Last updated on:August 21st, 2023
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Human monkeypox (MPX) is a zoonotic disease caused by the monkeypox virus (MPXV). It is an endemic disease in the tropical rainforest regions of Central and West Africa. In non-endemic countries, sporadic travel and animal-related cases were reported until the most recent ongoing outbreak worldwide.
MPXV belongs to the Orthopoxvirus genus of the Poxviridae family; it is an enveloped double-stranded DNA. There are two phylogenetically distinct clades of MPXV, the Central African clade (CAC), which is associated with a more severe and transmissible disease, and the West African clade (WAC). Squirrels, rats, and non-human primates have been identified as natural hosts of MPXV. However, the exact reservoir of monkeypox has not yet been identified. The WAC is responsible for the multi-country outbreaks in non-endemic countries in 2022. Smallpox, vaccinia, cowpox, horsepox and Cantagaio viruses are also part of the Orthopoxvirus genus. Viruses belonging to this genus show reactivity and cross-protection. Monkeypox was isolated from research animals in Denmark in 1958. In 1970, the first human cases were described.
MPXV is typically acquired through contact with an infected animal's bodily fluids or through a bite. Human-to-human transmission most often occurs through direct contact with infectious sores, scabs, or body fluids; indirect contact can occur via contact with materials or fomites contaminated with infected material. The virus enters the body also through the respiratory tract or the mucous membranes but prolonged face-to-face contact is required for the transmission via droplet respiratory particles. Vertical transmission (congenital) can also occur. After the incubation period, transmissibility occurs from the beginning of symptoms and goes until the crusts disappear, which can be up to 28 days.
Little information is available on MPX in immunocompromised patients but it seems that they may be at increased risk of worse outcomes.
MPX is a disease of global public health importance. The first outbreak outside Africa was reported in the United States of America in 2003. In May 2022 an unprecedented outbreak was first reported in Europe. Community-based transmission has been widespread across many countries worldwide and mainly in men who have sex with men (MSM), leading to the hypothesis that MPX may be spread via sexual activity.
Course of disease
The interval from infection to onset of symptoms (incubation period) of MPX is most often 6 to 13 days but can range from 5 to 21 days. The infection is divided in two phases: the prodromal period and skin eruptions.
Reducing the risk of human-to-human transmission, reducing the risk of zoonotic transmission, and preventing monkeypox through restrictions on animal trade are the main infection prevention strategies to reduce exposure to the virus.
Prevention of infection in community and health care settings
In the community setting, the isolation of patients in a separate room, coverage of skin, and wearing a face mask are measures recommended to prevent the spread of infection. Household members should use disposable gloves to minimize the risk of contact with lesions.
In the hospital setting, early recognition of patients with suspected MPX, implementation of source control measures (e.g., isolation in a private room) and the use of standard precautions (e.g., hand hygiene, use of personal protective equipment–PPE, and environmental cleaning) are measures recommended to prevent the spread of infection.
Health workers providing direct care to MPX patients should wear a face mask along with other PPE that are part of droplet and contact precautions.