Severe acute respiratory syndrome

Overview

Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by the SARS-associated coronavirus (SARS-CoV). It was first identified during a global outbreak in 2002–2003, which originated in Guangdong province, China, and subsequently spread to several countries across Asia, Europe, and North America. SARS is a zoonotic disease, meaning it originated in animals and was transmitted to humans. The syndrome is characterized by flu-like symptoms that can rapidly progress to pneumonia and acute respiratory distress. Due to its contagious nature and significant mortality rate, SARS prompted extensive international public health responses and surveillance.

Causes

SARS is caused by the SARS-CoV virus, a member of the coronavirus family, which also includes viruses responsible for the common cold, Middle East respiratory syndrome (MERS), and COVID-19. The initial transmission to humans likely occurred from an animal host, possibly civet cats or bats, through direct or indirect contact in live animal markets. Human-to-human transmission primarily occurs via respiratory droplets expelled when an infected person coughs or sneezes, as well as through contact with contaminated surfaces or objects. SARS-CoV can also be spread through close personal contact, including caring for or living with an infected person.

Symptoms

SARS typically begins with flu-like symptoms and can rapidly progress to severe respiratory illness. The incubation period ranges from 2 to 10 days. Common symptoms include:

• High fever (usually above 38°C or 100.4°F)

• Chills and rigors

• Headache and body aches

• Dry cough

• Shortness of breath or difficulty breathing

• Fatigue and malaise

• Diarrhea (less common but noted in some cases)

As the disease progresses, patients may develop pneumonia, hypoxia, and in severe cases, acute respiratory distress syndrome (ARDS), which can be fatal if not promptly managed. Elderly individuals and those with underlying medical conditions are at higher risk of severe outcomes.

Diagnosis

Diagnosing SARS involves a combination of clinical evaluation, exposure history, and laboratory testing. During the 2003 outbreak, diagnosis was based on the presence of symptoms consistent with SARS and a history of travel to affected regions or contact with a confirmed case.

• Clinical assessment: Identification of fever, respiratory symptoms, and potential exposure to SARS-CoV

• Imaging: Chest X-rays or CT scans showing signs of pneumonia or pulmonary infiltrates

• Laboratory testing:

  • Reverse transcription polymerase chain reaction (RT-PCR) to detect SARS-CoV RNA

  • Serologic testing to identify antibodies against SARS-CoV

  • Virus isolation from respiratory specimens, though not commonly used due to complexity

• Exclusion of other respiratory illnesses: Such as influenza or bacterial pneumonia

Prompt recognition and isolation of suspected cases are essential to control outbreaks.

Treatment

There is no specific antiviral treatment approved for SARS. Management is primarily supportive, aimed at relieving symptoms and addressing complications. Key treatment strategies include:

• Hospitalization: Most patients require hospital care, especially in moderate to severe cases

• Oxygen therapy: To manage hypoxia and maintain oxygen saturation levels

• Mechanical ventilation: For patients with respiratory failure or ARDS

• Fluid and electrolyte management: To prevent dehydration and maintain balance

• Empirical antibiotics: May be administered initially to rule out bacterial infections

• Experimental antivirals and corticosteroids: Used during the outbreak, but efficacy remains uncertain

Infection control measures, such as patient isolation, use of personal protective equipment (PPE), and strict hygiene practices, are critical to prevent spread within healthcare settings and the community.

Prognosis

The prognosis of SARS depends on several factors, including the patient's age, overall health, and the promptness of medical intervention. The case fatality rate during the 2002–2003 outbreak was estimated at around 9.6%, with higher mortality observed in older adults and those with underlying conditions such as diabetes and cardiovascular disease.

Most patients recover with appropriate supportive care, but some survivors may experience long-term complications such as reduced lung function, fatigue, or psychological impacts. Since the original SARS outbreak, no sustained human-to-human transmission has been documented, but the potential for re-emergence underscores the importance of global surveillance and preparedness.