Super spreading

from Wikipedia, the free encyclopedia

Super Spreader ( German  "super spreaders" ) are in the epidemiological context Infected which an unusually high number of organisms with a bacterial or viral pathogens infect. The number of those directly infected by a superspreader is significantly higher than the base reproduction number  - the average number of people, animals or plants infected by an infected organism. Just like super spreaders , certain events or circumstances can significantly contribute to the spread of infectious diseases; these are called superspreading events ( German "super spreading events " ).  

The base number of reproductions often varies widely with individual individuals and events. The dispersion of is determined by the overdispersion parameter in the statistical distribution of . Irregularities in the distribution (over- dispersion ) of are determined by measuring . = 1 means no dispersion, with falling it increases.

Pathogens prone to superspreading

For some infectious diseases such as measles or by coronavirus infectious diseases caused SARS , MERS and Covid-19 which is Superspreading particularly pronounced. James Lloyd-Smith and his colleagues published a study in 2005, according to which out of a group of people infected with SARS and measles, only 20 percent with more than 80 percent were responsible for infecting others. Most infected people therefore do not transmit the disease. At superspreading events , close contacts, loud talking or singing indoors could have led to infection with the SARS-CoV-2 coronavirus . Examples of values in the literature are (u Lloyd-Smith a..) For SARS 0.16 in MERS 0.25 and wherein as Spanish flu designated influenza - pandemic of 1918 to about 1. 19-Covid various estimates are given - in Mean 0.54, a little higher than SARS and MERS. The 20/80 rule is also often observed with HIV , gonorrhea and Ebola , which means that 20 percent of those infected cause 80 percent of new infections.

Examples

During the SARS epidemic in 2003, a hotel in Hong Kong became extremely widespread .

Superspreading events are e.g. B. exposed health workers who come into contact with infected patients, become infected with pathogens and unintentionally pass them on to other patients when they come into contact.

At Super spreader can also flight attendants are who become infected with an infected passenger and pass on germs to other passengers.

Various scientists believe that understanding superspreading can be key to preventing epidemics from spreading . They assume that infectious diseases  spread at the beginning of an epidemic depending on the level of the infection rate - the measure of the spread of a disease, measured by the number of (new) infections in relation to the total population in a certain period of time. But is already at the outbreak taken an epidemic that Superspreading events omitted, also decreases the likelihood of further spread.

“Typhoid Mary” in a newspaper illustration from 1909

A well-known historical example of a super-disseminator was Mary Mallon , better known as Typhoid Mary, who worked as a cook in New York City in the early 20th century and unconsciously infected numerous people with typhoid .

Examples in the 2020 Covid-19 pandemic

At the beginning of the spread of SARS-CoV-2 in Europe, a superspreading event took place in Ischgl, Austria, with over 600 infected people at the beginning of March 2020 . Many then traveled back to their predominantly European home countries (see: Coronavirus pandemic in Ischgl ). In June 2020 it became known that 42.4 percent of the population of Ischgl had developed antibodies against the virus, the highest published value worldwide to date. Only 15 percent of those who tested positive for the antibody had been previously diagnosed with being infected. In the COVID-19 pandemic in the USA, the members of a 61-member choir met for two and a half hours for a choir rehearsal in a church in Mount Vernon (Washington) on March 10, 2020 , interrupted by snack breaks. One of the singers had been showing cold symptoms for three days and was later found to have COVID-19. In the weeks that followed, 53 choir members contracted COVID-19, three of whom were hospitalized and two died as a result of the infection.

The Heinsberg study reports on superspreading events with SARS-CoV-2 at carnival events , in which a highly significant increase in the infection rate and the number of symptoms was found among the event participants. Since it has been shown that in general the rate of particle emission and superemission increases with volume when speaking , and since loud voices and singing are common at such events, it is assumed that a higher viral load the higher intensity of symptoms and thus more severe clinical Caused gradients. Results from experimental studies on influenza infections have shown that the symptom score depends on the dose of virus administered. Similar observations were made with MERS-CoV and SARS-CoV-1 .

In the Berliner Domkantorei there was a superspreading on March 9, 2020, despite the observed intervals . About 60 choir members were infected after virus-containing aerosols  - presumably from an infected choir singer - spread through singing in the room.

Other examples are religious assemblies that played a significant role in the initial phase of the COVID-19 pandemic in France (meeting of over 2000 members of an evangelical free church in Mühlhausen in mid-February 2020) and South Korea (meeting of members of the sect-like Shincheonji community in February 2020 ) played. In Frankfurt am Main on May 10, 2020, several people were infected with the SARS2 corona virus at a Baptist church service in Frankfurt-Rödelheim. The visitors also came from the surrounding communities and districts and, according to the community, usually consisted of families with children, often five or more. According to the deputy chairman of the association, the prescribed distance and hygiene rules were observed during the service, but there was no mask requirement and there was singing. It is believed that around 40 people became infected there and subsequently over 200 people.

Passengers of the cruise ship "Diamond Princess", which in February 2020 Japanese Yokohama under quarantine stand, have infected by a person who went to Hong Kong from aboard with Corona.

