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Carter T. Atkinson

Publications and source records attributed to Carter T. Atkinson.

At least 55 records · Page 3Linked to original sources
USGS2012

Analysis of the trap gene provides evidence for the role of elevation and vector abundance in the genetic diversity of Plasmodium relictum in Hawaii

Background: The avian disease system in Hawaii offers an ideal opportunity to investigate host-pathogen interactions in a natural setting. Previous studies have recognized only a single mitochondrial lineage of avian malaria (Plasmodium relictum) in the Hawaiian Islands, but cloning and sequencing of nuclear genes suggest a higher degree of genetic diversity. Methods: In order to evaluate genetic diversity of P. relictum at the population level and further understand host-parasite interactions, a modified single-base extension (SBE) method was used to explore spatial and temporal distribution patterns of single nucleotide polymorphisms (SNPs) in the thrombospondin-related anonymous protein (trap) gene of P. relictum infections from 121 hatch-year amakihi (Hemignathus virens) on the east side of Hawaii Island. Results: Rare alleles and mixed infections were documented at three of eight SNP loci; this is the first documentation of genetically diverse infections of P. relictum at the population level in Hawaii. Logistic regression revealed that the likelihood of infection with a rare allele increased at low-elevation, but decreased as mosquito capture rates increased. The inverse relationship between vector capture rates and probability of infection with a rare allele is unexpected given current theories of epidemiology developed in human malarias. Conclusions: The results of this study suggest that pathogen diversity in Hawaii may be driven by a complex interaction of factors including transmission rates, host immune pressures, and parasite-parasite competition.

Hawai'i↗
USGS2012

Ecology and conservation biology of avian malaria

Avian malaria is a worldwide mosquito-borne disease caused by Plasmodium parasites. These parasites occur in many avian species but primarily affect passerine birds that have not evolved with the parasite. Host pathogenicity, fitness, and population impacts are poorly understood. In contrast to continental species, introduced avian malaria poses a substantial threat to naive birds on Hawaii, the Galapagos, and other archipelagoes. In Hawaii, transmission is maintained by susceptible native birds, competence and abundance of mosquitoes, and a disease reservoir of chronically infected native birds. Although vector habitat and avian communities determine the geographic distribution of disease, climate drives transmission patterns ranging from continuous high infection in warm lowland forests, seasonal infection in midelevation forests, and disease-free refugia in cool high-elevation forests. Global warming is expected to increase the occurrence, distribution, and intensity of avian malaria across this elevational gradient and threaten high-elevation refugia, which is the key to survival of many susceptible Hawaiian birds. Increased temperatures may have already increased global avian malaria prevalence and contributed to an emergence of disease in New Zealand.

Hawai'i↗
USGS2012

Reversion to virulence and efficacy of an attenuated canarypox vaccine in Hawai'i 'Amakihi ( Hemignathus Virens )

Vaccines may be effective tools for protecting small populations of highly susceptible endangered, captive-reared, or translocated Hawaiian honeycreepers from introduced Avipoxvirus , but their efficacy has not been evaluated. An attenuated Canarypox vaccine that is genetically similar to one of two passerine Avipoxvirus isolates from Hawai‘i and distinct from Fowlpox was tested to evaluate whether Hawai‘i ‘Amakihi ( Hemignathus virens ) can be protected from wild isolates of Avipoxvirus from the Hawaiian Islands. Thirty-one (31) Hawai‘i ‘Amakihi were collected from high-elevation habitats on Mauna Kea Volcano, where pox transmission is rare, and randomly divided into two groups. One group was vaccinated with Poximune C®, whereas the other group received a sham vaccination with sterile water. Four of 15 (27%) vaccinated birds developed life-threatening disseminated lesions or lesions of unusually long duration, whereas one bird never developed a vaccine-associated lesion or “take.” After vaccine lesions healed, vaccinated birds were randomly divided into three groups of five and challenged with either a wild isolate of Fowlpox (FP) from Hawai‘i, a Hawai‘i ‘Amakihi isolate of a Canarypox-like virus (PV1), or a Hawai‘i ‘Amakihi isolate of a related, but distinct, passerine Avipoxvirus (PV2). Similarly, three random groups of five unvaccinated ‘Amakihi were challenged with the same virus isolates. Vaccinated and unvaccinated ‘Amakihi challenged with FP had transient infections with no clinical signs of infection. Mortality in vaccinated ‘Amakihi challenged with PV1 and PV2 ranged from 0% (0/5) for PV1 to 60% (3/5) for PV2. Mortality in unvaccinated ‘Amakihi ranged from 40% (2/5) for PV1 to 100% (5/5) for PV2. Although the vaccine provided some protection against PV1, both potential for vaccine reversion and low efficacy against PV2 preclude its use in captive or wild honeycreepers.

