The health of millions of indigenous people across Asia is at risk, experts say, as lack of recognition of their legal status hinders data collection, making their medical problems invisible in most national health surveys.
Indigenous peoples - defined by the UN as people with ancestral ties to a geographical region who retain "distinct characteristics" from other parts of the population - rank disproportionately high in most indicators of poor health, according to the UN Secretariat Department of Economic and Social Affairs.
"It is very regrettable that governments and their offices are reluctant to, or unable to, reveal the state of health of their indigenous populations," Michael Gracey, co-author of a 2009 medical study on indigenous health, told IRIN.
Approximately two-thirds of the world's estimated 300 million indigenous people live in Asia (207 million), according to 2011 estimates by the UN Population Fund (UNFPA).
Lack of education, geographic isolation and prejudice marginalize Asia's indigenous populations, boosting their risk for preventable sexually transmitted infections (STIs), according to the Joint United Nations Programme on HIV/AIDS (UNAIDS).
More than 40 percent of hill tribe women and girls in Thailand who migrate to cities for work end up in the sex industry, according to the International Fund for Agricultural Development (IFAD).
In the Greater Mekong region, home to 95 ethnic groups in Myanmar, Cambodia, Laos, Vietnam and Thailand, health education is often not conducted in native languages, said David Feingold, coordinator for the Bangkok-based Trafficking and HIV/AIDS Project at the UN Educational Scientific and Cultural Organization (UNESCO).
"No information guarantees bad choices, so it's not surprising that the Greater Mekong minorities are disproportionately represented amongst HIV-positive populations."
In part because of poor hygiene conditions in Vietnam's northern Ha Giang Province, gynaecological infections remain a persistent problem for women from the Hmong, Dao, Tay, and Nung groups who live in Hoang Su Phi District, according to the Thailand-based NGO, Asia Indigenous People's Pact (AIPP).
Only 24 percent of households in the district have potable water and almost no households have latrines or toilets, reported AIPP. "Even if there are health services available, they are of poor quality," said Shimreichon Luithi Erni, the coordinator for women's issues at AIPP.
Stateless and sick
Statelessness worsens the chances an indigenous person can afford healthcare, according to UNESCO. Almost four out of 10 hill tribe people in Thailand are not citizens and are, therefore, ineligible for national healthcare and formal employment, said Feingold.
In addition, resettlement increases health vulnerabilities, according to the UK-based indigenous rights NGO, Survival International.
"To tribal peoples, the connection to their land is so fundamental and central to their wellbeing that removal from it is almost inevitably devastating, nutritionally, psychologically and physiologically," said Sophie Grig, Survival's senior campaigner.
But without more health data, it is hard to know which problems to tackle. "There is insufficient disaggregation of data on indigenous people's health that could be used to advocate for specific interventions targeting their needs," said Anne Harmer, UNFPA's socio-cultural technical adviser for Asia.