Dengue Virus Getting Free Rides in Airports

Over the past several years, the incidence of dengue fever worldwide has increased 30-fold, with about half of the world's population, 3.9 billion people, now at risk from the dengue virus.

Before 1970, only 9 countries had experienced severe dengue epidemics. The disease is now endemic in more than 100 countries in the WHO regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The Americas, South-East Asia and Western Pacific regions are the most seriously affected.

A recent research study found that the air transportation network has played a more important role in shaping large-scale, geographic dispersal of the dengue virus.

This analyses suggest the centrality of air traffic hubs in Thailand and India have contributed to seeding current dengue epidemics. While China, Cambodia, Indonesia, and Singapore may establish future hubs for dengue diffusion throughout Asia.

“Although not a new idea, as past studies have shown that air travel spreads dengue in Europe and Brazil, this study brings together decades of genetic sequencing and air travel network data, to show clearly that air travel contributes to dengue spread in Asia,” says Annelies Wilder-Smith, professor of infectious diseases at Lee Kong Chian School of Medicine, Singapore.

Outbreaks of dengue, Zika, and chikungunya viruses are taking place in several countries in Asia, the Caribbean, Central and Latin America, according to the World Health Organization (WHO).

The simultaneous spreading of these arboviruses raises the possibility of co-infections in people.

"A mosquito, in theory, could give you multiple viruses at once," said Claudia Ruckert, post-doctoral researcher in Colorado State University's (CSU) Arthropod-borne and Infectious Diseases Laboratory.

This CSU research team stated that the chikungunya, dengue, and Zika viruses are all transmitted to humans by Aedes aegypti mosquitoes. These mosquitoes live in tropical, subtropical, and in some temperate climates.

As these viruses continue to emerge in new regions, the likelihood of coinfection by multiple viruses may be increasing.

According to this study, the first report of chikungunya and dengue virus coinfection occurred in 1967. More recently, coinfections of Zika and dengue viruses, Zika and chikungunya, and all three viruses have been reported during various outbreaks.

There are 4 distinct, but closely related, serotypes of the virus that cause dengue (DEN-1, DEN-2, DEN-3 and DEN-4). Recovery from infection by one provides lifelong immunity against that particular serotype.

However, cross-immunity to the other serotypes after recovery is only partial and temporary.

The first dengue vaccine, Dengvaxia (CYD-TDV) by Sanofi Pasteur, was first registered in Mexico in December 2015. CYD-TDV is a live recombinant tetravalent dengue vaccine that has been evaluated as a 3-dose series on a 0/6/12 month schedule in Phase III clinical studies. It has been registered for use in individuals 9-45 years of age living in endemic areas.

Funding for this study was provided by the National Natural Science Foundation of China (81673234); Fundamental Research Funds for the Central Universities, Key Research and Development Program of China (2016YFA0600104); Sir Henry Dale Fellowship (Wellcome Trust / Royal Society Grant 204311/Z/16/Z). This work was funded by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013)/European Research Council grant agreement number 614725-PATHPHYLODYN. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

The authors, Huaiyu Tian, Zhe Sun, Nuno Rodrigues Faria, Jing Yang, Bernard Cazelles, Shanqian Huang, Bo Xu,Qiqi Yang, have declared that no competing interests exist.