Hawaii↗
USGS2011

Keeping Hawai’i’s forest birds one step ahead of avian diseases in a warming world: a focus on Hakalau Forest National Wildlife Refuge. A case study from the National Conservation and Training Center Structured Decision Making Workshop

This report is a product of a one-week workshop on using Structured Decision Making to identify and prioritize conservation actions to address the threat of climate change on Hawaii‟s native forest bird community. Specifically, t his report addresses the issue of global warming ‟s likely role in increasing disease prevalence in upper elevation forests of Hawaii, negatively impacting native bird populations susceptible to the disease but currently disease - free because of the cooler temperatures at high elevations.

Hawaii↗
USGS2010

Avian malaria Plasmodium relictum in native Hawaiian forest birds: epizootiology and demographic impacts on ‵apapane Himatione sanguinea

The role of introduced avian malaria Plasmodium relictum in the decline and extinction of native Hawaiian forest birds has become a classic example of the potential effect of invasive diseases on biological diversity of naïve populations. However, empirical evidence describing the impact of avian malaria on fitness of Hawai‵i's endemic forest birds is limited, making it difficult to determine the importance of disease among the suite of potential limiting factors affecting the distribution and abundance of this threatened avifauna. We combined epidemiological force-of-infection with multistate capture––recapture models to evaluate a 7-year longitudinal study of avian malaria in ‵apapane, a relatively common native honeycreeper within mid-elevation Hawaiian forests. We found that malaria transmission was seasonal in this mid-elevation forest; transmission peaked during fall and during some years produced epizootic mortality events. Estimated annual mortality of hatch-year birds typically exceeded 50% and mortality of adults exceeded 25% during epizootics. The substantial impact of avian malaria on this relatively common native species demonstrates the key role this disease has played in the decline and extinction of Hawaiian forest birds.

Journal of Avian Biology↗
USGS2010

Can lowland dry forests represent a refuge from avian malaria for native Hawaiian birds?

Hawaii's native birds have become increasingly threatened over the past century. Introduced mosquito borne diseases such as avian malaria may be responsible for the near absence of endemic Hawaiian forest birds in low-elevation habitats. The recent recognition that some native Hawaiian forest birds may be repopulating moist lowland habitats as a result of evolved resistance to this disease has increased the conservation value of these areas. Here, we investigate whether remnant low elevation dry forests on Hawaii Island provide natural 'refuges' from mosquito-transmitted malaria by nature of their low rainfall and absence of suitable natural sources of water for mosquito breeding. Unlike lowland wet forests where high rates of disease transmission may be selecting for disease resistance, lowland dry forests may provide some refuge for native forest birds without natural resistance to malaria. We mistnetted forest birds in two lowland dry forests and tested all native birds by microscopy and serology for avian malaria caused by the Plasmodium relictum parasite. We also conducted surveys for standing water and mosquito larvae. Overall prevalence of infections with Plasmodium relictum in the Hawaii Amakihi Hemignathus virens virens was 15%. Most infected birds had lowlevel parasitemias, suggesting chronic infections. Although avian malaria is present in these lowland dry forest Amakihi populations, infection rates are significantly lower than in wet forest populations at similar elevations. Sources of breeding mosquitoes in these forests appeared to be largely anthropogenic; thus, there is potential to manage dry forests as mosquito-free habitat for Hawaii Amakihi and other Hawaiian forest birds.

