Scientists have developed a new paper-based disposable device that allows dengue-specific antibodies to be detected easily from saliva within 20 minutes.

The device developed by The Institute of Bioengineering and Nanotechnology (IBN) in Singapore is currently undergoing further development for commercialisation.

"Our rapid diagnostic kit can detect a key dengue antibody from saliva that is present in early-stage secondary infection," said IBN Executive Director Professor Jackie Y Ying.

"The ability to differentiate between primary and secondary dengue infections makes it a valuable early diagnosis tool that would help to ensure timely treatment and proper care of patients," said Ying.

Patients with secondary infection, who have previously been infected with other serotypes of dengue virus, stand a higher risk of developing dengue hemorrhagic fever or dengue shock syndrome.

According to Singapore's National Environment Agency, dengue fever and its more severe form, dengue hemorrhagic fever, are the most common mosquito-borne viral diseases in the world.

This disease poses a serious health threat, and is a leading cause of illness and death in tropical and subtropical climates. There are four known serotypes of the dengue virus but no vaccine or medicine has been developed to treat the illness.

The incubation period before symptoms develop generally ranges from 4 to 10 days after infection. Therefore, early diagnosis would enable the patient to receive prompt medical attention and avoid further complications.

Currently, dengue infection is diagnosed in the laboratory by testing the patient's blood sample for the presence of dengue antigens or antibodies.

The device, on the other hand, is capable of detecting IgG, a dengue-specific antibody found at the onset of secondary infections, directly from saliva in one step.

Unlike blood samples, saliva can be collected easily and painlessly for rapid point-of-care diagnostics. However, unlike other body fluids, it cannot be applied directly to commercially available test kits as it would cause the sensor nanoparticles to stick haphazardly to the test strip.

As described in the journal Lab on a Chip, the researchers used an innovative stacking flow design to overcome key challenges faced by existing lateral flow designs, such as those used in pregnancy test kits.

The diagnostic kit can also be adapted to detect other infectious diseases such as HIV and Syphilis. Researchers are also investigating the use of other common fluid samples, such as blood, urine and serum for rapid, high-sensitivity test kits.