Middle East respiratory syndrome

Overview

Middle East Respiratory Syndrome (MERS) is a viral respiratory illness caused by the Middle East Respiratory Syndrome coronavirus (MERS-CoV). First identified in Saudi Arabia in 2012, MERS belongs to the same family of viruses as the common cold and SARS-CoV (Severe Acute Respiratory Syndrome). The illness can range from mild respiratory symptoms to severe acute respiratory illness and death. MERS has a relatively high mortality rate compared to other respiratory infections, with a case fatality rate of approximately 35% based on reported cases.

MERS primarily affects the respiratory system but can also impact the gastrointestinal and renal systems. Although outbreaks have been largely contained to the Middle East, cases have been reported worldwide due to international travel. Human-to-human transmission, especially in healthcare settings, has contributed to limited outbreaks beyond the Arabian Peninsula.

Causes

MERS is caused by the Middle East Respiratory Syndrome coronavirus (MERS-CoV), a zoonotic virus, meaning it is transmitted from animals to humans. The primary reservoir for MERS-CoV is believed to be dromedary camels, which are widespread in the Middle East and parts of Africa. Transmission occurs through close contact with infected camels or consumption of raw camel products such as milk or meat.

Human-to-human transmission occurs primarily through close contact, especially in healthcare settings where infection control procedures are inadequate. The virus spreads via respiratory droplets when an infected person coughs or sneezes, although airborne transmission in some circumstances (like aerosol-generating procedures) cannot be ruled out.

Symptoms

The symptoms of MERS can range from mild to severe and usually appear 2 to 14 days after exposure. Common signs and symptoms include:

Initial Symptoms

• Fever

• Cough

• Shortness of breath

Additional Symptoms

• Muscle pain

• Sore throat

• Headache

• Chills

• Diarrhea, nausea, or vomiting (in some patients)

Severe Symptoms

• Severe pneumonia

• Acute respiratory distress syndrome (ARDS)

• Kidney failure

• Septic shock

• Multi-organ failure

Many patients with severe illness have underlying medical conditions such as diabetes, chronic lung disease, cancer, or weakened immune systems. However, healthy individuals can also develop serious complications in some cases.

Diagnosis

Diagnosis of MERS involves a combination of clinical evaluation, travel history, and laboratory testing. The process includes:

• History and exposure risk: Recent travel to the Middle East or contact with confirmed cases or camels

• PCR testing: Real-time reverse transcription-polymerase chain reaction (RT-PCR) is the standard test for detecting MERS-CoV RNA from respiratory specimens such as nasopharyngeal swabs, sputum, or bronchoalveolar lavage

• Serological testing: Used to detect past infections or confirm diagnosis in later stages

• Chest imaging: Chest X-ray or CT scan may show signs of pneumonia or lung infiltration in severe cases

Testing is typically recommended for individuals presenting with acute respiratory symptoms and a history of travel to affected regions or exposure to suspected cases within 14 days of symptom onset.

Treatment

There is no specific antiviral treatment approved for MERS-CoV. Management is primarily supportive and focuses on relieving symptoms and maintaining vital organ function. Treatment strategies include:

• Oxygen therapy: To manage respiratory distress

• Mechanical ventilation: For patients with severe respiratory failure

• Fluids and electrolytes: To maintain hydration and balance

• Antibiotics: May be used if there is a secondary bacterial infection

• Antiviral and immunomodulatory therapies: Experimental agents such as interferons, lopinavir/ritonavir, and monoclonal antibodies have been tested but are not yet standard treatment

In hospital settings, strict infection prevention and control measures are critical to prevent the spread of the virus. Isolation of suspected and confirmed cases, use of personal protective equipment (PPE), and proper disinfection protocols are essential.

Prognosis

The prognosis for patients with Middle East respiratory syndrome varies depending on age, underlying health conditions, and the severity of infection. While some individuals recover fully with mild or no symptoms, others develop severe disease leading to respiratory failure, multiorgan dysfunction, or death.

Key factors influencing prognosis include:

• Underlying conditions: Patients with diabetes, kidney disease, or compromised immune systems have higher mortality

• Age: Older adults are more likely to develop severe illness

• Access to supportive care: Prompt hospitalization and intensive care improve survival

According to the World Health Organization, the case fatality rate of MERS is approximately 35%, making it one of the more deadly human coronaviruses. Continued surveillance, research into vaccines and therapeutics, and public health preparedness are vital in reducing the impact of potential future outbreaks.