North Korea is experiencing an explosive outbreak of HIV amid limited access to diagnostic testing and treatments, according to an exclusive report by Science.

Independent researchers and government health officials tell the outlet that the isolated East Asian country confirmed its first HIV case in 1999 and has quietly watched infections balloon to over 8,300 cases in the last few years. The researchers and North Korean officials have submitted a report on the matter to the new medical preprint server medRxiv, which is scheduled to go live on Tuesday, June 25.

The case estimate stands in stark contrast to a celebration in Pyongyang last year on December 1—annual World AIDS Day—in which government officials declared that North Korea is an “AIDS-free zone” and that there is “not a single AIDS patient” in the country.

The truth of the matter came to light after an unusual collaboration formed. In 2013, North Korean health officials reached out to a US NGO called DoDaum for help tracking the infections. DoDaum already worked on health, education, and development programs in North Korea, and it built up a good rapport with officials. Together, the team worked on assessing the extent of disease spread, particularly in rural areas, as well as the factors driving it.

Blood donors and people who inject drugs appear to be the hardest hit by the outbreak. Efforts to halt the spread of infections have been difficult because there are only three labs in the country that use modern tests to screen for HIV infection. Additionally, international sanctions have made it difficult to import drug treatments, which are not produced domestically. DoDaum says it has helped 3,000 patients gain access to treatment.

North Korean officials at first wanted to stay mum about the outbreak, but they changed their minds amid the discouraging circumstances. Kim Mun Song, a physician and external affairs director at the North Korean Ministry of Public Health in Pyongyang, explained to Science:

On the one hand, reporting the existence of these patients may lead to a backlash from the central government, as they are very much afraid of communicable diseases in general. On the other hand, not reporting and not recognizing the existence will perpetuate the issue of not having treatments.

Moreover, DoDaum co-founder Taehoon Kim expressed concern that the government could criminalize HIV status and detain or deport patients if the situation worsens. Kim Mun Song called this a “realistic concern... But we hopefully will not have to take measures that violate human rights.”