The preferred drug for the treatment of syphilis and leptospirosis is penicillin. If there is a phenomenon of penicillin allergy, tetracycline or gentamicin can be selected for treatment. Both of these are infectious diseases. When using penicillin for treatment, a skin test needs to be performed to see if there is an allergic reaction, in order to avoid adverse effects.

Treatment Protocol:

1. For leptospirosis, penicillin is used for treatment. Abroad, large doses of penicillin are commonly used, while in China, an initial intramuscular injection of 400,000 U is administered, followed by repeated administration of the same dose every 6 to 8 hours until the body temperature decreases for 2 days, or for a total of 7 days of treatment. The dosage for children should be reduced accordingly [50,000 U/(kg·d)]. For patients with rapid onset and severe poisoning symptoms, 1.6 to 2.4 million U/d can be administered, divided into 4 to 6 intramuscular injections.

2. For the treatment of syphilis, which is divided into latent syphilis in stages I, II, and III, long-acting penicillin is used regardless of the stage or latent status. Benzathine penicillin is commonly used clinically. If the skin test is passed, three intramuscular injections are administered, once a week, for three consecutive weeks.

3. After completing a course of treatment, a follow-up examination can be performed after a month, mainly for titer and IgM. Follow-up examinations should be performed every three months thereafter, which is the requirement for the first year. In the second year, follow-up examinations should be performed every six months. A final follow-up examination should be performed in the third year. In other words, syphilis treatment requires follow-up examinations for three years, and the titer gradually decreases to negative.