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Ars Technica reports on a paper in PNAS that suggests the use of fire might have paved the way for Tuberculosis to become the killer it has been over our entire history.
How could fire influence transmission? The authors suggest that it enabled new contexts for human social interactions and thus transmission. Fires provided social focal points for early humans, particularly when food was being prepared or consumed or after daylight hours. The maintenance of a fire would have required increased cooperation and social interaction, all of which increased the probability of infectious disease transmission.
Additionally, the inhalation of smoke from fires, particularly in enclosed or indoor spaces, likely made the pulmonary tissues of early humans especially sensitive to infection. In support of this idea, the authors cite modern epidemiological evidence, which indicates that exposure to smoke from tobacco increases the risk of TB. They suggest that when early humans were tending fires, it was likely under very low ventilation conditions, which would have a similar effect to smoking on pulmonary tissues.
Living in close quarters in scarce shelters was probably bad enough. Adding smoke to irritate the lungs probably left everyone with a cough and a sore throat.
I've been in some of the places where TB stubbornly remained problematic well into the 70s. The Alaskan bush typically had poorly ventilated log cabins, with wood heating and lots of smoke. There is a limit to how much fresh air you want to let in when its 40 below for months on end.
This is a disease that preceded the white man, and history shows it was a problem before Seward bought the place from the Russians. The fight against Tuberculosis in Alaska was a long battle and the disease was a major problem into the early 1970s. In Southeast Alaska, the death rate from tuberculosis in 1932 was 1,302 per 100,000. since then, the rate Alaska Natives (the most impacted group) has declined from 653 per 100,000 in 1950 to merely three times the national average today. (9.2/100,000).
I suppose most of this is due to better medicine and vaccines. But at least some of has to do with modern housing and better heating systems.
(Score: 0) by Anonymous Coward on Wednesday August 03 2016, @10:59AM
It is highly misleading to report mortality rates (either overall or for some specific disease) averaged over all ages. Such stats are pretty much worthless since almost all deaths are in infants or the elderly. Demographic changes can easily cause large swings in mortality rates, so instead there should be a curve presented of rate vs age.
Also, a chronic problem with epidemiology has been that the definitions of diseases (eg what is the gold standard test) have changed a lot since 1900, and this goes totally ignored when comparing mortality/incidence as is done here. I don't know in the case of TB, but it wouldn't surprise me if these rates were comparing totally different things. As more tests are developed, more discriminatory power is available, and the rates of any individual disease drop. This is an extremely common flaw found in the medical literature, but people still get away with it so it continues to be used for all sorts of mischief.