Problem
As you know, TB is a serious problem around the world. After the fall of the USSR in 1990, overcrowded Russian prisons experienced high TB prevalence, but didn't have enough antibiotics to treat them. The infection must be treated for 6+ months to be fully cured. So prison health workers cut pills in half and split the doses among prisoners. This is thought to be one of the major sources of multi-drug-resistant (MDR) strains. There are now extensively drug-resistant strains (XDR-TB) as well, untreatable by virtually any antibiotic.
In order to stop resistance, a 1960s protocol, Directly Observed Therapy (DOT) was resurrected in several countries, including China and Haiti. When it proved effective at controlling TB without the evolution of resistance, it became the WHO standard for anyone at risk of skipping, selling, or cutting pills.
1. What about the biology of TB means it has to be treated for so long?
2. Why did the sharing of pills in Russia increase drug resistance?
3. How does DOT work to slow resistance?