The emergence of chikungunya virus infection in the Western hemisphere in 2013 and the introduction of Zika virus in Brazil in 2015 quickly became significant sources of travel-related arboviral infections among Philadelphia residents along with dengue virus, the most common arboviral infection worldwide. These infections can cause febrile illness in travelers returning from tropical and subtropical regions, with polyarthralgia occurring in most with chikungunya. Dengue infections can progress to more severe illness (hemorrhagic fever or shock syndrome) that can be fatal. While most individuals infected with Zika virus have mild illness or remain asymptomatic, infection in pregnant women may lead to congenital infection that results in neurologic abnormalities or fetal loss.

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Travel-Related Arboviral Infections For 2019 Season

Travel-Related Arboviral Infections:

Chikungunya Dengue Zika
Cases 2 19 59 c
2019 0 10 0
2018 a,b 0 1 0
2017 a 0 0 11
2016 a 0 3 48
2015 2 5 -
Median Age, y (Range) 46.5 (34-59) 38 (5-64) 33.5 (0-73)
Female, n (%) 1 (50%) 9 (47.3%) 45 (76.3%)
Foreign Born, n (%) 0 (0%) 7 (36.8%) 39 (66.1%)
Hospitalized, n (%) 1 (50%) 11 (57.8%) 0 (0%)
Death, n (%) 0 (0%) 0 (0%) 0 (0%)
a Revised Zika case definition implemented September 26, 2016. Unspecified flavivirus infections re-classified as probable Zika.
b Preliminary year to date data. Includes confirmed and probable cases.
c Two cases acquired through sexual contact with a returning traveler. Three cases were infants with probable, asymptomatic congenital infection and no identified birth defects. All others traveled to an affected area.

Travel Destinations: Arboviral Infections, Philadelphia, 2015 - 2019

Arboviral Infections By Travel Destination

Worldwide Distribution Reports

Aedes Species Mosquito Activity in Philadelphia - 2019 Season:

Chikungunya, dengue, and Zika viruses are spread by Aedes spp. mosquitoes, which are daytime biters and found around homes due to their short flight range. Aedes aegypti, a principle vector for transmission of these viruses is not found in Philadelphia. Aedes albopictus (Asian tiger mosquito), a less efficient vector are present and active during warmer months in Philadelphia. PDPH will continue to assess the presence of A. albopictus in Philadelphia and closely monitor human surveillance data to promptly identify local transmission should it occur.

Aedes Species Mosquito Activity - 2019 Season Summary:

Mosquito Activity 2019 - Philadelphia, PA
A. aegypti A. albopictus
Number of identifications since May 2019 0 721
Median number of mosquitoes per trap (range) - 52 (1-3154)
Percentage of all mosquito traps (with adult mosquitoes) set during 2018 season - 53.9%
Percentage of residential zip codes with Aedes mosquitoes - 85.1%

A. albopictus Locations*, Philadelphia, 2019

Arboviral Infections By Travel Destination
*** Adult A. albopictus identified 721 times at 191 locations.
  • Report suspected and confirmed infections to the Philadelphia Department of Public Health by telephone at 215-685-6742 (215-686-4514 after hours) or fax at 215-238-6947.

Updated: 10/25/2019