What is the epidemiology of monkeypox infection?

Recent articles published in journals infectious disease report Describes the epidemiology of monkeypox infection to understand the severity and extent of recent outbreaks in non-endemic countries.

Background

Monkeypox is a zoonotic virus belonging to the Orthopoxvirus genus of the Poxviridae family. This virus has been endemic in Central and West Africa for decades. Evidence suggests that the Gambian giant rat, also known as the African giant pouched rat, may be a potential natural host for the monkeypox virus.

The first animal case of monkeypox infection was identified in 1958 during an outbreak of bullous disease among laboratory monkeys. In 1970, the first human monkeypox infection was detected in a child in the Democratic Republic of the Congo.

The first monkeypox outbreak outside of Africa was detected in the United States in 2003. Importation of infected animals caused this outbreak. Between 2018 and 2021, only 12 travel-related monkeypox cases were found outside Africa.

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

As of July 2022, over 9,600 human monkeypox infections have been detected in several European countries, including Spain, Germany, France, the Netherlands, Italy and Portugal.

Transmission routes of monkeypox infection

Animal-to-human transmission of monkeypox virus occurs through direct or indirect contact with infected animals or pollutants. Prior to 2022, this was thought to be the main route of virus transmission.

Recent outbreaks outside Africa highlight that human-to-human transmission of the virus can also occur through close contact with lesions, body fluids, respiratory droplets, and contaminated material. .

Based on the 2017 Nigerian outbreak, sexual transmission of the virus was assumed to be possible via direct skin-to-skin contact or genital secretions. This fact has been confirmed by recent outbreaks, revealing that the majority of monkeypox infections occur in men who have multiple male sex partners. It has been identified as a major cause of smallpox outbreaks.

Course of monkeypox infection

The incubation period for monkeypox virus is 5 to 21 days. The most common symptoms include fever, headache, chills, fatigue, asthenia, swollen lymph nodes, back pain, and muscle aches. Within 3 days of onset of symptoms, a flat, raised rash begins to appear at the primary infection site, then spreads to other parts of the body.

Most travel-related cases detected in Western countries during recent outbreaks present with mild clinical symptoms, many exhibiting rashes in the anogenital area. Infection is mostly self-limiting and lasts only 2-4 weeks.

Should I worry about monkeypox outbreaks?

In view of the rapid spread of the disease in non-existent countries, the World Health Organization (WHO) has declared monkeypox infection a global health emergency.

In recent outbreaks, the viral reproduction number is estimated to be greater than 1. This highlights the potential spread of the outbreak in high-risk populations, including men with male sexual partners. However, an outbreak may not be a concern, as the infection is associated with a low mortality rate, a self-limiting clinical course, and limited transmission outside of Africa.

According to recent WHO guidelines, vaccination is the best means of controlling future outbreaks. For post-exposure prophylaxis, vaccination should be given to those who have been in contact with the patient within 4 days of exposure. In addition, clinical laboratory staff working with monkeypox virus and at-risk individuals should be vaccinated as preexposure prophylaxis.

There are currently no vaccines that specifically target the monkeypox virus. However, the smallpox vaccine is known to provide 85% cross-protection against monkeypox. Therefore, people who were vaccinated before her 1980, when smallpox was eradicated, would be expected to have some protection against monkeypox.But the rapid emergence of recent outbreaks points to a global decline herd immunity Over the years.

According to WHO guidelines, the smallpox vaccine should not be widely used to control monkeypox outbreaks due to limited clinical evidence and a shortage of vaccine supplies. Two smallpox vaccines (Imvanex) have been approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the prevention of monkeypox infection in high-risk populations.