What is Severe Acute Respiratory Syndrome?
In March 2003, a new and quickly developing illness affecting the lungs called severe acute respiratory syndrome, or SARS, was recognized as a global threat by the World Health Organization (WHO). The first case was identified in Guangdong, China, and it soon spread to over 30 countries, becoming the first pandemic of the 21st century. A pandemic is when a new disease spreads across a country or the world. This showed how quickly infections could spread in our interconnected world where people regularly travel internationally.
In the ten years leading up to the SARS outbreak, there were new diseases like the bird flu and Avian flu. However, SARS was different as it could be passed easily from person to person. By the time the outbreak ended in July 2003, there were 8,096 reported cases with 774 deaths, equalling a death rate of over 9.6%. Unusually, over a fifth of these cases were among healthcare workers, who were particularly vulnerable to catching SARS.
With help from partners like the Centers for Disease Control and Prevention (CDC), WHO identified the cause of SARS within two weeks as a new type of coronavirus. Researchers found this coronavirus in numerous SARS patients and suspected it was the cause before sequencing it (determining its DNA structure) and confirming this.
It’s believed that each person with SARS could infect between two to four others. However, some cases, including the first recorded case, were thought to be “super-spreaders” who could infect many more people. The virus mainly spread through tiny droplets from the nose and mouth that people breathed in. Treatment mostly involved managing and relieving symptoms as no specific antiviral drugs were effective. Since the middle of 2004, no new cases of SARS have been reported. Before the current COVID-19 pandemic, the global impact of SARS was only equalled by the 2009 H1N1 Influenza pandemic. The experiences and lessons learned from tackling SARS are helping healthcare professionals to address the current COVID-19 pandemic.
What Causes Severe Acute Respiratory Syndrome?
The SARS coronavirus, or SARS-CoV, was identified as the cause of the severe sickness known as severe acute respiratory syndrome (SARS). This was proven true based on specific scientific criteria for identifying disease-causing agents. SARS-CoV was discovered in the breathe and other body fluids of people with SARS. These fluids include urine, feces, and lung tissue, and were identified using a method called the reverse-transcriptase polymerase chain reaction (RT-PCR).
In experiments, the same virus caused a similar sickness in monkeys (macaques) as it did in humans. Other germs found in people with SARS didn’t cause this sickness in monkeys. Coronaviruses are named after their crown-like spikes on their surfaces, which are made of sugary proteins (glycoproteins). They are large viruses that carry their genetic information in a single strand of RNA and their genetic material is covered by a spiral-shaped protein structure.
Usually, coronaviruses cause the common cold in humans. In animals, though, they can cause a very severe disease. It’s believed that the SARS-CoV came from bats and then spread to a type of animal called a palm civet, before eventually spreading to humans.
Risk Factors and Frequency for Severe Acute Respiratory Syndrome
The first cases of Severe Acute Respiratory Syndrome, or SARS, were noted in China in 2002. It initially presented as an uncommon form of pneumonia. The first people to contract it were handlers of animals like palm civets, thought to be carriers of the virus. The disease then spread to Hong Kong by a super-spreader, a person who transmits the virus at a higher rate than usual. The typical rate of transmission, not including super-spreaders, is 2 to 4 people infected per each person carrying the virus.
The disease quickly spread beyond China and Hong Kong to over 30 other countries across Asia, Europe, and North America. China had the bulk of cases (83%), while the United States had only 27 probable cases and no deaths. The global outbreak resulted in 8096 cases and 774 deaths overall. Older patients over 60 had a higher mortality rate, up to 43%. SARS mostly affected adults, with children making up a smaller percentage of cases, usually with milder symptoms and no reported deaths. It’s interesting to note that with COVID-19, as with SARS and the Middle East Respiratory Syndrome (MERS), it seems adults are impacted more severely, while children as greater spared. Health care workers and medical facilities were heavily affected, making up 21% of the cases. By mid-2004, however, no new cases have been reported, and the World Health Organization announced the end of the pandemic.
The SARS virus, like many respiratory viruses, is spread mainly through person-to-person contact, such as through face-to-face contact, suggesting it spreads via droplets. Transmission can also occur by touching contaminated objects, or fomites. The typical period between contracting the virus and the onset of symptoms is between 2 to 7 days, with 95% of patients showing symptoms by the 10th day. Other possible means of transmission, such as fecal-oral route or airborne spread, have been suggested. Most patients shed the virus in their respiratory secretions 6 to 11 days after showing symptoms.
