Persistence of Two Isolates of Trichomonas gallinae in Simulated Bird Baths With and Without Organic Material.

Trichomonas gallinae, a well-documented protozoan parasite of avian hosts, has been implicated in major passerine mortality events recently and historically throughout the literature. It has been suggested that bird baths and artificial water sources could serve as a source of infection for naive birds; however, trichomonad persistence in water is not well understood. We measured the persistence of T. gallinae isolates from two avian hosts in distilled water and distilled water with the addition of organic material. We inoculated plastic containers in a laboratory setting with 1 × 10(6) trichomonads and then sampled 500 µl from each container at various time points postinoculation (0-20 hr). The 500-µl aliquots were inoculated into flasks with 5 ml of modified Diamond media at each time point. Flasks were incubated at 37 C and examined by light microscopy for five consecutive days for the characteristic movements of live trichomonads. The maximum persistence was 16 hr with a Cooper's hawk (Accipiter cooperii) isolate in the organic material treatment, far longer than the 1 hr persistence previously reported. We show that T. gallinae isolates are capable of persisting for long periods of time in water, illustrating that bird baths may be validated as a potential source of transmission in epidemics.

Detection of Trichomonas gallinae in Wild Birds Admitted to a Rehabilitation Center, Florida, USA.

We screened raptors (n=188) and columbids (n=2) presenting to a Tampa, Florida, US rehabilitation center from June 2016 to April 2017 for Trichomonas gallinae. One juvenile Cooper's Hawk (Accipiter cooperii) was culture- and PCR-positive and sequencing identified as genotype E1. A subset of culture-negative (10%, n=19) samples were negative via PCR.

Retrospective investigation of Echinococcus canadensis emergence in translocated elk (Cervus canadensis) in Tennessee, USA, and examination of canid definitive hosts.

BACKGROUND: Few reports of Echinococcus spp. have been described in the USA; however, the geographical distribution of Echinococcus spp. in wild hosts is increasing consequent to human activities. In the early 2000's, 253 elk (Cervus canadensis) originating from Alberta, Canada were released into the Great Smoky Mountains National Park and North Cumberland Wildlife Management Area in an effort to re-establish their historical range. METHODS: We investigated the prevalence of Echinococcus spp. in re-established elk populations in the North Cumberland Wildlife Management Area and the Great Smoky Mountains National Park via a retrospective analysis of banked elk tissues and helminth examinations on intestinal contents from coyotes (Canis latrans) from the North Cumberland Wildlife Management Area. RESULTS: Four elk were PCR and sequence positive for E. canadensis. Each sequence had 98% or greater coverage and identity to multiple E. canadensis genotypes on GenBank. Adult Echinococcus spp. were not detected in any of the coyotes examined in this study. CONCLUSIONS: Continued surveillance of this disease in susceptible species in these areas is warranted, and these data further underscore the risk of zoonotic pathogen introduction secondary to wildlife translocation.

Artificially decreased dissolved oxygen increases the persistence of Trichomonas gallinae in water.

Water containing organic material has been shown to increase the persistence of the avian pathogenic protozoa, Trichomonas gallinae. We hypothesized that the decrease in dissolved oxygen due to microbes in the organic material could increase persistence of the microaerophilic trichomonads. Using simulated birdbaths, we determined 1) the levels of dissolved oxygen in distilled water with various amounts of organic material, 2) the concentration of the oxygen-scavenging enzyme Oxyrase® needed to achieve the dissolved oxygen levels obtained in organic material contaminated water, and finally, 3) the persistence of two T. gallinae isolates in Oxyrase®-supplemented water. An average of 9.6% dissolved oxygen was obtained with the addition of 15 g organic material to 500 ml of distilled water, whereas organic material-free water had 86.2% dissolved oxygen. The addition of 0.5% and 1.0% (vol/vol) Oxyrase® to organic material-free water yielded dissolved oxygen of 18.6% and 6.9%, respectively. Using 0.5% and 1.0% concentrations of Oxyrase®, we evaluated the persistence of two trichomonad isolates by inoculating ∼1 million trichomonads into 500 ml distilled water in triplicate. At various time-points, 0.5 ml aliquots of trichomonad-inoculated water were obtained and placed into Hollander Fluid media, incubated at 37 °C, and read by light microscopy every other day for 5 days. In our 1% Oxyrase® treatments, the longest recorded persistence of broad-winged hawk 1 increased from the previously reported 4hrs to 30hrs and Cooper's hawk 4 from 16hrs to 30hrs. These results indicate that the mechanism for organic material-mediated trichomonad persistence is associated with decreased dissolved oxygen, further demonstrating the importance of keeping birdbaths free of organic debris to discourage trichomonad persistence.

PREVALENCE AND RISK FACTORS OF TRICHOMONAS GALLINAE AND TRICHOMONOSIS IN GOLDEN EAGLE ( AQUILA CHRYSAETOS) NESTLINGS IN WESTERN NORTH AMERICA.

