Kei te piki haere tonu ngā mate rewharewha o te ao. E ai ki te World Health Organization (WHO),neke atu i te 27 ngā whenua, i Ūropi me Amerika Te Raki te nuinga, kua whakaūngia ngā kēhi. Kua kitea e ētahi atu pūrongo ngā kēhi kua whakaūngiai roto i te neke atu i te 30.

Kāore te āhuatanga e tino haereka whanake hei mate urutā, engari kei reira ētahi tohu āwangawanga. Ko te mea nui pea ko te kore e kitea he hononga i waenganui i ngā kēhi katoa, ā, ko ētahi kēhi takitahi kāore he hononga mārama ki tētahi pakarutanga o nāianei. He tohu tēnei ki tētahi raruraru rapu, ā, e kī ana he maha ngā kēhi hono kāore e kitea.