Severe acute respiratory syndrome

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Classification according to ICD-10
U04.9 Severe acute respiratory syndrome [SARS], unspecified
J17.1 * Pneumonia in Viral Diseases Classified Elsewhere
ICD-10 online (WHO version 2019)

The Severe acute respiratory syndrome , or Severe Acute Respiratory Syndrome ( english severe acute respiratory syndrome , SARS ) is an infectious disease , the first time in November 2002 in the southern Chinese province of Guangdong was observed. According to the Bernhard Nocht Institute for Tropical Medicine in Hamburg, the clinical picture corresponds to an atypical pneumonia . The SARS pathogen was a previously unknown coronavirus , which is now referred to as the " SARS coronavirus " (SARS-CoV-1). The first major outbreak of the disease was the SARS pandemic in 2002/2003 with almost 800 fatalities.

Pathogen

Non- scale illustration of a related virus in the Coronaviridae family

discovery

Bacterial pathogens such as chlamydia , mycoplasma or legionella , which normally cause atypical pneumonia , were not found in this new form. Since the sick did not respond to treatment with antibiotics , the assumption was made that the pathogen is a virus .

Initially, paramyxoviruses were suspected to be the cause of SARS. Around March 26, 2003, however, the suspicion that the pathogen belongs to the Coronaviridae family was reinforced . It was identified as a new coronavirus at the same time at the University of Hong Kong , the Centers for Disease Control and Prevention in Atlanta and the Bernhard Nocht Institute for Tropical Medicine in Hamburg. Based on the gene sequences, it is assumed that a known coronavirus is either mutating or that a type of virus that has previously only attacked animals has "jumped over" to humans. Further investigations therefore focused on the newly discovered coronavirus and, as further factors, on chlamydia and paramyxoviruses. So far nothing has been found "that speaks against the causal role of the coronavirus," it said from specialist circles. On April 12, 2003, Marco Marra, director of the Michael Smith Genome Sciences Center of the British Columbia Cancer Agency, announced that he and other Canadian researchers had succeeded in deciphering the virus's RNA sequence . Four days later, the WHO released a press release stating that the coronavirus identified by several laboratories was the official cause of SARS. It was given the scientific name " severe acute respiratory syndrome coronavirus " (SARS-CoV). Two days after the virus was identified, virologists Christian Drosten and Stephan Günther from the Bernhard Nocht Institute were the first to develop a diagnostic test that is now used worldwide.

ancestry

Some experts initially suspected that the virus behind the Asian lung disease could originate from rare wild animals as the main host ( reservoir host ) (e.g. the larvae roller ( Paguma larvata ) from the clown cat family ), which are eaten as a delicacy in southern China. The latter is supported by reports in the Singapore daily Lianhe Wanbao that the disease may have originated from a chef at a specialty restaurant for wild animals in Shenzhen , southern China. Even virologists a WHO team find this theory plausible. Cockroaches have been identified as vectors for the mechanical transmission of viruses .

In September 2005, a study of various wild animals in the greater Hong Kong area found that the SARS coronavirus is also transmitted by bats. The animals are Chinese horseshoe bats ( Rhinolophus sinicus ). Coronaviruses were found in forty percent of the smears that are genetically very similar to the SARS pathogen identified in humans and in larval rollers. The bats showed no signs of disease. In 2013 and 2017 further genetic evidence was published that refer to Chinese horseshoe bat as a reservoir host. However, it is still not clear whether bats or crawling cats are the original reservoir host of the virus. The Chinese bats could also be a direct vector of transmission to humans, as they are considered a delicacy, like crawling cats, and their feces are used in traditional Chinese medicine ( TCM ).

transmission

The original assumption that the virus was not very resistant to air also had to be revised. According to recent findings, it survives outside the human body for up to 24 hours. A transmission via air conditioning is still considered unlikely.

The pathogen is mainly transmitted by droplet infection from a short distance and thus through contact with coughing and sneezing infected people. The indirect route via contact infection or smear infection with the viruses of the infectious expiratory droplets that have fallen on objects or body surfaces when they subsequently pass through the mucous membranes z. B. can get into the body in the mouth, nose or eyes, cannot be ruled out. Transmission via body excretions (the faecal-oral route) cannot be ruled out either. Furthermore, according to the WHO, pathogen transmission through infected animals (e.g. cockroaches ) is possible.

The X-ray image of the lungs of a SARS patient shows diffuse patch-like densities or so-called "milk glass" over both subfields that exceed the lobe borders . In comparison to typical bacterial pneumonia, there is no positive bronchopneumogram .

Symptoms

The incubation period is two to seven days. According to the World Health Organization, symptoms are :

Initial laboratory tests indicate that a decrease in the number of blood platelets ( thrombocytopenia ) and white blood cells ( leukocytopenia ) is also a consequence of the disease.

therapy

There are no special treatment measures yet. At that time, doctors initially administered the nucleoside analogue ribavirin , which is also used in hepatitis C , as well as cortisone as an antiviral . Afterwards, those affected were usually given a mixture of different antibiotics to heal the accompanying inflammation of the airways caused by bacteria, because the additional bacterial infection is what makes pneumonia so dangerous. The RNA sequence of the suspected SARS pathogen was later deciphered in Canada, but the development of an effective drug is not yet in sight. With the help of the genetic data, new diagnostic methods could be developed; but it will take an indefinite amount of time before drugs or vaccines are available.

