Over the past few years we've looked at a growing number of Monkeypox outbreaks in Africa, with the most recent beginning last October in Nigeria - a country that had gone nearly 40 years without a case - and which continues today (see chart below).
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.The name `monkeypox’ is a bit of a misnomer. It was first detected (in 1958) in laboratory monkeys, but further research has revealed its host to be rodents or possibly squirrels.
Humans can contract it in the wild from an animal bite or direct contact with the infected animal’s blood, body fluids, or lesions, but consumption of under cooked bushmeat is also suspected as an infection risk.
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 - such as hs been spreading recently in Nigeria - is associated with milder disease, fewer deaths, and limited human-to-human transmission.
The more severe form of Monkeypox is most commonly found in the Central Africa countries of the DRC and the CAR - where outbreaks have been on the rise for years - presumably because smallpox vaccinations (which provided up to 85% protection) were halted in the late 1970s.As the percentage of vaccinated members of the community dwindles, the risks of outbreaks are only expected to increase (see 2010 PNAS study Major increase in human monkeypox incidence 30 years after smallpox vaccination campaigns cease in the Democratic Republic of Congo).
In 2013, the DRC reported a 600% increase in cases over both 2011, and 2012 (see EID Journal:Extended H-2-H Transmission during a Monkeypox Outbreak) . The authors also cite a higher attack rate, longer chains of infection, and more pronounced community spread than have earlier reports.
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.Although monkeypox is normally restricted to small outbreaks in Africa, in 2003 we saw a rare 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).Routine vaccination against smallpox ended in the United States in 1972, and worldwide by the end of that decade. 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.
All of which makes the potential evolution and spread of monkeypox of growing international concern.In yesterday's MMWR, the CDC published a detailed overview of the emergence of monkeypox in Africa over the past 6 decades. They cite growing concerns over its zoonotic potential, and describe recent informal consultations with the WHO and other global public health partners on ways to better contain this rising threat.
I've only included some excerpts, follow the link to read it in its entirety.
Emergence of Monkeypox — West and Central Africa, 1970–2017
Weekly / March 16, 2018 / 67(10);306–310
Kara N. Durski, MPH1; Andrea M. McCollum, PhD2; Yoshinori Nakazawa, PhD2; Brett W. Petersen, MD2; Mary G. Reynolds, PhD2; Sylvie Briand, MD, PhD1; Mamoudou Harouna Djingarey, MD3; Victoria Olson, PhD2; Inger K. Damon, MD, PhD2; Asheena Khalakdina, PhD1 (View author affiliations)
The recent apparent increase in human monkeypox cases across a wide geographic area, the potential for further spread, and the lack of reliable surveillance have raised the level of concern for this emerging zoonosis.
In November 2017, the World Health Organization (WHO), in collaboration with CDC, hosted an informal consultation on monkeypox with researchers, global health partners, ministries of health, and orthopoxvirus experts to review and discuss human monkeypox in African countries where cases have been recently detected and also identify components of surveillance and response that need improvement.
Endemic human monkeypox has been reported from more countries in the past decade than during the previous 40 years. Since 2016, confirmed cases of monkeypox have occurred in Central African Republic, Democratic Republic of the Congo, Liberia, Nigeria, Republic of the Congo, and Sierra Leone and in captive chimpanzees in Cameroon. Many countries with endemic monkeypox lack recent experience and specific knowledge about the disease to detect cases, treat patients, and prevent further spread of the virus.
Specific improvements in surveillance capacity, laboratory diagnostics, and infection control measures are needed to launch an efficient response. Further, gaps in knowledge about the epidemiology and ecology of the virus need to be addressed to design, recommend, and implement needed prevention and control measures.
What is already known about this topic?
Human monkeypox is a viral zoonosis that occurs in West Africa and Central Africa. Most cases are reported from Democratic Republic of the Congo. The disease causes significant morbidity and mortality, and no specific treatment exists.
What is added by this report?
Nigeria is currently experiencing the largest documented outbreak of human monkeypox in West Africa. During the past decade, more human monkeypox cases have been reported in countries that have not reported disease in several decades. Since 2016, cases have been confirmed in Central African Republic (19 cases), Democratic Republic of the Congo (>1,000 reported per year), Liberia (two), Nigeria (>80), Republic of the Congo (88), and Sierra Leone (one). The reemergence of monkeypox is a global health security concern.
What are the implications for public health practice?
A recent meeting of experts and representatives from affected countries identified challenges and proposed actions to improve response actions and surveillance. The World Health Organization and CDC are developing updated guidance and regional trainings to improve capacity for laboratory-based surveillance, detection, and prevention of monkeypox, improved patient care, and outbreak response.