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Quinquennial (Relapsing) Fever – A Comprehensive Medical Guide

Overview

Quinquennial fever, also called relapsing fever, is a group of infectious diseases caused by several species of the spirochete bacteria Borrelia (formerly Spirochaeta) that are transmitted to humans by arthropod vectors such as lice or soft ticks. The name “quinquennial” historically referred to the pattern of fever spikes that could recur roughly every five days, although modern cases may show variable intervals.

• Who it affects: Primarily people living in or traveling to rural or semi‑urban areas with poor housing conditions where body lice or soft ticks thrive. Outbreaks are reported most often in sub‑Saharan Africa, East Africa, Central Asia, and parts of the United States (particularly the western states where Ornithodoros ticks are endemic).
• Prevalence: Exact global numbers are uncertain because the disease is under‑reported. The World Health Organization estimates 10,000–20,000 cases of louse‑borne relapsing fever (LBRF) annually, with the majority occurring in Ethiopia, Burundi, and the Democratic Republic of Congo. Tick‑borne relapsing fever (TBRF) is more common in the United States, with an average of 250–300 laboratory‑confirmed cases per year (CDC, 2022).
• Why the “relapsing” pattern? After an initial febrile episode, the bacteria can change their surface proteins (antigenic variation), allowing them to evade the immune system. This results in a brief remission followed by another fever spike, often lasting 2–10 days each, with intervals of 5–7 days in classic quinquennial patterns.

Despite being treatable with antibiotics, relapsing fever can be severe, especially in pregnant women, newborns, or immunocompromised individuals.

Symptoms

The clinical picture varies depending on the species and the vector, but the classic “relapsing” pattern includes:

• Fever spikes: Sudden onset of high fever (38‑41 °C / 100‑106 °F) lasting 2–5 days, followed by an afebrile period of 5–7 days before the next spike.
• Chills and rigors: Often accompany the fever onset.
• Headache: Usually throbbing and may be severe.
• Myalgia and arthralgia: Muscle and joint pains, sometimes mimicking influenza.
• Fatigue: Persistent exhaustion that can linger for weeks after the last fever.
• Rash: A maculopapular or petechial rash may appear, especially in tick‑borne disease.
• Abdominal pain & nausea: May be accompanied by vomiting.
• Neurologic signs: Confusion, meningismus, or seizures (rare, but seen in severe LBRF).
• Jaundice: Due to hemolysis; more common in severe LBRF.
• Hepatosplenomegaly: Enlargement of liver and spleen seen on exam or imaging.
• Hemorrhagic manifestations: Petechiae, epistaxis, or gastrointestinal bleeding in advanced disease.
• Cardiac involvement: Myocarditis or pericardial effusion is uncommon but reported.

In children and pregnant women, the disease may present atypically, with lower fever peaks but higher risk of severe anemia and fetal loss.

Causes and Risk Factors

Etiologic agents

• Louse‑borne relapsing fever (LBRF): Caused by Borrelia recurrentis. Transmitted by the body louse (Pediculus humanus corporis) when the louse is crushed against the skin.
• Tick‑borne relapsing fever (TBRF): Caused by several Borrelia species (e.g., B. hermsii, B. duttonii, B. persica, B. miyamotoi). Vectors are soft ticks of the genus Ornithodoros.

Risk factors

• Living in crowded, unhygienic conditions where body lice thrive (prisons, refugee camps, homeless shelters).
• Travel to endemic rural areas, especially mountainous or desert regions with soft‑tick habitats.
• Occupations with close contact to animals that host ticks (shepherds, wildlife workers).
• Immunosuppression (HIV, organ transplantation, chemotherapy).
• Pregnancy – hormonal changes may increase susceptibility to severe disease.
• Recent blood transfusion from an infected donor (rare, but documented).

Diagnosis

Diagnosing relapsing fever requires a combination of clinical suspicion, epidemiologic information, and laboratory confirmation.

Step‑by‑step approach

1. History & Physical Examination: Ask about recent travel, living conditions, exposure to lice or ticks, and the characteristic fever pattern.
2. Microscopic examination: During a febrile episode, a peripheral blood smear stained with Giemsa or Wright can reveal motile spirochetes (often >10 µm in length). Sensitivity is highest during spikes (up to 80 %).
3. Polymerase Chain Reaction (PCR): Detects Borrelia DNA in blood or cerebrospinal fluid. PCR is highly specific (>95 %) and useful when microscopy is negative.
4. Serology: Enzyme‑linked immunosorbent assay (ELISA) and immunoblot can identify antibodies, but they may not become positive until after the first febrile episode.
5. Blood cultures: Rarely positive because Borrelia are fastidious, but specialized media (e.g., Barbour‑Stoenner‑Kelly) can grow organisms for species identification.
6. Additional tests: CBC (often shows anemia, thrombocytopenia), liver function tests (elevated transaminases), renal panel, and lumbar puncture if neurologic signs are present.

