Infectious diseases Internal Medicine Pulmonology

Severe Acute Respiratory Syndrome (SARS)

Severe Acute Respiratory Syndrome (SARS)
The most recent "outbreak" of severe acute respiratory syndrome, SARS, was reported in China (9 cases in Beijing and Anhui provinces) in April and May 2004. The index case was a virologist working with inactivated SARS CoV. The Chinese authorities and the WHO found, after the investigation that the laboratory was the likely source of infection. Improvement of biosafety at virological laboratories handling SARS-CoV (control of virus casualties, maintenance of class 3 safety) was implemented.
The outbreak of the mystery SARS virus is a chilling reminder of our frailty in the face of Mother Nature. This program follows the story of an epidemic that brought the world to the edge of panic.

WHO reports that local transmission of SARS is not currently ongoing in any region of the world(www.who.int/csr/don/en) .


Introduction – Severe Acute Respiratory Syndrome (SARS)

Severe acute respiratory syndrome (SARS), formerly referred to as severe acute respiratory infection, is caused by the coronavirus SARS-CoV that gives rise to, fever and respiratory symptoms among other signs. MERS-CoV (Middle Eastern respiratory syndrome coronavirus) is SARS-CoV-related, but not identical, the virus causes a clinical picture similar to that of SARS.

SARS is believed to have occurred in Guangdong province of China in the fall of 2002. Thereafter, the disease spread to other parts of China and Hong Kong, from where the SARS virus spread internationally in February 2003. During the pandemic leading up to 06/03/15, the WHO reported 8100 cases, of which 774 had a fatal outcome. Most SARS cases have been reported from mainland China, Hong Kong, and Taiwan. Many of the people who became ill in other parts of the world had cared for someone or had a close relative, who had recently been in one of these areas. A number of people have obviously been infected by SARS through close contact with sick people at work, hotels, aircraft, etc.

Vietnam was the first country to have the SARS epidemic under control (at the end of April -03) and was erased from the WHO’s list of affected areas. Since the end of May -03, the number of new cases has steadily declined in all affected areas and on the 15th of June, the last SARS case in the world (in Taiwan) was reported during the more than six months epidemic. Since then, only a few sporadic cases without further spread of infection have been reported.

Despite this, there is a global vigilance regarding SARS, especially in those countries that had previously suffered from the spread of the disease. WHO has also emphasized the importance of continued vigilance, as the state of knowledge about SARS is incomplete.


Etiology – Severe Acute Respiratory Syndrome (SARS)

SARS is caused by the coronavirus SARS virus (SARS-CoV). Other types of coronavirus cause, among other things, mild colds in humans. The DNA sequence of the SARS virus is known in its entirety. There has been speculation about host animals and animal reservoirs for SARS. 

SARS infects mainly via drip and contact infections. The virus has been found to survive up to 4 days in feces and defective sewage is believed to have been a contributing cause of infection in a small number of cases in Hong Kong.


Definition

NOTE! SARS is an exclusion diagnosis and should, therefore, be written off if another diagnosis can fully explain the symptoms and other findings. The definitions below have been developed by WHO.

Clinical case definition

High fever (> 38 o C)

AND

At least one symptom of lower respiratory disease:

  • cough
  • difficulty breathing
  • superficial breathing

AND

  • Radiologically verified pulmonary infiltrates compatible with pneumonia or RDS

    OR
  • Autopsy findings consistent with pathology in pneumonia or RDS without an identifiable cause.

AND

No other diagnosis can fully explain the symptoms.


Laboratory case definition

A person with symptoms and clinical signs suggestive of SARS with laboratory-confirmed presence of SARS-CoV according to any of the following methods:

1. PCR (used by the Public Health Authority)
Positive PCR test on:

  • samples from two or more different premises (e.g. nasopharyngeal aspirate and urine sample)
    OR
  • samples from the same site at different times during the course of the disease
    OR
  • two different assays or repeat PCR on new RNA extract from the original sample material at each test occasion.

2. Seroconversion with ELISA or IFA (however, the sensitivity and specificity of these assays are only reliably high after a few weeks of infection and are therefore mainly used to detect later stages of the disease course).

3. Virus isolation


Symptoms and Clinical Findings – Severe Acute Respiratory Syndrome

The incubation period is approximately 2-10 days.

SARS can have an extremely variable course of action; The symptoms have very varying degrees of severity and all of the following signs do not necessarily occur. However, fever and the effect on respiration are mandatory findings (see definition).

  • Respiratory symptoms:
    • Cough (dry, non-productive)
    • breathlessness
    • Respiratory distress

  • Fever> 38 ° C

  • Influenza-like symptoms:
    • Muscle aches
    • Sore throat
    • Headache

  • Radiological signs of pneumonia or RDS

Other reported symptoms include loss of appetite, feeling sick, confusion, rash, and diarrhea.

The majority of patients have become ill with an initial “flu-like” image with rapid onset of fever, followed by muscle pain, headache, sore throat, and cough. This has in many cases been followed by pneumonia.

80-90% of those with SARS have gradually improved after 6-7 days of illness, while the remaining 10-20% of cases have progressed and developed such severe respiratory effects that respiratory care is often necessary. Mortality in SARS varies widely in different groups, cf. depending on age, but is a total of about 10%. See “Forecast” below for more information.

It is currently unknown how long SARS is contagious after illness. There is nothing to suggest that asymptomatic individuals can pass SARS on.


Diagnostics and laboratory procedures – Severe Acute Respiratory Syndrome (SARS)

The purpose of the investigation is primarily to exclude other causes of pneumonia, and to collect material for further sampling. Prior to sampling, contact the Public Health Authority.

Sampling should include:

  • Acute serum
  • Nasopharyngeal aspirates
  • Throat culture swab
  • Urine sample
  • Fecal samples

and possibly

  • Bronchoalveolar lavage, BAL
  • EDTA blood for molecular biological analysis
  • Eye secretions

Chest X-rays should be performed. Blood counts should be monitored – thrombocytopenia, leukopenia and anemia have been reported in some cases. Other tests are guided by the clinical picture on a case-by-case basis.

Samples from probable cases, after telephone contact, should be sent to the Public Health Authority as a contagious consignment for disposal in the safety laboratory. Samples from patients with suspected SARS can generally be disposed of at the local laboratory under barrier protection. Contact the laboratory before sampling to observe local infection control procedures.


Treatment – Severe Acute Respiratory Syndrome (SARS)

Currently, causal treatment against SARS is lacking. Instead, the treatment is aimed at relieving the symptoms, primarily facilitating breathing, and carefully monitoring the homeostasis and, if necessary, correcting it. In addition, treatment is directed at those pathogens that usually cause typical and atypical socially acquired pneumonia. Respiratory care must often be taken in case of serious illness.

Intravenous ribavirin and steroids have stabilized the condition of some critically ill patients.


Prognosis – Severe Acute Respiratory Syndrome (SARS)

Studies from Hong Kong show that age> 40 years and hepatitis B infection are prognostic aggravating factors for SARS.

Mortality in SARS has averaged around 10%, but major differences between different patient groups, especially age groups, have been reported by WHO. Mortality is <1% in the group <24 years, while it is >50% in the group >65 years. When the SARS epidemic was at its worst between March and May-03, drastic forms of restrictions were imposed on travelers, forced investigations at airports and quarantine in many countries. These measures are believed to have been an important contributing factor to the cessation of the epidemic and are likely to be relevant in the wake of a new epidemic.


Further Reading