Survival of the sickest
Hittade en Slashdotkommentar om en bok som heter "Survival of the sickest" (ISBN 9780061177644). Den verkar intressant. Den tar upp det faktum att olika sjukdomar är olika farliga för oss beroende på hur den "tänker" sig att spridas vidare. Om man ska bli stucken av mygg, som malaria, ser den till att man blir orörlig och lätt att hitta för mygg. Om den ska sprida sig genom kontakt med många människor så blir den mild. Ur Slashdotkommentaren:
Läs mer: One Species' Genome Discovered Inside Another's
(Styckeindelning av mig)
The book even went over some guidelines for predicting how lethal a disease would be, based on its mode of transmission: typically, we've thought that diseases get less lethal over time because that increases their ability to spread, but the book says it depends on the transmission path. Malaria wants -- inasmuch as a disease can want anything -- people to be very ill indeed, so that they spend lots of time not moving, giving mosquitoes a better chance of finding the people, while colds do want people to be as mildly sick as possible so they can maximize their distribution.
A particularly neat case is cholera, which can be spread by human-human contact, or more usually by contamination of drinking water. In the latter case, the sicker the person, the better, because more bacteria will be voided by the person through diarrhea, while in the former case, milder infections spread more because there's longer-term contact with heath care personnel, meaning more chances to spread.
Watching cholera epidemics in South America, that's exactly what they observed: in countries that were poor, where there wasn't really any official health care, the disease became progressively more lethal over time, while in countries where infected people got immediate health care, the disease got less lethal over time.
Läs mer: One Species' Genome Discovered Inside Another's