New video released by the Peruvian government shows a potentially disastrous encounter between tourists and indigenous people long isolated from the outside world. In a motor boat tourists follow a group of Mashco-Piro people walking along the shores of the Manu River in Manu National Park. At one point one of the tribal members prepares to fire at the boat with an arrow. But danger doesn't only come from the possibility of a violent clash: uncontacted indigenous people, those who have chosen isolation from the world, are incredibly susceptible to disease.
According to indigenous-rights group Survival International, uncontacted people from the Mashco-Piro tribe have been seen numerous times recently in the park with one ranger being hit by an arrow without a tip as a message to back off.
Tourists have also been accused of leaving clothes for the indigenous people, a practice that could threaten the lives of tribal peoples since the clothes could carry disease.Ed - emphasis and :banghead: added
Survival International says the area where the indigenous people have been seen is a restricted zone.
The Peruvian government says it is working on mitigating the issue, by warning tourists not to approach indigenous people and updating policies related to isolated tribes.
EDIT
http://news.mongabay.com/2011/1019-hance_tourists_indigenous.html