Monkeypox is a zoonotic virus, transmitted from animals to humans, and comes from the same family of viruses as smallpox [1]. It is primarily found in locations close to tropical rainforests, in Central and West Africa, but in the past months has become more prevalent in urban areas due to an outbreak that spread significantly before being detected, fueling the current emergency.  

Monkeypox was first identified in the Democratic Republic of the Congo in the 1970s and has been reported in 11 different African countries [2]. In 2003, the first outbreak outside of Africa occurred in the United States related to an infected prairie dog which had been imported from Ghana, leading to over 70 infectious cases. Since May 2022, over 3000 infections have been reported in more than 50 countries worldwide, making this virus a major public health concern [3]. 

Transmission of monkeypox among humans occurs through contact with skin lesions, the clothing or linens, or respiratory secretions and droplets of an infected person [4]. Transmission can also occur from mother to fetus, during birth, or after. Young children and those who are immunocompromised have been reportedly at an increased risk of more severe infections [6]. Though it is not classified as a sexually transmitted disease (STD), sexual contact does create the close physical conditions that can lead to transmission. The current outbreak has disproportionately affected men who have sex with men [5].  

Monkeypox can initially present with fever, intense headache, swelling of the lymph nodes, and muscle pains. Within 1-3 days of initial symptoms, skin lesions typically tend to appear on the face and extremities. 95% of cases involve the face, and a lesser percentage involving the hands, feet, mucous membranes, and, rarer, genitalia and eyes. It is self-limited and typically lasts between 2-4 weeks. While most cases are mild, one study showed 13% were admitted to the hospital, but with no serious complications [7]. Some of the reported rare but severe complications include pneumonia, sepsis, myocarditis, epiglottitis, encephalitis, and corneal infection leading to vision loss.  

Preventing monkeypox with vaccinations against smallpox was demonstrated to be 85% effective [1]. People who have had prior smallpox vaccinations may have an immune response against this virus which could result in a milder infection. A newer vaccine based on a modified monkeypox strain was approved in 2019, however, research and data remain limited. Currently, some countries are offering vaccines to those at high risk of infection such as laboratory personnel, healthcare workers, and rapid response teams [1].  

Treatment involves treating underlying symptoms and preventing complications, which may lead to long term sequelae. Conservative management includes fluids and adequate nutrition. In 2022, an antiviral developed for smallpox, Tecovirimat, was licensed by the European Medicines Agency (EMA) for monkeypox but is currently not widely available. In one study of active monkeypox infections, only 5% of people received antiviral therapy with either tecovirimat or cidofovir [6]. While data on the effectiveness of the antiviral therapy is largely limited, two animal models demonstrated tecovirimat as an effective therapy for smallpox or monkeypox [8]. Overall, the increasing prevalence of monkeypox highlights the need for further research on prevention and treatment of this disease. 

References  

1. Monkeypox fact sheet. World Health Organization, May 2022. https://www.who.int/news-room/fact-sheets/detail/monkeypox 

2. Ladnyj, I D et al. “A human infection caused by monkeypox virus in Basankusu Territory, Democratic Republic of the Congo.” Bulletin of the World Health Organization vol. 46,5 (1972): 593-7. 

3. Multi-country monkeypox outbreak: situation update. World Health Organization, June 27, 2022. https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON396 

4. Monkeypox: Background Information. UK Health Security Agency, 2018 https://www.gov.uk/guidance/monkeypox 

5. Mbala, Placide K, et al. “Maternal and Fetal Outcomes among Pregnant Women with Human Monkeypox Infection in the Democratic Republic of Congo.” The Journal of Infectious Diseases, vol. 216, no. 7, 2017, pp. 824–828., https://doi.org/10.1093/infdis/jix260.  

6. Ogoina, Dimie, et al. “Clinical Course and Outcome of Human Monkeypox in Nigeria.” Clinical Infectious Diseases, vol. 71, no. 8, 2020, https://doi.org/10.1093/cid/ciaa143.  

7. Thornhill, John P., et al. “Monkeypox Virus Infection in Humans across 16 Countries — April–June 2022.” New England Journal of Medicine, 2022, https://doi.org/10.1056/nejmoa2207323.  

8. Grosenbach , Douglas W, et al. “Oral Tecovirimat for the Treatment of Smallpox.” New England Journal of Medicine, vol. 379, no. 21, 2018, pp. 2084–2085., https://doi.org/10.1056/nejmc1811044.