A few days ago we have learned that an outbreak of pneumonic plague has killed two people in China, and forced the quarantining of a town of 10,000 to halt its spread. Today the news is that a fourth victim may be on the way.

Is this a sign of things to come? Is there a reason for panic outside China? Read on to find out.

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What is it?

Plague, first described in the Old Testament, is a deadly infectious disease affecting the lymph nodes, the lungs or the blood. It is also known by the names “The Black Plague” and “The Black Death”.

Who gets it?

In the United States, about 10 cases of plague are reported each year. Around the world it’s mostly encountered in developing countries in Africa and Asia. During 1990-1995, 12,998 cases of plague were reported.

Most cases of infection occur in people younger than 20 years.

What causes it?

Plague is caused by a type of bacteria called Yersinia Pestis. This is how it looks under a microscope:

How does this germ infect people?

Rats are the most common animals carrying the disease. A rat flea by the exotic name of Xenopsylla cheopis is the link between rats and humans. When the flea feeds on the blood of an infected rat, it carries the germ in its blood. When the flea then bites a human, it transfers the germ to their blood.

The process. Rat drawing by opk.

How does it feel?

There are 3 types of plague:

1. Bubonic plague – This is the most common type of plague – responsible for 80-95% of plague cases. (It was also featured on a Grey’s Anatomy episode). The germs enter the lymphatic system (the system responsible for killing infections from the outside, although here not successfully). The lymphatic system is made of lymph nodes, which are sort of stations along the system. The bacteria infect the nodes, causing inflammation in them. The nodes get swollen, a finding called bubo, which characterizes the disease.

   
   An example of buboes.

2. Septicemic plague – This happens when the germs enter the bloodstream, and from there travel to any area in the body, wreaking havoc on its way, including bleeding in various sites in the body.
3. Pneumonic plague – This is the form which has now started in China. It infects the lungs. Once it does, people can infect one another by coughing. Since it resembles pneumonia, doctors may confuse it for something less severe. This is a mistake, of course, since without proper treatment, 50-90% of people die of it.

How is it discovered?

To find out if you have been infected, the doctor can take a sample from a bubo or from your blood or sputum. These samples are then looked at under a microscope to discover the germ.

How is it treated?

If treated immediately, mortality can be reduced to 5% or less. The treatment includes antibiotics which kill the germ.

Another important issue in treatment is isolation of patients, so that other people don’t get infected.

What happens after treatment?

Like mentioned above, mortality is reduced to 5% or less if the disease is treated on time. It doesn’t tend to return afterwards. If not treated, though, there is a high chance of dying from it.

If you have been in contact with a person or animal whom you know are infected, if you have been bitten by a flea in an area known to have plague cases, or if you plan to travel to a region with plague outbreak, you can take preventive antibiotics. Consult your doctor about those.

If you live in an area where plague has been discovered, take the following precautions:

1. Avoid contact with sick or dead animals – Such as when hunting. Even though rats are the main culprits to avoid, field mice, cats, camels, chipmunks, prairie dogs, rabbits, and squirrels can carry the germ as well.
2. Rodent-proof your home – This includes removing potential nesting areas, such as piles of brush, rock, firewood and junk. Avoid leaving pet or bird food or any other foods in areas that rodents can easily access.
3. Prevent your pets from contracting fleas – You can use flea-control products (consult with your veterinarian about those).
4. Take precautions when outdoors – Such as using insect repellents.

What do you think? Will the disease leave the boundaries of China and become the next Swine Flu?

What next?

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