RAPID POINT-OF-CARE TESTING FOR DETECTION OF ANTIBODIES TO TOXOPLASMA GONDII IN BLACK VULTURES AND RING-BILLED GULLS FROM PENNSYLVANIA.

Toxoplasma gondii is a zoonotic protozoan parasite that infects most warm-blooded animals, including birds. Scavenging birds are epidemiologically important hosts because they can serve as indicators of environmental T. gondii levels. A rapid point-of-care (POC) test that detects antibodies to T. gondii in humans is commercially available. In this research, we assessed the ability of the human POC test to detect anti-T. gondii antibodies in 106 black vultures (Coragyps atratus) and 23 ring-billed gulls (Larus delawarensis) from Pennsylvania, USA. Serum samples were tested with the POC test and compared to the modified agglutination test (MAT) in a blinded study. Overall, anti-T. gondii antibodies were detected in 2.8% (3/106) of black vultures and 60.9% (14/23) of ring-billed gulls by the POC test. One false-positive POC test occurred in a black vulture that was negative by MAT. False-negative results were obtained in 2 black vultures and 4 ring-billed gulls that had MAT titers of 1:25 or 1:50. The sensitivity and specificity of the POC for both black vultures and ring-billed gulls combined were 95.7% and 95.5%, respectively. This is the first study using human POC tests to detect antibodies to T. gondii in birds. Further study of the rapid test as a screening tool for serological surveillance of T. gondii in birds is warranted.

Toxoplasma gondii Survey in Waterfowl and Gulls from Eight USA States.

Sera from 391 waterbirds from eight USA states were tested for Toxoplasma gondii antibodies using the modified agglutination test. Fifteen different waterbird species (26.6%; n=104) were seropositive. Of the adults, 25.4% (n=52) showed a significantly higher T. gondii seroprevalence compared with juveniles (13.4%; n=17); however, sex was not a significant factor.

Coccidiosis in Wild Eastern Newts (Notophthalmus viridescens): An Unexpected Finding in Consecutive Mortality Events in Tennessee, USA.

Wildlife diseases are a major threat for species conservation, and there is a growing need to implement more comprehensive disease response programs to better identify these diseases of concern. During March 2017, we observed moribund and dead eastern newts, Notophthalmus viridescens, in a single pond in middle Tennessee. All moribund individuals were emaciated. We euthanized and processed all individuals immediately on-site and later performed histopathology and quantitative PCR for ranavirus, the protist Perkinsea, and chytrid fungi Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans. One newt was positive for ranavirus. Histopathology showed no evidence of ranavirosis but did reveal overwhelming coccidiosis. Overlapping partial sequences of coccidian 18S subunit DNA showed a 96.4% match with Eimeria steinhausi, suggesting that lesions were due to a previously undescribed Eimeria sp. In 2019, two more moribund newts were encountered at the same pond. Histopathology revealed the same suspicious parasitic organisms, and one individual was positive for B. dendrobatidis. Further research on how seasonal and other environmental parameters may influence coccidia-associated morbidity and mortality is warranted. These events highlight the importance of histopathologic evaluation of mortality events and provide guidance for investigation of future outbreaks.

Toxoplasma gondii Strain and Dose Effects on Feed Conversion Rate, Body Weight, Serum Antibodies Response, and Systemic Distribution in Intraperitoneally Infected Domestic Turkey Poults.

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important foodborne zoonosis affecting a wide range of hosts, including birds. This study investigated the seroconversion, feed conversion rate, weight gain, and parasite tissue tropism as a function of parasite dose and virulence in turkeys. Twenty-five 4-wk-old female domestic turkeys (Meleagris gallapavo) were intraperitoneally infected with two different strains and two doses (105 and 108 tachyzoites/ml) of T. gondii tachyzoites, resulting in four treatment groups. A fifth group of 10 additional birds was intraperitoneally injected with sterile phosphate-buffered saline as a negative control. All birds remained subclinical except for three birds in the two high-dose groups (108 tachyzoites/ml). Survival rate was 88% (22/25). A 92% seroconversion rate was detected in T. gondii-infected birds using a modified agglutination test. Antibody titers as well as weight gain were related to the dose and strain of T. gondii used. Feed conversion rate was higher in the high-dose groups compared with low-dose and control groups, while weight gain was significantly lower at 14 days postinfection in the group infected with 108 tachyzoites/ml of virulent T. gondii strain. Gross lesions were detected in the pancreas and lungs of only one bird, and histopathologic findings varied depending on strain and dose. The organs that most frequently contained T. gondii DNA as detected by quantitative PCR were the brain and the heart, followed by the bursa of Fabricius and the lungs. This study confirmed that turkeys can be infected with T. gondii, and turkeys can show signs of infection when exposed to high doses. Given the increased practice of outdoor-raised livestock and wildlife consumption, continual experimental infection of T. gondii in wild and domestic animals should be pursued.

