Middle East respiratory syndrome (MERS) is caused by a coronavirus (MERS-CoV) that was first identified in 2012. The Kingdom of Saudi Arabia has been the primary hotspot for cases, which have mostly resulted from human-to-human transmission in healthcare settings. Camels are an important reservoir for the virus and transmit it to humans, though transmission does not always result in illness. While MERS-CoV causes severe respiratory disease and high mortality, person-to-person transmission is generally weak and sporadic. A large outbreak in South Korea in 2015 highlighted the role of inadequate infection control and patient management in healthcare facilities in enabling superspreading events.
1. 4 years on, what do we know?
Ian M. Mackay, PhD
Public and Environmental Health â Virology
Forensic & Scientific Services | Health Support Queensland
Department of Health
& Associate Professor, The University of Queensland
Ian.Mackay@health.qld.gov.au
Opinions expressed here are my own; references available upon request
Middle East respiratory
syndrome (MERS)
3. 3
Kingdom of Saudi Arabia (KSA) is the hot zone
â˘1st
report of novel CoVâ 20th
Sept 2012
â˘Most cases are from human-to-human transmission
⢠respiratory disease caused by a respiratory virus
⢠weak & sporadic transmission between humans
⢠acquired mostly from humans in healthcare settings
â˘Seroprevalence: 0.15%
⢠2013, 15 of 10,009 adults, KSA
⢠highest seroprevalence among shepherds and slaughterhouse
workers
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4. The hot zone is hot & subtropical
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5. Hajj: âThe massest of Mass gatheringsâ
-Helen Branswell
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6. The MERS coronavirus (MERS-CoV)
â˘Enveloped, 30,000nt (+) RNA virus
â˘4 structural ( ), 16 NS proteins; recombination
â˘Little sign of adapting to humans so far
â˘Single serotype
â˘Uses dipeptidyl peptidase 4 (DPP4; LRT>URT) for entry
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7. Hu et al. Virol J .2015 12:221
Ancestors of MERS-CoV
â˘Bats
⢠focus of first papers
⢠many recent CoVs discovered
⢠likely ancestor found
â˘Conspecific virus
⢠Neoromicia (Pipistrellus)
capensis
⢠South Africa
⢠âNeoCoVâ
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MERS-CoV in bats
â˘1 rtPCR amplicon
⢠1 sample
⢠1 bat
⢠1 species (Taphozous perforatus)
⢠1,003 samples Oct 2012 / April 2013
⢠not convincing
10. 10
Why camels?
â˘Important animals â much contact
⢠Arabian peninsula
â˘Mild camel disease â common cold
⢠1st
MERS case did own camels
⢠juvenile camels more often virus positive
⢠high level of virus in camel secretions
⢠Camel herds can be 100% seropositive
⢠Camel-to-human infection reported
â˘No other animal found to host virus
⢠alpaca with antibody
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Camel virus > human spillover
â˘Same virus in camels & humans
â˘225 genomes
⢠3 genetic groupings
â˘Camel & human variants
⢠interspersed
⢠96.5-100% nt identity
16. Persistence
â˘MERS-CoV is stable on surfaces
⢠more stable than influenza A(H1N1) virus in aerosol (10min) &
on hard surfaces
â˘MERS-CoV RNA can shed for >1 month
⢠detected from a HCW for 42 days
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17. The disease, MERS
â˘Incubation period 2-16 days (median 4/5 days)
â˘Comorbidity (e.g. 87%) & cough (e.g. 100%) common
⢠asymptomatic
⢠acute URT illness incl. fever, headache, myalgia
⢠progressive pneumonitis, respiratory failure, septic shock,
multi-organ failure
â˘20% -74% (ICU) mortality (median: 12 days onset>death)
⢠SARS-10%
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18. Treatment
â˘No antivirals available
â˘Passive immunotherapy (antibody) - clinical effect?
⢠infrequent donors (2%)
⢠antibody titres low/short-lived in convalescent human sera
â˘Vaccines
⢠a range in the pipeline for humans and animals
â˘Supportive care
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21. South Korea outbreak, May-Dec 2015
â˘186 cases, 38 fatalities (20%), 4 waves of infection
â˘Biggest outbreak outside KSA
⢠>16,000 people quarantined
â˘No sustained h2h transmission
⢠no community outbreaks
â˘1/186 case travelled to China
â˘7.4 day incubation period (6.2 > 7.7 > 7.9 by generation)
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22. South Korea outbreak, May-Dec 2015
â˘1 patient responsible for 81 cases
⢠visited 4 hospitals
⢠coughed in the open
⢠walked through ER to public toilet
â˘Receptor binding domain mutant in 13/14 variants
⢠reduced receptor affinity
⢠not every virus mutates according to a Hollywood script
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23. South Korea outbreak, May-Dec 2015
â˘Lower proportion fatal
â˘20% compared to 41% in KSA
⢠due to the mutation?
⢠lower % underlying comorbidities in general community
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24. South Korea outbreak washup
â˘Quarantine was initially limited
⢠casual contacts needed to be included as well as close contacts
â˘4 beds/room â cases initially not isolated
⢠overcrowding
â˘Family members were responsible for some hospital care
⢠prolonged, close contact
â˘Patients easily moved between hospitals
⢠hospitals didnât share past disease history on patients
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25. South Korea outbreak, May-Dec 2015
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1-Choi. Yonsei Med J. 2015 56(5):1174-76
27. Issues to address large healthcare
outbreaks of MERS
â˘Identify symptomatic patients early; test & re-test
â˘Strong contact tracing, monitoring and quarantine
â˘Strong infection, prevention and control measures
⢠PPE â selection, use, donning/doffing, disposal
⢠distance between beds
⢠be aware of aerosol generating procedures
⢠cleaning & disinfection
⢠treat / manage patients in isolation
â˘Communicate with public to build/maintain trust
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28. 28
Cases are rare but travel is not
â˘Control MERS in the hotzone, avoid global spread
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29. Stop hospital outbreaks, reduce MERS cases
â˘Humans create circumstances for super-spreading events
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