Middle East Respiratory Syndrome (MERS) is a viral respiratory illness caused by the MERS-CoV coronavirus. First identified in 2012, the virus is part of a large family that causes diseases ranging from the common cold to more severe conditions. The illness primarily affects the respiratory system, and all reported cases have been linked to individuals who traveled to or resided in countries on or near the Arabian Peninsula.
Origin and Transmission of MERS-CoV
MERS-CoV is a zoonotic virus, meaning it is transmitted from animals to people. Evidence points to dromedary camels as the primary natural reservoir and source of human infection, though the virus may have originated in bats. Humans can become infected through direct or indirect contact with these animals or by consuming raw or undercooked camel products like milk and meat.
Human-to-human transmission can occur but requires close contact, as the virus does not spread easily. This has led to clusters of cases within healthcare facilities, spreading from patients to staff before a diagnosis was confirmed. The primary mode of person-to-person spread is through respiratory droplets from an infected individual’s coughs or sneezes.
Symptoms and Health Complications
The presentation of MERS ranges from asymptomatic to severe respiratory illness. Common initial symptoms include fever, a persistent cough, and shortness of breath, while some people experience gastrointestinal issues like diarrhea and nausea. The incubation period, the time between exposure and symptom onset, is between 2 and 14 days.
Severe infections can lead to life-threatening health complications like pneumonia. The illness can progress to acute respiratory distress syndrome (ARDS), a condition where fluid builds in the lungs and deprives organs of oxygen. Another significant complication is kidney failure.
Diagnosis and Medical Management
Confirming a MERS-CoV infection requires specific laboratory tests on respiratory samples. The most common and reliable method is a reverse transcription-polymerase chain reaction (RT-PCR) test. This test detects the virus’s genetic material in samples like nose swabs or lung fluid. Diagnosis also involves a clinical evaluation of symptoms and potential exposure history.
Currently, there is no specific antiviral medication or vaccine for MERS-CoV, although several are in development. Medical management is focused on supportive care to relieve symptoms and support the body’s functions. This can include providing fluids, administering oxygen, and using mechanical ventilation for respiratory failure in an intensive care unit.
Prevention and Risk Factors
Preventing MERS-CoV infection involves general hygiene and specific precautions, particularly for those traveling to or living in affected regions. Recommended practices include frequent handwashing, avoiding close contact with sick individuals, and adhering to food safety practices. This includes not consuming raw or undercooked camel meat or milk.
Older adults, individuals with weakened immune systems, and those with certain pre-existing conditions are at a higher risk for severe MERS. These chronic conditions include:
- Diabetes
- Cancer
- Chronic lung disease
- Hypertension
- Cardiovascular disease
These individuals should take extra precautions, such as avoiding contact with dromedary camels when visiting farms, markets, or barns.
Comparison with Other Coronaviruses
MERS-CoV belongs to the same family of viruses as SARS-CoV, which caused the 2003 SARS outbreak, and SARS-CoV-2, the virus responsible for COVID-19. While related, there are distinct differences. MERS-CoV has a significantly higher case-fatality rate, with approximately 35% of reported patients dying from the illness.
MERS-CoV spreads less efficiently between people compared to SARS-CoV-2. This has resulted in MERS outbreaks being more contained and geographically localized to the Arabian Peninsula, whereas COVID-19 became a global pandemic. Genetically, MERS-CoV is not closely related to the other two viruses, sharing only about 50% of its genome with SARS-CoV.