4 ms·

Consider the following scenario: a small number of pathogenic bacteria (perhaps 10-100) enter the human body and cause an infection. This might be a naive ques

by nkurz 8y ago

Consider the following scenario: a small number of pathogenic bacteria (perhaps 10-100) enter the human body and cause an infection. This might be a naive question, but why do we want to assume that more than one bacteria was initially introduced? Is it just to increase the chances that at least one will find a suitable habitat and begin to reproduce, or is there actually some sort of group effect happening, whereby a larger initial concentration increases the chances of infection more than random chance would imply?

nonbel 8y ago
It seems unlikely to come into contact with only a single cell... although a strange thing about HIV is that it seems only a single viral particle usually gets transmitted from one person to another. Even though there are millions of variants in each infected person only a single one is usually passed on: >"The reverse transcriptase of HIV lacks proofreading activity, the ability to confirm that the DNA transcript it makes is an accurate copy of the RNA code, and confers a mutation rate of approximately 3.4×10−5 mutations per base pair per replication cycle. Since the HIV genome is an estimated 104 base pairs in length and the baseline rate of viral production is approximately 1010 virions per day, millions of viral variants are produced within any infected person in a single day." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614444/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614444/ >"Transmission of a single viral variant occurs in about 76–90% of cases of heterosexual transmission [2], [6], [7], in about 60% of cases of HIV-1-infected men who have sex with men (MSM) [5], and only in about 40% of injection drug users (IDU) who acquired HIV-1 infection [4]." https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016714 https://journals.plos.org/plosone/article?id=10.1371/journal...

by nkurz 8y ago

nonbel 8y ago

It seems unlikely to come into contact with only a single cell... although a strange thing about HIV is that it seems only a single viral particle usually gets transmitted from one person to another. Even though there are millions of variants in each infected person only a single one is usually passed on: >"The reverse transcriptase of HIV lacks proofreading activity, the ability to confirm that the DNA transcript it makes is an accurate copy of the RNA code, and confers a mutation rate of approximately 3.4×10−5 mutations per base pair per replication cycle. Since the HIV genome is an estimated 104 base pairs in length and the baseline rate of viral production is approximately 1010 virions per day, millions of viral variants are produced within any infected person in a single day." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614444/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614444/ >"Transmission of a single viral variant occurs in about 76–90% of cases of heterosexual transmission [2], [6], [7], in about 60% of cases of HIV-1-infected men who have sex with men (MSM) [5], and only in about 40% of injection drug users (IDU) who acquired HIV-1 infection [4]." https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016714 https://journals.plos.org/plosone/article?id=10.1371/journal...