With MDR-TB, children are by far the most at risk
It is estimated that between 10-15% of TB cases each year occur in children. Given the known rates of TB in children in South Africa (where all children are vaccinated at birth), it's possible that these percentage rates may be even higher in Africa.
Whatever the rate may truly be, it's likely that something similar occurs in new MDR-TB cases.
Astonishingly, despite most drugs being about fifty years old, only two second line drugs have been developed as paediatric formulations - and even these are not widely available.
What this means is that treatment providers have to risk manipulating adult doses by breaking or crushing tablets to guess the required dose. Naturally this carries major risks of over- or under-dosing each child.
In addition, safety and efficacy data for children simply do not exist for the majority of the medicines used in DR-TB treatment.
In fact only three second line drugs are actually licensed for use in children - and one of these is only approved for a maximum of fourteen days, when the child might need it for two years. For another of these three drugs different guidelines offer different recommendations, so there is simply no current clarity regarding the safety and efficacy of this drug.