The Transmission Potential of Monkeypox Virus in Human Populations

Abstract

Data on monkeypox in Zaire over the five years 1980-1984 are analysed to assess the protection imparted by past smallpox vaccination and the transmission potential of the virus in unvaccinated communities. Attack rates in individuals with and without vaccination scars indicated that smallpox vaccination (discontinued in 1980) imparted approximately 85% protection against monkeypox. It is predicted that monkeypox virus will continue to be introduced into human communities from animal sources, and that the average magnitude and duration of monkeypox epidemics will increase as vaccine-derived protection declines in the population. On the other hand, current evidence indicates that the virus is appreciably less transmissible than was smallpox, and that it will not persist in human communities, even in the total absence of vaccination. The findings thus support the recommendation of the Global Commission for the Certification of Smallpox Eradication to cease routine smallpox vaccination in monkeypox endemic areas, but to encourage continued epidemiological surveillance.

Vacated niches, competitive release and the community ecology of pathogen eradication

“…Fenner et al [4] acknowledged that there was natural concern about the vacated smallpox niche when monkeypox virus was first discovered to infect humans in Africa in 1970. They then reviewed subsequent genetic and epidemiological evidence, showing that monkeypox is not a direct ancestor of smallpox and transmissibility among humans had been concluded to be too low to allow establishment in human populations [23]. (These arguments run parallel to those cited by Breman & Henderson [6] in dismissing any imminent risk from monkeypox.)…”

“…In a pioneering analysis, Jezek et al [48] extrapolated their findings to show that-if nothing changed except the proportion vaccinated in the population-monkeypox would not establish sustained transmission among humans. A follow-up article re-stated this finding in terms of the basic reproductive number, reporting that R 0 for monkeypox in an unvaccinated population (in rural DRC) was approximately 0.83, less than the threshold value of 1 needed for persistent circulation [23]. This conclusion influenced the decision to cease intensified surveillance for monkeypox and maintain the cessation of smallpox vaccination.…”

A prairie dog animal model of systemic orthopoxvirus disease using West African and Congo Basin strains of monkeypox virus

“…In humans, MPXV and variola virus have similar asymptomatic incubation periods ranging from 7-17 days followed by development of generalized rash. However, smallpox had a much higher secondary attack rate (25-96 %) than monkeypox (5-11 %) (Arita & Gromyko, 1982;Fine et al, 1988). Previous studies defined two distinct MPXV clades, West African and Congo Basin, with unique disease manifestations (Chen et al, 2005;Likos et al, 2005).…”

Monkeypox Transmission, Need and Treatment of Humans with an Antiviral Drug

“…Survey showed that 85% immunity against monkey pox comes from the small pox vaccination but human only caught infection by having contact with infected animals and there is no transmission of infection from human to human because viruse is not capable of surviving in human if vaccination is absent (Fine et al, 1988). Now monkey pox is able to survive in humans due to genetic changes (gene loss) and human to human transmission is possible.…”