#12,802
On Thursday, in Nigerian CDC: Suspected Monkeypox Outbreak in Baylesa State, we looked at the initial reports, and official acknowledgement, of an outbreak of Monkeypox virus (MPXV) in the south of Nigeria.
The Monkeypox virus 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 diseaseHumans 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 (see the CDC’s Factsheet on Monkeypox).
Monkeypox outbreaks - while rare - have grown increasingly common over the past three decades, 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 is expected to increase.
Concerns that were explored in a 2010 PNAS study that warned there has been a Major increase in human monkeypox incidence 30 years after smallpox vaccination campaigns cease in the Democratic Republic of Congo.
While the Nigerian CDC website has yet to post an update, yesterday multiple media sources reported on Three suspected cases recorded in Rivers State, although we've seen no confirmation by the state yet.
In the past couple of hours Nigerian social media has come alive with reports of 1 confirmed and 2 suspected cases in neighboring Akwa Ibom state. Typical of this morning's twitter traffic is this from the Punch newspaper.
Another report, this time from The Next Edition reads:
Barely a week after Monkey Pox, a dreaded viral epidemic broke out in Yenegoa, Bayesla State, Akwa Ibom State has recorded its first infection, NEXT EDITION can authoritatively report.The state Commissioner for Information, Charles Udoh, confirmed the spread of the infection to the state.
There are very few reports of Monkeypox in West Africa over the past 40 years, with the vast majority of cases have been reported in central Africa - most commonly in the DRC and the CAR.
I haven't found any reports of Monkeypox in Nigeria since the 1970s, making this an unusual outbreak both in size and location.Like all viruses, Monkeypox continues to evolve and diversify, as the following EID Journal article discusses, and which ends with a cautionary note:
Emerg Infect Dis. 2014 Feb; 20(2): 232–239.
doi: 10.3201/eid2002.130118
PMCID: PMC3901482
Genomic Variability of Monkeypox Virus among Humans, Democratic Republic of the Congo
Jeffrey R. Kugelman,1 Sara C. Johnston,1 Prime M. Mulembakani, Neville Kisalu, Michael S. Lee, Galina Koroleva, Sarah E. McCarthy, Marie C. Gestole, Nathan D. Wolfe, Joseph N. Fair, Bradley S. Schneider, Linda L. Wright, John Huggins, Chris A. Whitehouse, Emile Okitolonda Wemakoy, Jean Jacques Muyembe-Tamfum, Lisa E. Hensley, Gustavo F. Palacios,2 and Anne W. Rimoin
Abstract(SNIP)
Monkeypox virus is a zoonotic virus endemic to Central Africa. Although active disease surveillance has assessed monkeypox disease prevalence and geographic range, information about virus diversity is lacking. We therefore assessed genome diversity of viruses in 60 samples obtained from humans with primary and secondary cases of infection from 2005 through 2007. We detected 4 distinct lineages and a deletion that resulted in gene loss in 10 (16.7%) samples and that seemed to correlate with human-to-human transmission (p = 0.0544). The data suggest a high frequency of spillover events from the pool of viruses in nonhuman animals, active selection through genomic destabilization and gene loss, and increased disease transmissibility and severity. The potential for accelerated adaptation to humans should be monitored through improved surveillance.
The global effects of the emergence of MPXV strains that are highly adapted to humans could be devastating. Importation of MPXV by infected vertebrates is of concern because of the potential for establishment of new reservoirs outside Africa. In fact, American ground squirrels have been found to be susceptible to infection (39), suggesting that other rodent species worldwide might also be susceptible.
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. Therefore, active disease surveillance should continue to be used monitor MPXV for changes that are consistent with increasing adaptation to humans. Continued active surveillance of the Sankuru District, and expansion to all other regions where the virus is known or predicted to circulate, would help determine the true geographic range of this virus.
Given the apparent rapid evolution of this virus, when suspected or confirmed cases in humans are observed, health authorities in presently unaffected areas should become vigilant and actively prepare to take immediate action.(Continue . . . )
While it's always a concern whenever we see a zoonotic disease break from its established patterns of transmission or geographic range, it is too soon to know where this outbreak will lead. It does, however, bear watching.
Stay tuned.
