The frequency of sexually transmitted infections (STIs), due to a variety of reasons, has increased during the last 10 years, and they appear to be a major public health problem.1 Not only well-known pathogens, such as Treponema pallidum, Neisseria gonorrhea, or Chlamydia trachomatis, but also those not typically transmitted via a sexual route, such as hepatitis A and hepatitis C (HCV) viruses or Shigella dysenteriae, must be taken into consideration during differential work-up.1 Health care professionals should be aware of the risk of new emerging STIs.

We present a case of a 47-year-old man infected with HIV-1 on stable antiretroviral therapy for 7 years, previously treated for STIs (syphilis, HCV) who reported to the Outpatient Clinic of Infectious Diseases Department (IDD) because of painless genital rash with local enlargement of right inguinal lymph nodes. The symptoms had started 20 days before, with 3 papules on the foreskin that transformed into blisters filled with white fluid and subsequently into ulcerations with painful right inguinal lymphadenopathy. The patient denied travelling to other countries but he had unprotected sex with unfamiliar men 7 and 14 days before the symptom onset. Due to the suspicion of monkeypox, the patient was referred to the IDD for further diagnostic work-up. On admission, he was in good general condition, with 3 ulcerations of the foreskin, 1 umbilicated pustule on the dorsal surface of the penis (Figure 1A and 1B), and a painful enlargement of the right inguinal lymph node up to 5 cm in size. A reverse transcriptase–polymerase chain reaction test of the lesion swabs was positive for monkeypox virus (MPXV) DNA. Tests for other STIs were performed, showing no significant abnormalities except for an increased rapid plasma reagin (RPR) ratio from 1:2 to 1:8. Urethral swabs were negative for Neisseria and Chlamydia trachomatis. Because of the increased RPR ratio, 2.4 million units of benzylpenicillin were administered intramuscularly. Without specific treatment, an improvement in local condition was observed and the patient was discharged home 5 days later.

Figure 1. A – an umbilicated pustule on the dorsal surface of the penis; B – ulceration of the foreskin

Monkeypox is an infectious disease caused by MPXV belonging to the Orthopoxvirus genus in the Poxviridae family. Until recently, most of the monkeypox cases have been reported in Africa and occasional exported infections have been linked to an animal vector or travel to endemic regions.2 Since May 2022, the ongoing human-to-human transmission outside of Africa has been responsible for the global outbreak.3

The MPXV is transmitted mainly through direct contact with skin lesions and respiratory droplets.3 During the current outbreak, most of the infections were diagnosed in men who have sex with men, which, together with the relatively high prevalence of concomitant STIs, suggests an important role of sexual transmission.4

Incubation period ranges between 5 and 21 days. The disease typically starts with a prodromal stage, which precedes the onset of a rash by 1 to 4 days. Lymphadenopathy is frequently observed and is a helpful clinical feature differentiating monkeypox from smallpox and chickenpox.5 Skin lesions appear synchronously and may affect mucous membranes, palms, and soles. During the current outbreak, limitation of lesion localization only to the anogenital region has been observed.4 Local transmission of MPXV in Poland should be taken into consideration.