Signs and Symptoms of Severe Acute Respiratory Syndrome
SARS, or Severe Acute Respiratory Syndrome, typically manifests with symptoms such as fever, muscle pain, coughing, tiredness, and headaches, with fever being the most frequent symptom. Unlike most respiratory illnesses caused by viruses, SARS has a longer initial phase, ranging between 2 to 14 days, during which patients usually don’t experience any breathing-related issues. Following this, more respiratory symptoms start to manifest which usually start with a dry cough. This can potentially advance to difficulty in breathing and even severe respiratory failure. A cough producing phlegm or a runny nose are less common. In one study, it was found that about 20% of patients also had diarrhea.
- Fever
- Muscle pain
- Coughing
- Fatigue
- Headache
- Dry cough advancing to breathing difficulties
- Diarrhea in some cases
About 70% of people with SARS experience struggle with breathing. While about 30% of patients see their health improve within a week, many continue to be unwell into the second week. In serious cases, there is a sharp decline in the patients’ health towards the end of this second week. If a patient with SARS passes away, it typically happens later in the course of the disease and is often due to severe respiratory distress (ARDS), additional infections, severe body-wide infection (septic shock), and blood clot-related complications.
Testing for Severe Acute Respiratory Syndrome
The severe acute respiratory syndrome (SARS) is a type of illness that affects the respiratory system. This condition is identified or ‘defined’ by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). Someone is said to have SARS when they’ve been confirmed to have the virus in lab tests, and they either show certain physical symptoms or have been working with the live SARS virus in a lab setting.
The physical, or clinical, symptoms used to identify SARS include a fever or history of fever, along with at least one respiratory system issue like a cough, shortness of breath, or difficulty breathing. Sometimes, X-ray findings that show pneumonia or another severe condition called acute respiratory distress syndrome (ARDS) may also be present. There might also be signs of pneumonia or ARDS found during an autopsy that were not caused by another identified disease.
To provide a definite lab-based diagnosis of SARS, two separate virus samples must be obtained. This could be two samples from different parts of the body, or two samples taken at different times from the same location, that show the presence of the SARS virus when a test called reverse transcriptase PCR is performed.
When a patient is suspected of having SARS, multiple tests are recommended. These could include a complete blood count, chest X-ray, pulse oximetry (a test that measures the oxygen level in your blood), and several other tests. Also, testing specifically for the SARS virus should be done in collaboration with local health authorities, the CDC, or WHO.
This specific test for SARS should be done using a method called PCR, from two different sample sites, as early in the illness as possible, and then should be repeated after five to seven days if symptoms continue. Another test, known as ELISA, can also be used, but its results may take a few weeks to develop, making it less reliable for an immediate diagnosis.
The test results for patients with SARS can vary, with common abnormalities being low total lymphocytes (a type of white blood cell), high serum lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) levels (these enzymes are found in various body tissues and indicate that there’s damage to the liver), and some other noted issues. Platelet count (which are tiny blood cell fragments that help your body form clots to stop bleeding) is generally noted to decrease when the respiratory symptoms of the illness are most severe.
X-ray findings for SARS patients can look like those seen in other cases of viral pneumonia, and may even appear normal during the early phase of the illness. However, chest X-rays show a range of patterns, from normal to diffuse infiltrates (which means there are substances within the lungs that shouldn’t be there). A chest CT scan can show additional abnormalities, such as ground-glass infiltrates, which typically indicates a specific type of lung disease.
Treatment Options for Severe Acute Respiratory Syndrome
At present, there is no specific cure for the severe respiratory condition known as SARS. Doctors mainly focus on providing supportive care to relieve symptoms and improve the patient’s wellbeing. So far, no medications, such as antiviral drugs or glucocorticoids (medications that reduce inflammation), have been shown to have a significant positive effect on this disease.
Potential medications for SARS are being explored. One such is Lopinavir-ritonavir, which has demonstrated some effectiveness in laboratory settings. Remdesivir, an experimental drug previously tested for the treatment of Ebola, has shown promise against both SARS and another similar virus called MERS.