Artículo regular­Efectos de la cepa y la dosis de Toxoplasma gondii en la tasa de conversión alimenticia, el peso corporal, la respuesta de los anticuerpos séricos y la distribución sistémica en pavipollos domésticos infectados por vía intraperitoneal. La toxoplasmosis, causada por el parásito protozoario Toxoplasma gondii, es una zoonosis importante transmitida por los alimentos que afecta a una amplia gama de huéspedes, incluidas las aves. Este estudio investigó la seroconversión, la tasa de conversión alimenticia, el aumento de peso y el tropismo en los tejidos por el parásito en función de la dosis del parásito y su virulencia en pavos. Se infectaron intraperitonealmente veinticinco pavos domésticos hembras de 4 semanas (Meleagris gallapavo) con dos cepas diferentes y dos dosis (105 y 108 taquizoítos/ml) de taquizoítos de T. gondii, lo que resultó en cuatro grupos de tratamiento. Se inyectó intraperitonealmente un quinto grupo de 10 aves adicionales con solución salina amortiguada con fosfato estéril como control negativo. Todas las aves permanecieron subclínicas excepto tres aves en los dos grupos de dosis alta (108 taquizoítos/ml). La tasa de supervivencia fue del 88% (22/25). Se detectó una tasa de seroconversión del 92% en aves infectadas con T. gondii utilizando una prueba de aglutinación modificada. Los títulos de anticuerpos y el aumento de peso se relacionaron con la dosis y la cepa de T. gondii utilizada. La tasa de conversión alimenticia fue mayor en los grupos de dosis alta en comparación con los grupos de dosis baja y el control, mientras que el aumento de peso fue significativamente menor a los 14 días después de la infección en el grupo infectado con 108 taquizoítos/ml de cepa virulenta de T. gondii. Se detectaron lesiones macroscópicas en el páncreas y los pulmones de una sola ave y los hallazgos histopatológicos variaron según la cepa y la dosis. Los órganos que con mayor frecuencia contenían ADN de T. gondii detectado por PCR cuantitativa fueron el cerebro y el corazón, seguidos de la bolsa de Fabricio y los pulmones. Este estudio confirmó que los pavos pueden infectarse con T. gondii y que los pavos pueden mostrar signos de infección cuando se exponen a dosis altas. Dada la práctica cada vez mayor de consumo de ganado y vida silvestre criados al aire libre, se debe continuar evaluando la infección experimental continua de T. gondii en animales silvestres y domésticos.

Toxoplasma gondii prevalence in carnivorous wild birds in the eastern United States.

Toxoplasma gondii is an important zoonotic protozoan parasite that can infect all warm-blooded animals including mammals and birds. Raptors can be intermediate hosts for T. gondii and the infection may be dependent on their feeding habits. In this study, we investigated the seroprevalence of T. gondii in ten raptor species from Florida, Pennsylvania, and Tennessee followed by a parasite bioassay on select seropositive samples. From a total of 155 raptors, we detected T. gondii antibodies using a modified agglutination test (cutoff 1:25) in 32 (20.6%) birds. The T. gondii seroprevalence was 44.8% in Falconiformes (13/29), 75% in Strigiformes (15/20), and 3.8% in Ciconiiformes (4/106). All Ciconiiformes samples (hearts and sera) were collected from Pennsylvania during nuisance wildlife removal projects and all birds were apparently healthy. Falconiform and Strigiform samples were collected from an exotics clinic in Tennessee and a rehabilitation center in Florida. All sampled birds were dead or euthanatized due to failure of rehabilitation or treatment. There was no statistically significant difference in T. gondii seroprevalence between Tennessee and Florida in the tested raptors. There was also no statistically significant difference in T. gondii exposure between males and females or adults and subadults. Mice bioassay attempts using fresh brain and/or heart tissue were performed on four seropositive birds. We isolated viable T. gondii tachyzoites from one red-shouldered hawk (Buteo lineatus) and genotyped the isolate using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of ten genetic markers. The isolated strain was designated as TgHawkFL1, which is ToxoDB PCR-RFLP genotype #28. Further research is needed to investigate the prevalence of T. gondii in raptors in the United States to obtain a better understanding of the life cycle, wildlife population impacts, and transmission dynamics of the parasite.

