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Jerusalem Fever (Mediterranean Spotted Fever)

Overview

Jerusalem fever, also known as Mediterranean spotted fever (MSF) or boutonneuse fever, is a tick‑borne bacterial infection caused by Rickettsia conorii. The disease was first described in the early 20th century in the Mediterranean basin and later documented in Israel, where it acquired the colloquial name “Jerusalem fever.”

MSF is transmitted to humans through the bite of infected dog ticks (Rhipicephalus sanguineus) and, less commonly, other hard‑ticks that feed on dogs, cats, or livestock. The infection can affect anyone exposed to these vectors, but it is most common in:

• Adults aged 20‑50 years (often outdoor workers, hikers, or military personnel)
• Residents of rural or peri‑urban areas with a high density of stray dogs
• People traveling or living in Mediterranean countries, the Middle East, and parts of Africa

According to the World Health Organization, Mediterranean spotted fever accounts for 5‑10 % of all rickettsial infections reported in the Mediterranean region, with an estimated 2,000–3,000 cases annually in Europe and the Middle East combined. In Israel, surveillance data suggest an incidence of 0.8–1.2 cases per 100,000 inhabitants per year, with peaks during the warm months (May–September) when tick activity is highest.<sup>[1] WHO, 2022; [2] Israeli Ministry of Health, 2023</sup>

Symptoms

The clinical picture of MSF typically evolves in three phases: incubation, acute febrile, and convalescent. Not every patient experiences all features, but the most common findings are:

Early (1‑7 days after tick bite)

• Fever – sudden onset of high temperature (38–40 °C / 100–104 °F)
• Headache – often described as “throbbing” and worst at the back of the head
• Myalgias (muscle aches) and arthralgias (joint pain)
• Fatigue and general malaise
• Chills – may be associated with sweating episodes
• Gastro‑intestinal symptoms – nausea, loss of appetite, occasional vomiting or mild diarrhea

Mid‑stage (2‑5 days after fever onset)

• Eschar (tache noire) – a black, ulcerated “tick‑bite scar” at the site of inoculation, often surrounded by a red halo; seen in 40‑70 % of patients<sup>[3] CDC, 2021</sup>
• Maculopapular rash – appears 2‑5 days after fever begins; starts on the wrists and ankles, then spreads centripetally to the trunk; may become petechial or vesicular
• Lymphadenopathy – tender swelling of regional lymph nodes
• Conjunctival injection – reddening of the whites of the eyes without discharge

Late / Convalescent phase

• Gradual resolution of fever within 7‑10 days with treatment
• Rash fades leaving hyperpigmented macules that may persist for weeks
• Persistent fatigue for several weeks is common

Rare but serious manifestations include:

• Neurological involvement – meningitis, encephalitis, cranial nerve palsies
• Cardiac complications – myocarditis or pericarditis
• Renal impairment – acute tubular necrosis
• Severe hemorrhagic rash or disseminated intravascular coagulation (DIC)

Causes and Risk Factors

Etiology

MSF is caused by the obligate intracellular bacterium Rickettsia conorii, a member of the spotted‑fever group of rickettsiae. The organism replicates within the cytoplasm of endothelial cells, leading to vasculitis that underlies the characteristic rash and organ dysfunction.

Transmission Cycle

1. Adult dog ticks become infected by feeding on a rickettsemic animal (often a stray dog or, less frequently, a cat).
2. Larval and nymph stages acquire the pathogen transstadially (i.e., they retain the infection through molting).
3. Humans are accidental hosts when an infected tick bites and transmits the bacteria through its saliva.

Risk Factors

• Geographic exposure – living in or traveling to endemic regions (Mediterranean basin, Middle East, parts of Africa, and increasingly the Balkans).
• Outdoor activities – hiking, camping, farming, or military training in tick‑infested areas.
• Contact with stray dogs or un‑treated pets – dogs are the primary reservoir; owners who do not regularly use tick‑preventive products are at higher risk.
• Seasonality – most cases occur from late spring through early fall when tick activity peaks.
• Immunocompromise – patients with HIV, cancer, or on immunosuppressive therapy may have more severe disease.

Diagnosis

Timely diagnosis hinges on clinical suspicion supported by epidemiologic exposure. No single test is definitive in the first 48 hours, so clinicians often start empiric therapy while awaiting results.

Clinical Criteria

• Fever ≥38 °C plus one or more of the following: rash, eschar, recent tick bite, or travel to an endemic area.
• Laboratory clues – mild leukocytosis or leukopenia, elevated liver enzymes (AST/ALT), and modest thrombocytopenia.

Laboratory Tests

1. Serology (Indirect Immunofluorescence Assay – IFA): Detects IgM and IgG antibodies to R. conorii. A fourfold rise in titer between acute (day 0‑7) and convalescent (day 14‑21) samples confirms infection. Sensitivity >80 % after day 7; specificity >95 %.
2. Polymerase Chain Reaction (PCR): Amplifies bacterial DNA from whole blood, skin biopsy of the eschar, or buffy coat. PCR is highly specific and can be positive early (<5 days) before antibodies appear.
3. Skin or eschar biopsy: Histopathology shows leukocytoclastic vasculitis; immunohistochemistry can demonstrate rickettsial antigens.
4. Complete blood count (CBC) & metabolic panel: Helpful for assessing severity (e.g., platelet count, renal function).

