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Deborah L. Carter

Publications and source records attributed to Deborah L. Carter.

6 recordsLinked to original sources
USGS2025

Highly pathogenic avian influenza virus H5N1 in double-crested cormorants (Nannopterum auritum) of the Chesapeake Bay, USA

Double-crested Cormorants ( Nannopterum auritum ) have historically exhibited low levels of infection and antibodies to avian influenza virus (AIV). The recent global expansion of clade 2.3.4.4b A/goose/Guangdong/1/1996 highly pathogenic (HP) avian influenza virus H5N1 (HPAI H5N1) has resulted in large-scale mortalities across diverse waterbird taxa including cormorants. We sampled 32 and 29 Double-crested Cormorants breeding in the Chesapeake Bay, US, during the summers of 2023 and 2024, respectively, to assess HPAI H5N1 infection and AIV antibodies. Although no mortality was observed in the area, one bird sampled in 2023 was infected with HPAI H5N1. Additionally, 21/31 individuals in 2023 and 10/25 individuals in 2024 for which sera were collected had AIV antibodies. Based on additional testing using hemagglutination inhibition, virus neutralization, and an enzyme-linked lectin assay, 94 and 100% (2023 and 2024, respectively) of the seropositive birds tested positive for antibodies to both H5 and N1, suggesting previous infection with HPAI H5N1. These results are consistent with survival and limited clinical effects related to HPAI H5N1 infections. Furthermore, these results suggest that population immunity to HPAI H5N1 within the Chesapeake Bay might reduce future infections and potential population impacts should HP H5N1 remain on the landscape, though immunity may be waning across time. Because results are based on a single population, additional testing for both infection and antibodies as well as continued monitoring could enhance understanding of antibody persistence.

Maryland, Virginia↗
USGS2025

Highly pathogenic avian influenza virus exposure and infection in free-ranging bobcats (Lynx rufus) in New York, USA

Highly pathogenic H5N1 influenza A virus (HP H5N1) cases in wild mammals have been increasing globally. Carnivora has been the most affected mammal order; however, the extent of morbidity and mortality in carnivores exposed to HP H5N1 remains undefined. We assessed the presence of antibodies to H5 and N1 in the sera of 16 live-captured bobcats ( Lynx rufus ) in New York State, USA; reported on postcapture outcomes of HP H5N1-exposed bobcats; and reported on a case of HP H5N1 infection in one bobcat. In 2024, 4/16 bobcats (25%) tested positive for antibodies to H5 and N1. Two bobcats were confirmed alive as of November 2024 according to GPS data; the other two were alive as of June 2024, when their GPS collars stopped communicating. Another bobcat, which was negative for HP H5N1 antibodies at capture, died from HP H5N1 infection within 5 wks of capture. Our results provide evidence of bobcats both surviving and succumbing to HP H5N1 infection and highlight the importance of focused health studies paired with monitoring data to better understand exposure, infection, and outcomes for novel pathogens and species.

New York↗
USGS2024

Sampling for disease surveillance: Assessing effects on blue-winged teal survival and recovery

Outbreaks of highly pathogenic avian influenza virus in wild animals highlight the need for disease surveillance in wild birds to improve our understanding of their role as reservoirs and dispersers, and potential threats to domestic poultry and wild bird populations. Surveillance for avian influenza varies in its approach, objectives, and coordination with other monitoring efforts. For waterfowl, a common host to avian influenza viruses, banding represents a concerted effort of capturing and marking thousands of individuals annually to estimate survival and harvest rates, but users of these data have generally taken a conservative approach to remove any banded birds from analyses that had a sample taken for disease surveillance during capture. We tested for differences in survival and encounter probabilities of blue-winged teal ( Spatula discors ) marked ( n = 21,702 teal) and sampled for disease surveillance ( n = 4,216) during the nonbreeding season in Louisiana, USA, from 2016 to 2023. Although we found no consistent effect of collecting biological samples on survival probability, including an additional test showing no detectable effects of sampling for disease surveillance with oropharyngeal and cloacal swabs versus sampling with swabs and a syringe-drawn blood sample, wide 95% credible intervals on the posterior survival estimates (mean 0.36 difference between upper and lower values across all year-sex-sampling groups; 0.44 for sampling type groups) indicated low statistical power to detect an effect. Seber recovery probability during the first interval following sampling was lower among birds sampled using swabs only, but we assume this stems from low sample sizes rather than an effect of collecting biological samples. Because recovery probabilities can vary as a function of individual covariates, we also examined direct recovery probabilities and observed no meaningful effect of disease surveillance sampling type but strong effects of capture date, suggesting the effect on Seber recovery probability may have been due to heterogeneity in exposure to natural and harvest mortality risks. Although we suggest that aligning disease surveillance sample collection efforts with landscape-scale waterfowl banding efforts may have little effect on observed demographic rates, additional studies with larger sample sizes are likely needed to provide the statistical power necessary to formally conclude no effect of biological sampling on survival probabilities.

Louisiana↗
USGS2024

Infectivity of wild-bird origin Influenza A viruses in Minnesota wetlands across seasons

The environmental tenacity of influenza A viruses (IAVs) in the environment likely plays a role in their transmission; IAVs are able to remain infectious in aquatic habitats and may have the capacity to seed outbreaks when susceptible wild bird hosts utilize these same environments months or even seasons later. Here, we aimed to assess the persistence of low-pathogenicity IAVs from naturally infected ducks in Northwestern Minnesota through a field experiment. Viral infectivity was measured using replicate samples maintained in distilled water in a laboratory setting as well as in filtered water from four natural water bodies maintained in steel perforated drums (hereafter, mesocosms) within the field from autumn 2020 to spring 2021. There was limited evidence for the extended persistence of IAVs held in mesocosms; from 65 initial IAV-positive samples, only six IAVs persisted to at least 202 days in the mesocosms compared to 17 viruses persisting at least this long when held under temperature-controlled laboratory settings in distilled water. When accounting for the initial titer of samples, viruses detected at a higher concentration at the initiation of the experiment persisted longer than those with a lower starting titer. A parallel experimental laboratory model was used to further explore the effects of water type on viral persistence, and the results supported the finding of reduced tenacity of IAVs held in mesocosms compared to distilled water. The results of this investigation provide evidence that many factors, including temperature and physicochemical properties, impact the duration of viral infectivity in natural settings, further extending our understanding of the potential and limitations of environmental-based methodologies to recover infectious IAVs.

Minnesota↗