Doun Kaev

Researchers are studying how the immune system responds to viruses that can pass from animals to humans, focusing on healthy adults aged 18 to 65 years in Cambodia. The study aims to understand immunity to specific zoonotic viruses such as H5N1, Nipah virus, and bat coronaviruses by recruiting people with high-risk exposure to animals or their waste, or who live near animal habitats like bat caves or markets. This observational research is conducted by Cambodian and NIH scientists to gather important immune data without direct intervention. Participants provide blood samples to help identify immune responses to these viruses. The main procedure involves collecting 30 mL of whole blood at the start of the study, with up to two optional additional collections at least 30 days apart, between six months and two years after enrollment. The study focuses on analyzing antibodies and immune cells that react to viral proteins at various time points. During the study, participants will have blood drawn and may attend up to three visits over a period ranging from 180 to 720 days. Researchers will measure antibody activity and isolate specific immune cells from plasma samples to better understand immune signatures. The study monitors participant health and stores samples and data for future research, all while ensuring voluntary participation and informed consent throughout the process.

Vector-borne diseases, caused by bites from infected mosquitoes, flies, fleas, ticks, or other blood-feeding insects, result in nearly one million deaths annually and are increasing, especially in Southeast Asia. In Cambodia, these diseases may account for about 10 percent of fevers, but many cases go undiagnosed. This research aims to better understand the range of febrile illnesses by using advanced metagenomic sequencing to identify pathogens in affected individuals. Participants include people aged 2 months and older who have a fever of at least 38 degrees Celsius or are diagnosed with a concerning pathogen. Close contacts of infected individuals may also join. The study collects blood samples, and for those with respiratory symptoms, nasal swabs. Participants share information on their age, sex, health history, and recent travel. If a highly transmissible or virulent pathogen is found, follow-up samples and testing of close contacts are performed to deepen understanding of disease spread. During the study, participants undergo screening with medical history review and physical assessments such as weight for children. They complete questionnaires and provide biological samples for pathogen identification. Optional follow-up samples may be collected within 1 to 2 weeks and again at 3 months after enrollment. Researchers measure pathogen sequences and immune responses to vector saliva proteins. The study continues through July 2027, aiming to improve knowledge of febrile diseases in Cambodia.