Jarisch–Herxheimer reaction

Jarisch–Herxheimer reaction (JHR) is a febrile reaction – often accompanied by headache, myalgia (muscle pain), arthralgia (joint pain), and other symptoms – that can occur after the initiation of antibiotics in the treatment of certain infectious diseases, notably syphilis, Lyme disease, and relapsing fever. The reaction is named after Adolf Jarisch, an Austrian dermatologist, and Karl Herxheimer, a German dermatologist, who independently described the phenomenon in the late 19th and early 20th centuries.

Causes and Pathophysiology

The Jarisch–Herxheimer reaction is believed to be caused by the release of pyrogens or endotoxin-like substances from the dying bacteria during the first few hours of treatment with antibiotics. This sudden influx of pyrogens into the bloodstream is thought to trigger an inflammatory response mediated by the body's immune system, leading to the symptoms associated with the reaction.

Symptoms

Symptoms of the Jarisch–Herxheimer reaction typically begin within a few hours of starting antibiotic therapy and may include fever, chills, rigor, hypotension, headache, myalgia, arthralgia, nausea, vomiting, and an exacerbation of skin lesions in the case of syphilis treatment. The intensity of the reaction varies from mild to life-threatening but usually resolves within 24 hours.

Diagnosis

Diagnosis of the Jarisch–Herxheimer reaction is primarily clinical, based on the temporal relationship between the onset of symptoms and the initiation of antibiotic therapy in a patient being treated for an infection known to cause the reaction. There are no specific laboratory tests for the Jarisch–Herxheimer reaction, but tests may be performed to rule out other causes of the symptoms.

Treatment

Treatment of the Jarisch–Herxheimer reaction is mainly supportive and symptomatic. It includes antipyretics for fever, analgesics for headache and myalgia, and fluid replacement for dehydration. In severe cases, hospitalization may be required for supportive care, including intravenous fluids and monitoring of vital signs. Prevention of the reaction involves the cautious initiation of antibiotic therapy, with consideration for the potential severity of the reaction in certain patients.

Epidemiology

The Jarisch–Herxheimer reaction is most commonly associated with the treatment of syphilis, particularly in the early stages of the disease. It can also occur in the treatment of Lyme disease and relapsing fever, but is less common in these conditions. The exact incidence of the reaction is difficult to determine due to underreporting and the variability in the severity of symptoms.

History

The reaction was first described by Adolf Jarisch in 1895 while observing the effects of mercury treatment on syphilitic lesions. Karl Herxheimer reported similar findings in 1902. Their contributions to the understanding of this reaction have led to it being named after them.

See Also

• Antibiotic
• Syphilis
• Lyme disease
• Relapsing fever
• Infectious disease
• Immunology

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