Nur weil wir das diskutiert haben, ist es noch nicht gesichert. Ich bin da wie bekannt skeptisch und habe noch keine verlässliche Quelle mit eben diesem Nachweis gefunden.
Zusammenfassung:
Fuer Influenza ist es nachgewiesen - es wurden Menschen infiziert mit verschieden Dosen.
Fuer SARS-CoV-2 gibt es sehr widerspruechliche gegensaetzliche Veroeffentlichungen.
Dennoch fand man beim verwandten SARS und MERS ebenfalls einen Zusammenhang zwischen Inital Dosis und Verlauf im Tiermodell.
Fuer mich sprechen allerdings einige Dinge dagegen das die Dosis keine Rolle spielt.
Wenn man Infektionsketten nachweisen konnte dann waren es doch immer Mensch zu Mensch Uebertragungen.
Ich fand nichts das z.B. ein infizierter Verkäufer einer Baeckerei ueber Backwaren oder Geld zum Ursprung eines Ausbruchs geworden waere.
Dann schauen wir doch mal was wir noch finden koennen mit Tante Google
Virus Last und Infektion
Prof Wendy Barclay, Action Medical Research Chair Virology, and Head of Department of Infectious Disease, Imperial College London, said:
“In general with respiratory viruses, the outcome of infection – whether you get severely ill or only get a mild cold – can sometimes be determined by
how much virus actually got into your body and started the infection off.
It’s all about the size of the armies on each side of the battle, a very large virus army is difficult for our immune systems army to fight off.
“So standing further away from someone when they breathe or cough out virus likely
means fewer virus particles reach you and then you get infected with a lower dose and get less ill.
Doctors who have to get very close to patients to take samples from them or to intubate them are at higher risk so need to wear masks.
Professor Willem van Schaik, Professor in Microbiology and Infection at the University of Birmingham, said:
“The minimal infective dose is defined as the lowest number of viral particles that cause an infection in 50% of individuals (or ‘the average person’).
For many bacterial and viral pathogens we have a general idea of the minimal infective dose but because SARS-CoV-2 is a new pathogen we lack data.
On the basis of previous work on SARS and MERS coronaviruses,
we know that exposure to higher doses are associated with a worse outcome and this may be likely in the case of Covid-19 as well.
Dr Edward Parker, Research Fellow in Systems Biology at the London School of Hygiene and Tropical Medicine, said:
The amount of virus we are exposed to at the start of an infection is referred to as the ‘infectious dose’.
For influenza, we know that that initial exposure to more virus – or a higher infectious dose –
appears to increase the chance of infection and illness. Studies in mice have also shown that
repeated exposure to low doses may be just as infectious as a single high dose.
Das hier ist interessant weil es einen Unterschied macht zwischen Nachweisbarkeit und Infektionsrisiko auf Oberflaechen
From Prof Richard Tedder, Visiting Professor in Medical Virology, Imperial College London:
Of course, when one deals with infectivity rather than detectability, extinguishing infectivity is far quicker.
Studies with cultured virus starting at relatively high levels have shown loss of infectivity within around 12-15 hours on copper, under 10 hours on cardboard, around 50 hours on steel and 70 hours on plastic.
Oder das hier:
www.cebm.net
The evidence suggests an association of viral dose with the severity of the disease....
1918-19 Spanish Flu pandemic.
Simulation models showed that the infectious dose was related to the number of simultaneous contacts a susceptible person has with infectious ones;
that severe cases of influenza result from higher infectious doses of the virus; and over-crowded places are the ideal environment for a susceptible person to be exposed to very high infectious doses of influenza.
- High infectious dose and influenza disease progression have been shown in experimental animals;
- The high infectious dose is associated with a higher viral load; and
- The high infectious dose is associated with a smaller period of time to maximum viral load. [2]
Beste Gruesse Bernd
Da brauchst schon ziemliche Widerstandskraft um dem Insgesichtfassenreflex nicht nachzugeben. Und ja, Handschuhe helfen da