Ratchaburi Province lies 100 km west of Bangkok, and has a population of 828,930. Ratchaburi province has high levels of dengue transmission. It ranks among the top 10 provinces for dengue incidence rates in Thailand. The primary health facility in Ratchaburi is the Ratchaburi Regional Hospital, a 855-bed tertiary-care hospital. Local dengue control officers and provincial public health officials are exceptionally motivated and committed to dengue vaccine development. Schoolteachers and parents are very receptive to participation in dengue vaccine studies.

Annual age-specific incidence of dengue cases (per 100,000 population) from passive reporting in Muang District, Ratchaburi:

The specific aims of the PDVI-supported study are: 1. Developing and maintaining a comprehensive active surveillance system for the rapid identification of children with febrile illness, dengue fever and dengue hemorrhagic fever. 2. To determine the epidemiology of symptomatic and apparent dengue virus infection, and, 3. Creating a repository of characterized serum specimens for further studies by qualified investigators.

Symptomatic dengue infections are identified by active surveillance for students with fever ( ≥ 38°C) and clinically suspected dengue infection determined by a pediatrician. Surveillance is performed by providing parents with thermometers to identify fever, and by monitoring the school absenteeism due to illnesses or other reasons. All subjects with acute or history of recent fever are bled for laboratory identification of dengue infection. Asymptomatic dengue infections are identified by dengue sero-conversion between serum samples taken annually. For laboratory confirmation, ELISA test for dengue antibody is performed on annual samples. Fifteen percent of samples are tested. Asymptomatic dengue infection is diagnosed if the patients demonstrate sero-conversion but have no history of fever in the respective year.

Due to the excellent systems in place in Ratchaburi, and the high incidence of dengue in the province, the Ratchaburi site has been identified as a trial site for one of the early dengue vaccine candidates, and is presently preparing for the enrollment of trial participants.

Professor Arunee Sabchareon is the principal investigator for the PDVI project "Dengue epidemiology in Thai Children in Ratchaburi Province, Thailand 2006 -2010". She holds an Emeritus Professorship of Tropical Pediatrics, Mahidol University, Thailand. She is a senior clinical researcher working at the Research and Development Unit, Department of Tropical Pediatrics, Faculty of Tropical Medicine Mahidol University, Bangkok, Thailand. Dr. Arunee is a member of the WHO Steering Committee on Vaccine Research for Dengue and Other Flaviviruses, and a member of the WHO Expert Advisory Panel on Viral Diseases 2002 - 2006. She has received various awards including a Fulbright Award, Daravithayalai Academy Best Student, Kanjika Devakul's Prize, Thai National Researcher, and Mahidol Outstanding Alumni.