Disease Ecology In the Pacific Basin: Wildlife and Public Health Concerns

Science Center Objects

Both wildlife and human health in Hawai‘i and other island ecosystems in the Pacific Basin face continued threats from introductions of diseases and vectors. Accidental introduction of mosquito-borne avian malaria and pox virus to Hawai‘i is an outstanding example of how biological invasions can have a profound effect on endemic wildlife. The geographic distribution, density, and community structure of endemic Hawaiian avifauna has changed dramatically in the last century, in large part because of the spread of these diseases and their introduced mosquito vector. More recently, the spread of chikungunya virus in the Caribbean and western Pacific and west nile virus on the mainland U.S. place the Hawaiian Islands at high risk for introduction of new human diseases. 

Carter Atkinson collects a blood sample from a Bonin petrel

Dr. Carter Atkinson prepares a Bonin petrel for blood collection. Photo: D. LaPointe

Overview:

Both wildlife and human health in Hawai‘i and other island ecosystems in the Pacific Basin face continued threats from introductions of diseases and vectors. Accidental introduction of mosquito-borne avian malaria and pox virus to Hawai‘i is an outstanding example of how biological invasions can have a profound effect on endemic wildlife. The geographic distribution, density, and community structure of endemic Hawaiian avifauna has changed dramatically in the last century, in large part because of the spread of these diseases and their introduced mosquito vector. More recently, the spread of chikungunya virus in the Caribbean and western Pacific and west nile virus on the mainland U.S. place the Hawaiian Islands at high risk for introduction of new human diseases. USGS scientists have collected and analyzed large spatial and temporal datasets on the prevalence and incidence of avian malaria and pox virus in forest bird populations in the Hawaiian Archipelago and American Samoa, the ecology of their primary mosquito vector, complementary data on the genetic variation of hosts, vectors and parasites and epidemiological factors such as host susceptibility and resistance, parasite virulence and vector competency.  Continued analysis and integration of these data into epidemiological models is needed to support Strategic Decision Making (SDM) and adaptive management toward the continued protection and restoration of migratory and endangered Hawaiian forest bird species on DOI managed lands such as Hakalau Forest National Wildlife Refuge, Hawaii Volcanoes National Park, Haleakala National Park and the National Park of American Samoa. At the same time, current field and laboratory studies maintain capabilities for rapid response to new vectors and emerging pathogens that continue to arrive on isolated Pacific Islands.

Project Objectives: 

We continue to work closely with partners from the National Park Service, U.S. Fish and Wildlife Service (Region 1 Migratory Birds, Region 1 Ecological Services and Region 1 USFWS Refuge Offices), and the Department of Marine and Wildlife Resources in American Samoa to  acquire basic knowledge of the biology and impact of existing and new vectors and pathogens affecting wildlife and public health in the Pacific Basin and to develop tools and strategies for predicting disease outbreaks, assessing their severity, and monitoring success of adaptive management for the control of mosquito vectors and disease. Specific objectives of this task are to:

  1. continue analysis of existing data sets to refine model parameters for developing transmission models,
  2. develop and evaluate models for predicting severity and location of disease outbreaks and effects of specific management actions and environmental changes on transmission of introduced diseases,
  3. monitoring emergent pathogens like knemidokoptic mange in Hawai‘i ‘amakihi and
  4. determining the genetic diversity of the mosquito endosymbiote Wolbachia pipientis as a potential control measure for Culex mosquitoes.
Dennis LaPointe holds an albatross chick

Dr. Dennis LaPointe inspects the face of a Laysan albatross chick. Photo: USGS

Highlights and Key Findings: 

We have completed manuscripts with colleagues at the University of Hawai‘i, Hilo and the Wisconsin Cooperative Wildlife Research Unit on the impacts of malaria and pox transmission on Apapane populations at Hawai‘i Volcanoes National Park, genetic diversity of malarial isolates in Hawaiian forest birds, modeling avian malaria at the landscape level, dispersal of vectors of avian disease, the effects of temperature and climate change on avian disease in Hawai‘i, and adaptive responses of native forest birds to avian malaria. We have published 6 book chapters and online compendiums on avian malaria, avian pox and disease management. Key findings include the significant impact that avian malaria has on the most common native species with annual mortality rates that may approach 100% in juvenile birds and unexpected genetic diversity in both malarial and pox organisms that may contribute to virulence and transmission of these diseases. Computer models that we have developed in conjunction with colleagues at the Wisconsin Cooperative Wildlife Research Unit indicate that global climate change will have a significant impact on disease transmission in Hawai‘i and will contribute to loss of high elevation refugia where many native species are currently able to avoid pox and malaria. We have worked with colleagues at the University of Hawai‘i, Hilo to develop a TaqMan Real Time PCR assay for avian pox virus that will allow us to improve transmission models for avian pox and to ultimately explore in more detail how this disease interacts with malaria. We have documented the prevalence, geographic, and altitudinal distribution of a new pathogen in Hawai‘i ‘Amakihi, the scaley leg mite (Knemidokoptes jamaicensis) and collected data that suggest that knemidoptic mange may impact survivorship of wild birds.

 

 

Midway Atoll

Albatross and chicks gather around Midway Atoll National Wildlife Refuge sign. Photo: D. LaPointe

2016 Progress: 

Completion of a final report on climate change and avian malaria at Hakalau Forest National Wildlife Refuge

Completion of a final report on genetic diversity of Wolbachia endosymbionts in Culex mosquitoes from Hawaii, Midway Atoll, and American Samoa

Completion of a final report on effects of climate and land use on diversity, prevalence, and seasonal transmission of avian hematozoa in American Samoa

 

2017 Planned Work: 

Work in 2017 will focus on the completion of reports on 1) the diversity and distribution of avian blood parasites from SW Pacific island archipelagoes, 2) disease assessment at sites on the island of Hawai‘i and 3) effects of Rapid ‘Ōhi‘a Death on Hawaiian avifauna. Additionally, analysis will continue on interactions of avian pox and avian malaria in native Hawaiian forest birds.