Avian trichomonosis, caused by the protozoan Trichomonas gallinae, affects bird-eating raptors worldwide. Raptors can develop trichomonosis by feeding on infected prey, particularly Rock Pigeons (C olumba livia), which are a reservoir for T. gallinae. Raptors may be particularly vulnerable to T. gallinae infection in degraded habitats, where changes in resources may cause raptors to switch from foraging on native prey to synanthropic avian species such as Rock Pigeons. Golden Eagles ( Aquila chrysaetos) typically forage on mammals; however, habitat across much of their range is experiencing degradation through changes in land use, climate, and human encroachment. In 2015, we examined the prevalence of T. gallinae infection in Golden Eagle nestlings across western North America and conducted an intensive study on factors associated with T. gallinae infection and trichomonosis in southwestern Idaho. We found T. gallinae infection in 13% (12/96) of eagle nestlings across 10 western states and in 41% (13/32) of nestlings in southwestern Idaho. At the Idaho site, the probability of T. gallinae infection increased as the proportion of Rock Pigeons in nestling diet increased. Nestlings with diets that consisted of ≥10% Rock Pigeons had a very high probability of T. gallinae infection. We compared historical (1971-81) and recent (2014-15) diet data and incidence of trichomonosis lesions of nestling eagles in Idaho and found that the proportion of Rock Pigeons in eagle diets was higher in recent versus historical periods, as was the proportion of eagle nestlings with trichomonosis lesions. Our results suggested that localized shifts in eagle diet that result from habitat degradation and loss of historical prey resources have the potential to affect Golden Eagle nestling survival and supported the hypothesis that land use change can alter biologic communities in a way that might have consequences for disease infection and host susceptibility.

Use of FTA technology for detection of Trichomonas gallinae.

Trichomonas gallinae is the causative agent for avian trichomonosis, which can have important population implications for domestic turkeys, columbids, raptors, and various passeriformes. Continued population surveillance and genotype distribution is needed to elucidate transmission dynamics and prevalence of T. gallinae among free-ranging birds. However, obtaining live cultures for laboratory testing is logistically challenging, limiting the ability to perform surveillance and genotype investigations. In this study, we evaluated non-indicating FTA Elute cards as a potential sampling storage substrate for downstream use in molecular identification of two T. gallinae isolates. Isolate concentrations of 10 or 100 trichomonads/40 µl were inoculated onto a FTA Elute card in triplicate. At each time point (48 h, 2 weeks, and 3 weeks), DNA elution procedures were performed on the cards, and the eluents were analyzed by conventional polymerase chain reaction (PCR) using trichomonad-specific primers. Three PCR-positive samples were detected at 48 h from one isolate; however, all eluents from cards held for 2 and 3 weeks were PCR-negative. Our results suggest that use of FTA Elute cards for nucleic acid storage can lead to low PCR sensitivity of T. gallinae in low concentrations, such as those found in non-clinical birds; however, more research is needed to fully evaluate the efficacy of FTA Elute cards as a diagnostic tool for T. gallinae.

Survey for Trichomonas gallinae in Northern Bobwhites (Colinus virginianus) from the Rolling Plains Ecoregion, Oklahoma and Texas, USA.

Northern Bobwhites (Colinus virginianus) have been in decline throughout the southeastern US. Prevalence of Trichomonas gallinae in wild bobwhites is unknown, although T. gallinae caused morbidity and mortality in experimentally infected bobwhites. Many species of Columbidae (pigeons and doves) in Texas are hosts to T. gallinae. Bobwhites potentially may become exposed to this protozoan through supplemental feed or water sources contaminated by columbids infected with T. gallinae. All of 506 bobwhites collected in Oklahoma and Texas, 2011-13, were PCR negative for T. gallinae. These data suggest T. gallinae is not contributing to the population decline of bobwhites in this region.

Trichomonas gallinae Persistence in Four Water Treatments.

Trichomonas gallinae is a protozoan parasite commonly found in columbids, passerines, and several raptor species. Although T. gallinae is thought to spread between individuals and across species through shared water sources, little research has been conducted regarding the persistence of T. gallinae in the environment. To determine the persistence of T. gallinae in various communal water sources, we inoculated 1 × 10(6) trichomonads into 500 mL samples of distilled water, quarry water, bird bath water, and rain barrel water in two replicates. Aliquots of 0.5 mL were collected from each source at -1, 0, 15, 30, and 60 min; aliquots were incubated at 37 C and examined for trichomonads by light microscopy for five consecutive days. Live trichomonads were observed in all samples and at all sampling times except prior to inoculation (-1 min). The pH of water sources ranged from an average of 5.9 to 7.4 postsampling. Our findings indicate that T. gallinae can persist for up to 60 min in various water treatments and thus be infectious for birds drinking T. gallinae-contaminated water.