In Singapore , after temporary successful action by the government through tough crackdown and systematic follow-up of the infected, a new outbreak occurred in April 2020, which was caused by the cramped living conditions of the more than 320,000 guest workers, mainly from India and Bangladesh, with up to twenty Individuals live in a room in residential areas on the outskirts of the city. Slaughterhouses in the USA and Germany, for example, turned out to be particularly critical hot spots . It was characteristic in Germany that the employees worked closely side by side in the workrooms, which were cooled to six to ten degrees Celsius, and that the companies had a large number of workers, some of whom were recruited via subcontractors and whose composition fluctuated strongly, and largely recruited from other European countries. In June 2020, for example, the large Tönnies meat factory in Rheda-Wiedenbrück was temporarily shut down and a lockdown was imposed on the Gütersloh district when more than 1,500 infected people appeared. In the operation, one of the causes was found to be that the ventilation was insufficient. The air conditioning system supplied insufficient fresh air from outside and circulated the room air, with the risk of aerosols being distributed. According to the hygiene expert Martin Exner, this aspect of ventilation in slaughterhouses had not previously been included in the hygiene concepts. Collective shelters and problems with keeping their distance at work also led to hot-spot risks for seasonal workers in agriculture.

literature

  • Reuven Cohen, Shlomo Havlin , Daniel ben-Avraham: Efficient Immunization Strategies for Computer Networks and Populations. In: Physical Review Letters 91, No. 24 (2003), doi : 10.1103 / physrevlett.91.247901 .
  • Alison P. Galvani, Robert M. May: Dimensions of superspreading. In: Nature 438, No. 7066 (2005), doi : 10.1038 / 438293a , pp. 293-295.
  • Gaston De Serres et al .: Largest Measles Epidemic in North America in a Decade — Quebec, Canada, 2011: Contribution of Susceptibility, Serendipity, and Superspreading Events. In: The Journal of infectious diseases 207, no. 6 (2013), doi : 10.1093 / infdis / jis923 , pp. 990-998.
  • JO Lloyd-Smith, SJ Schreiber, PE Kopp, WM Getz: Superspreading and the Effect of Individual Variation on Disease Emergence. In: Nature 438, No. 7066 (2005), doi : 10.1038 / nature04153 , pp. 355-359.
  • Zhuang Shen et al .: Superspreading SARS Events, Beijing, 2003. In: Emerging infectious diseases 10, No. 2 (2004), pp. 256-260, doi : 10.3201 / eid1002.030732 . PMC 3322930 (free full text).
  • Richard A. Stein: Super-Spreaders in Infectious Diseases. In: International Journal of Infectious Diseases 15, No. 8 (2011), doi : 10.1016 / j.ijid.2010.06.020 , pp. E510-e513.

Web links

Individual evidence

  1. ↑ a b Kai Kupferschmidt: Why do some COVID-19 patients infect many others, whereas most don't spread the virus at all? , Science, May 19, 2020
  2. ^ A b J. O. Lloyd-Smith, SJ Schreiber, PE Kopp, WM Getz: Superspreading and the effect of individual variation on disease emergence , Nature, Volume 438, 2005, pp. 355-359
  3. ↑ What role do superspreaders play in the spread of the coronavirus , Deutschlandfunk, June 3, 2020
  4. ↑ Julien Riou, Christian Althaus: Pattern of early human-to-human transmission of Wuhan 2019 novel coronavirus (2019-nCoV), December 2019 to January 2020], Eurosurveillance, Volume 25, Issue 4, January 30, 2020
  5. ↑ Lars Fischer: Coronavirus could also die out due to super spreading. In: Badische Zeitung , June 15, 2020.
  6. ↑ Wolfgang Kiehl: Infection protection and infection epidemiology. Technical terms - definitions - interpretations. Ed .: Robert Koch Institute, Berlin 2015, ISBN 978-3-89606-258-1 , p.?, Keyword ?
  7. ^ Antibody study: Many citizens of Ischgl were infected , FAZ.net, June 25, 2020
  8. ↑ Santiago Barreda, Nicole M. Bouvier, William D. Ristenpart et al .: Aerosol emission and superemission during human speech increase with voice loudness Scientific Reports volume 9, Article number: 2348 (2019)
  9. ↑ S. Asadi, AS Wexler, CD Cappa, S. Barreda, NM Bouvier, WD Ristenpart: Aerosol emission and superemission during human speech increase with voice loudness . In: Scientific Reports . tape 9 , no. 1 , February 2019, p. 2348 , doi : 10.1038 / s41598-019-38808-z , PMID 30787335 , PMC 6382806 (free full text). . Quoted from: Hendrik Streeck, Bianca Schulte et al .: Infection fatality rate of SARS-CoV-2 infection in a German community with a super-spreading event, page 12
  10. ↑ Hendrik Streeck, Bianca Schulte et al .: Infection fatality rate of SARS-CoV-2 infection in a German community with a super-spreading event, page 12
  11. ↑ Corona and choir - How risky is singing? In: ndr.de
  12. ^ FR from May 26, 2020
  13. ^ Information letter from the Evangeliums Christen Baptisten Frankfurt. In: seiheilig.de , accessed on May 26, 2020
  14. ↑ Tsuyoshi Sekizuka, Kentaro Itokawa, Tsutomu Kageyama, Shinji Saito, Ikuyo Takayama: Haplotype networks of SARS-CoV-2 infections in the Diamond Princess cruise ship outbreak . In: Proceedings of the National Academy of Sciences . July 28, 2020, ISSN  0027-8424 , doi : 10.1073 / pnas.2006824117 ( pnas.org [accessed July 29, 2020]).
  15. ↑ André Groenwood: Singapore: From Model Country to Corona Hotspot , zdf.de, April 28, 2020
  16. ↑ Many infected people, zero trust , tagesschau.de, June 20, 2020
  17. ↑ Oda Lambrecht: Corona outbreak at Tönnies. Air conditioning as a virus thrower , ndr.de, June 24, 2020