A groundbreaking new study on human transmission of the dengue virus conducted in Kompong Cham province has shown that the virus can be spread back to mosquitoes by asymptomatic carriers, who are actually more infectious than those displaying symptoms.
Carried out by the Pasteur Institute and the French National Center for Scientific Research at three public hospitals in Kompong Cham province during the rainy seasons of 2012 and 2013, the study was published online by the journal Proceedings of the National Academy of Sciences on Monday.
The research, funded by the European Union, found that those infected with dengue are able to transmit the virus back to mosquitoes, even if they do not display any of the characteristic symptoms of dengue fever, such as headaches, rashes and muscle and joint pain.
“Our work provides evidence that people who are infected with dengue virus without developing detectable clinical symptoms or prior to the onset of symptoms are infectious to mosquitoes,” the study says.
“At a given level of viremia, symptom-free people were markedly more infectious to mosquitoes than clinically symptomatic patients,” it adds.
“Our results fundamentally change the current paradigm for dengue epidemiology and control, based on detection of dengue virus-infected cases with apparent illness.”
Veasna Duong, a researcher from the Pasteur Institute Cambodia’s virology unit and lead author of the study, said yesterday that the study was the first to look specifically at asymptomatic patients.
“The results are not just important for Cambodia, but also for the wider scientific community. We show that dengue from normal people, those going about their lives, can infect much better than those showing symptoms,” he said, noting that Asian strains of dengue have been found in South America.
“Asymptomatic people can fly to countries and spread dengue to countries which have mosquitoes.”