Dengue virus and other arboviruses: a global view of risks
Authors: Anez G. , Chancey C. , Grinev A. , Rios M. 
Published: June 2012

Arboviruses (arthropod‐borne viruses) are an ecological group of viruses from different families (e.g. Bunyaviridae, Flaviviridae and Togaviridae) that use arthropods such as mosquitoes, flies and ticks as vectors for transmission between different hosts. The superb plasticity of these viruses allows propagation to different host systems including both invertebrates and vertebrates. More than 500 species of arbo‐virus have been described and are listed in the International Catalogue of arbo‐virus (http://www.cdc.gov/nczved/divisions/dvbid/arbovirus.html), many of which are of medical importance.

Globally, arboviral infections have become increasingly common and human diseases caused by these infections have expanded their frontiers in the last few decades emerging in places with no previous history of epidemic activity or localised transmission of a specific arbovirus. One example is the recent arrival of West Nile virus (WNV) in the Western Hemisphere and its subsequent propagation in the Americas. Arboviral diseases are also re‐emerging in places where the disease had previously been well‐controlled or eradicated, resulting in an increasing number of cases and more severe forms of disease in endemic regions.

Human infections with arboviruses are mostly asymptomatic, but symptomatic infections can range from malaise, mild febrile illness (with flu‐like symptoms) to severe disease that may progress to long‐term physical or cognitive impairment and/or mortality.

Arboviral infections have an incubation period during which viral replication with a viremic phase takes place in the absence of symptoms. Viremic blood has the potential to transmit infection to blood recipients and therefore arboviruses can pose a threat to the safety of the blood supply. For instance, during an epidemic, asymptomatic individuals may donate blood and transmit the infection to blood component recipients.

Among the arboviral infections that have been on the radar for increased activity in the last decade are: WNV, Dengue viruses (DENV) and Chikungunya virus (CHIKV). In addition, other arboviral infections such as Yellow Fever, Saint Louis encephalitis, Tick‐borne encephalitis, Rift Valley fever, Japanese encephalitis, Powassan encephalitis, Murray Valley encephalitis and Zika fever have been reported as emerging or re‐emerging in various areas around the globe. Alertness and surveillance are required to allow implementation of measures to mitigate risk of transmission to blood recipients including blood screening tests when available and appropriate.

In addition, the evidence of increased arbovirus activity worldwide points to the critical need for the development of affordable diagnostic and screening assays with high sensitivity and specificity as well as new vaccines and therapies, since most populations at risk reside in less privileged parts of the world. The need for these tools is pressed by the imminent possibility of outbreaks in any part of the world due to the combination of expanding distribution of vectors and increased mobility of infected hosts by travel and trade.