"Primates of the Greater Mekong: Status, Threats and Conservation Efforts" notes that the region — which includes Vietnam, Cambodia, Laos, Thailand and Myanmar — is home to 44 known primate species, 19 of which are only found in this part of the world. 

Vietnam is home to 24 species, the most in the region, but almost all of these primates are in trouble across the Greater Mekong: 11 are considered critically endangered, and another 21 are endangered, according to the IUCN Red List. 

Some of these animals have the benefit of a relatively wide distribution area, but others, such as Vietnam's Cát Bà langur, are only found in one location, and thus at particular risk of further population loss.

"Deforestation, habitat degradation and poaching driven by trade and consumption have forced many primate species to the brink of extinction," the report states. "Additionally, there is the potential for human pathogens to jump to primates, threatening them with deadly epidemics."

While much of this is bleak, WWF also notes that very targeted conservation efforts are ongoing. In Vietnam, protected areas specifically intended for the Delacour's and Cát Bà langurs have been created, while the Endangered Primate Rescue Center in Cúc Phương National Park is attempting to breed threatened species that could be reintroduced to the wild. 

The authors highlight a number of conservation NGOs working in the region, and ultimately conclude that "We must make all necessary efforts for the long-term survival of these fascinating, diverse and iconic primates of the Greater Mekong."