Middle East respiratory syndrome (MERS) outbreak was reported in September 2012 when many cases presented with severe lung infection, it was first recognized in Saudi Arabia when a man died because of severe pneumonia and multiple organ failure.
After that 27 countries reported similar case, 12 of them was in middle east region but 80% of the cases have been reported in Saudi Arabia.
MERS-COV is the name of the virus that lead to this outbreak.
What is MERS-COV virus ?
MERS-COV is a lineage C betacorona virus , Which is RNA viruses , positive sense , enveloped with crown like spikes.
Corona virus belong to Coronaviridae family and it have 4 subgroups :Alpha, Beta, Gamma, Delta.
Alpha and Beta groups are the only groups can infect mammals.
There is seven species of corona virus that can infect humans :
- SARS-CoV -2
The Origin of MERS-CoV :
All corona viruses originate from animals, especially from bats and rodents. MERS-COV transmitted directly and indirectly from dromedary camels.
Pathogenesis of MERS :
MERS-COV surface spikes have a receptor called Dipeptidyl peptidase 4 (DPP4) or CD26, this receptor present on many types of human cell, such the non-ciliated bronchial epithelial tissue.
DPP4 attracts neutrophils and monocytes, So it might start the inflammatory reaction when MERS-COV attach to it.
MERS-COV Transmission :
MERS-COV virus transmitted from camels to human by direct contact with the infected camel or it’s meat and milk or indirectly by touching surfaces infected with the virus then touching the mouth, nose or eyes.
It’s not easily transmitted from human to human unless there is close contact such health care workers, close family contact , and in the work place.
MERS-COV incubation period :
Incubation period is the duration between first exposure to the virus and when the sign and symptom of disease caused by the virus first appear.
MERS-COV virus incubation period is usually 9 to 12 days, the reported median incubation period is 5.2 days.
presentation of MERS :
Common symptoms are acute severe respiratory disease with:
- fever > 38 °C (98%)
- fever with chills (87%)
- cough (83%)
- shortness of breath(72%)
- Abnormal chest radiograph (100%)
Primarily all MERS-COV patients suffer from respiratory disease, But there is secondary complication that can happen including:
- Acute renal failure
- Multi-organ failure
- Acute respiratory distress syndrome (ARDS)
- consumptive coagulopathy
many patients also reported gastrointestinal symptoms, including diarrhea. some patient present with fatigue, myalgia, congested nose and throat .
Patients with underlying medical condition, e.g :diabetes mallitus, renal failure, chronic lung disease, compromised immune system and health care worker are the most at risk of this infection.
There is 2495 confirmed MERS-COV cases and 858 confirmed MERS-COV deaths, which mean 35% case fatality rate.
MERS-COV Lab test :
The CDC recommends collecting multiple specimens from different sites and times after symptoms onset:
- Nasopharyngeal swab
- Oropharyngeal swab
- Stool swab
RT-PCR ( real-time reverse-transcriptase polymerase chain reaction ) test is used to detect MERS-COV. Serology test is used to detect MERS-COV antibodies including, indirect fluorescent antibody (IFA) for Immunoglobulin M (IgM) and Immunoglobulin G (IgG) detection.
Chest radiograph of MERS vary but consistent with viral pneumonia and ARDS.
MERS Treatment :
There is no specific treatment for illnesses caused by MERS-COV but supportive care help in relieving symptoms , this include :
- Respiratory support
- Antibiotic ( for bacterial superinfection)
There is a study about treatment With Lopinavir/Ritonavir or Interferon-β1b Improves Outcome of MERS-CoV Infection. https://www.ncbi.nlm.nih.gov/pubmed?term=26198719
There is no vaccine available to prevent MERS-COV infection but Novavax announced that it had successfully produced a vaccine based on major surface spike protein .https://ir.novavax.com/news-releases/news-release-details/novavax-produces-mers-cov-vaccine-candidate
Proper infection control is recommended by WHO when caring for suspected or confirmed MERS cases including:
- standard and droplet precautions when caring for patients with acute respiratory tract infections .
- Contact precautions and eye protection when caring for probable or confirmed cases of MERS-CoV infection.
- Airborne precautions when performing aerosol-generating procedures. https://www.who.int/csr/disease/coronavirus_infections/MERS_CoV_Update_09_May_2014.pdf?ua=1
Avoidance of the source of the infection is a must for immuno-compromised which is camels and it’s product ( milk and meat).
RESEARCH RELATED TO THIS TOPIC :