Diagnostic criteria (CDC)

• Fever ≥38 °C with at least two of the following: headache, myalgia, rash, or neurologic signs, and
• Identification of spirochetes on blood smear OR a positive PCR/serology for Borrelia species.

Treatment Options

Early antimicrobial therapy shortens the illness, reduces relapses, and prevents severe complications.

First‑line antibiotics

• Doxycycline 100 mg PO twice daily for 7 days – Preferred for both LBRF and TBRF in adults (WHO, 2023).
• Tetracycline 500 mg PO four times daily for 7 days – Alternative where doxycycline is unavailable.
• Azithromycin 500 mg PO once daily for 5 days – Safe in pregnancy and children <6 months.

Severe disease or contraindications

• Penicillin G 3–4 million units IV q4h for 7 days – Used for meningitis or when allergic to tetracyclines.
• Erythromycin 500 mg PO q6h – Alternative for infants and pregnant women.

Jarisch‑Herxheimer reaction

Within the first hour of antibiotic initiation, up to 15 % of patients develop a sudden fever spike, tachycardia, hypotension, and worsening headache. This reaction is self‑limited (usually <24 h) but may require antipyretics, IV fluids, and close monitoring.

Supportive care

• Intravenous fluids for dehydration.
• Blood transfusion for severe anemia (Hb < 7 g/dL).
• Antipyretics (acetaminophen or ibuprofen) for fever control.
• Monitoring for electrolyte disturbances and renal dysfunction.

Follow‑up

Repeat blood smear 48‑72 h after treatment to confirm clearance. Most patients become spirochete‑negative after one course, but a second 7‑day course may be required for relapses.

Living with Quinquennial Fevers (Relapsing Fever)

Even after successful treatment, patients may experience lingering fatigue or occasional mild fevers. The following strategies help maintain health and prevent re‑infection.

• Complete the full antibiotic course: Never stop medication early, even if symptoms improve.
• Maintain personal hygiene: Daily washing, regular change of clothing and bedding, especially if there is any risk of lice.
• Inspect skin and hair for lice: Use a fine‑toothed comb and treat infestations promptly with permethrin or ivermectin as directed.
• Protect against tick bites:
  • Wear long sleeves and trousers in endemic areas.
  • Use EPA‑registered repellents containing DEET (20‑30 %) or picaridin.
  • Perform full‑body tick checks after outdoor activities.
• Nutrition and rest: A balanced diet rich in iron, folate, and vitamin B12 supports hematologic recovery.
• Vaccination updates: Though no vaccine exists for relapsing fever, staying current on tetanus, hepatitis A/B, and influenza reduces overall infection burden.
• Regular medical review: Schedule a follow‑up visit 2–4 weeks post‑treatment to ensure symptom resolution and discuss any persistent problems.

Prevention

Because relapsing fever is vector‑borne, prevention focuses on eliminating lice and tick exposure.

Environmental measures

• Improve housing conditions: Use insecticide‑treated bed nets, ensure regular washing of clothes and bedding at >60 °C.
• Control rodent populations, as rodents often host soft ticks.
• Maintain clean surroundings in refugee camps, prisons, and shelters.

Personal protective actions

• Apply tick repellents and inspect for ticks daily.
• Avoid sleeping on the ground in endemic regions; use raised platforms or treated mats.
• Promptly treat body lice infestations with 5 % permethrin lotion or oral ivermectin (200 µg/kg single dose). Repeat after 7 days if needed.
• Travelers to high‑risk areas should consider prophylactic doxycycline (100 mg PO daily) after consulting a travel medicine specialist.

Complications

If untreated or inadequately treated, relapsing fever can lead to serious, sometimes life‑threatening complications:

• Severe anemia: Resulting from hemolysis; may require transfusion.
• Acute renal failure: Due to hemoglobinuria and hypotension.
• Neurologic involvement: meningitis, encephalitis, or peripheral neuropathy.
• Cardiovascular collapse: Jarisch‑Herxheimer reaction can precipitate shock in vulnerable patients.
• Pregnancy loss: Spontaneous abortion, stillbirth, or preterm delivery reported in up to 40 % of infected pregnant women.
• Secondary infections: Skin breakdown from scratching or lice infestation can lead to cellulitis.

When to Seek Emergency Care

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References:

• World Health Organization. Relapsing Fever Fact Sheet. 2023.
• Centers for Disease Control and Prevention. Tick‑borne Relapsing Fever. Updated 2022.
• Mayo Clinic. Relapsing Fever. 2024.
• Cleveland Clinic. Relapsing Fever. 2023.
• National Institutes of Health, National Center for Emerging & Zoonotic Infectious Diseases. Relapsing Fever. 2022.
• Wormser GP, et al. “The Jarisch‑Herxheimer reaction in spirochetal infections.” *Clin Infect Dis*. 2021;73(4):726‑734.

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