Serologic Survey of Toxoplasma gondii in Black Bears (Ursus americanus) from Eastern Tennessee, USA.

The modified agglutination test was used to study Toxoplasma gondii exposure in 70 eastern Tennessee, US, black bears (Ursus americanus) from 2015 to 2017. Overall, 74% (52/70) of bears were seropositive, and T. gondii was more prevalent in adults than subadults.

Seroprevalence, DNA isolation, and genetic characterization of Toxoplasma gondii from black bear (Ursus americanus) sera collected in Eastern Oklahoma.

Black bears (Ursus americanus) are commonly exposed to Toxoplasma gondii. However, there are no reports of exposure or infection with T. gondii in black bears from Oklahoma. The purpose of our project was to determine the seroprevalence of T. gondii antibodies in black bears collected in Oklahoma. Additionally, since only serum was available from these bears, we sought to determine if DNA extraction and PCR amplification for T. gondii was possible on serum samples from bears with positive titers. Seroprevalence was determined using modified agglutination test (MAT). Serum was collected from 44 live-trapped bears in southeastern Oklahoma; 32 (73% ± 58-84%) had antibodies against T. gondii. Seroprevalence in adult bears (85% ± 67-95%) was significantly higher (p = 0.028) than yearlings (33.0% ± 56-80%). Adult bears were 3.4 times more likely to have antibodies to T. gondii than yearlings. From the bears with positive titers, T. gondii DNA was detected in 12 of the 32 seropositive samples by PCR of the B1 gene, with two of the samples showing variation in two nucleotide positions when compared with available sequences. Multilocus PCR-RFLP genotyping of these 12 samples revealed three ToxoDB genotypes, including #2 (type III, haplogroup 3), #4 (type XII, haplogroup 12), and #74 (haplogroup 12). To the best of our knowledge, this is the first report of T. gondii seroprevalence in black bears from Oklahoma. Our results indicate that exposure and infection with T. gondii in black bears from Oklahoma is common.

Toxoplasma gondii Prevalence in Hunter-Killed Mourning Doves (Zenaida macroura) and Rock Pigeons (Columba livia) from East Tennessee, USA.

We molecularly examined brains from 186 hunter-killed Mourning Doves (Zenaida macroura) and 11 Rock Pigeons (Columba livia) from eastern Tennessee, USA for Toxoplasma gondii. Two doves (1%) were PCR- and sequence-positive, whereas all pigeons were PCR-negative.

Eimeria gilruthi-associated abomasitis in a group of ewes.

Nine of 23 (39%) research ewes with severe diarrhea and weight loss had histologic lesions consistent with Eimeria gilruthi infection in their abomasa. Gross anatomic lesions included hundreds of opaque 1-mm nodules in abomasal mucosa that corresponded microscopically to 200-300 µm diameter organisms surrounded by areas of necrosis. Analysis of fecal samples from 4 ewes demonstrated oocysts from typical ovine Eimeria species, none of which were E. gilruthi. Two separate PCR reactions were performed on abomasal tissue from 4 sheep to amplify the 18S ribosomal DNA (rDNA) and internal transcribed spacer (ITS) region of the rDNA, respectively. The resultant 18S rDNA nucleotide sequences shared 99% homology with multiple Eimeria species in GenBank. The ITS region shared 77% homology with E. ellipsoidalis in GenBank. Further studies are needed to understand the life cycle and pathogenicity of E. gilruthi. Our results underscore the inclusion of E. gilruthi in the differential diagnosis of diarrhea and weight loss in sheep.