Lisa A. Tell

EVIDENCE FOR CRYPTIC SPECIATION OF LEUCOCYTOZOON SPP. (HAEMOSPORIDA, LEUCOCYTOZOIDAE) IN DIURNAL RAPTORS

Species of Leucocytozoon (Haemosporida, Leucocytozoidae) traditionally have been described based on morphological characters of their blood stages and host cells, with limited information on their avian host specificity. Based on the current taxonomy, Leucocytozoon toddi is the sole valid species of leucocytozoids parasitizing falconiform birds. Using a nested polymerase chain reaction protocol, we determined the prevalence of Leucocytozoon infection in 5 species of diurnal raptors from California. Of 591 birds tested, 177 (29.9%) were infected with Leucocytozoon toddi. Subsequent phylogenetic analysis of the cytochrome b gene revealed that distinct haplotypes are present in hawks of these genera. Haplotypes present in Buteo spp. are not found in Accipiter spp., and there is a 10.9% sequence divergence between the 2 lineage clades. In addition, Leucocytozoon sp. from Accipiter spp. from Europe group more closely with parasites found in Accipiter spp. from California than the same California Accipiter species do with their sympatric Buteo spp. Similarly, a Leucocytozoon haplotype from a Common Buzzard (Buteo buteo) from Kazakhstan forms a monophyletic lineage with a parasite from B. jamaicensis from California. These results suggest that Leucocytozoon toddi is most likely a group of cryptic species, with 1 species infecting Buteo spp. and 1 or more species, or subspecies, infecting Accipiter spp.

Pharmacokinetics of veterinary drugs in laying hens and residues in eggs: a review of the literature

Poultry treated with pharmaceutical products can produce eggs contaminated with drug residues. Such residues could pose a risk to consumer health. The following is a review of the information available in the literature regarding drug pharmacokinetics in laying hens, and the deposition of drugs into eggs of poultry species, primarily chickens. The available data suggest that, when administered to laying hens, a wide variety of drugs leave detectable residues in eggs laid days to weeks after the cessation of treatment.

Blood Parasites in Owls with Conservation Implications for the Spotted Owl (Strix occidentalis)

The three subspecies of Spotted Owl (Northern, Strix occidentalis caurina; California, S. o. occidentalis; and Mexican, S. o. lucida) are all threatened by habitat loss and range expansion of the Barred Owl (S. varia). An unaddressed threat is whether Barred Owls could be a source of novel strains of disease such as avian malaria (Plasmodium spp.) or other blood parasites potentially harmful for Spotted Owls. Although Barred Owls commonly harbor Plasmodium infections, these parasites have not been documented in the Spotted Owl. We screened 111 Spotted Owls, 44 Barred Owls, and 387 owls of nine other species for haemosporidian parasites (Leucocytozoon, Plasmodium, and Haemoproteus spp.). California Spotted Owls had the greatest number of simultaneous multi-species infections (44%). Additionally, sequencing results revealed that the Northern and California Spotted Owl subspecies together had the highest number of Leucocytozoon parasite lineages (n = 17) and unique lineages (n = 12). This high level of sequence diversity is significant because only one Leucocytozoon species (L. danilewskyi) has been accepted as valid among all owls, suggesting that L. danilewskyi is a cryptic species. Furthermore, a Plasmodium parasite was documented in a Northern Spotted Owl for the first time. West Coast Barred Owls had a lower prevalence of infection (15%) when compared to sympatric Spotted Owls (S. o. caurina 52%, S. o. occidentalis 79%) and Barred Owls from the historic range (61%). Consequently, Barred Owls on the West Coast may have a competitive advantage over the potentially immune compromised Spotted Owls.

Diagnosis of avian mycobacteriosis: comparison of culture, acid-fast stains, and polymerase chain reaction for the identification of Mycobacterium avium in experimentally inoculated Japanese quail (Coturnix coturnix japonica).

Abstract In this study we compared culture, acid-fast stains, and polymerase chain reaction (PCR) for the detection of acid-fast organisms in fecal and tissue samples from Japanese quail (Coturnix coturnix japonica) that were experimentally inoculated intravenously with Mycobacterium avium. For culture, three different culture media (modified Herrold egg yolk with mycobactin; Lowenstein–Jensen [L-J]; and L-J with cyclohexamide, naladixic acid, and lincomycin) were tested to determine which medium had the greatest success in isolating mycobacteria. Acid-fast staining methods included Ziehl–Neelsen (Z-N) and Truant. The PCR assay detected mycobacterial DNA with primers specific for the 65-kD heat shock protein gene. Culture was considered the “gold standard.” Compared with other culture media, L-J yielded more positive cultures and greater numbers of colonies on positive tubes, and incubation times were shorter. Mycobacterium avium was isolated from all of the harvested tissue samples (liver, spleen, and intestine) of inoculated birds. Mycobacteria were isolated from 53% (69/130) of fecal samples from inoculated birds. As the disease advanced, fecal culture was positive on more culture days, indicating that the culture-positive rate was higher later in the course of the disease. Compared with culture, all of the laboratory methods had 100% specificity for the tissue samples. Sensitivities for the tissue samples were 82.6% (Z-N), 95.7% (Truant), and 100% (PCR). For the fecal samples, the specificity was >95% for all methods. Sensitivities compared with fecal culture were 7.2% (Z-N), 30.4% (Truant), and 20.3% (PCR). Tissue and fecal samples from the two control birds were negative for acid-fast organisms by any method. These results were comparable with clinical cases of avian mycobacteriosis where culture and PCR of tissue samples seem to be the most sensitive and specific laboratory tests and evaluation of fecal samples still remains challenging. On the basis of the results of this study, identification of mycobacteria in fecal samples from Japanese quail can be optimized by repeated cultures and Truant acid-fast staining of fecal smears.

