MERS

Middle East Respiratory Syndrome Coronavirus (MERS) is an infectious disease caused by one of seven subtypes of coronavirus that infect humans.

First detected in 2012 in the city of Jeddah in Saudi Arabia, but present in all regions of the country, since 2018 it has been identified in 27 countries, with 2,260 confirmed cases and a total of 803 deaths.

CAUSES

Orthocoronavirinae is a subfamily of viruses, also known as coronaviruses, from the Coronaviridae family, which includes the Coronavirus genus. It is a helical symmetry, single-stranded RNA virus enveloped by a capsid.

It is composed of viral spikes, glycoproteins that cross the pericapsid, called S proteins, with hemagglutinating and binding properties. Between the nucleocapsid and pericapsid is a protein coating formed of M protein (matrix).

There are seven viruses belonging to this family that can infect human beings. All of them can cause respiratory illnesses, like the common cold, pneumonia, and bronchitis, but three in particular cause very serious and sometimes fatal respiratory infections:

• Sars-Cov 2, a new coronavirus, identified as the cause of coronavirus disease in 2019 (COVID-19), which originated in Wuhan, China, in late 2019 and spread worldwide;
• The MERS-CoV coronavirus, identified in 2012 as the cause of Middle East respiratory syndrome (MERS);
• Sars-CoV, identified in 2003 as the cause of an outbreak of severe acute respiratory syndrome that began in China in late 2002.

TRANSMISSION

MERS-CoV is zoonotic: this means it develops in animals and then is later transmitted to humans.

Since the emergence of the disease in 2012, researchers continue to try to identify the main culprits responsible for the infection in humans. Epidemiologically, camels have been found to be the main source of infection in humans, while surveys in several countries, including Europe and South Africa, have brought to attention the high viral load of MERS-CoV in the faecal samples of certain species of bat.

Transmission from an infected patient to a healthy one is also possible, typically by direct contact or through infected particles (droplets) emitted during breathing. Indirect infection is also possible, following contact with contaminated materials and surfaces.

GEOGRAPHICAL DISTRIBUTION

The outbreak of MERS-CoV infection in Saudi Arabia has resulted in many infections and deaths. Since the main outbreak, the virus has subsequently spread to neighbouring countries in the Middle East, including Qatar, Bahrain, Kuwait, Tunisia and Jordan.

The epidemic has also spread to Europe, North Africa, Southeast Asia ,and the United States, through infected travellers returning from the Middle East.

During the MERS-CoV outbreak, cases of infection were reported in 27 countries, 12 of which were located in the Eastern Mediterranean region. A total of 1,227 cases of MERS-CoV, were reported in Saudi Arabia from June 2012 to December 2015; out of these, 728 patients recovered and 549 died from the infection.

SYMPTOMS

Symptoms observed among the documented cases of MERS-CoV infection, include cough, fever, rhinorrhea (runny nose), shortness of breath, gastrointestinal symptoms, nausea, vomiting, fatigue, and muscle aches. In severe cases the disease can cause respiratory failure. However, there have been a number of confirmed asymptomatic cases.

MERS-CoV can cause more severe complications in immunocompromised patients with a history of diabetes and lung disease. This is because these individuals are generally much more prone to infection.

DIAGNOSIS

Identification is complicated in the early stages of the disease due to the non-specificity of the symptoms. Pneumonia can be a marker for identification, but it is not always present. Infection may be suspected if the symptoms appear two weeks after a trip to the Middle East.

Diagnosis is mainly carried out using two tools: serological tests, which measure the presence of antibodies produced after infection, and tests based on the PCR techniques, which detect the presence of pieces of the virus in the body.

TREATMENT

There is currently no approved treatments for SARS and MERS infections. To date, the main management strategy for MERS-CoV is administration of antipyretics and analgesics, hydration support and respiratory support by means of mechanical ventilation or extracorporeal oxygenation.

If a patient with MERS-CoV has bacterial co-infection, the use of antibiotics is indicated.

Recent publications have discussed several options, such as interferon, lopinavir/ritonavir, ribavarin, virus replication inhibitors (e.g., cilcophilin inhibitors), and MERS-CoV neutralizing antibodies, but none of these agents have been shown to be definitively effective.

Recently, three human, monoclonal antibodies, m336, m337 and m338, which target the receptor-binding domain (CD26/DPP4) of the MERS-CoV glycoprotein spike, were successful in neutralising the virus.

PREVENTION

To prevent the spread of MERS-CoV infection, it is essential to adopt the use of PPE (Personal Protective Equipment): gowns, gloves and the use of surgical masks. It is the duty of local health authorities to enforce compliance with the appropriate precautions when treating patients infected with MERS-CoV.

For travellers to endemic regions, the risk of acquiring MERS-CoV infection is relatively low. This risk depends on possible contact with infected patients in health care facilities, dromedaries, or any products derived from these animals.

In many Persian Gulf countries, camelids are a valuable source of milk and meat. The movement and trade of infected animals, particularly camels, is a potential source of spread in MERS-CoV infection. Consequently, travellers should avoid contact with sick people or animals, adopt appropriate personal hygiene measures, and makes sure the food they eat is safe, properly cooked through, and still hot when served.

Currently, there is no vaccine to prevent MERS-CoV infection, and it is still not known whether the vaccines introduced during the COVID-19 pandemic can also provide cross-protection for MERS-CoV infection.

 

Bibliography:

1. Abbas Al Mutair, Zainab Ambani. Narrative review of Middle East respiratory syndrome coronavirus (MERS-CoV) infection: updates and implications for practice. Journal of International Medical Research. The Author(s) 2019;
2. Brian Rha, Jessica Rudd, Daniel Feikin, John Watson, Aaron T. Curns, David L. Swerdlow, Mark A. Pallansch, Susan I. Gerber. Update on the Epidemiology of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Infection, and Guidance for the Public, Clinicians, and Public Health Authorities. Morbidity and Mortality Weekly Report. MMWR, January 30, 2015 / Vol. 64
3. Jaffar A. Al-Tawfiqd,e, Alimuddin Zumlaa,c, and Ziad A. Memish. Coronaviruses: severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus in travelers. 0951-7375.2014 Wolters Kluwer Health | Lippincott Williams & Wilkins.
4. Sonja A. Rasmussen, Susan I. Gerber, and David L. Swerdlow. Middle East Respiratory Syndrome Coronavirus: Update for Clinicians. Clinical Infectious Diseases 2015;60(11):1686–9