[valarauko]

The majority of healthy people develop a latent infection, and won't manifest symptoms in their lifetimes. The bacteria are encapsulated into nodules by the immune system, which weaken if the immune system weakens. The bacteria escape and active symptomatic infection occurs.

[dyauspitr]

Yeah but the US has very low levels of latent TB in the population at only 4%. Compared that to places like Brazil where 40% of the population has latent TB. It’s not the climate because in Russia 80% of the population has latent TB.

[toast0]

In order to get latent TB, you need exposure to someone with active TB. If someone with active TB meets the healthcare system, you get a rapid response from health departments. In May 2024, the Long Beach, CA declared a public health emergency [1] based on a cluster of 14 cases. This kind of reaction is typical and makes it difficult to spread to others, and keeps the levels of latent TB low.

[1] https://www.longbeach.gov/press-releases/official-city-of-lo...

[valarauko]

Yes, and it's a self-perpetuating cycle. If so few people have latent TB, fewer people develop active TB that will go on to infect others. As other comments have mentioned, poverty and its resultant poor health is the biggest correlation for developing active TB. I wonder if most of the Russian latent infections happened during the Soviet/Post Soviet collapse era, with newer latent infections falling off as quality of life improved over time?

[fuoqi]

80% sounds like a BS number. It's cited on Wikipedia, but references are either "opinions" or do not contain such information at all.

A proper study [1] shows mean infection rate of ~20% in the worst regions (Far East and North) with the highest rate up to 47%. The situation should be better in the western regions. For comparison, in the US studies show ~4% infection rate [2], so situation in Russia is relatively bad, but improves steadily since 90s and it's far from being catastrophic as the 80% number paints it.

[1]: https://www.tibl-journal.com/jour/article/view/1706

[2]: https://www.cdc.gov/tb/hcp/clinical-overview/latent-tubercul...