What is Boutonneuse Fever?
Boutonneuse fever, first identified in Tunisia, North Africa around a hundred years ago, was named “boutonneuse” (French for “spotty”) due to the rash that appeared after the fever. This disease is caused by a type of bacteria known as rickettsia. It’s commonly found in areas like the Mediterranean, sub-Saharan Africa, India, Greece, and some places around the Black Sea.
The culprit behind Boutonneuse fever is a bacteria called Rickettsia conorii. It needs to be inside a host cell to reproduce and is technically known as a gram-negative bacteria, meaning it doesn’t hold a particular dye (crystal violet) when scientists try to identify it.
The disease is spread through the bite of a dog tick. It’s classified as a spotted fever because most people who get sick with it will have a black scab, known as a “tache noire” or black spot, at the tick bite site. The tick bite helps the bacteria, which usually live in animals, to enter the human bloodstream and spread.
After a tick bite, it generally takes about 5 to 7 days for Boutonneuse fever to set in. The tick bite is often painless and might be overlooked if it happens in a hidden spot. Medics usually diagnose the disease based on the patient’s recent travels to places where the disease is common and by certain symptoms, such as fever, rash, and the black scab. The illness usually causes symptoms similar to the flu. It’s generally less serious than Rocky Mountain spotted fever, another tick-borne disease, but in some cases, can lead to more serious problems like enlarged liver, yellowing of the skin and eyes, meningitis, other neurological issues, testicular inflammation, retinal disease, bleeding in the digestive tract, and pneumonia.
Treating Boutonneuse fever is usually similar to treating all rickettsial infections. Doxycycline, a type of antibiotic, is commonly used. Patients with mild symptoms are generally treated with antibiotics for 7 days, while those with more severe symptoms usually need treatment for 14 days. For children and pregnant women, another antibiotic known as azithromycin is typically effective.
What Causes Boutonneuse Fever?
This illness is caused by a germ called Rickettsia conorii. This germ is a type of bacteria that needs to live inside cells and is spread through the bite of ticks. Ticks are tiny, spider-like creatures that live in woods and areas with long grass. This particular bacteria is spread only by the Brown Dog Tick, and it usually affects humans by accident.
It’s important to note that according to recent data, pets like domesticated dogs might play a more significant role in spreading the bacteria than we previously realized. The transmission takes place very quickly after a tick bite.
Once in humans, the bacteria attach to the walls of blood vessels and enters them. This is how they cause systemic disease, which means that it affects the entire body.
Risk Factors and Frequency for Boutonneuse Fever
Boutonneuse fever is a condition that was first described back in 1910 in Tunis. Since then, it’s been frequently reported in the Mediterranean region, particularly southern Europe. Over time, we’ve discovered different subspecies of the bacterium called Rickettsia conorii, such as Rickettsia conorii israelensis, in several other places like sub-Saharan Africa, India, Greece, and areas near the Black Sea including Turkey, Bulgaria, and Ukraine. Although these subspecies have slightly different molecular and genetic characteristics, they all cause very similar symptoms. We see the most cases during the summer, likely due to the increased activity of ticks, which spread the disease. The disease doesn’t discriminate; it affects all ages and genders equally.
Cases in the U.S. are very rare and usually involve travellers coming back from places where the disease is common. The rate at which people have signs of prior infection (known as seroprevalence) varies across European countries: it’s 3.9% in Italy, 11.9% in Spain, and can be up to 23% in mountainous areas of Serbia. The disease seems to be just as common in urban and rural areas.
There are certain groups who might experience more severe symptoms should they contract Boutonneuse fever. These include:
- elderly individuals
- people with a compromised immune system
- chronic alcoholics
- those with a genetic condition known as glucose-6-phosphate dehydrogenase (G6PD) deficiency
- people who were previously treated with the wrong antibiotics
- and those who experience a delay in receiving treatment.
Signs and Symptoms of Boutonneuse Fever
Patients with this condition usually start to experience symptoms about 6 to 10 days after a tick bite. The symptoms can be similar to the flu and include fever and a rash. There may also be a mark on the skin, commonly known as a “Tache noire”, which is a distinctive feature of this disease. Once in a while, more than one of these marks can form. The rash usually appears 2 to 4 days after the fever starts and often begins on the palms of the hands and the soles of the feet, avoiding the face.
Rarer still is a rash that looks like small blisters. In places where this disease is common, doctors must be alert for patients who show up with unexplained rashes, fever, or flu-like symptoms. Knowing whether the person has travelled recently can also be an important clue in diagnosing this condition.
- Symptoms start 6 to 10 days after a tick bite
- Common symptoms include fever and rash
- “Tache noire” or skin mark is a distinctive feature
- Rash usually appears 2 to 4 days after fever starts
- Rash often begins on the palms and soles, avoiding the face
- Occasionally, the rash may look like small blisters
- Travel history can be an important clue for diagnosis
Testing for Boutonneuse Fever
Diagnosing certain medical conditions can be determined mostly by observing the symptoms and considering other factors related to the patient’s lifestyle and background. However, to verify a clinical diagnosis, doctors may use different methods, among them being the lab tests.
