Borrelia burgdorferi, the cause of Lyme disease, is just one of the many harmful bacteria that ticks can transmit. A tick bite can also cause a rickettsiosis. This is a nasty infection due to a bacterium from the Rickettsia group. Examples of such infections include typhus and Q fever. Plenty of reasons to wear tick-repellent clothing when you go for a walk in nature. You'll find more information about Ricketssia bacteria and the diseases they can cause below.

What are Rickettsia bacteria?

Rickettsia is the umbrella name for a group of bacteria that can only live in the cells of another organism. To reproduce, these bacteria also need the cells of a host. For some Rickettsia, humans are the main host. However, most Rickettsia parasitize on animals. From these animals, Rickettsia are transmitted to humans via bites from ticks, mites, fleas, lice, and rats (the so-called vectors).

Each Rickettsia bacterium has its own host and vector. This also applies to Ehrlichia, a group of bacteria that closely resemble Rickettsia and cause similar diseases.

Examples of specific Rickettsia bacteria are:

Rickettsia Felis
Rickettsia Japonica
Rickettsia Akari
Rickettsia Africae
Rickettsia Australis
Rickettsia Burnetii
Rickettsia Quintana
Rickettsia Massilae.

What is a Rickettsiosis?

A Rickettsiosis is an infection by a Rickettsia bacterium. The term stands for all diseases that such an infection can cause, regardless of which Rickettsia bacterium it is. The following diseases are examples of Rickettsiosis:

(epidemic) typhus
Rocky Mountain spotted fever
Brill-Zinsser
Fievre Boutonneuse.

What are the symptoms of a Rickettsiosis?

In humans, Rickettsia bacteria infect the cells lining the small blood vessels. As a result, these blood vessels become blocked or inflamed. They can also start bleeding. The blood then enters the surrounding tissue. The site of infection in the body determines the symptoms.

All Rickettsia infections have the following early characteristic symptoms:

fever
severe headache
skin rash
feeling unwell

In a later stage, the following symptoms may also develop:

confusion
coughing
breathing problems
vomiting
diarrhea

In some patients, the spleen or liver becomes enlarged, the kidneys stop functioning, and blood pressure drops dangerously. If a Rickettsiosis is not detected and/or treated in time, it can result in death.

How is a Rickettsiosis diagnosed?

The initial symptoms of a Rickettsiosis resemble those of the flu. To determine that there's more at play than just a harmless viral infection like the flu, it is important to check if the patient has been bitten by a vector of a Rickettsia bacterium, such as a tick, mite, or flea. Such a bite may indicate a Rickettsia infection, especially in areas where this infection is common. Unfortunately, most people cannot remember a bite. When the patient develops a rash, that is also an indicator of a Rickettsiosis.

There is (as of yet) no laboratory test that can quickly and distinctly identify a Rickettsia bacterium in the blood. The patient cannot wait for prolonged (blood) research. Treatment cannot be delayed and will therefore have to be based on a suspected diagnosis of Rickettsiosis.

How is a Rickettsiosis treated?

The Rickettsia is an obligate intracellular bacterium. This means it hides in the cells of its host. Because of this, our immune system has difficulty reaching and combating the bacterium. For the same reason, not all antibiotics are effective against a Rickettsiosis.

A Rickettsiosis can best be treated early with one of the following three antibiotics:

tetracycline
doxycycline
chloramphenicol

These antibiotics can be taken orally. When the patient is too ill to take them orally, these drugs can be administered intravenously.

After treatment with one of these antibiotics, the patient will soon start to feel better, and the fever will disappear within three days. The course of antibiotics lasts at least a week, longer if the fever persists after that. The later the treatment starts, the slower the improvement and the longer the fever lasts.

Failing to treat or starting treatment too late can have fatal consequences for a patient with Rickettsiosis.

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