A woman (>20 years of age) with no noteworthy known medical history was transferred from a local health center to a reference hospital because of generalized cutaneous pustule-like lesions that appeared in mid-2024. She had no history of smallpox vaccination. The patient self-identified as a sex worker and had recently returned from a 6-month stay in Kinshasa, where she had multiple casual sexual partners. She reported no recent contact with persons with confirmed or suspected mpox and no recent contact with wildlife. Her first symptom was fever, followed by vulval rash and itching, which began in Kinshasa. Acetaminophen, amoxicillin, and clotrimazole vaginal pessaries were given, but no diagnostic tests were performed. Observing no improvement 4 days after symptoms started, she returned home from Kinshasa by bus. She consulted a local health center 2 days later for fever, joint pain, and generalized cutaneous and genital lesions. She was admitted and treated with ceftriaxone, vitamin C, and cetirizine before transfer 3 days later by motorcycle to the reference hospital.

At admission, clinical examination revealed fever, joint tenderness, and generalized and genital pustular lesions. Suspecting mpox, the physician placed the patient in isolation. HIV rapid diagnostic test results in 2 different health facilities were discordant. The first test at the health center was negative using the Determine HIV-1/2 kit (Abbott, https://www.abbott.com). The second test, performed 3 days later at the hospital using Uni-Gold kit (Trinity Biotech, https://www.trintybiotech.com), returned a positive result. A PCR test for HIV was not performed (Table). She was treated with artemisinin-based combination therapy for malaria and antibiotic drugs (ceftriaxone followed by lincocin) and topical antiseptic solutions to prevent secondary bacterial infections arising from skin lesions. She also received oxygen therapy for signs of respiratory distress, acetaminophen for fever, and intravenous fluids for dehydration. Despite those interventions, the patient died 16 days after symptom onset.

A case investigation team from INRB (Institut National de Recherche Biomédicale) was mobilized during a monitoring and surveillance visit on the day the patient died. The patient was in respiratory distress and had lesions at varying stages of development, some with crusting, leading to a diagnosis of mpox complicated by acute respiratory distress syndrome. Counting lesions manually was not possible because of the generalized distribution and high number. Crust and vesicle swab samples were collected and sent to INRB for diagnosis. Mpox was confirmed by PCR using pan-orthopoxvirus and MPXV-generic primers (7,8). PCR results indicated amplification cycle threshold values of 16.08 in crust samples and 15.89 in vesicle samples for the pan-orthopoxvirus primers and cycle threshold values of 14.45 in crust samples and 15.80 in vesicle samples for the MPXV-generic primers (using the same samples).

Figure

Figure. Phylogenetic tree of mpox virus sequences from patient with clade Ia mpox virus linked to sexual transmission and reference sequences, Democratic Republic of the Congo, August 2024.

After PCR confirmation, we performed whole-viral genome sequencing using the clade IIb tiling sequencing protocol (https://www.protocols.io/view/monkeypox-virus-multiplexed-pcr-amplicon-sequencin-5qpvob1nbl4o/v2) and prepared the library on the basis of the Illumina DNA Prep protocol. We loaded the final enriched libraries onto an Illumina iSeq100 (https:/www.illumina.com). We generated MPXV consensus genomes by processing FASTQ files using CZid pipeline (https://czid.org); we used clade I MPXV genome (GenBank accession no. NC_003310.1) as reference. We used the Nextclade online tool (https://clades.nextstrain.org) to assign the clade of MPXV genomes. In addition, we used SQUIRREL to align sequences (https://github.com/aineniamh/squirrel) and inferred a maximum-likelihood phylogeny using IQ-TREE version 2.1.4 (https://github.com/Cibiv/IQ-TREE) with the Kimura 3-substitition plus empirical base frequencies plus invariant sites model as the best fit. Branch support was estimated by the ultrafast bootstrap approximation with 10,000 replicates (9). The phylogenetic tree showed that both sequences from the patient were closely related and cluster with clade Ia MPXV sequences from the ongoing outbreak in Kinshasa (Figure). This finding is consistent with severe mpox caused by clade Ia MPXV acquired during the patient’s stay in Kinshasa.

As part of routine contact tracing, 37 contacts were identified: 10 family members, 4 healthcare workers, 20 friends, and 3 sexual partners; 19 were high-risk contacts. No clinical symptoms of mpox were identified among contacts after 21 days of follow-up.

This case report describes fatal mpox caused by clade Ia MPXV in a woman with indeterminate HIV test results and early onset of genital symptoms. This finding could represent HIV seroconversion syndrome in the context of mpox infection, given the history of sexual contacts, clinical symptoms, location of lesions, and discordant HIV test results. In this resource-limited setting, details from clinical examination and laboratory investigations were insufficient to exclude other comorbidities. A false-positive HIV test result is also possible, given the low prevalence of HIV in the general population (15–49 years of age) in the DRC (0.5%–0.7%) (10). HIV prevalence of 7.5% was estimated among the key population of sex workers in 2023 (10). Given that the sex worker population might be ≈1% in DRC (11), this group might be at risk for poor outcomes from mpox, especially if HIV testing rates are low (12). PCR testing confirmed the mpox diagnosis, and whole-viral genome sequencing identified clade Ia MPXV.

This report highlights the potential severity of mpox in DRC and the need to mobilize the community to mitigate spread. The patient was a sex worker and had lived in Kinshasa, from where we reported co-circulation of clades Ia and Ib MPXV during July–August 2024 (6). This fact underscores increasing concerns about the expansion of MPXV in DRC, including to a large urban center with extensive regional and international connections, and the changing epidemiology for clade I MPXV. Although MPXV transmission through sexual contact has been predominantly associated with clade Ib (4), this case of clade Ia MPXV infection might have been linked to sexual contact, as evidenced by presence of genital lesions. The findings are consistent with our previous report of a cluster of mpox cases associated with sexual contacts in Kwango Province, which also involved clade Ia (3).

In summary, this report highlights the importance of prompt diagnosis and public health intervention, specifically among high-risk groups, to prevent the spread of mpox, as well as early diagnosis and management of HIV infection. In regions where mpox is emerging, healthcare providers must maintain a high index of suspicion, particularly in patients with vesiculopustular rash and systemic symptoms.