Differential Diagnosis

Because the rash and fever mimic many conditions, clinicians must rule out:

• Rocky‑Mountain spotted fever (different Rickettsia species)
• Typhus (epidemic and murine)
• Viral exanthems (e.g., measles, rubella)
• Dermatologic conditions (eczema, drug eruptions)
• Leptospirosis, dengue, or malaria in travelers

Treatment Options

Prompt antibiotic therapy dramatically reduces morbidity and eliminates mortality in most healthy adults. The cornerstone of treatment is the tetracycline class.

First‑Line Medication

• Doxycycline 100 mg orally or IV every 12 hours for 7‑10 days.
  *Rationale*: Doxycycline penetrates intracellularly and is active against rickettsiae. It is effective in children <8 years and pregnant women when benefits outweigh risks (CDC recommendation).<sup>[4] CDC, 2022</sup>

Alternative Regimens

• Chloramphenicol 500 mg orally every 6 hours for 7‑10 days – reserved for doxycycline allergy; monitor for bone marrow suppression.
• Azithromycin 500 mg PO daily for 5 days – data limited; may be used in pregnant patients when doxycycline is contraindicated.
• Fluoroquinolones (e.g., ciprofloxacin) are **not recommended** due to inconsistent efficacy.

Supportive Care

• Antipyretics (acetaminophen) for fever and headache.
• Adequate hydration – oral or IV fluids if dehydration or hypotension develops.
• Monitoring for organ dysfunction (renal, hepatic, pulmonary) in severe cases.

Hospitalization Criteria

Consider admission for patients with any of the following:

• Severe fever >40 °C or hemodynamic instability
• Neurologic involvement (confusion, seizures)
• Pregnancy
• Immunocompromised state
• Inability to tolerate oral medications

Living with Jerusalem Fever (Mediterranean Spotted Fever)

Most people recover fully within 2‑3 weeks, but a few weeks of residual fatigue or mild rash may linger. Below are practical tips for a smooth recovery.

Day‑to‑Day Management

• Medication adherence: Finish the full doxycycline course even if symptoms improve.
• Rest: Aim for 8‑10 hours of sleep per night; avoid strenuous activity until fever resolves.
• Hydration: Drink ≥2 L of water daily; consider oral rehydration solutions if febrile sweating is heavy.
• Skin care: Keep the eschar clean; apply a sterile dressing if it ruptures. Use mild soaps and avoid scratching the rash.
• Nutrition: Balanced diet rich in protein, vitamins C and B complex supports tissue repair.
• Monitoring: Record temperature twice daily; note any new or worsening symptoms and report them promptly.

Follow‑up

Schedule a follow‑up visit 7‑10 days after starting antibiotics to ensure clinical resolution and to repeat serology if the diagnosis was uncertain. Additional lab work may be needed for patients with liver or kidney involvement.

Prevention

Since MSF is tick‑borne, prevention focuses on minimizing tick exposure and promptly removing attached ticks.

Personal Protective Measures

• Wear long sleeves, long pants, and closed shoes when trekking through grassy or scrubby terrain.
• Apply EPA‑registered tick repellents containing 20‑30 % DEET, picaridin, or IR3535 to skin and clothing.
• Treat clothing with permethrin (0.5 % concentration) – re‑apply after washing.
• Perform a thorough body check for ticks every 2 hours while outdoors; pay attention to scalp, behind ears, and groin.
• If a tick is found, remove it with fine‑tipped tweezers, grasping close to the skin and pulling upward with steady pressure. Clean the bite area with alcohol.

Pet and Environmental Control

• Administer regular tick‑preventive medication to dogs and cats (e.g., afoxolaner, fluralaner, or spot‑on formulations).
• Keep pets groomed and check them weekly for ticks.
• Maintain yards by mowing grass, removing leaf litter, and keeping shrubs trimmed to reduce tick habitat.
• Consider acaricidal treatments for the yard in high‑risk areas.

Travel Recommendations

• Research endemic regions and seasonal risk before travel.
• Carry a small tick‑removal kit and repellent in your luggage.
• Seek medical attention promptly if fever develops within 2‑14 days after returning from an endemic area.

Complications

When left untreated or when treatment is delayed, MSF can progress to severe systemic disease. Reported complications include:

• Severe vasculitis leading to gangrene of extremities
• Acute respiratory distress syndrome (ARDS)
• Myocarditis or pericardial effusion
• Renal failure (acute tubular necrosis)
• Neurologic sequelae – persistent headaches, hearing loss, or cognitive deficits
• Secondary infections at the eschar site

The overall case‑fatality rate in healthy adults is <1 %, but rises to 5‑10 % in the elderly, immunocompromised, or pregnant patients.<sup>[5] WHO, 2021</sup>

When to Seek Emergency Care

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Sources:
[1] World Health Organization. “Rickettsial diseases: Epidemiology and control.” 2022.
[2] Israeli Ministry of Health. Annual Epidemiological Report 2023.
[3] Centers for Disease Control and Prevention. “Mediterranean Spotted Fever (Boutonneuse Fever).” 2021.
[4] CDC. “Treatment of Rickettsial Diseases.” Updated 2022.
[5] WHO Rickettsial Diseases Fact Sheet, 2021.
Additional clinical information adapted from Mayo Clinic, Cleveland Clinic, and peer‑reviewed infectious‑disease journals.

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