A medical doctor working for the NGO, the Australia West Papua Association, says figures showing a jump in the number of people affected by HIV/AIDS in Indonesia's Papua and West Papua seems conservative.
Latest health figures report the number of people living with HIV/AIDS there has risen by more than 30 percent to over 17,000 in just four months.
But Dr Anne Noonan, who has worked there, says she believes the actual number is likely to be much higher.
She says many Papuans don't go to the few clinics available as there is limited medication on offer, and others don't trust local health officials.
"One of the big problems, I think, is that West Papuans have a lot of misgivings about Indonesian medical services. There's a lot of deliberate infection of HIV by Indonesian medical services, and so they don't usually go as much as they would, say, in Australia."
Dr Anne Noonan says there's also a belief among local people that HIV AIDS symptoms is linked to witchcraft.