Health concerns and management of select veterinary drug residues

The aim of this manuscript is to review the potential adverse health effects in humans if exposed to residues of selected veterinary drugs used in food-producing animals. Our other objectives are to briefly inform the reader of why many of these drugs are or were approved for use in livestock production and how drug residues can be mitigated for these drugs. The selected drugs include several antimicrobials, beta agonists, and phenylbutazone. The antimicrobials continue to be of regulatory concern not only because of their acute adverse effects but also because their use as growth promoters have been linked to antimicrobial resistance. Furthermore, nitroimidazoles and arsenicals are no longer approved for use in food animals in most jurisdictions. In recent years, the risk assessment and risk management of beta agonists, have been the focus of national and international agencies and this manuscript attempts to review the pharmacology of these drugs and regulatory challenges. Several of the drugs selected for this review can cause noncancer effects (e.g., penicillins) and others are potential carcinogens (e.g., nitroimidazoles). This review also focuses on how regulatory and independent organizations manage the risk of these veterinary drugs based on data from human health risk assessments.

A model of avian mycobacteriosis: Clinical and histopathologic findings in japanese quail (Coturnix coturnix japonica) intravenously inoculated with Mycobacterium avium

Abstract Mycobacterial infections are an important cause of morbidity and mortality in birds and a considerable diagnostic challenge until the disease is advanced. In order to develop more clinically useful antemortem tests, a biological model was created that replicated naturally occurring disease. Japanese quail (Coturnix coturnix japonica; n = 8) were inoculated intravenously with Mycobacterium avium. Two additional birds served as uninoculated controls. Mean survival time of the inoculated birds was 68 ± 13 days postinoculation (PI). Seven of the eight inoculated birds died naturally. Clinical and postmortem abnormalities in inoculated birds were characteristic of naturally occurring mycobacteriosis. Abnormal clinical findings included decreased activity, feather erection, and sudden death. Mean body weight and packed cell volume declined and mean total white blood cells (primarily heterophils, bands, and monocytes) increased from 28 days PI onward. Similar to birds that are naturally infected with mycobacteriosis, the inoculated birds were thin and had severe hepatosplenomegaly on postmortem examination. All eight birds had lesions in the liver, spleen, intestine, lung, gonads, and serosa. Less commonly affected tissues included bone marrow, thymus, gizzard, heart, pancreas, and brain. Lesions were invariably severe in the liver and spleen. These gross postmortem findings were consistent with natural infections of avian mycobacteriosis. Mycobacterium avium was isolated from the liver, spleen, and intestine of all inoculated birds. Both control birds remained disease free and culture negative. This inoculation protocol is a reliable and practical means of inducing avian mycobacteriosis for further study.

Pharmacokinetics of ceftiofur sodium and ceftiofur crystalline free acid in neonatal foals

Ceftiofur, a third generation cephalosporin, demonstrates in vitro efficacy against microorganisms isolated from septicemic neonatal foals. This pharmacokinetic study evaluated the intravenous and subcutaneous administration of ceftiofur sodium (5 mg/kg body weight; n = 6 per group) and subcutaneous administration of ceftiofur crystalline free acid (6.6 mg/kg body weight; n = 6) in healthy foals. Plasma ceftiofur- and desfuroylceftiofur-related metabolite concentrations were measured using high performance liquid chromatography following drug administration. Mean (±SD) noncompartmental pharmacokinetic parameters for i.v. and s.c. ceftiofur sodium were: AUC(0→∝) (86.4 ± 8.5 and 91 ± 22 h·μg/mL for i.v. and s.c., respectively), terminal elimination half-life (5.82 ± 1.00 and 5.55 ± 0.81 h for i.v. and s.c., respectively), C(max(obs)) (13 ± 1.9 μg/mL s.c.), T(max(obs)) (0.75 ± 0.4 h for s.c.). Mean (± SD) noncompartmental pharmacokinetic parameters for s.c. ceftiofur crystalline free acid were: AUC(0→∝) (139.53 ± 22.63 h·μg/mL), terminal elimination half-life (39.7 ± 14.7), C(max(obs)) (2.52 ± 0.35 μg/mL) and t(max(obs)) (11.33 ± 1.63 h). No adverse effects attributed to drug administration were observed in any foal. Ceftiofur- and desfuroylceftiofur-related metabolites reached sufficient plasma concentrations to effectively treat common bacterial pathogens isolated from septicemic foals.

