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Prophylaxis is not usually recommended but prophylaxis may be used if there was a blacklegged tick bite in an area that was known to be endemic for Lyme disease, and if the tick was engorged and other defined criteria are met. Transmission is during the nymphal or adult stages but more commonly the small nymphs because they are smaller and therefore avoid detection. The risk of disease is 1.2-3.2% if one is in an endemic area. The infected tick needs to be attached for at least 24 hours and the risk of infection increases with the time the tick has been attached (higher if greater than 36 hours or tick is engorged), however this time cannot be determined with precision by most patients.
Studies of doxycycline prophylaxis have been conducted in adults and older children (greater than or equal 12 years). In areas of high risk, a single prophylactic dose of doxycycline can be used in children of any age to reduce the risk of acquiring Lyme disease after the bite of an infected I. scapularis tick. Benefits of prophylaxis may outweigh risks when the tick is engorged (ie, has been attached for at least 36 hours based on exposure history) and prophylaxis can be started within 72 hours of tick removal
Note amoxicillin is not recommended for prophylaxis due it's short half life
50 kg or greater: Doxycycline 200 mg PO once
Less 50 kg: 4 mg/kg/dose PO once Round dose to nearest 25 mg (1/4 tablet) Maximum: 200 mg/dose
Note: Prophylaxis is usually not recommended but prophylaxis may be used if there was a black legged tick bite in an area that was known to be endemic for Lyme disease, and if the tick was engorged and other defined criteria are met.Transmission is during the nymphal or adult stages but more commonly the small nymphs because they are smaller and therefore avoid detection. The risk of disease is 1.2-3.2% if one is in an endemic area. The infected tick needs to be attached for at least 24 hours and the risk of infection increases with the time the tick has been attached (higher if greater than 36 hours or tick is engorged), however this time cannot be determined with precision by most patients.
Studies of doxycycline prophylaxis have been conducted in adults and older children (greater than or equal to 12 years). In areas of high risk, a single prophylactic dose of doxycycline can be used in children of any age to reduce the risk of acquiring Lyme disease after the bite of an infected I. scapularis tick. Benefits of prophylaxis may outweigh risks when the tick is engorged (ie, has been attached for at least 36 hours based on exposure history) and prophylaxis can be started within 72 hours of tick removal
Monitor for early Lyme disease
Generally presents within 7-14 days of bite, up to 30 days.
70-80% of patients present with a classic Erythema Migrans (EM) rash which consists of a single erythematous, expanding, greater than 5 cm rash +/- central clearing at the site of the tick bite.
This may be associated with symptoms such as arthralgia, headaches, fatigue and fever.
If a person develops evidence of early Lyme disease, they should consult a physician and receive appropriate antimicrobial treatment (not prophylaxis).
