The Re-Emergence of Mpox: Old Illness, Modern Challenges

The Mpox virus (MPXV) is known to cause zoonotic disease in humans. The virus belongs to the genus Orthopoxvirus, of the family Poxviridae, and was first reported in monkeys in 1959 in Denmark and in humans in 1970 in the Congo. MPXV first appeared in the U.S. in 2003, re-emerged in 2017, and spread globally within a few years. Wild African rodents are thought to be the reservoir of MPXV. The exotic trade of animals and international travel can contribute to the spread of the Mpox virus. A phylogenetic analysis of MPXV revealed two distinct clades (Central African clade and West African clade). The smallpox vaccine shows cross-protection against MPXV infections in humans. Those who have not previously been exposed to Orthopoxvirus infections are more vulnerable to MPXV infections. Clinical manifestations in humans include fever, muscle pain, headache, and vesicle formation on the skin of infected individuals. Pathognomonic lesions include ballooning degenerations with Guarnieri-like inclusions in vesicular epithelial cells. Alterations in viral genome through genetic mutations might favor the re-emergence of a version of MPXV with enhanced virulence. As of November 2023, 92,783 cases and 171 deaths have been reported in 116 countries, representing a global public health concern. Here, we provide insights on the re-emergence of MPXV in humans. This review covers the origin, emergence, re-emergence, transmission, pathology, diagnosis, control measures, and immunomodulation of the virus, as well as clinical manifestations. Concerted efforts of health professionals and scientists are needed to prevent the disease and stop its transmission in vulnerable populations.