Avian Mycobacteriosis in Free-Living Raptors in California: 6 Cases (1997–2001)

Abstract Avian mycobacteriosis has been documented commonly in poultry, companion birds, and birds in zoological collections or wildlife parks. However, reports in free-ranging raptors are relatively rare. We describe 6 cases of mycobacteriosis in free-living raptors. Four red-tailed hawks (Buteo jamaicensis), 1 red-shouldered hawk (Buteo lineatus), and 1 great horned owl (Bubo virginianus) were presented for examination after being found on the ground unable to fly. Common clinical findings in these birds included coelomic distention or palpable coelomic mass, nonregenerative anemia, and leukocytosis characterized by heterophilia, monocytosis, and lymphopenia. Results of radiography, ultrasonography, coelomoscopy, and biopsy, in combination with acid-fast staining of specimens obtained by biopsy or fine-needle aspiration, provided evidence of a presumptive diagnosis of mycobacteriosis. All birds were euthanatized (n = 5) or died (n = 1). At necropsy, diffuse granulomas with intralesional acid-fast bacilli were present in all birds. Mycobacteriosis was confirmed by culture in 4 birds, and polymerase chain reaction testing confirmed Mycobacterium avium in 3 of these 4 birds. On the basis of clinical and postmortem findings, mycobacteriosis should be considered as a differential diagnosis in adult raptors that are found debilitated and in poor body condition. Detection of acid-fast bacilli in biopsy or necropsy specimens allows a presumptive diagnosis of mycobacteriosis; however, definitive diagnosis requires mycobacterial culture or polymerase chain reaction analysis.

Pharmacokinetics of tulathromycin following subcutaneous administration in meat goats

Tulathromycin is a triamilide antibiotic that maintains therapeutic concentrations for an extended period of time. The drug is approved for the treatment of respiratory disease in cattle and swine and is occasionally used in goats. To investigate the pharmacokinetics of tulathromycin in meat goats, 10 healthy Boer goats were administered a single 2.5 mg/kg subcutaneous dose of tulathromycin. Plasma concentrations were measured by ultra-high pressure liquid chromatography tandem mass spectrometry (UPLC-MS/MS) detection. Plasma maximal drug concentration (Cmax) was 633 ± 300 ng/ml (0.40 ± 0.26 h post-subcutaneous injection). The half-life of tulathromycin in goats was 110 ± 19.9 h. Tulathromycin was rapidly absorbed and distributed widely after subcutaneous injection 33 ± 6 L/kg. The mean AUC of the group was 12,500 ± 2020 h ng/mL for plasma. In this study, it was determined that the pharmacokinetics of tulathromycin after a single 2.5 mg/kg SC injection in goats were very similar to what has been previously reported in cattle.

Real-Time Polymerase Chain Reaction Testing for the Detection of Mycobacterium genavense and Mycobacterium avium Complex Species in Avian Samples

Abstract SUMMARY. Diagnosis of avian mycobacteriosis, caused by Mycobacterium genavense or species belonging to the Mycobacterium avium complex (MAC), is problematic. Polymerase chain reaction (PCR) offers rapid and sensitive detection of minute quantities of DNA, and conventional protocols have been used for evaluating avian specimens. The recent development of real-time PCR offers several advantages over conventional PCR. In attempts to improve diagnosing avian mycobacteriosis, a real-time TaqMan® PCR assay was developed targeting the 65-kD heat shock protein gene of M. genavense and MAC spp. Nineteen reference isolates, 16 clinical isolates, and 32 avian tissue samples were used to evaluate the assay. When sufficient amplicons were produced, the species of mycobacteria was determined by standard sequencing of TaqMan® PCR products and compared with results from commercial mycobacteriology laboratories and/or standard sequencing of conventional PCR products. The TaqMan® PCR detected DNA from reference isolates of M. genavense, MAC spp., and Mycobacterium tuberculosis complex spp. Of the clinical isolates, the TaqMan® PCR detected DNA from 10 of 12 Mycobacterium avium avium isolates and two of three Mycobacterium avium intracellulare isolates. For the tissue samples, the TaqMan® PCR amplified DNA in six of nine samples that were identified by sequencing of conventional PCR products and/or by commercial mycobacteriology laboratories as being MAC spp. positive and three of four samples that were positive for M. genavense. There was some disagreement between speciation results from the TaqMan® PCR and those from commercial mycobacteriology laboratories or conventional PCR or both. This disagreement was suspected to be because of relatively small numbers of base pairs in the TaqMan® PCR products. The TaqMan® PCR may provide a useful tool for evaluating clinical samples for DNA from mycobacteria species that most commonly infect birds; however, further refinement is needed in order to improve sensitivity and provide more accurate speciation.