Monkeypox in the Democratic Republic of the Congo

Monkeypox in Liberia (1971)

The world's first case of human monkeypox was detected in a nine-month old child in 1970 in the Democratic Republic of the Congo (then Zaire),[4][5] two years after it reported its last case of smallpox.[6] The onset of their rash was on 24 August.[7] That year, the disease was identified in another four children, including three in Liberia who were playmates.[8] At the time, evidence of the virus was found in non-human primates in Liberia and Sierre Leone.[8]

Active surveillance by the World Health Organization (WHO) between 1981 and 1986, identified 338 cases with a human-to-human transmission rate of 28%.[9][10] Until 1986, 95% of cases worldwide were identified in the DRC.[11] Cases were rare in people over the age of 15-years, and over two-thirds of infections could be traced to animal contact within the rainforests.[12] Initially it was uncommon for a family member to contract the infection unless they did not have a smallpox scar.[12]

A reemergence of the disease in the DRC in 1996 also saw a large number of reported but not all laboratory confirmed cases, with a high transmission rate and lower fatality rate; leading experts to believe a significant number may have actually been chicken pox.[10][13] Some likely had both monkeypox and chickenpox at the same time.[6] The DRC's Kasaï-Oriental region saw the largest number of cases during 1996-1997.[6]

Between 1996 and 2005, monkeypox cases appeared increasingly in gradually older people, with less than a quarter of cases being traced to rainforest animal contact, and with greater close contact infections.[12] Between January 2001 and December 2004, 2,734 cases of suspected human monkeypox were reported from the DRC.[10] However, civil war limited surveillance and only 171 clinical specimens were obtained from 136 suspected cases; less than 5% of all reported cases.[10]

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  Monkeypox outbreak in DRC (1997)
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  The US epidemiologic team after having landed at Lodja Airport - Zaire 1997
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  Testing of Gambian rats (1997)
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  Educational meeting DRC (1997)

After 2005, the DRC was reporting more than 1000 suspected cases per year.[14] Between November 2005 and November 2007, 760 laboratory-confirmed human monkeypox cases were detected; particularly in people living in forested areas, males, age less than 15-years, and no previous smallpox vaccination.[15]

Many cases occur sporadically or in small clusters, but large outbreaks also occur.[2] The risk of human-to-human transmission within households in the DRC was noted to range from 50% to 100% during the 2013 outbreak.[6] The DRC's Bokungu Health Zone saw an increase in cases of 600-fold that year.[2] In 2019 the DRC reported 3,794 suspected cases and 73 deaths.[11] In the first nine-months of 2020, it reported over 4,500 suspected cases of monkeypox, including 171 deaths.[11]

Monkeypox is reportable in the DRC, where the disease is endemic, and disease burden remains high.[2][16] There, the more virulent Congo basin virus type has been affecting some of the world's poorest and socially excluded communities.[3] A regional surveillance system collects reports of all suspected monkeypox cases, and where possible, they may be investigated.[2]