What is the acute management, including drugs and prophylaxis, for Lyme disease (Lyme borreliosis) and Rocky Mountain Spotted Fever (RMSF) following insect sting and bite injuries?

From the Guidelines

For Lyme disease and Rocky Mountain Spotted Fever (RMSF) management after tick bites, prompt removal of the tick is essential, and doxycycline is the first-line treatment for both infections. For Lyme disease prophylaxis, a single 200mg dose of doxycycline is recommended if the tick was attached for ≥36 hours, is identified as an Ixodes species, and prophylaxis can be started within 72 hours of removal in an endemic area 1. The following key points are crucial for management:

• For established Lyme disease, treatment consists of doxycycline 100mg twice daily for 10-21 days (adults) or amoxicillin 500mg three times daily for patients who cannot take doxycycline.
• RMSF requires immediate empiric treatment with doxycycline 100mg twice daily for 5-7 days (adults) or 2.2mg/kg twice daily (children) until at least 3 days after fever resolves, as recommended by the CDC 1.
• No prophylaxis exists for RMSF after tick exposure; instead, patients should monitor for symptoms (fever, headache, rash) for 2 weeks.
• Doxycycline is the first-line treatment for both infections because it effectively targets the causative bacteria - Borrelia burgdorferi for Lyme disease and Rickettsia rickettsii for RMSF.
• Early treatment is crucial to prevent complications, as delayed therapy can lead to severe outcomes, particularly with RMSF which has a high mortality rate if untreated. It is also important to note that the use of protective clothing and tick repellents, checking the entire body for ticks daily, and prompt removal of attached ticks before transmission of infection can occur are key preventive measures 1.

From the FDA Drug Label

Doxycycline is indicated for the treatment of the following infections: Rocky Mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsialpox, and tick fevers caused by Rickettsiae. Relapsing fever due to Borrelia recurrentis. Doxycycline is indicated for the prophylaxis of malaria due to Plasmodium falciparum in short-term travelers (<4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains

The acute management of sting and bite injuries may involve the use of doxycycline for the treatment of Rocky Mountain spotted fever (RMSF) and relapsing fever due to Borrelia recurrentis, which can be transmitted through tick bites.

• RMSF treatment: Doxycycline is indicated for the treatment of RMSF.
• Lyme disease treatment: Although not explicitly stated in the label, doxycycline is commonly used for the treatment of Lyme disease, but the label only mentions relapsing fever due to Borrelia recurrentis.
• Prophylaxis: Doxycycline is not indicated for the prophylaxis of Lyme disease or RMSF in this label, but it is indicated for the prophylaxis of malaria 2.

From the Research

Acute Management of Sting and Bite Injuries

• The acute management of sting and bite injuries involves prompt removal of the tick or other insect, cleaning the affected area, and monitoring for signs of infection or allergic reaction.

Drugs and Prophylaxis for Lyme Disease

• A single 200-mg dose of doxycycline given within 72 hours after an I. scapularis tick bite can prevent the development of Lyme disease 3.
• Prophylaxis with single-dose doxycycline has been shown to be effective in preventing Lyme disease after a tick bite, with a relative risk reduction of 67% (95% CI 31 - 84%) 4.
• The efficacy of treatment with doxycycline was 87% (95% confidence interval, 25 to 98 percent) in one study 3.

Prophylaxis for RMSF

• There is no specific prophylaxis recommended for Rocky Mountain Spotted Fever (RMSF) after a tick bite.
• However, prompt removal of attached ticks and use of protective measures such as insect repellents and wearing protective clothing can help prevent tick bites and reduce the risk of RMSF.

Tick-Borne Disease Prevention

• Understanding the role of wildlife hosts in the establishment and maintenance of tick populations is important for preventing tick-borne diseases such as Lyme disease 5.
• Ixodes ticks have immune responses against Lyme disease pathogens, including the recognition of invading pathogens like Borrelia burgdorferi 6.

Note: There is no relevant information available for RMSF prophylaxis in the provided studies. Study 7 is not relevant to the topic of sting and bite injuries, Lyme disease, or RMSF.