A Rare Case of <i>Hymenolepis diminuta</i> Infection: Case Report of a Middle-Aged Female in Yunnan, China

<b><i>Background:</i></b> <i>Hymenolepis diminuta</i>, a rat tapeworm, is a rare zoonosis typically affecting children. We report the first confirmed human case in Yunnan Province, China, not able for its occurrence in an adult. <b><i>Methods:</i></b> A 42-year-old female farmer from Dali presented with unilateral painless vision loss. <i>H. diminuta</i> infection was diagnosed incidentally through routine stool microscopy during her ophthalmological workup. <b><i>Results:</i></b> Examination of fecal samples confirmed the presence of <i>H. diminuta</i> eggs. This identifies the first autochthonous human case in Yunnan Province and underscores infection in an atypical adult demographic. <b><i>Conclusion:</i></b> This case highlights the unexpected detection of a rat tapeworm in a new geographic region and age group, emphasizing the value of basic diagnostics in uncovering zoonotic diseases, even with unrelated clinical presentations.