When you’re a kid in Honduras, trapped in the cycles of deprivation, what’s a good way to forget your troubles for a while? Easy. You proudly show off your makeshift toy bow and arrows to your pals. It’s a moving image – one of many in Nick Danziger’s compelling new book of photojournalism. After all, when the kids stop playing, then we’ll really be done for.

Not that many of the characters portrayed in the book have much time for fun. We meet 13-year-olds scraping a living in Niger’s gold mines and Armenian children coping with horrible diseases. They are already on what Danziger calls the treadmill: the endless struggle to keep going in the face of poverty, squalor and fear. There’s one deceptively lovely image of several dozen boys crammed into a night shelter in Uganda and you’re tempted to think that, as soon as the lights go out, all sorts of innocent mischief will ensue. No such luck. The boys spend their nights worrying that rebel troops will turn up and cart them off to become child-soldiers.

The UN made big plans at the turn of the millennium: to improve water, education, female empowerment and much else besides. In some areas, notably the fight against disease, a lot has improved. But too much remains the same. Danziger has repeatedly visited the front lines – from Burma to Armenia, from Cambodia to Honduras – and taken some dazzling snaps. He lets the images speak for themselves, with only brief captions alongside, and this is far more eloquent than page after page of indignant commentary. Danziger is winningly frank about his status in such environments. He is set apart (he ‘always has a ticket home’) and he is, inevitably, an intruder. But the condescension that is so often packed in the well-intentioned Westerner’s kit-bag is absent. Danziger just takes photos: of smiles, of sorrows, of silly daily chores, and of labours that ought to crush the spirit.