Diagnosis of dengue infection by detecting specific immunoglobulin M antibodies in saliva samples

To investigate whether saliva could be used for diagnosis of recent dengue, serum and saliva samples were collected simultaneously from patients with suspected dengue infection. Sera (1:10 dilution) and saliva (undiluted) were tested by using an IgM capture enzyme linked immunosorbent assay (MAC-ELISA) with minor modifications (serum and saliva absorption for 3 h at 37 degrees C). The quality of saliva was evaluated by determining the IgG total concentration (enzyme immunoassay) which ranged from 2.7 to > 50 mg/l. Recent dengue infection was confirmed in 38 cases. Forty-six serum and saliva specimens were collected from these patients 1-30 days after the onset of symptoms. IgM was detected in 65.8% saliva samples. High rate of positivity ( > 80%) was observed for the saliva samples collected > or = 5 days after the onset of the disease. Fifty serum and saliva samples from other 32 patients with rash diseases were also tested and all the specimens were unreactive by MAC-ELISA. These results indicate that saliva may be a convenient non-invasive alternative to serum for diagnosis of recent dengue fever infection, especially for epidemiological studies during outbreaks of the disease.