or direct personal contact, such as a hand-shake

How long can the virus survive?

The length of time the virus will survive depends on the type of surface:

  • One or two days on hard surfaces such as plastic or metal
  • About fifteen minutes on paper tissues
  • Five minutes on the skin

The good news is that viruses can be deactivated by using soap, so make sure you wash your hands regularly!

Epidemics and pandemics, same thing right?

About half a million people die of flu every year: mostly the very young and old. About once every 30 years or so, a flu pandemic strikes effecting hundreds of millions of people. The number of deaths depends on the strain of flue: some are more virulent than others.

What is a virulent strain of flu?

Virulence means the strength of the disease the virus produces. Rabies is a virulent virus: everybody dies from it once they start getting symptoms. Rhinovirus infection (the common cold) isn't very virulent.

Just how virulent can flu get?

The flu virus has a massive range: it can either be as harmless as the common cold (almost no one dies) or it can get as bad as 1 in 10 people dying from it, that’s a whopping 10%! So, if you consider that in a flu pandemic over a billion people could catch the disease, then a hundred million people could die. That’s a massive amount, right!

Well, this actually happened in 1918. The virus was called the Spanish flu. No one is quite sure how many people died, but it was probably over 100 million! This is about ten times as many people than were killed in World War 1. It may even have killed more people than the Black Death.

What does the swine flu hold in store for us?

Flu pandemics can be truly global catastrophes…So what surprises is our current flu pandemic likely to hold?

Thankfully it looks like the ‘swine or Mexican flu’ isn’t very virulent. At the moment its looks as if it may be less virulent than typical seasonal flu. The problem is it also looks like a lot of people may get it.

The WHO and pandemics

The World Health Organisation (W.H.O.) defines a pandemic as a disease that is spreading rapidly in at least two places on the globe. This is certainly true as this is being written (June 09). So we do have a pandemic and how much it will spread? Only time will tell. We won’t really know until the winter is here. So, you may be reading this with a cup of ‘Lemsip’ perched on the mouse mat!

Project

Use the Internet to gather information to develop a map that shows the spread of swine flu around the globe. This is not as easy as it sounds as there is a lot data out there and much of it is contradictory!

The big questions:

Why are there so many different strains of flu?

How does flu mutate or change from year to year?

What is meant by a ‘virulent’ virus?

What is a pandemic?

Where do pigs come into all this?