Monkeypox (MPX) is an endemic Orthopox virus in West and Central Africa. MPX is now occurring infrequently in other countries, causing healthcare concerns. Most human MPX infections are reported from the Congo Basin of the Democratic Republic of Congo (Hughes et al., 2021). MPX is most commonly found in rural, forested communities with poor sanitation and chronic malnutrition (Beer & Rao, 2019).
MPX cases are being reported sporadically around the world. It is believed to have spread worldwide due to the lack of immunization after the smallpox vaccine was stopped (Grant et al., 2020). Therefore, people who did not receive a smallpox vaccine (those younger than 40-50 years of age) may be susceptible.
MPX is categorized into 2 genetic clades. These include the genetic clades of West Africa and Central Africa (also called Congo Basin). These clades have epidemiological and clinical differences. The mortality rate of the West African clade is less than 1%, and there is no human-to-human transmission. The Central African clade is more frequent, can have a mortality of up to 11%, and has human-to-human transmission (Singh et al., 2021). Beer and Rao (2019) conducted a systematic review of the research published in English before August 15, 2018. They found an often-quoted 10% mortality rate. This rate came from early 1981-1986 data: 33 deaths out of 338. Data from the Democratic Republic of Congo (2001-2013) consistently reported mortality of <5%. Case fatality rate (CFR) from countries with the West African MPX were mostly 0%. The mortality for the Nigeria outbreak was 2.8%. Six deaths, 4 of whom were immunocompromised, out of 228 suspect cases. The mortality for 47 cases in United States outbreaks was 0%. No deaths have been reported from the April 2018 outbreak in Cameroon or the recent outbreak in the Central African Republic. In reports documenting the cause of death, people in high-risk groups comprised most of the deaths (Beer & Rao, 2019).
Because of inconsistencies in healthcare and surveillance systems in rural African settings, MPX data is incomplete and unreliable (Beer & Rao, 2019). This unreliable data is insufficient for statistical analysis (Beer & Rao, 2019). Due to the clinical overlap and insufficient laboratory availability, varicella-zoster virus (VZV) is often misdiagnosed as MPX, and the conditions may be co-infected in the same patient (Beer & Rao, 2019; Hughes et al., 2021). There is some suggestion that MPX is increasing in incidence. Data in more developed countries is more reliable.