Endemic syphilis: causes, symptoms, diagnosis, and treatment

Endemic syphilis, also known as nonvenereal syphilis or bejel, is an endemic disease caused by treponema pallidum, but not through sexual transmission.


Causes

The pathogen is treponema pallidum subsp. endemicum (TEN). Treponema pallidum is extremely sensitive to dryness, and can be quickly deactivated under the sun or dry conditions.

The disease mainly occurs in children and is transmitted mostly through skin contact, kisses, and contaminated tableware and clothes. The skin, oral mucosa, and bones are the main organs involved.


Signs and Symptoms

Primary endemic syphilis is subtle and is manifested by painless inflammatory reaction.

Secondary endemic syphilis is usually characterized by mucous patches on the lips, corners of the mouth, tongue, and pharyngeal isthmus, and genital papules or condyloma lata on the external genitalia, perianal areas, and skin folds. There are large amounts of treponema pallidum on the surface of the mucous patches or condyloma lata. There are papules on the corners of the mouth, paronychia, and systemic lymphadenopathies. The seroreaction is positive. Without treatment, the lesions can persist for 6 - 9 months.

Secondary endemic syphilis can progress into latent endemic syphilis after treatment.

Tertiary endemic syphilis is manifested by gummas on the skin, nasopharynx, and bones, and gangosa. Copper red, raised, indurated nodular syphilids may occur and evolve into ulcers after rupture. There may be indurated, painless nodules on the extensor surfaces of large joints. Mothers lactating the infected infants may present with gummas on their breast.

Cardiovascular and neurological involvement is less common.


Diagnosis

The diagnosis is mainly based on the pathogen found in dark field microscopy and positive seroreaction.


Treatment

Adult patients can be treated with penicillin G benzathin 1,200,000 units intramuscularly once every 4 days for 16 days, while children with body weight less than 45kg can be treated with penicillin G benzathin 600,000 units intramuscularly.

Adults allergic to penicillin can be administered with azithromycin 30mg/kg, maximally 2g, orally in single dose or doxycycline 100mg orally twice a day for 14 days.