Hawai'i↗
USGS2010

Thermal constraints to the sporogonic development and altitudinal distribution of avian malaria Plasmodium relictum in Hawai'i

More than half of the Hawaiian honeycreepers (Drepanidinae) known from historical records are now extinct. Introduced mosquito-borne disease, in particular the avian malaria Plasmodium relictum , has been incriminated as a leading cause of extinction during the 20th century and a major limiting factor in the recovery of remaining species populations. Today, most native Hawaiian bird species reach their highest densities and diversity in high elevation (>1,800 m above sea level) forests. We determined the thermal requirements for sporogonic development of P. relictum in the natural vector, Culex quinquefasciatus , and assessed the current distribution of native bird species in light of this information. Sporogonic development was completed at constant laboratory and mean field temperatures between 30 and 17 C, but development, prevalence, and intensity decreased significantly below 21 C. Using a degree-day (DD) model, we estimated a minimum threshold temperature of 12.97 C and a thermal requirement of 86.2 DD as necessary to complete development. Predicted (adiabatic lapse-rate) and observed summer threshold isotherm (13 C) correspond to the elevation of high forest refuges on the islands of Maui and Hawai'i. Our data support the hypothesis that avian malaria currently restricts the altitudinal distribution of Hawaiian honeycreeper populations and provide an ecological explanation for the absence of disease at high elevation.

Hawaii↗
USGS2010

Trip report: pilot study of factors linking watershed function and coastal ecosystem health in American Samoa

Coral reef resources in the territory of American Samoa face significant problems from overfishing, non-point source pollution, global warming, and continuing population growth and development. The islands are still relatively isolated relative to other parts of the Pacific and have managed to avoid some of the more devastating invasive species that have reached other archipelagoes. As a result, there are opportunities for collaborative and integrative research and monitoring programs to help restore and maintain biodiversity and functioning natural ecosystem in the archipelago. We found that the “Ridge to Reef” paradigm already exists in American Samoa, with a high degree of interagency cooperation and efficient use of limited resources already taking place in the Territory. USGS may be able to make contributions as a partner organization in the Coral Reef Advisory Group (CRAG) through deployment of sediment monitoring instrumentation to supplement stream monitoring by the American Samoa Environmental Protection Agency, by providing high resolution vegetation and land-use maps of main islands, by providing additional support to the American Samoa Department of Marine and Wildlife Resources and the National Park Service for monitoring of invasive species, by working with members of CRAG to initiate sediment transport studies on Samoan reefs, and by developing new projects on the effects of bacterial contamination and pollutants on coral reef physiology and demography.

Open-File Report↗
USGS2010

Efficacy of commercial canarypox vaccine for protecting Hawai'i 'Amakihi from field isolates of Avipoxvirus

At least three variants of avian pox virus are present in Hawai‘i - Fowlpox from domestic poultry and a group of genetically distinct viruses that cluster within two clades (Pox Variant 1 and Pox Variant 2) that are most similar to Canarypox based on DNA sequence of the virus 4b core protein gene. We tested whether Hawai‘i ‘Amakihi can be protected from wild virus isolates with an attenuated live Canarypox vaccine that is closely related to isolates that cluster within clade 1 (Pox Variant 1) based on sequence of the attenuated Canarypox virus 4b core protein. Thirty-one (31) Hawai`i ‘Amakihi ( Hemignathus virens ) with no prior physical evidence of pox infection were collected on Mauna Kea from xeric, high elevation habitats with low pox prevalence and randomly divided into two groups. One group of 16 was vaccinated with Poximmune C® while the other group received a sham vaccination with virus diluent. Four of 15 (27%) vaccinated birds developed potentially life-threatening disseminated lesions or lesions of unusually long duration, while one bird never developed a vaccine-associated lesion or "take". After vaccine-associated lesions healed, vaccinated birds were randomly divided into three groups of five and challenged with either a wild isolate of Fowlpox, a Hawai`i `Amakihi isolate of a Canarypox-like virus from clade 1 (Pox Variant 1) or a Hawai`i `Amakihi isolate of a Canarypox-like virus from clade 2 (Pox Variant 2). Similarly, three random groups of five unvaccinated ‘Amakihi were challenged with the same virus isolates. Vaccinated and unvaccinated ‘Amakihi challenged with Fowlpox had transient infections with no clinical signs of infection. Mortality in vaccinated ‘Amakihi that were challenged with Pox Variant 1 and Pox Variant 2 ranged from 0% (0/5) for Pox Variant 1 to 60% (3/5) for Pox Variant 2. Mortality in unvaccinated ‘Amakihi ranged from 40% (2/5) for Pox Variant 1 to 100% (5/5) for Pox Variant 2. While the vaccine provided some protection against Pox Variant 1, serious side effects and low efficacy against Pox Variant 2 make it risky to use in captive or wild honeycreepers.

