Tuesday, November 28, 2017

Nigeria: CDC Monkeypox Update - Week 48



In early October, in Nigerian CDC: Suspected Monkeypox Outbreak in Baylesa State, we saw the first report of suspected Monkeypox in the West African nation of Nigeria in nearly 40 years.  Five days later the Nigerian CDC Activated Their Emergency Operation Centre as the number of reported cases climbed. 
The first suspect case was an 11 year old male patient in Baylesa State, but  within days 11 other suspect cases were identified.
Unable to test for the virus locally, samples were sent to the WHO Regional Laboratory in Dakar, Senegal - where - after 11 days (Oct 16th), we learned that 3 cases had tested positive for the virus, while 12 others were negative.

At that time the CDC also reported `a total of 43 other SUSPECTED cases have been reported from eight other States (Akwa Ibom, Cross River, Ekiti, Lagos, Enugu, Nasarawa, Rivers, and FCT)'. Four cases from Lagos State had already tested negative, and the CDC predicted that many of those cases would test negative as well. 
Despite this reassurance - and the fact that no deaths had been reported - the level of panic and the number of conspiracy theories in the local press and on social media began to swell.
As Nigeria had not reported a case of Monkeypox since 1978, the finding of any lab-confirmed cases was unexpected, and some states were slow to respond. By the beginning of November (week 45), however, the Nigerian CDC's epi summary read:
  • A total of 116 suspected cases have been reported from 20 States (Abia, Akwa-Ibom, Bayelsa, Benue, Cross River, Delta, Ekiti, Edo, Enugu, Imo, Kano, Katsina, Kwara, Kogi, Lagos, Ondo, Nasarawa, Niger, Oyo, Rivers) and the FCT
  • Of these, 38 laboratory confirmed cases from Akwa Ibom, Bayelsa, Delta, Edo, Ekiti, Enugu, Lagos, Rivers and FCT
  •  A total of 103 samples have been collected and sent to National Reference Laboratory (NRL), Lagos for testing
  • Male to female ratio is 2:1
  • The most affected age group is 21-40 years (Median Age = 31)
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. 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.
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.
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 (see here and here) - 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 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).

Nigeria's CDC has published a new Sitrep (#8), which provides updates through November 19th.  While suspected cases continue to be investigated in multiple states, the number of new suspect cases had declined over the past few weeks, and the number confirmed cases now stands at 42.
Monkeypox Outbreak in Nigeria Situation Report (No. 008) (November 19, 2017)

  • The Nigeria Centre for Disease Control (NCDC) continued to coordinate the response through its activated Emergency Operations Centre (EOC)
  • Four new positive results were recorded from previously reported cases in Cross River (2), Imo (1) and Delta (1) states
  • Fourteen new suspected cases reported in the last one week
  • NCDC National Reference Laboratory, Abuja continued laboratory diagnosis of monkeypox.
  • There has been a decline in the number of new suspected cases reported over the last three weeks
  • Since the onset of the outbreak, a total of 146 cases have been recorded from 21 States and the Federal Capital Territory (FCT)
  • No death attributable to monkeypox has been recorded so far
  • Laboratory investigation has so far confirmed 42 cases of monkeypox in ten states (Akwa Ibom, Bayel sa, Cross River, Delta, Edo, Ekiti, Enugu, Imo, Lagos, Rivers) and the FCT
  • Suspected cases reported from other States are being investigated
  • In furtherance of the one health approach to the outbreak response, a multi-sectoral team of human and animal epidemiologists have been deployed to some affected states to conduct detailed outbreak investigations among human and animal populations


While the lack of deaths (which are rare with the West African clade of Monkeypox) has been reassuring, Monkeypox - like all viruses - continues to evolve and diversify, as discussed in a 2014 EID Journal article Genomic Variability of Monkeypox Virus among Humans, Democratic Republic of the Congo where the authors caution:
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.

Given the unusual location and size of this Nigerian outbreak, and the limits of surveillance in this part of the world, this outbreak certainly bears watching. 

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