Arboviral Diseases in BC Travellers

Key Points:

         Rates of arboviral (arthropod borne) infection (Dengue, Chikungunya and recently Zika virus) transmitted by day-biting Aedes mosquitoes in endemic areas have increased throughout the tropical and sub-tropical Americas.  All three can produce fever, body aches and less frequently more severe systemic symptoms and organ dysfunction.

         BC travellers should be reminded to practice mosquito avoidance in endemic areas, day and night.

         While a new association between Zika virus infection and microcephaly in infants born to infected women has yet to be proven causal, it is strong enough that travel clinics should provide special cautions to pregnant women planning on travelling to Zika-endemic areas.

         Management of returning travellers is supportive. Though there are no specific antivirals for use, maintenance of good hydration reduces the risks of complications.  We have been asked by WHO and PHAC to apprise them of any observations of infections that may be new to a specific geographical area. 

         In the absence of competent Aedes vectors in BC, local transmission would not be expected and person to person transmission is not an issue.

         Diagnosis of these infections can be made with serological testing available at the BCCDC Public Health Laboratory.  PCR testing may help during the viremic phase.

         Quadrivalent Dengue vaccine is very early in its release globally.  While approved in Mexico, the Phillipines and Brazil there are no current plans for filing a notice of compliance in Canada to date.

Background:

         These three arboviruses (arthropod-borne) can produce similar febrile illness, severe body aches and are less frequently associated with more severe complications such as hemorrhagic fever and shock. These complications are more common in people infected with a second serotype of Dengue. 

         These viruses are all transmitted by Aedes mosquitoes which may well prosper in urban settings with standing water and can be aggressive at biting by day. 

         Four strains of Dengue are broadly distributed globally.  http://www.healthmap.org/dengue/en/

         We have seen an increasing trend in positive Dengue lab identifications (IgM positive serology) in BC over the last few years from tests submitted for returning travellers.  Acute and convalescent serological testing is the gold standard for diagnosis.

o   http://www.bccdc.ca/resource-gallery/Documents/Statistics%20and%20Research/Statistics%20and%20Reports/Labs/May2015LaboratoryTrends.pdf

         Chikungunya virus arrived in the Americas in 2013 and is now found throughout many tropical and subtropical regions of the hemisphere.  http://www.paho.org/hq/images/stories/AD/HSD/IR/Viral_Diseases/Chikungunya/CHIKV-Data-Caribbean-2016-EW-1.jpg

         Zika virus has also spread to the Americas in the last decade.  BC logged its first case of Zika virus infection in a traveller returning from an area in Latin America where Zika is believed to be circulating.  http://www.cdc.gov/zika/geo/index.html

         The concern with Zika virus is the observation in late 2015 of an epidemic of microcephaly in infants born to women during an epidemic of Zika virus infection in Brazil.  This information and advice on how to reduce the risk of infection should be shared with pregnant women intending on travelling to endemic areas.

o   http://www.phac-aspc.gc.ca/tmp-pmv/notices-avis/notices-avis-eng.php?id=143