Chulalongkorn Study Finds 61% of Mpox Patients Had Genital Lesions
A Chulalongkorn Hospital study of 154 Mpox patients found 61% had anal or genital lesions, with 98.7% of cases occurring in men, mostly men who have sex with men. Genetic analysis shows the virus has become endemic in Thailand with local transmission, though imported cases continue. The research also found tecovirimat ineffective for Clade IIb treatment.
The ID Chula page released findings on Mpox from the Chulalongkorn Hospital Mpox cohort and the Emerging Infectious Diseases Clinical Center, published in the Journal of Infectious Diseases in October 2026 as doctoral research work. A total of 154 confirmed Mpox (monkeypox) patients participated from 14 clinics. The vast majority were male (152 cases, 98.7%) with a median age of 35 years (IQR 28–41). Most identified as men who have sex with men (86.4%), while 9 reported being bisexual (5.6%) and 2 heterosexual (1.3%).
A new case involves a 32-year-old woman with Mpox presenting with sore throat but no visible lesions, indicating the disease presentation is changing.
Overall, patients had relatively mild symptoms, with only a small proportion requiring hospitalization. Non-specific symptoms included fever (37.7%), chills (1.9%), muscle aches (19.6%), cough (8.4%), sore throat (15.6%), and swollen lymph nodes (10.4%).
Skin or mucosal lesions were found in 71.4% of participants: facial lesions (44.8%), disseminated body lesions (26.0%). Notably, 94 patients (61.0%) had lesions in the anal and genital areas. Some also had conjunctivitis (2.6%), runny nose (2.6%), oral ulcers (2.6%), difficulty swallowing (2.6%), vomiting (0.6%), diarrhea (4.5%), abnormal rectal or genital discharge (13.0%), and genital swelling (3.9%).
Therefore, some patients may present atypically — such as with sore throat, conjunctivitis, painful urination, or abnormal bowel movements — and without a thorough physical examination, skin lesions might be missed.
Genetic sequencing revealed the initial outbreak phase involved imported viruses, while later phases showed local transmission within Thailand until the virus became endemic. Some imported viruses persist, and there is evidence of viral export to other countries. The virus has adapted to humans with mutations in immune modulator genes and viral replication sites.
Other Mpox work by the department includes the use of tecovirimat for Clade IIb treatment (STOMP study), which found the drug ineffective.
