A recent article published within the journal Infectious Disease Reports has described the epidemiology of monkeypox infections to know the severity and extent of recent outbreaks in non-endemic countries.  

Study: The Monkeypox Pandemic as a Worldwide Emergence: Much Ado? Image Credit: FOTOGRIN/Shutterstock

Background

Monkeypox is a zoonotic virus belonging to the Orthopoxvirus genus within the family Poxviridae. The virus is endemic in Central and West Africa for a lot of many years. Evidence suggests that Gambian giant rats, also generally known as African giant pouched rats, is likely to be a possible natural reservoir of the monkeypox virus.

The primary animal case of monkeypox infection was identified in 1958 during an outbreak of vesicular disease amongst laboratory monkeys. The primary human monkeypox infection was detected in 1970 in a baby from the Democratic Republic of the Congo.

The primary outbreak of monkeypox infection outside of Africa was detected in the USA in 2003. The importation of infected animals caused this outbreak. Between 2018 and 2021, only 12 travel-related monkeypox cases were detected outside of Africa.

In May 2022, multiple outbreaks of monkeypox infection were detected in non-endemic countries worldwide. These outbreaks were unrelated to any travel history or importation of infected animals.

As of July 2022, greater than 9600 cases of human monkeypox infection have been detected in several European countries, including Spain, Germany, France, the Netherlands, Italy, and Portugal.

Route of transmission of monkeypox infection

The animal-to-human transmission of the monkeypox virus occurs through direct or indirect contact with infected animals or contaminated materials. Before 2022, this was considered to be the first route of viral transmission.

The recent outbreaks outside of Africa have highlighted that human-to-human transmission of the virus may occur through close contact with lesions, body fluids, respiratory droplets, and contaminated materials.

Based on an outbreak in Nigeria in 2017, it was assumed that sexual transmission of the virus can also be possible through direct skin-to-skin contact or genital secretions. This fact has been confirmed by the recent outbreaks, which reveal that nearly all of monkeypox infections occur in men who’ve multiple male sex partners. Currently, the sexual transmission route has been identified as a primary driver of monkeypox outbreaks.   

Clinical course of monkeypox infection

The incubation period of the monkeypox virus ranges from 5 to 21 days. Essentially the most common symptoms include fever, headache, chills, fatigue, asthenia, lymph node swelling, back pain, and muscle pain. Flat and raised rashes start appearing at the first infection site inside three days of symptom onset, which subsequently spread to other body parts.

Most travel-related cases detected in Western countries in the course of the recent outbreaks exhibit mild clinical manifestations, with many presenting rashes within the anogenital region. The infection is generally self-limiting and lasts for under 2 to 4 weeks.

Should we be concerned a few monkeypox outbreak?

Given its rapid propagation in non-endemic countries, the World Health Organization (WHO) has declared monkeypox infection a worldwide health emergency.

In recent outbreaks, the reproduction variety of the virus has been estimated to be higher than one. This highlights the potential for expanding outbreaks in a high-risk population, including men who’ve male sexual partners. Nonetheless, the outbreaks won’t be worrisome because the infection is related to a low mortality rate, self-limiting clinical course, and limited transmission outside of Africa.

In response to the recent WHO guidelines, vaccination is the perfect possible measure to manage the emergence of future outbreaks. Regarding post-exposure prophylaxis, vaccination ought to be done in those that have had contact with cases inside 4 days of exposure. As well as, clinical laboratory staff working with monkeypox virus and at-risk individuals should receive vaccination as pre-exposure prophylaxis.

Currently, no vaccine is obtainable to focus on the monkeypox virus specifically. Nonetheless, smallpox vaccines are known to offer 85% cross-protection against monkeypox. Thus, individuals who had received smallpox vaccination before its eradication in 1980 are expected to have some level of protection against monkeypox. Nonetheless, the rapid emergence of recent outbreaks indicates a worldwide decline in herd immunity through the years.

In response to the WHO guidelines, smallpox vaccines shouldn’t be used widely to manage monkeypox outbreaks due to limited clinical evidence and a scarcity of vaccine supplies. Currently, one smallpox vaccine (Imvanex) has received approval from the US Food and Drug Administration (FDA) and the European Medicine Agency (EMA) for the prevention of monkeypox infection in high-risk populations.