Lues

Lues is an archaic term for syphilis, a sexually transmitted infection caused by the bacterium Treponema pallidum. The expression lues venerea or lues venerealis appears in older medical literature, reflecting historic terminology. In contemporary usage, the disease is referred to as syphilis, with lues understood as its historical name.

The infection is primarily transmitted through sexual contact, including vaginal, anal, and oral sex. It can also be transmitted from a pregnant person to a fetus, causing congenital syphilis, and more rarely through blood transfusion or shared needles. The causative organism is a spirochete, which disseminates through the body and elicits variable clinical manifestations over time.

Syphilis progresses through stages. Primary syphilis presents with a painless ulcer (chancre) at the inoculation site and regional lymphadenopathy, typically resolving without treatment in weeks. Secondary syphilis can include a diffuse rash, mucous patches, fever, malaise, and condylomata lata. After a latent period, possible late manifestations arise, including cardiovascular and neurosyphilis. Tertiary syphilis may cause gummatous lesions, aortitis or aneurysm, and neurosyphilis presenting as tabes dorsalis or general paresis. Congenital syphilis results from in utero infection and can lead to stillbirth, facial and skeletal abnormalities, Hutchinson teeth, and other sequelae.

Diagnosis relies on serology: non-treponemal tests (RPR, VDRL) for screening and monitoring, and treponemal tests (FTA-ABS, TP-PA) for confirmation. Direct detection methods include dark-field microscopy of lesions when appropriate, and CSF examination if neurosyphilis is suspected.

Treatment of all stages is with penicillin G as the first-line therapy; alternatives exist for allergy, though penicillin remains essential in pregnancy. Early detection and treatment prevent complications and reduce transmission.