Hawai'i↗
USGS2010

Efficacy of a commercial canarypox vaccine for protecting Hawai'i 'Amakihi from field isolates of avipoxvirus

At least three variants of avian pox virus are present in Hawai’i - Fowlpox from domestic poultry and a group of genetically distinct viruses that cluster within two clades (Pox Variant 1 and Pox Variant 2) that are most similar to Canarypox based on DNA sequence of the virus 4b core protein gene. We tested whether Hawai’i ‘Amakihi can be protected from wild virus isolates with an attenuated live Canarypox vaccine that is closely related to isolates that cluster within clade 1 (Pox Variant 1) based on sequence of the attenuated Canarypox virus 4b core protein. Thirty-one (31) Hawai`i ‘Amakihi ( Hemignathus virens ) with no prior physical evidence of pox infection were collected on Mauna Kea from xeric, high elevation habitats with low pox prevalence and randomly divided into two groups. One group of 16 was vaccinated with Poximmune C® while the other group received a sham vaccination with virus diluent. Four of 15 (27%) vaccinated birds developed potentially life-threatening disseminated lesions or lesions of unusually long duration, while one bird never developed a vaccine-associated lesion or “take”. After vaccine-associated lesions healed, vaccinated birds were randomly divided into three groups of five and challenged with either a wild isolate of Fowlpox, a Hawai`i `Amakihi isolate of a Canarypox-like virus from clade 1 (Pox Variant 1) or a Hawai`i `Amakihi isolate of a Canarypox-like virus from clade 2 (Pox Variant 2). Similarly, three random groups of five unvaccinated ‘Amakihi were challenged with the same virus isolates. Vaccinated and unvaccinated ‘Amakihi challenged with Fowlpox had transient infections with no clinical signs of infection. Mortality in vaccinated ‘Amakihi that were challenged with Pox Variant 1 and Pox Variant 2 ranged from 0% (0/5) for Pox Variant 1 to 60% (3/5) for Pox Variant 2. Mortality in unvaccinated ‘Amakihi ranged from 40% (2/5) for Pox Variant 1 to 100% (5/5) for Pox Variant 2. While the vaccine provided some protection against Pox Variant 1, serious side effects and low efficacy against Pox Variant 2 make it risky to use in captive or wild honeycreepers.

