A Review of Evidence Related to the Zoonotic Characteristics of the Monkeypox Virus

The 2022 monkeypox virus (MPXV) outbreaks spurred global public health concern. In response, we undertook a living systematic review of its zoonotic characteristics, including potential reservoirs and susceptible species, transmissibility, and clinical presentation in nonhuman species. Electronic database searches yielded 148 eligible records published between 2000 and 2022. Primary reservoirs remain unidentified, with natural isolation identified in 2 species, the sooty mangabey monkey and rope squirrel. Transmission primarily occurs from animals to humans, but evidence of reverse zoonosis has emerged. Data on clinical infection and manifestations are sparse, with evidence of potentially susceptible species drawn primarily from experimental studies. Only 10% of articles were appropriate for quality assessment and most of these were rated as critically low. Overall, while evidence regarding MPXV exists, the quality of data are extremely poor, resulting in significant uncertainty regarding MPXV's zoonotic traits. High-quality empirical research to understand the impact of MPXV on animal and human populations is warranted.