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| Geographic Range of Monkeypox - Credit WHO |
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Two months ago, in WHO: Modelling Human-to-Human Transmission of Monkeypox, we revisited the growing threat of Monkeypox, which is endemic in parts of central Africa (see map above).
The incidence, and geographic spread of the virus has increased in recent years, and during the first 7 months of 2020 the Democratic Republic of the Congo reported over 2,500 known infections (and 97 deaths).
Nigeria reported its first Monkeypox outbreak in nearly 40 years in the fall of 2017, and while surveillance and reporting is limited, they continued to report cases up until December of 2019. Like with so many other diseases, reporting has dropped off since the start of the COVID-19 pandemic.
The name `monkeypox’ is a bit of a misnomer. It was first detected (in 1958) in laboratory monkeys, but further research has revealed its primary hosts to be rodents or possibly squirrels.
Human monkeypox was first identified in 1970 in the DRC, and since then has sparked small, sporadic outbreaks in the Congo Basin and Western Africa. It produces a remarkably `smallpox looking' illness in humans, albeit not as deadly. The CDC's Monkeypox website states:
The illness typically lasts for 2−4 weeks. In Africa, monkeypox has been shown to cause death in as many as 1 in 10 persons who contract the disease.Human-to-human transmission is also possible. This from the CDC’s Factsheet on Monkeypox:
The disease also can be spread from person to person, but it is much less infectious than smallpox. The virus is thought to be transmitted by large respiratory droplets during direct and prolonged face-to-face contact. In addition, monkeypox can be spread by direct contact with body fluids of an infected person or with virus-contaminated objects, such as bedding or clothing.According to the CDC there are two distinct genetic groups (clades) of monkeypox virus—Central African and West African. West African monkeypox - which has been spreading recently in Nigeria - is associated with milder disease, fewer deaths, and limited human-to-human transmission.
Routine vaccination against smallpox - which supposedly provides about 85% protection against Monkeypox - ended in the 1970s. Today more than half of the world's population is unvaccinated, and the level of protection remaining among those vaccinated 50+ years ago is highly suspect.
WHO: Monkeypox Update & Risk Assessment - Nigeria
MMWR: Emergence of Monkeypox — West and Central Africa, 1970–2017
EID Journal:Extended H-2-H Transmission during a Monkeypox Outbreak
Like all viruses, Monkeypox continues to evolve and diversify, as discussed in the 2014 EID Journal article Genomic Variability of Monkeypox Virus among Humans, Democratic Republic of the Congo, where the authors cautioned:
Small genetic changes could favor adaptation to a human host, and this potential is greatest for pathogens with moderate transmission rates (such as MPXV) (40). The ability to spread rapidly and efficiently from human to human could enhance spread by travelers to new regions.In the two months since our last update, the number of diagnosed Monkeypox cases in the DRC for 2020 has increased by roughly 80% (n=4594, 171 fatal), far outpacing the totals from 2019 and 2018. Yesterday the World Health Organization published a lengthy report and risk assessment.
I've only included a few excerpts from a much longer report, so you'll want to follow the link below to read it in its entirety. When you return, I'll have more on the history of exported cases to the UK, Israel, Singapore and the United States.
Disease outbreak news1 October 2020From 1 January through 13 September 2020, a total of 4,594 suspected cases of monkeypox, including 171 deaths (case fatality ratio 3.7%), have been reported in 127 health zones from 17 out of 26 provinces in the Democratic Republic of the Congo. The first epidemic peak was observed at the beginning of March 2020 (epi week 10), with 136 cases reported weekly (Figure1). From 1 January through 7 August, the Institut National de Recherche Biomédicale (INRB) received 80 samples from suspected cases of monkeypox, of which 39 samples were confirmed positive by polymerase chain reaction. Four out of the 80 specimens were skin lesions (crusts/vesicles), the remaining samples were blood. There is no further information at this time regarding the outcome of these 80 patients whose samples were tested. Confirmatory testing remains ongoing.During the same period in 2019, 3,794 suspected cases and 73 deaths (CFR 1.9%) were reported in 120 health zones from 16 provinces while a total of 2,850 suspected cases (CFR 2.1%) were reported in 2018.(SNIP)WHO risk assessmentMonkeypox is a sylvatic zoonosis with incidental human infections that occur sporadically in the rain forests of Central and West Africa. It is caused by the monkeypox virus (MPXV) which belongs to the Orthopoxvirus family, the same group of viruses as smallpox.There are two distinct clades of monkeypox virus, the Congo Basin clade and the West African clade. Monkeypox due to the Congo Basin clade virus has seen reported mortality of up to 10% of cases, whereas the West African clade usually displays fatal outcomes in less than 1% of cases. HIV infection appears to increase the risk of death in people infected with monkeypox virus.The animal reservoir remains unknown. However, evidence suggests that native African rodents may be potential sources. Contact with live and dead animals through hunting and bush meat are presumed drivers of human infection. The disease is self-limiting with symptoms usually resolving within 14-21 days. Severe cases occur more commonly among children and immunocompromised population, particularly persons with HIV, and are related to the extent of virus exposure, patient health status and severity of complications. The case fatality ratio has varied between epidemics but has been between 1% and 10% in documented events. There is no specific treatment licensed for monkeypox and a recently approved vaccine is not yet widely available for the public sector.Since identification of the first human case of monkeypox in 1970 in the Democratic Republic of the Congo (then known as Zaire) in a 9-month-old boy, and until the year 1986, 95% of cases worldwide were reported in the DRC. Cases of monkeypox have also been reported from other African countries - Benin, Cameroon, the Central African Republic, Gabon, Côte d’Ivoire, Liberia, Nigeria, the Republic of the Congo, Sierra Leone, and South Sudan. In 2003, an outbreak occurred in the United States of America following the importation of infected animals. Single imported cases were identified in Israel and the United Kingdom in 2018, and in Singapore in 2019, all following diagnosis in travelers from Nigeria. In the UK, a secondary case was confirmed in a health worker.With the eradication of smallpox and the subsequent cessation of routine smallpox vaccination, human monkeypox has appeared with increasing frequency in unvaccinated populations.The risk is assessed as high at national level, moderate at regional level, and low at global level.
Although monkeypox is normally restricted to small outbreaks in Africa, in 2003 we saw a rare multi-state (Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin) outbreak in the United States when a Texas animal distributor imported hundreds of small animals from Ghana, which in turn infected prairie dogs that were subsequently sold to the public (see MMWR Update On Monkeypox 2003).
By the time that outbreak was quashed, the U.S. saw 37 confirmed, 12 probable, and 22 suspected human cases. Among the confirmed cases 5 were categorized as being severely ill, while 9 were hospitalized for > 48 hrs; although no patients died (cite).
More recently, we've seen several imported cases around the globe, including 2 cases to the UK in September of 2018 (see Eurosurveillance Rapid Comms: Two cases of Monkeypox imported to the UK), followed a month later by Israel: MOH Confirmed An Imported Monkeypox Case, and a case reported by Singapore in May of 2019.
Between increased incidence in Central Africa (including Nigeria), increased international travel, and waning immunity among the global population, Monkeypox is becoming more a of a global public health concern.
Enough so that just over a year ago the FDA Approved the 1st live, Non-replicating Vaccine to Prevent Smallpox & Monkeypox.
This new vaccine will be incorporated into the Strategic National Stockpile (see Upcoming Webinar: The Strategic National Stockpile), which should provide a safer, and more readily available, medical countermeasure in the event that Monkeypox or Smallpox threaten again.
