Christine M. Hughes

: Incidence of human monkeypox (mpox) has been increasing in West and Central Africa, including in the Democratic Republic of Congo (DRC), where monkeypox virus (MPXV) is endemic. Most estimates of the pathogen’s transmissibility in the DRC are based on data from the 1980s. Amid the global 2022 mpox outbreak, new estimates are needed to characterize the virus’ epidemic potential and inform outbreak control strategies. We used the R package vimes to identify clusters of laboratory-confirmed mpox cases in Tshuapa Province, DRC. Cases with both temporal and spatial data were assigned to clusters based on the disease’s serial interval and spatial kernel. We used the size of the clusters to infer the effective reproduction number, R_t, and the rate of zoonotic spillover of MPXV into the human population. Out of 1,463 confirmed mpox cases reported in Tshuapa Province between 2013 and 2017, 878 had both date of symptom onset and a location with geographic coordinates. Results include an estimated R_t of 0.82 (95% CI: 0.79–0.85) and a rate of 132 (95% CI: 122–143) spillovers per year assuming a reporting rate of 25%. This estimate of R_t is larger than most previous estimates. One potential explanation for this result is that R_t could have increased in the DRC over time owing to declining population-level immunity conferred by smallpox vaccination, which was discontinued around 1982. R_t could be overestimated if our assumption of one spillover event per cluster does not hold. Our results are consistent with increased transmissibility of MPXV in Tshuapa Province.

Incidence of human mpox has been increasing in West and Central Africa, including in the Democratic Republic of Congo (DRC), where monkeypox virus (MPXV) is endemic. Most estimates of the pathogen’s transmissibility in DRC are based on data from the 1980s. Amid the global 2022 mpox outbreak, new estimates are needed to characterize the virus’ epidemic potential and inform outbreak control strategies. We used the R package vimes to identify clusters of laboratory-confirmed mpox cases in Tshuapa Province, DRC. Cases with both temporal and spatial data were assigned to clusters based on the disease’s serial interval and spatial kernel. We used the size of the clusters to infer the effective reproduction number, R _t , and the rate of zoonotic spillover of MPXV into the human population. Out of 1,463 confirmed mpox cases reported in Tshuapa Province between 2013 and 2017, 878 had both date of symptom onset and a location with geographic coordinates. Results include an estimated R _t of 0.82 (95% CI: 0.79 – 0.85) and a rate of 132 (95% CI: 122 – 143) spillovers per year assuming a reporting rate of 0.25. This estimate of R _t is larger compared to most previous estimates. One potential explanation for this result is that R _t could have increased in DRC over time due to declining population-level immunity conferred by smallpox vaccination, which was discontinued around 1982. R _t could be overestimated if our assumption of one spillover event per cluster does not hold. Our results are consistent with increased transmissibility of MPXV in Tshuapa Province.

Recent enhanced monkeypox (MPX) surveillance in the Democratic Republic of Congo, where MPX is endemic, has uncovered multiple cases of MPX and varicella zoster virus (VZV) coinfections. The purpose of this study was to verify if coinfections occur and to characterize the clinical nature of these cases. Clinical, epidemiological, and laboratory results were used to investigate MPX/VZV coinfections. A coinfection was defined as a patient with at least one Orthopoxvirus/MPX-positive sample and at least one VZV-positive sample within the same disease event. Between September 2009 and April 2014, 134 of the 1,107 (12.1%) suspected MPX cases were confirmed as MPX/VZV coinfections. Coinfections were more likely to report symptoms than VZV-alone cases and less likely than MPX-alone cases. Significantly higher lesion counts were observed for coinfection cases than for VZV-alone but less than MPX-alone cases. Discernible differences in symptom and rash severity were detected for coinfection cases compared with those with MPX or VZV alone. Findings indicate infection with both MPX and VZV could modulate infection severity. Collection of multiple lesion samples allows for the opportunity to detect coinfections. As this program continues, it will be important to continue these procedures to assess variations in the proportion of coinfected cases over time.

Monkeypox virus (MPXV), a close relative of Variola virus, is a zoonotic virus with an unknown reservoir. Interaction with infected wildlife, bites from peri-domestic animals, and bushmeat hunting are hypothesized routes of infection from wildlife to humans. Using a Risk Questionnaire, performed in monkeypox-affected areas of rural Democratic Republic of the Congo, we describe the lifestyles and demographics associated with presumptive risk factors for MPXV infection. We generated two indices to assess risk: Household Materials Index (HMI), a proxy for socioeconomic status of households and Risk Activity Index (RAI), which describes presumptive risk for animal-to-human transmission of MPXV. Based on participant self-reported activity patterns, we found that people in this population are more likely to visit the forest than a market to fulfill material needs, and that the reported occupation is limited in describing behavior of individuals may participate. Being bitten by rodents in the home was commonly reported, and this was significantly associated with a low HMI. The highest scoring RAI sub-groups were ‘hunters’ and males aged ≥ 18 years; however, several activities involving MPXV-implicated animals were distributed across all sub-groups. The current analysis may be useful in identifying at-risk groups and help to direct education, outreach and prevention efforts more efficiently.

The prevalence of North American orthopoxviruses in nature is unknown and may be more difficult to ascertain due to wide spread use of vaccinia virus recombinant vaccines in the wild. A real time PCR assay was developed to allow for highly sensitive and specific detection of North American orthopoxvirus DNA in animal tissues and bodily fluids. This method is based on the amplification of a 156 bp sequence within a myristylated protein, highly conserved within the North American orthopoxviruses but distinct from orthologous genes present in other orthopoxviruses. The analytical sensitivity was 1.1 fg for Volepox virus DNA, 1.99 fg for Skunkpox virus DNA, and 6.4 fg for Raccoonpox virus DNA with a 95% confidence interval. Our assay did not cross-react with other orthopoxviruses or ten diverse representatives of the Chordopoxvirinae subfamily. This new assay showed more sensitivity than tissue culture tests, and was capable of differentiating North American orthopoxviruses from other members of Orthopoxvirus. Thus, our assay is a promising tool for highly sensitive and specific detection of North American orthopoxviruses in the United States and abroad.

In order to determine how best to tailor outreach messages about poxvirus diagnosis and infection control for health practitioners, we surveyed infectious disease physicians in the Infectious Diseases Society of America's Emerging Infections Network.