Abstract
Dengue disease is an important problem in global public health. Annually, 390 people are infected with dengue virus. The majority of infections results in asymptomatic cases. For symptomatic cases, patients will develop either mild dengue fever (DF) or severe dengue hemorrhagic fever (DHF). DF is a self-limiting disease meaning the patients will recover within 4-7 days without any significant intervention. However, DHF patients will eventually develop plasma leakage which may progress into potentially fatal hypovolemic shock known as dengue shock syndrome (DSS) without prompt and adequate fluid management. Dengue disease is caused by dengue virus which belongs to the genus Flavivirus. There are four serotypes of the virus including dengue virus 1, 2, 3 and 4. The virus is transmitted by Aedes mosquitoes. There is no antiviral drug against dengue virus and the only available vaccine has limited efficacy and elevates the risk of hospitalization from dengue disease in seronegative vaccines. Dengue infection is usually confirmed by assaying patient’s blood obtained by invasive procedures, such as venipuncture or fingertip pricking. Qualified personnel are required to effectively and safely collect and process blood specimen. In addition, the blood specimen processing is usually costly in terms of budget and personnel. However, previous studies reported the presence of dengue virus, NS1 protein, and anti-dengue virus antibodies in non-invasively obtained clinical specimens such as saliva and urine. Recently, oral fluid was interestingly used for detecting anti-virus antibodies and virus genomes for HIV, hepatitis viruses (HAV, HBV, HCV). We believe oral fluid specimen could be an alternative for study dengue virus. Oral fluid is non-invasively obtained so the specimen collection and processing are inexpensive and simple. Minimally trained personnel should be able to collect, handle and process oral fluid specimen safely and effectively. In addition, oral fluid could be obtained from people in the household or workplace of the index case to capture asymptomatic dengue cases. Therefore, we tested whether oral fluid specimen could be used to detect virus genome, NS1 protein and anti-dengue IgM/IgG. We also compared the accuracy for assaying oral fluid specimen to that of blood specimen. Consequently, we evaluated whether oral fluid could be an alternative to blood specimen. We found that although viral genome and NS1 antigen were rarely detected in oral fluid, anti-dengue IgM and IgG were dramatically detected for 3 day of illness and still completely detected until 1 -2 months after illness. Efficiency of anti-dengue IgM and IgG detection in oral fluid specimens was not statistically different with plasma specimens after analyzed by Fisher’s exact test. Thus, oral fluid could be a suitable specimen for screening of asymptomatic infection in dengue season or screening of immune response after vaccination.