Hawaii↗
USGS2010

Changes in prevalence of avian malaria on the Alakai`i Plateau, Kaua`i. Hawai`i

We determined prevalence of malarial infections in samples of native and non-native forest birds that were sampled at three locations on the Alaka`i Plateau between 1994-1997 and again between 2007-2009. The three sites spanned the elevational range of the plateau and were located at Kawaikōī Stream (1100 m), the upper drainage of Mōhihi Stream (1250 m) and the vicinity of Halepa`akai Stream near Sincock’s Bog (1350 m). We detected a dramatic and significant increase in prevalence of avian malaria both at the lower (Kawaikōī) and upper (Halepa`akai) ends of the Alaka`i Plateau during the past decade. Overall prevalence of infection increased threefold from 11% to 30% at Kawaikōī Stream and tenfold from 2% to 20% at Halepa`akai Stream. Much of this increase is likely a result of local transmission, since two sedentary native species, `Elepaio and Kaua`i `Amakihi, have experienced some of the largest increases in prevalence. Curiously, prevalence has not changed significantly at Mōhihi Stream and remains at approximately 10%. We also detected avian trypanosomes ( Trypanosoma sp. ) in both recent and historic blood samples from Nutmeg Mannikins ( Lonchura punctulata ) that were captured on the plateau. This is the first report of this mosquito-transmitted blood protozoan from the Hawaiian Islands and evidence indicates that it has been a previously undetected blood parasite in the islands for at least 15 years and likely longer. We found no evidence to indicate that the parasite has spread to native Hawaiian forest birds, but our sample sizes are limited. While our study was not designed to detect the specific factors responsible for the changes in prevalence of malaria at lower and upper portions of the plateau, the results are consistent with predicted increases in prevalence that might be expected in a warming climate and clearly show that environmental conditions necessary to support transmission of malaria now exist throughout major portions of the Alaka`i Plateau. Additional field work to identify larval habitat for mosquitoes, adult mosquito distribution and density, and the relative role of human activity, feral ungulates, and interactions between changing climatic conditions and the deeply dissected topography of the plateau may help to identify why some areas have experienced significant increases in malarial prevalence.

Hawaii↗
USGS2005

Prevalence of pox-like lesions and malaria in forest bird communitites on leeward Mauna Loa volcano, Hawaii

Introduced avian pox virus and malaria have had devastating impacts on native Hawaiian forest birds, yet little has been published about their prevalence and distribution in forest bird communities outside of windward Hawaii Island. We surveyed native and non-native forest birds for these two diseases at three different elevations on leeward Mauna Loa Volcano at the Kona Forest Unit of Hakalau Forest National Wildlife Refuge. Prevalence of malaria by both serology and microscopy varied by elevation and ranged from 28% at 710 m to 13% at 1830 m. Prevalence of pox-like lesions also varied by altitude, ranging in native species from 10% at 710 m to 2% at 1830 m. Native species at all elevations had the highest prevalence of malarial antibody and pox-like lesions. By contrast, pox-like lesions were not detected in individuals of four non-native species and only 5% of Japanese White-eye ( Zosterops japonicus ) was positive for malaria. A significantly high proportion of birds with pox-like lesions also had serological evidence of concurrent, chronic malarial infections, suggesting an interaction between these diseases, dual transmission of both diseases by the primary mosquito vector ( Culex quinquefasciatus ) or complete recovery of some pox-infected birds without loss of toes. Results from this study document high prevalence of malaria and pox at this refuge. Development of effective disease control strategies will be important for restoration of remnant populations of the endangered ‘Akiapola‘au ( Hemignathus munroi ), Hawaii Creeper ( Oreomystis mana ), and Hawaii ‘Akepa ( Loxops coccineus coccineus ) that still occur on the refuge.

Hawai'i↗
USGS2005

Ecology and diagnosis of introduced avian malaria in Hawaiian forest birds

Avian malaria is a disease caused by species of protozoan parasites (Plasmodium) that infect birds. Related species commonly infect reptiles, birds and mammals in tropical and temperate regions of the world. Transmitted by mosquitoes, the parasites spend part of their lives in the red blood cells of birds (Figure 1). Avian malaria is common in continental areas, but is absent from the most isolated island archipelagos where mosquitoes do not naturally occur. More than 40 different species of avian Plasmodium have been described, but only one, P. relictum, has been introduced to the Hawaiian Islands. Because they evolved without natural exposure to avian malaria, native Hawaiian honeycreepers are extremely susceptible to this disease. Malaria currently limits the geographic distribution of native species, has population level impacts on survivorship, and is limiting the recovery of threatened and endangered species of forest birds.

Fact Sheet↗