In the lab, they look for signs like a relative left shift (a change in the types of white blood cells found in your blood), low white blood cell counts (leukopenia), low platelet count (thrombocytopenia), high levels of a liver enzyme called aspartate aminotransferase, high Lactate Dehydrogenase (LDH) levels (another enzyme that can indicate damage to the body’s cells), and low sodium levels (hyponatremia).
More alarming signs that could indicate a serious and widespread condition might be worsening liver function, lowering platelets in the blood, and widespread skin bruising or bleeding without any clear cause (diffuse epidermal purpura). However, these lab tests aren’t always helpful for diagnosing specific conditions, as their occurrence can differ widely.
So, the final diagnosis can often come from a clinical assessment alone, followed by confirmatory tests. These tests confirm the condition by looking for certain signs of the disease in blood or tissue samples.
These confirmatory tests include serology (testing of blood serum), polymerase chain reaction (a method to copy small segments of DNA), immunologic detection (identifying the presence of certain immune responses), and isolating the organism causing the disease. Among these, serologic testing is currently the most frequently used for diagnosing.
There are several types of serologic tests available, like the Enzyme-linked immunosorbent assay (ELISA) and the Western blot immunoassay. Both tests can detect two types of antibodies, IgM and IgG, usually 10 to 14 days after symptoms start. However, these tests aren’t always useful during early illness, especially at the onset of symptoms.
One problem with serologic testing is that it can show cross-reactivity between various subspecies, that is, it might react to similar, but not identical, substances, which reduces its specificity. In such cases, diagnosing specific species is commonly done by a follow-up polymerase chain reaction test, complemented by a culture test.
Treatment Options for Boutonneuse Fever
If you show signs of BF (a disease caused by bacterial infection), it’s critical to start treatment as soon as possible. This action can help ensure the sickness doesn’t last as long and reduces the chance of complications. You shouldn’t have to wait until lab tests confirm you have this disease before beginning treatment.
In the past, doxycycline, a class of antibiotics, was avoided for children and pregnant individuals due to potential side effects like dental staining in children or harm to the unborn baby. However, recent studies have shown that this medication is relatively safe, especially when used for short treatments. So, today, it is the top choice for treating infections caused by rickettsia bacteria, including BF, irrespective of your age or whether you’re pregnant.
However, if you’ve had severe allergic reactions to doxycycline or this medication has harmed your liver before, an alternative drug may be used. For mild cases, azithromycin, another antibiotic, might be suitable for children and pregnant women. For severe cases, or for pregnant women who can’t use doxycycline, chloramphenicol, yet another antibiotic, could be an appropriate choice. There might also be circumstances where azithromycin can be used if a pregnant woman is unable to take doxycycline or chloramphenicol.
Fluoroquinolones, a type of antibiotics, were once used to treat this infection but are no longer recommended due to their association with poor outcomes.
What else can Boutonneuse Fever be?
When someone experiences fever and rash, the cause can be numerous different conditions, such as:
- Viral skin infections like chickenpox (caused by varicella-zoster virus)
- Rubella or measles
- Fifth disease (a mild viral infection)
- Infectious mononucleosis (mono)
- Scarlet fever
- Toxic shock syndrome, a serious bacterial infection
- Various other infections caused by rickettsia, a type of bacteria
- Connective tissue disorders, like lupus and dermatomyositis
- Conditions which involve fever and a skin sore or ‘eschar’, such as cutaneous anthrax or some tropical diseases
- Non-rickettsial protozoal infections like malaria
So, it’s crucial for healthcare providers to evaluate any such symptoms thoroughly and consider a broad range of potential causes to make an accurate diagnosis.
What to expect with Boutonneuse Fever
The outlook for patients has greatly improved thanks to early detection and spreading awareness about the disease in areas where it’s common. Also, starting antibiotic treatment as soon as possible plays a crucial role. Death rates have significantly declined from nearly 20% in 1949 to less than 5% today.
One important thing to note is that treatment shouldn’t be put on hold to wait for results from blood tests or bacterial cultures. Several cases have proven that recognizing and treating the disease early on significantly improves the patient’s chance of a successful recovery.
Possible Complications When Diagnosed with Boutonneuse Fever
In most cases, people recover without major complications. However, people who are more vulnerable may experience more severe conditions. These can include heart inflammation, irregular heartbeats, eye inflammation or retinopathy, eye blood vessel inflammation, brain stroke, brain and spinal cord inflammation, loss of sense related to nerves, sudden four-limb paralysis due to a nerve-related disease, rupture of the spleen, and a condition where the body’s immune system attacks its own cells and tissues.
Possible Complications:
- Heart inflammation
- Irregular heartbeats
- Eye inflammation or retinopathy
- Eye blood vessel inflammation
- Brain stroke
- Brain and spinal cord inflammation
- Loss of sense related to nerves
- Sudden four-limb paralysis due to a nerve-related disease
- Rupture of the spleen
- A condition where the body’s immune system attacks its own cells and tissues
Preventing Boutonneuse Fever
To reduce the total number of cases and deaths worldwide, we must first work on preventing tick-borne encephalitis (BF). This begins with educating people about what causes the disease and how to improve their hygiene habits. For those living in or visiting areas where the disease is common, regular checks for ticks can help in preventing this ailment. It is also important to be aware of the typical symptoms of this disease and to seek medical help promptly if you think you may have been affected. This is crucial because the earlier the disease is treated, the better the chances of recovery.