There have been attempts to develop vaccines against SARS and other similar viruses, with a particular focus on the spike glycoprotein, a component of the virus. However, no vaccine is currently recommended.
With SARS, the focus is on preventing the spread of infection. If a patient is suspected of having SARS, it’s vital to identify them quickly and isolate them, adopting adequate measures to control the infection and prevent transmission.
A process that uses clinical and epidemiological criteria should be in place to promptly recognize patients with suspected SARS. Measures to control the infection include contact precautions (using gloves, gowns, and eye protection), droplet precautions (securing a private room for the patient and limiting their movement), and airborne precautions (using N-95 respirators and making sure the isolation room has a negative pressure environment).
If N95 respirators are not available, a surgical mask should be worn. Research suggests that nurses consistently wearing a surgical mask or N95 respirator, particularly in intensive care units, can help protect them from infection. Other protective equipment such as gloves, gowns, and eye protection has also been linked to a reduced transmission of infection.
These precautions are particularly crucial during high-risk procedures, such as inserting a tube in the airway for artificial ventilation (endotracheal intubation), providing mechanical breathing support (mechanical ventilation), using a nebulizer for medication delivery, and suctioning secretions from patients’ airway.
What else can Severe Acute Respiratory Syndrome be?
There are several other infections that can look like severe acute respiratory syndrome (SARS), including different types of pneumonia and ARDS (acute respiratory distress syndrome). These can be caused by either bacteria or viruses.
- Bacterial causes can include:
- Streptococcus pneumoniae
- Moraxella catarrhalis
- Haemophilus influenza
- Viral causes may range from:
- Influenza
- Parainfluenza
- Respiratory syncytial virus
- Varicella
- Hantavirus
What to expect with Severe Acute Respiratory Syndrome
Studies have found several factors that may lead to poorer health outcomes. These include having diabetes, chronic hepatitis B, or other existing health conditions; being of older age; showing unusual symptoms; and having high levels of lactate dehydrogenase, which is a type of enzyme, in your blood at the time of hospital admission.
Of all these factors, having diabetes or heart disease can especially signal more severe health outcomes. Also, having a high amount of the virus in your body at the start of illness is linked to a worse prognosis, meaning it can negatively affect the success of your treatment.
Age also plays a major role. Patients older than 65 have the highest death rates, which can even exceed 50%. On the other hand, children under 12 typically experience less severe illnesses and have good outcomes.
Possible Complications When Diagnosed with Severe Acute Respiratory Syndrome
Severe Acute Respiratory Syndrome (SARS) can lead to many health problems in the lungs and elsewhere in the body. Here are some examples:
- About 12% of the people in one study had spontaneous pneumomediastinum, a condition where air leaks into the center of the chest.
- Kidney and liver damage
- Low white blood cell and platelet count
- Cardiac dysfunction, specifically issues with the filling phase of the heartbeat
- Increased blood pressure in the lungs
- Nervous system disorders
- Rhabdomyolysis, a condition that could cause muscle breakdown
- Hospital-acquired infections such as bacteremia (bacteria in the blood), sepsis related to the use of catheters, and pneumonia
In the early stages of the SARS epidemic, corticosteroids were trialed as a treatment, but they did not prove to be beneficial. In SARS patients, side effects of prolonged high-dose corticosteroid therapy were observed, such as avascular necrosis (death of bone tissue due to a lack of blood supply) and widespread fungal infection.
Preventing Severe Acute Respiratory Syndrome
Preventing the spread of certain diseases can be challenging when there aren’t any reliable treatments, vaccines, antibodies specifically created in a lab, or natural immunity available. In such situations, quickly finding and isolating new cases becomes incredibly important for public health. For instance, in the early stages of a disease like severe acute respiratory syndrome (SARS), patients aren’t as contagious, which means that once they start showing symptoms, health measures can be applied to stop the spread.
In order to effectively manage such a disease, we need to identify potential cases early on, isolate them, and take vigorous measures to control the infection. It’s also been found that SARS can spread through something called the ‘fecal-oral’ route, which happened during one outbreak in Hong Kong. This means that the disease can spread if someone accidentally ingest small particles of feces from an infected person. So apart from fluids from the respiratory system, fecal material and urine should also be regarded as infectious. It’s also worth noting that SARS can stay active on surfaces for several days.
