What is plague?

Plague is a disease caused by a type of bacteria that is transmitted from animals to humans. It is mainly found in wild rodents. Fleas carry the bacteria from rodents to humans.

Plague used to be very common all over the world. Since the early 20th century, plague has been eradicated in the Netherlands. Some countries in Africa, North and South America and Asia do still have plague.

There are three forms of plague:

• Bubonic plague: This is the most common type. In this form, the lymph nodes are swollen and inflamed, causing painful lumps known as buboes.
• Septicaemic plague: If the bacteria get into the bloodstream, they cause blood poisoning. This can happen as a result of the bubonic plague, but direct infection is also possible.
• Pneumonic plague: This is the most dangerous type. In this form, the bacteria are in the lungs.

Without treatment, all forms of plague are very dangerous and can be fatal.

What are the symptoms of bubonic plague?

Bubonic plague starts with:

• fever
• headache
• cold chills

Then swollen lumps appear, especially in the groin and armpits. These buboes are very painful and can grow to as large as 10 centimetres.

If bubonic plague is not treated in time, the bacteria could enter the bloodstream. This happens in half of the cases without timely treatment. (See the symptoms of septicaemic plague below.)

What are the symptoms of septicaemic plague?

If the bacteria that cause plague enter the bloodstream, they can cause blood poisoning (septicaemia). This form of plague not only causes fever and chills, but can also result in stomach pain or make you go into shock. It is also possible for the bacteria to travel from the bloodstream into the lungs. If that happens, the patient could develop pneumonic plague (see below).

Without treatment, septicaemic plague is almost always fatal.

What are the symptoms of pneumonic plague?

The symptoms of pneumonic plague are similar to severe pneumonia:

• coughing up mucus, often with blood
• chest pain
• difficulty breathing
• (sometimes) nausea and vomiting

Rapid treatment is very important if a person has pneumonic plague. This form almost always leads to death unless the infected person is treated within 24 hours after the first symptoms.

Who can become very ill from plague?

Some people have a higher risk of getting the plague:

• people living near areas where plague is common
• people travelling in an area where plague is common
• people in these areas who have frequent contact with infected livestock or wild animals and their fleas, such as soldiers, hunters, veterinarians and forest rangers
• people who are caring for or providing medical assistance to a patient who has plague
• laboratory workers and researchers handling Yersini pestis bacteria or contaminated materials.

There is no information about which people might have a higher risk of serious illness. Anyone could become very seriously ill if they do not receive treatment in time.

How does plague spread?

People can contract plague if they are bitten by a flea that is carrying the plague bacteria. It is also possible to get infected through direct contact with infected animals (through a scratch or bite) or things that come from these animals, such as urine or meat.

People can also infect each other. Different forms are transmitted in different ways:

Bubonic plague can be spread if pus from the painful lumps (buboes) gets into the body of a healthy person.

The time between exposure and illness (the incubation period) for bubonic plague is 2 to 8 days.

Pneumonic plague can be transmitted through tiny droplets in the air. These droplets are released when a person coughs, sneezes or talks. Animals can also spread airborne droplets containing the bacteria. If a healthy person inhales these droplets, they could become ill. Pneumonic plague is even more contagious if a person is coughing, especially if they are coughing up blood.

The time between exposure and illness (the incubation period) for pneumonic plague is 1 to 10 days. The first symptoms usually appear within 4 days after exposure.

How can I prevent plague?

When you are in areas where plague is common, stay away from ill or dead animals as much as possible – especially rodents. If you live in an area where plague is common, keep your house clean and clear away any food scraps to discourage rats and other vermin. Also make sure pets are well protected against fleas. Treat pets with flea medicine and keep them away from ill or dead animals. This helps lower the risk of infection.

Is there any treatment for plague?

If plague is detected in time, it can be treated with antibiotics. Treatment is given in isolation, so the patient cannot infect others. If the patient has blood poisoning, they will need supporting treatment. This may include treating them for shock, or using artificial respiration.

People who had contact with pneumonic plague patients may be given medicine to prevent them from becoming ill.

How common is plague?

Plague cases are decreasing all over the world. Several hundred cases are reported to the World Health Organization (WHO) every year. Since many countries do not keep close track of plague cases, this may actually be higher.

What does the Netherlands do to prevent an outbreak of plague?

RIVM works with international organisations, such as the WHO and the European Centre for Disease Control and Prevention (ECDC), to monitor where plague is still present worldwide. This makes it possible for the Netherlands to respond quickly if an infected patient is identified anywhere.

Moreover, plague is a notifiable disease. That means that it is subject to mandatory reporting in the Netherlands. When doctors or laboratory workers discover a possible or confirmed case of plague, they are required to notify the Municipal Public Health Service (GGD) immediately. The GGD investigates which people might have been exposed and arranges for appropriate measures to be taken.