Vaccine development

The US research team led by Hilary Koprowski changed in early 2005 tomato and tobacco plants so that the plants a part of the so-called genetically Spike - protein produce the SARS virus. The protein obtained in this way, which is normally located in the outer shell of the virus and helps the pathogen to penetrate human cells, has now been successfully tested as a vaccine against the virus in mice. However, more studies are still needed to better administer the vaccine.

Follow-up of the patient and antibody formation

Around 25% of the SARS patients who were cared for at a military hospital in Beijing after discharge showed remaining changes in the lung structure in the sense of pulmonary fibrosis . 40 patients had a measurable impairment of the diffusion capacity of the lungs. This improved spontaneously in half of those affected. The pulmonary fibrosis shown on the radiograph also showed a tendency to improve in the one-year follow-up period, but did not completely disappear in all patients. The authors hypothesized that the improvement was due to a different mechanism from that in common pulmonary fibrosis. In the same study, IgG antibodies to the virus were found in around 80% of patients. Due to the change in the antibody titers over the course of the disease, the authors assume that the immunity is limited in time.

A very small study consisting of infected health care workers followed patients for 15 years. This showed an improvement in the lung damage of the patients who had radiologically detectable residues of the disease after healing. After one year, however, a plateau phase with mild restrictive disorders and diffusion disorders set in . The femoral head necrosis observed in the previous follow-up examinations was seen as a late consequence of steroid therapy as part of the treatment of SARS.

Warnings

On March 12, 2003, the World Health Organization (WHO) classified SARS as a global threat.

Reporting requirement

In Austria, SARS (Severe Acute Respiratory Syndrome) is a notifiable disease in accordance with Section 1 (1) of the 1950 Epidemic Act . The obligation to notify relates to suspected illnesses and deaths. Doctors and laboratories, among others, are obliged to report this ( Section 3 Epidemics Act).

In Switzerland there is mandatory reporting of SARS in terms of clinical suspicion, consultation with specialist or a specialist in infectious diseases. Initiation of a pathogen-specific laboratory diagnosis and epidemiological connection by the attending physician. In addition, in the event of positive and negative laboratory findings for the SARS coronavirus pathogen by the examining laboratory. This results from the Epidemics Act (EpG) in conjunction with the Epidemics Ordinance and Annex 1 or Annex 3 of the Ordinance of the FDHA on the reporting of observations of communicable diseases in humans .

literature

  • 1st floor: Coronaviruses: causative agents of SARS and other infections. In: Medical monthly for pharmacists , 2004, 27/1, pp. 4–12, ISSN  0342-9601 .
  • S. Hecker: SARS and bird flu - the knowledge gaps. In: Österreichische Ärztezeitung , 4/2004, pp. 30–31, ISSN  0029-8786 .
  • R. Gottschalk: New and highly infectious pathogens - disease protection by the public health service using the example of SARS. Academy for Public Health, Düsseldorf 2005, ISBN 3-9807313-5-9 .
  • Michael Schillmeier , Wiebke Pohler: Cosmo-political events. On the social topology of SARS . In: Soziale Welt , 2006, no. 4, pp. 331–349.

Web links

Commons : SARS  - collection of images, videos and audio files

Individual evidence

  1. ↑ Barbara Bertisch: Small Influenza History . 2009
  2. ↑ WHO: SARS cases
  3. ^ Bernhard Nocht Institute for Tropical Medicine: Virologists from the Tropical Institute receive a prize from the Werner Otto Foundation. December 4, 2003, accessed on January 21, 2020 (German).
  4. ↑ Xing-Yi Ge et al .: Isolation and characterization of a bat SARS-like coronavirus that uses the ACE2 receptor. In: Nature . Volume 503, 2013, pp. 535-538, doi: 10.1038 / nature12711
  5. ↑ Ben Hu, Lei-Ping Zeng, Xing-Lou Yang et al. : Discovery of a rich gene pool of bat SARS-related coronaviruses provides new insights into the origin of SARS coronavirus. In: PLoS Pathogens. 13 (11): e1006698, doi: 10.1371 / journal.ppat.1006698
    Bat cave solves mystery of deadly SARS virus - and suggests new outbreak could occur. On: nature.com from December 1, 2017
  6. ^ Maren Oldbod: SARS transmission, diagnostics and therapy .
  7. ↑ Pogrebnyak et al .: Severe acute respiratory syndrome (SARS) S protein production in plants: Development of recombinant vaccine . In: Proceedings of the National Academy of Sciences , 102 (25), p. 9062.
  8. ↑ L. Xie, Y. Liu, B. Fan et al .: Dynamic changes of serum SARS-Coronavirus IgG, pulmonary function and radiography in patients recovering from SARS after hospital discharge. Respir Res 6: 5 (2005). doi: 10.1186 / 1465-9921-6-5
  9. ↑ P. Zhang, J. Li, H. Liu et al .: Long-term bone and lung consequences associated with hospital-acquired severe acute respiratory syndrome: a 15-year follow-up from a prospective cohort study. Bone Res 8, 8 (2020). doi: 10.1038 / s41413-020-0084-5
  10. ^ WHO issues a global alert about cases of atypical pneumonia. WHO , March 12, 2003, accessed December 22, 2012 .