Saturday 12 August 2017

human biology - We know that the hepatitis C virus can live on surfaces for at least six weeks. Maybe longer. The infectivity study ended after just six weeks; why?




A paper has found that the hepatitis C virus (HCV) can remain infective for at least six weeks on ordinary household surfaces. You can see the free full text, or a summary for busy clinicians.


Elsewhere, Brian Krause has added:


"They tested their samples for (up to) 6 weeks. At the time of the 6th week they still found infectious virus. They did not test samples beyond 6 weeks, so they can't say anything about infection past that time."



So, at six weeks, they saw that the virus was still infective. Why might they have ended the study right away instead of continuing it for a few more months?



Answer



They ran out of samples


Their test is destructive, they can't test the same sample twice. They planned out a number of samples to test for each time period and tested them. At the end of six weeks, they were done.


It doesn't really matter


The point of the paper is that HCV is infectious long-term on surfaces when not cleaned properly, indicating there is a risk of fomite transmission long after an infected patient leaves the area.



They also show that if surfaces are cleaned, the virus is killed effectively. The authors are not advocating to quarantine a hospital room until any residual HCV dies from air exposure, they are advocating being sure to appropriately clean hospital surfaces to prevent potential disease.


It isn't typical (in fact, it is impossible) for a single scientific study to answer all open questions in one shot. If someone wants to put an upper bound on the duration that HCV remains infectious in the world they can do a new study with longer time points.


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