The pharmacokinetics and pharmacodynamics of oral ponazuril in the treatment of systemic isosporosis in passerine birds

Systemic isosporosis, previously referred to as atoxoplasmosis, an infection caused by apicomplexan protozoa in the genus Isospora, is a significant cause of mortality in nestling and fledgling passerine birds. Recommended treatment regimens are largely empirical and vary greatly in efficacy. The goal of this research was to determine the pharmacokinetics and pharmacodynamics of the antiparasitic agent, ponazuril for use in treating systemic isosporosis. Diluted oral ponazuril solution (50 mg/mL) was administered (100 mg/kg) to 72 European starlings (Sturnus vulgaris) either by a single dose via direct oral gavage (n=24), a single dose injected into Zophobas morio (superworm) larvae (n=24), or a daily dose mixed with commercial dog food to top-dress feed for 4 days (n=24). Peak plasma concentrations, at 4.51 h, 2.46 h, and 11.52 h, were 5.84 µg/mL, 2.46 µg/mL, and 9.13 µg/mL for the direct gavage group, injected larvae, and top-dressed feed groups, respectively. With repeated dosing, mean plasma concentrations from the top-dressed feed group were maintained between 8.12-13.11 µg/mL. Results suggested ponazuril at a dosage of 100 mg/kg administered via direct gavage or top-dressed feed, but not via injected larvae, would exceed the concentrations needed to inhibit merogony of other apicomplexan parasites in cell culture (5 µg/mL). To assess the efficacy of ponazuril in preventing the fecal shedding of systemic Isospora spp, seven passerine birds (red-vented bulbuls (Pycnonotus cafer, n=2), blue-grey tanager (Thraupis episcopus, n=1), and red-capped cardinals (Paroaria gularis, n=4)) were identified as shedders of systemic Isospora spp. via fecal qPCR. These birds were treated with ponazuril (100 mg/kg) daily on top-dressed feed for 14 days. Fecal samples were collected throughout treatment and four weeks afterwards. The proportions of fecal shedding were reduced during the treatment period and the first week following treatment but shedding resumed in all birds by the end of the treatment. Use of this dose in breeding or fledgling birds is recommended to reduce the shedding of active oocysts that could produce infection in nestling and fledgling passerines.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

VMS-Veterinary Clinical Medcne

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• McEntire, Michael Stephen

Contributors dc:contributor

• Allender, Matthew C
• Reinhart, Jennifer M
• Landolfi, Jennifer A
• Adkesson, Michael J

• Passerines
• Systemic Isosporosis
• Pharmacokinetics
• Ponazuril

Statement dc:rights

• Copyright 2022 Michael McEntire

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/117528

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F117528