Tuberculosis Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! === Transmission === When people with active pulmonary TB cough, sneeze, speak, sing, or spit, they expel infectious [[aerosol]] droplets 0.5 to 5.0 [[Β΅m]] in diameter. A single sneeze can release up to 40,000 droplets.<ref name=Cole_1998>{{cite journal | vauthors = Cole EC, Cook CE | title = Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies | journal = American Journal of Infection Control | volume = 26 | issue = 4 | pages = 453β64 | date = August 1998 | pmid = 9721404 | doi = 10.1016/S0196-6553(98)70046-X | pmc = 7132666 }}</ref> Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very small (the inhalation of fewer than 10 bacteria may cause an infection).<ref>{{cite journal | vauthors = Nicas M, Nazaroff WW, Hubbard A | title = Toward understanding the risk of secondary airborne infection: emission of respirable pathogens | journal = Journal of Occupational and Environmental Hygiene | volume = 2 | issue = 3 | pages = 143β54 | date = March 2005 | pmid = 15764538 | doi = 10.1080/15459620590918466 | pmc = 7196697 }}</ref> ==== Risk of transmission ==== People with prolonged, frequent, or close contact with people with TB are at particularly high risk of becoming infected, with an estimated 22% infection rate.<ref name="Ahmed_2011">{{cite journal | vauthors = Ahmed N, Hasnain SE | title = Molecular epidemiology of tuberculosis in India: moving forward with a systems biology approach | journal = Tuberculosis | volume = 91 | issue = 5 | pages = 407β13 | date = September 2011 | pmid = 21514230 | doi = 10.1016/j.tube.2011.03.006 }}</ref> A person with active but untreated tuberculosis may infect 10β15 (or more) other people per year.<ref name="WHO2012data" /> Transmission should occur from only people with active TB β those with latent infection are not thought to be contagious.<ref name="Robbins" /> The probability of transmission from one person to another depends upon several factors, including the number of infectious droplets expelled by the carrier, the effectiveness of ventilation, the duration of exposure, the [[virulence]] of the ''M. tuberculosis'' [[strain (biology)|strain]], the level of immunity in the uninfected person, and others.<ref name="CDCcourse">{{cite web|publisher=[[Centers for Disease Control and Prevention]] (CDC), Division of Tuberculosis Elimination|url=https://www.cdc.gov/tb/education/corecurr/pdf/corecurr_all.pdf|title=Core Curriculum on Tuberculosis: What the Clinician Should Know|page=24|edition=5th|year=2011|url-status=live|archive-url=https://web.archive.org/web/20120519141115/http://www.cdc.gov/tb/education/corecurr/pdf/corecurr_all.pdf|archive-date=19 May 2012}}</ref> The cascade of person-to-person spread can be circumvented by segregating those with active ("overt") TB and putting them on anti-TB drug regimens. After about two weeks of effective treatment, subjects with [[Antibiotic resistance|nonresistant]] active infections generally do not remain contagious to others.<ref name="Ahmed_2011" /> If someone does become infected, it typically takes three to four weeks before the newly infected person becomes infectious enough to transmit the disease to others.<ref>{{cite web|url=http://www.mayoclinic.com/health/tuberculosis/DS00372/DSECTION=3|title=Causes of Tuberculosis|access-date=19 October 2007|date=21 December 2006|publisher=[[Mayo Clinic]]|url-status=live|archive-url=https://web.archive.org/web/20071018051807/http://www.mayoclinic.com/health/tuberculosis/DS00372/DSECTION%3D3|archive-date=18 October 2007}}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page