Diagnostic Challenges of Syphilis in a Resource-Limited Rural Setting: A Case Report.

Syphilis, a sexually transmitted infection caused by Treponema pallidum, continues to represent an important public health challenge worldwide, especially in underserved and resource-limited settings. We report a 65-year-old man from a rural area who presented with progressive weight loss, malaise, generalized lymphadenopathy, and a trunk rash, features that can mimic HIV, tuberculosis, viral infections, or lymphoma. A rapid HIV/Syphilis Duo test (SD BIOLINE, Standard Diagnostics Inc., South Korea) was reactive for syphilis and negative for HIV, but no nontreponemal or confirmatory assays were available. According to international guidelines, accurate diagnosis requires both treponemal and nontreponemal testing, yet in rural settings, clinicians often must act on incomplete data. Based on the clinical findings and reactive treponemal test, a presumptive diagnosis of secondary syphilis was made, and benzathine penicillin G 2.4 million units intramuscularly was administered. This case highlights the diagnostic and management challenges faced in resource-limited environments, where overlapping clinical features, incomplete diagnostic algorithms, and restricted access to treatment and follow-up increase the risk of persistent infection and continued transmission.