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Simple Summary: There are growing concerns about wildlife and livestock interactions and the impacts of those interactions on the sustainability of livestock. One of those concerns is the spillover of wildlife pathogens, including helminths, into livestock. This concern will likely become realized as the demand for free-range animal products increases. One such helminth with spillover potential is the eyeworm Oxyspirura petrowi. This eyeworm is common in many wild birds, and particularly common in Northern bobwhite quail. Related helminths are already commonly found in poultry raised in free-range conditions in developing nations. The purpose of this research was to investigate the lethality of fenbendazole, a widely available drug for treating parasites, to these eyeworms. The lethality estimates were similar to estimates of lethality to other roundworm parasites. However, studies that have investigated concentrations in host blood following administration of the drug indicate that it does not stay in the system long enough to achieve elimination of the parasite after a single dose. This indicates that in order to effectively treat eyeworm, fenbendazole must be delivered in a repeated or continuous manner. Oxyspirura petrowi is a heteroxenous nematode that infects the harderian gland and other ocular tissues in birds. High-intensity infections often cause damage to the infected tissues. Due to the nature of the infection sites, treatment of O. petrowi in these hosts can be difficult. Fenbendazole (FBZ) is a common anthelmintic used to treat birds for helminth infections; however, little information exists as to the efficacy of the drug on O. petrowi infections. The present study aims to estimate lethal concentrations of FBZ to O. petrowi. Adult O. petrowi were maintained in vitro and exposed to doses of 5, 50, 100, and 200 µM concentrations of FBZ and included both negative and vehicle controls. Exposure lasted 7.5 days and lethality was determined for each treatment. Negative and vehicle controls did not differ, and both had 75% survival at the end of the treatment period. The percentage survivorship in ascending order of concentration, corrected for the controls, was 66.67%, 44.44%, 33.33%, and 0%. LC10, LC50, and LC90 estimates were 7.5 ± 0.26, 49.1 ± 1.69, and 163.2 ± 5.63 µM, respectively. In the context of known pharmacokinetics of FBZ in birds, a single oral dose of FBZ can achieve exposure levels that are lethal to O. petrowi, but the drug does not stay in the system long enough. Thus, treatment of O. petrowi infections will require multiple oral doses over several days. [ABSTRACT FROM AUTHOR]

Interest in the effects of stressors on wildlife has grown substantially over the past few decades. As this interest has grown, so has the need for minimally invasive and reliable methods for estimating differences in the levels of stress hormones. An enzyme immunoassay using standardized methods was validated for detecting concentrations of corticosterone (cort) metabolites from northern bobwhite fecal samples. Two physiological challenges and one biological challenge were applied to 18 northern bobwhites (nine males and nine females), and the fecal cort metabolite concentrations were compared to baseline levels. The interactions of sex and treatment, treatment and time and sex and time were all significant. Thus, the methods and tools used here were sensitive enough to detect expected changes to the hypothalamo–pituitary–adrenal axis of northern bobwhite. [ABSTRACT FROM AUTHOR]

Grassland birds have been declining substantially for the past several years. Habitat loss, degradation, and fragmentation as well as climate change are all thought to be the main drivers of the decline. However, as the declines continue to accelerate, it is becoming imperative to examine other factors that may contribute to population fluctuations. The nematodes Oxyspirura petrowi, Aulonocephalus pennula, and Physaloptera sp. are commonly found infecting northern bobwhite (Colinus virginianus), a game species of economic importance, and all 3 nematodes use insects as an intermediate host. Here we used polymerase chain reaction techniques to determine the occurrence of the 3 nematodes in 7 insect orders to uncover epidemiological patterns of the greatest potential for transmission to northern bobwhite. Insects were collected from March through September using sweep nets and pitfall traps. An R 3 C chi-squared test with Monte Carlo simulation was used to determine differences in the occurrence of the parasites across taxa and time. The results of the statistical analysis showed the nematodes are predominantly found in the order Orthoptera, and A. pennula and Physaloptera sp. showed epidemiological patterns in insects. However, no such pattern was observed with O. petrowi. An explanation for the lack of epidemiological pattern in O. petrowi is proposed and the diversity of known insect hosts of the 3 nematodes is increased. [ABSTRACT FROM AUTHOR]

Northern bobwhite quail (Colinus virginianus) are an important game bird that generates substantial revenue for rural communities and is also an important grassland conservation species. Unfortunately, Northern bobwhite populations have been declining across their range for over 50 years. In the southwest bobwhite range, parasites are suspected to contribute substantially to the decline. To test the relationship of parasites and wild Northern bobwhite populations, an anthelmintic medicated feed was developed. The medicated feed was then tested as part of the U.S. Food and Drug Administration registration process. Because Northern bobwhite are a game species and harvested birds are ingested by people, it was necessary to estimate the tissue clearance rate of the drug. This study examined how quickly the conjugated metabolite fenbendazole sulphone was cleared from quail liver. A validated LC/MS-MS method was used to determine clearance rate from pen-reared northern bobwhite fed the anthelmintic at 110 ppm in feed. Results of the tissue clearance study found the drug never exceeded the maximum allowable concentration of 6 ppm and was cleared from the liver in 9.38 hours. Based on the Center for Veterinary Medicine guidance for industry #3, a 0-day withdrawal period was assigned to the recently registered medicated feed in wild northern bobwhite. Thus, the anthelmintic fenbendazole was shown to be rapidly cleared from Northern bobwhite and represents a viable option for treating wild populations for parasite infections while treated game birds remain safe for human consumption., (© The Author(s) 2025. Published by Oxford University Press on behalf of the Society of Environmental Toxicology and Chemistry. All rights reserved. For permissions, please email: journals.permissions@oup.com.)