Emergence and dissemination of monkeypox, an intimidating global public health problem

Abstract

The monkeypox virus (MPXV) is the cause of a zoonotic infection similar to smallpox. Although it is endemic to Africa, it has recently begun to circulate in other parts of the world. In July 2022, the World Health Organization declared monkeypox an international public health emergency. This review aims to provide an overview of this neglected zoonotic pathogen. MPXV circulates as two distinct clades, the Central African and West African, with case fatality rates of 10.6% and 3.6%, respectively. The risk of infection is greater for those who work with animals or infected individuals. The virus' entry into the human body provokes both natural and acquired immunity. Although natural killer cells, CD4 + T cells, and CD8 + T cells play an essential role in eradicating MPXV, there is still a gap in the understanding of the host immune response to the virus. Currently, there are no specific therapeutic guidelines for treating monkeypox; however, some antiviral drugs such as tecovirimat and cidofovir may help to abate the severity of the disease. The use of nonpharmaceutical interventions and immunization can reduce the risk of infection. Increased surveillance and identification of monkeypox cases are crucial to understand the constantly shifting epidemiology of this resurging and intimidating disease. The present review provides a detailed perspective on the emergence and circulation of MPXV in human populations, infection risks, human immune response, disease diagnosis and prevention strategies, and future implications, and highlights the importance of the research community engaging more with this disease for an effective global response.

Keywords: Disease outbreaks; Epidemiology; Immune evasion; Orthopoxviruses; Smallpox virus.

Fig. 1

Suspected/confirmed cases of human monkeypox reported worldwide from 1970 to 2021. The total number of suspected/confirmed monkeypox cases reported during 1970–2021 from each country is given at the top of each bar. The different colors of each bar indicate the percentages of cases in different years in the same country , , , , , , .

Fig. 2

Human monkeypox cases from January 1 to July 25, 2022. The radial tree shows a hierarchy of 75 countries in the current monkeypox outbreak and the number of cases in each country. The deaths in two African countries are shown separately in the box.

Fig. 3

Emergence and circulation of monkeypox virus (MPXV). The figure illustrates MPXV transmission from animal to human, human to human, and via fomites; clinical presentations; treatment; and preventive measures.

Fig. 4

Manipulation of the host immune response by the monkeypox virus. MPXV can escape from the protein kinase R pathway through reduction of mRNA synthesis and ablation of type-I interferon mediating protein kinase R phosphorylation. MPXV can also reduce the production of inflammatory mediators by interfering with phosphorylation of the MAPK/ERK1/2 pathways. It suppresses cell apoptosis by increasing phosphorylation of the ATK pathway. MPXV can prevent natural killer cells from killing virus-infected cells and secreting inflammatory cytokines. MPXV can also interfere with the adaptive immune response by hindering T cell receptor trans-signaling.