Relapsing fever (RF) is a condition caused by a spirochete and is characterized by typical features of episodic and recurrent high fever, headache, myalgias, and arthralgias. The symptoms last for approximately 3 days, then abate for a week but then recur for another 3 days. This process could continue unless treated. There are two types of RF: tick-borne RF (TBRF) and louse-borne RF (LBRF). TBRF occurs after individuals have lived or slept in rodent-infested mountain cabins while LBRF is transmitted by the body louse and happens in refugee camps or developing regions of the world.

Clinical presentation of TBRF is sudden onset of high fever lasting up to a week and ending with rigors, hypertension, and tachycardia [1]. The first episode is often accompanied by headaches, myalgias, arthralgias, neck stiffness, and nausea. Neurologic symptoms are more common in TBRF after the second episode of fever and include facial palsy, meningismus, myelitis, and radiculopathy followed in certain cases by deficits like hemiplegia and aphasia [1] [2]. Ophthalmic involvement is associated with a possibility of permanent visual impairment secondary to unilateral or bilateral iridocyclitis or panophthalmitis. Hepatosplenomegaly and myocarditis may be present in fatal cases. Infection of pregnant women has a higher incidence of miscarriages and stillbirths. Gravid women and children have a more serious form of the disease [3] [4]. During TBRF crises, adult respiratory distress syndrome is also known to develop [5].

The incidence of jaundice, petechiae, hemoptysis, epistaxis and CNS involvement is higher in LBRF [6]. Patients of LBRF have been reported to have mainly one relapse while those with TBRF have averagely 3 relapses [7]. Delirium and coma can arise in both TBRF and LBRF.

The diagnosis of RF depends on identifying the typical characteristics of the fever along with a thorough medical, social, and travel history as findings of physical examination are not predictable. Spirochetes can be detected on thin and thick peripheral blood smears using Wright’s or Giemsa stain or by isolating them in Kelly culture medium in the period between onset of fever and its peak [8] [9] [10]. Peripheral blood smears have a sensitivity of 70% and are more sensitive in detecting TBRF than LBRF [11].

Direct and indirect immunofluorescence can be used to visualize spirochetes with a fluorescence microscope while polymerase chain reaction testing can identify most Borrelia species [12] [13]. Other laboratory findings include elevated erythrocyte sedimentation rate, anemia, proteinuria,leukocytosis, thrombocytopenia, increased serum unconjugated bilirubin levels, elevated hepatic transaminase levels, prolonged partial thromboplastin and prothrombin times and microhematuria. In TBRF myocarditis, an electrocardiogram may show a prolonged corrected Q-T interval [14] [15] [16]. Analysis of cerebrospinal fluid (CSF) in patients with neurological symptoms is likely to reveal mononuclear pleocytosis, an elevated protein level, and normal glucose levels [3] [7].

Features of pulmonary edema can be noticed on a plain chest X-ray when present. Other imaging studies are indicated only in cases where intracranial or other complications are suspected.

Histological studies help to detect spirochetes using silver stains like Warthin-Starry or modified Dieterle.

The primary treatment for relapsing fever is antibiotics. Commonly used antibiotics include doxycycline, tetracycline, erythromycin, or penicillin, depending on the patient's age and health status. Treatment is usually effective, and symptoms typically improve within a few days. However, a reaction known as the Jarisch-Herxheimer reaction may occur shortly after starting antibiotics, characterized by worsening symptoms due to the rapid killing of bacteria. This reaction is usually self-limiting and can be managed with supportive care.

With appropriate antibiotic treatment, the prognosis for relapsing fever is generally good. Most patients recover fully without long-term complications. However, if left untreated, the disease can lead to severe complications, including damage to the liver, spleen, or central nervous system. Early diagnosis and treatment are crucial to prevent these outcomes. In rare cases, relapsing fever can be fatal, particularly in vulnerable populations such as young children, the elderly, or those with weakened immune systems.

Relapsing fever is caused by infection with Borrelia bacteria. There are two main types: louse-borne relapsing fever (LBRF) and tick-borne relapsing fever (TBRF). LBRF is transmitted by the human body louse, while TBRF is transmitted by soft-bodied ticks. The specific species of Borrelia involved can vary depending on the geographic region. The bacteria enter the human bloodstream through the bite of an infected louse or tick, leading to the characteristic symptoms of the disease.

Relapsing fever is more common in certain parts of the world. Louse-borne relapsing fever is primarily found in areas with poor sanitation and overcrowding, such as refugee camps, and is most prevalent in parts of Africa. Tick-borne relapsing fever occurs in rural areas of Africa, the Americas, and parts of Asia and Europe. The incidence of relapsing fever can vary widely depending on local environmental conditions, human behavior, and the presence of vector populations.

The pathophysiology of relapsing fever involves the cyclical nature of Borrelia infection. After entering the bloodstream, the bacteria multiply and trigger an immune response, leading to fever and other symptoms. The immune system eventually reduces the bacterial load, causing symptoms to subside temporarily. However, Borrelia can change its surface proteins, evading the immune response and causing a relapse of symptoms. This cycle can repeat several times until the infection is cleared by treatment or the immune system.

Preventing relapsing fever involves reducing exposure to the vectors that transmit the disease. For louse-borne relapsing fever, improving sanitation and reducing overcrowding are key measures. Personal hygiene and regular washing of clothing can help prevent lice infestations. For tick-borne relapsing fever, avoiding tick-infested areas, using insect repellent, wearing protective clothing, and performing regular tick checks are effective strategies. In endemic areas, public health measures to control vector populations can also reduce the risk of transmission.

Relapsing fever is an infectious disease caused by Borrelia bacteria, transmitted through lice or tick bites. It is characterized by recurring episodes of fever and other systemic symptoms. Diagnosis is confirmed through blood tests, and treatment with antibiotics is usually effective. The disease is more common in certain geographic regions and can be prevented by reducing exposure to the vectors. Early diagnosis and treatment are crucial to prevent complications and ensure a good prognosis.

If you suspect you have relapsing fever, it is important to seek medical attention. The disease is treatable with antibiotics, and early intervention can prevent complications. Be aware of the symptoms, especially if you have been in areas where the disease is common or have had potential exposure to lice or ticks. Practicing good hygiene, using insect repellent, and avoiding areas with high vector populations can help reduce your risk of infection.

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