Mosquito Vectors of Dengue and Zika Viruses in Hawaii National Parks

Science Center Objects

Six species of biting mosquitoes have been introduced to the Hawaiian Islands since Western contact, two of which are vectors of dengue, chikungunya, and Zika viruses. Environmental conditions favorable for the transmission of dengue and Zika occur year-long across Hawai‘i’s coastline. To better understand the ecology of vector mosquitoes and support public health efforts, mosquito monitoring at Kaloko Honokōhau and Pu‘uhonua O Hōnaunau National Historical Parks on the island Hawai‘i were implemented to determine relative species abundance, habitat conditions, seasonal patterns, and identify larval habitat.

Photograph of USGS technician holding sampling bag with mosquito eggs

USGS technician, Mike Riney, with Aedes mosquito egg sample at at Pu‘uhonua O Hōnauna National Historical Park on Hawai‘i island, Hawai‘i. (Credit: Dennis LaPointe, USGS. Public domain.)

Overview:

Six species of biting mosquitoes have been introduced to the Hawaiian Islands since Western contact (LaPointe 2007).  Two species, the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), are vectors of dengue, chikungunya, and Zika virus. Immature stages of A. aegypti are generally restricted to domestic and peridomestic containers but  A. albopictus can be found in a variety of naturally occurring habitats as well as peridomestic containers.  While the distributions of these species overlap, A. albopictus often displaces A. aegypti populations. Since the 1920s, A. aegypti populations have disappeared entirely from the islands of O‘ahu, Kaua‘i, Moloka‘i and Maui (Usinger 1944, Winchester and Kapan 2013).  Today, A. aegypti occurs in small, isolated populations along the south and west coastlines of the Island of Hawai‘i (Larish and Yang 2009). Like many mosquito species, A. albopictus populations respond positively to increased precipitation. A. aegypti, however, may have a competitive edge under drier conditions and changing precipitation regimes in the Hawaiian Islands may have a profound impact on species dominance.  Because of its domestic nature A. aegypti may be a more competent vector of these viruses and recent dengue outbreak in Hawai‘i has focused around the coastal areas where A. aegypti is still present.

Dengue is endemic throughout much of the tropical Pacific and outbreaks have occurred sporadically in Hawai‘i since 1903. Notable outbreaks occurred in 1903, 1943, 2001, and 2011 (Effler et al. 2005, Winchester and Kapen 2012). Since 1943, the interval between dengue outbreaks has decreased from 58 to 4 years.  The first human cases of Zika were detected in East Africa in 1952 and outbreaks have been reported in Africa, southeast Asia and Pacific. More recently outbreaks have occurred in South and Central America, the Caribbean.  In 2007, local transmission of Zika virus was first reported in the Pacific from the Island of Yap in the Federal State of Micronesia. Zika outbreaks have since occurred in American Samoa, Samoa and Tonga. Recently, Hawaii has seen travel-associated cases of Zika Virus. Environmental conditions favorable for the transmission of dengue and Zika occur year-long across Hawai‘i’s coastline.

Project Objectives:

Document the seasonal dynamics of mosquito vector abundance in the Pu‘uhonua O Hōnaunau and Kaloko Honokōhau National Historical Parks and determine the role of precipitation and the proximity of infrastructure and anchialine pools to species presence and abundance.

Photograph of a pitted lava rock with water in the pits

Potential mosquito larval habitat - pitted lava rock with water at the Kaloko Honokōhau National Historical Park, Hawai‘i.(Credit: Dennis LaPointe, USGS. Public domain.)

Photograph of an oil separator in parking lot water drain

Potential mosquito larval habitat - oil separator in parking lot drain at the Pu‘uhonua O Hōnaunau National Historical Park.(Credit: Dennis LaPointe, USGS. Public domain.)

 

Plastic bags with mosquito larvae

Mosquito larvae being reared to identify species. Samples collected at the Pu‘uhonua O Hōnaunau National Historical Park, Hawai‘i. (Credit: Dennis LaPointe, USGS. Public domain.)