A government-led study into a mysterious mass outbreak of HIV in Battambang province’s Roka commune has found that the virus was most likely transmitted via injections or intravenous drips.
In a joint statement issued Friday, the Health Ministry’s National Center for HIV/AIDS, Dermatology and STD (NCHADS), the World Health Organization (WHO) and UNAIDS identified the use of injections or intravenous infusions for medical reasons as the top risk factor for 212 residents of Sangke district’s Roka commune who tested positive for the virus between December 8 and 31.
“The study showed that the percentage of people that reported receiving an injection or intravenous infusion as part of their health treatment was significantly higher among the people who tested positive for HIV than the people who were HIV negative,” the statement says. “This difference is statistically significant.”
Seventy-five of the 212 people had also been tested for Hepatitis C as of December 31, with nearly 50 percent testing positive, the statement says. Hepatitis C is predominantly spread via infected blood, especially when syringes or needles are shared.
The study found that other possible forms of transmission—namely engaging in unprotected sex and injection drug use—were unlikely to be the main factor in the outbreak, as there was no significant difference in the answers to survey questions about those habits provided by HIV-positive and HIV-negative villagers, the statement says.
Mother-to-child transmission was also likely not a factor in the cases, it says, “as most of the children and young people who tested HIV positive had an HIV negative mother.”
According to the statement, 78 of the infected villagers started antiretroviral therapy between December 22 and 31.
Of the 212 Roka commune residents who tested positive for HIV, the statement says, 18 percent were under the age of 14, 60 percent were between the ages of 15 and 59, and 22 percent were over the age of 60. The majority of them, 82 percent, lived in the commune’s Roka village.
Yem Chrin, an unlicensed doctor from Roka village who made house calls throughout the commune, was jailed on murder charges on December 22. Mr. Chrin regularly treated his patients using injections, and admitted to reusing syringes on multiple occasions.
But the survey carried out as part of the HIV study in Roka commune—which polled 300 villagers, roughly one-third of whom had tested positive for HIV—did not ask respondents whether they were treated by Mr. Chrin, Masami Fujita, the WHO’s HIV team leader in Cambodia, said Sunday.
“It was not a criminal investigation. The purpose was not to point out any specific individual; that is the purpose of a criminal investigation,” he said.
Mean Chhi Vun, director of NCHADS, which has been leading the study, said it was not the “duty” of his team to determine whether the affected villagers had been treated by Mr. Chrin.
Mr. Chhi Vun said that HIV-positive villagers were continuing to be tested for Hepatitis C, while blood samples from those individuals had been sent to South Korea to determine whether they shared the same HIV subtype, which can further narrow down the mode of transmission.
“We have not received the test results yet from the laboratory [in South Korea],” he said.
Provincial police raided Mr. Chrin’s home on December 18 and seized dozens of used syringes and needle tips.
Heng Luy, a deputy prosecutor at the Battambang Provincial Court who is in charge of the murder case against Mr. Chrin, said the medic’s equipment was currently being tested.
“His equipment has been sent to Pasteur Institute to test for AIDS [HIV],” he said. “I have not got the test results yet.”
