Comparative investigation of IFN-γ-producing T cells in chickens and turkeys following vaccination and infection with the extracellular parasite Histomonas meleagridis

The re-emerging disease histomonosis is caused by the protozoan parasite Histomonas meleagridis that affects chickens and turkeys. Previously, protection by vaccination with in vitro attenuated H. meleagridis has been demonstrated and an involvement of T cells, potentially by IFN-γ production, was hypothesized. However, comparative studies between chickens and turkeys on H. meleagridis-specific T cells were not conducted yet. This work investigated IFN-γ production within CD4⁺, CD8α⁺ and TCRγδ⁺ (chicken) or CD3ε⁺CD4^-CD8α^- (turkey) T cells of spleen and liver from vaccinated and/or infected birds using clonal cultures of a monoxenic H. meleagridis strain. In infected chickens, re-stimulated splenocytes showed a significant increase of IFN-γ⁺CD4⁺ T cells. Contrariwise, significant increments of IFN-γ-producing cells within all major T-cell subsets of the spleen and liver were found for vaccinated/infected turkeys. This indicates that the vaccine in turkeys causes more intense systemic immune responses whereas in chickens protection might be mainly driven by local immunity.

Epidemiologic significance of Toxoplasma gondii infections in turkeys, ducks, ratites and other wild birds: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Wild and domestic avian species are important in the epidemiology of T. gondii infections because felids prey on them and excrete millions of oocysts in the environment, disseminating the infection. Herbivorous birds are also excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Toxoplasma gondii infections in birds of prey reflect infections in intermediate hosts. Humans can become infected by consuming undercooked avian tissues. Here, the authors reviewed prevalence, persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from turkeys, geese, ducks, ratites and avian species (excluding chickens) worldwide 2009-2020. Genetic diversity of 102 T. gondii DNA samples isolated worldwide is discussed. The role of migratory birds in dissemination of T. gondii infection is discussed.

Identification of parasitic arthropods collected from domestic and wild animals in Yucatan, Mexico

The morphological characterization of ectoparasites from domestic and wild animals is crucial to distinguish those that may be involved in the transmission of zoonotic pathogens. The objectives of this work were to identify parasitic arthropods collected from several hosts in Yucatan State, Mexico and to determine the prevalence of the parasite Trypanosoma cruzi in sylvatic specimens of Triatoma dimidiata. Morphological traits and scanning electron microscopy were used to confirm some parasitic identities. In total, 834 parasitic arthropods of various taxa were identified. Amblyomma americanum, Amblyomma maculatum, Amblyomma parvum, Dermacentor variabilis, and Rhipicephalus sanguineus were identified from dogs, horses, sheep, and deer. The flea Ctenocephalides felis was identified from dogs and the human flea, Pulex irritans was found on horses and sheep. The Neotropical deer ked Lipoptena mazamae was identified from brown brocket deer Mazama pandora. The chewing lice Chelopistes meleagridis, Menacanthus stramineus, Menopon gallinae, Myrsidea sp. and Lipeurus caponis were identified from poultry (Meleagris gallopavo and Gallus gallus). Other chewing lice, Tyranniphilopterus sp., Columbicola columbae, and Physconelloides eurysema were identified from wild birds Pachyramphus aglaiae, Patagioenas flavirostris and Zenaida asiatica, respectively. Trypanosoma cruzi was present in 52.5% of sylvatic adult T. dimidiata. Several of these findings represent new records of ectoparasites for Yucatan and new distribution areas in Mexico. The implications for human and animal health are discussed.

Isolation and Genetic Characterization of Toxoplasma gondii from Tissues of Wild Turkeys (Meleagris gallopavo) in Pennsylvania

Toxoplasmosis in wild turkeys (Meleagris gallopavo) is of epidemiological interest because turkeys feed from the ground, and detection of infection in turkeys indicates contamination by oocysts in the environment. During the 2018 spring hunting season in Pennsylvania, fresh (unfixed, not frozen) samples were obtained from 20 harvested wild turkeys and tested for Toxoplasma gondii infection. Hearts from all wild turkeys and skeletal muscle from 1 were bioassayed for T. gondii by inoculation in outbred Swiss Webster (SW) and interferon-gamma gene knockout (KO) mice. Antibodies to T. gondii were detected in 1:5 dilution of neat serum from 5 of 15 wild turkeys and in fluid from the heart of 1 of 4 wild turkeys with the modified agglutination test (MAT); neat serum was not available from 4 wild turkeys. Viable T. gondii was isolated from hearts of 5 wild turkeys, 1 with MAT of 1:10, 1 with MAT of 1:5, and 3 seronegative (MAT < 1:5). Toxoplasma gondii was isolated from both heart and skeletal muscle in the 1 wild turkey that had skeletal muscle submitted. The KO mice inoculated with tissue from all 5 infected wild turkeys died or were euthanatized when ill, 7-21 days post-inoculation (PI). Tachyzoites were detected in lungs of all KO mice, and the T. gondii strains were successfully propagated in cell culture. The SW mice inoculated with tissues of wild turkeys remained asymptomatic, and tissue cysts were seen in the brains of infected mice when euthanatized in good health at 46 days PI; 1 of the 2 SW mice inoculated with the heart of 1 turkey died on day 26, and tachyzoites were detected in its lung. Genetic typing on DNA extracted from culture-derived tachyzoites using the PCR restriction fragment length polymorphism with 10 genetic markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) revealed that 4 isolates belonged to ToxoDB PCR-RFLP genotype #5 and 1 was genotype #216.

Distribution and abundance of Eimeria species in commercial turkey flocks across Canada

Diversity and regional abundance of Eimeria species infecting Canadian commercial turkey flocks are largely unknown. To address this paucity of data regarding coccidiosis and its distribution in Canada, fecal samples from turkey flocks (N = 39) representing 27 commercial farms [ON (n = 20), SK (n = 2), BC (n = 3), AB (n = 1), NS (n = 1)] were screened for coccidia. Identification of all Eimeria species present in each sample was accomplished using a nested-polymerase chain reaction (PCR) assay targeting the mitochondrial cytochrome C oxidase subunit I gene. Most samples (33/39) were Eimeria-positive with 6 Eimeria species identified by the nested-PCR assay (1 to 6 species/sample, average 3.2); 4 samples (4/39, > 10% of samples) contained all 6 species. Eimeria species were common and distributed widely in Canadian commercial turkey flocks. Turkeys reared using in-feed medication or live vaccination for coccidiosis control had similar Eimeria species diversity within individual flocks. These preliminary observations highlight that coccidiosis remains a concern for Canadian turkey producers.

Distribution and host associations of ixodid ticks collected from wildlife in Florida, USA

A tick survey was conducted to document tick-host associations with Florida (USA) wildlife, and to determine the relative abundance and distribution of ixodid ticks throughout the state. The survey was conducted using collection kits distributed to licensed Florida hunters as well as the examination of archived specimens from ongoing state wildlife research programs. Collected tick samples were obtained from 66% of Florida counties and were collected from nine wildlife hosts, including black bear, bobcat, coyote, deer, gray fox, Florida panther, raccoon, swine, and wild turkey. In total, 4176 ticks were identified, of which 75% were Amblyomma americanum, 14% Ixodes scapularis, 8% A. maculatum, 3% Dermacentor variabilis, and < 1% were I. affinis and I. texanus. americanum, D. variabilis, and I. scapularis had the broadest host range, while A. maculatum, D. variabilis, and I. scapularis had the widest geographic distribution. While the survey data contribute to an understanding of tick-host associations in Florida, they also provide insight into the seasonal and geographic distribution of several important vector species in the southeastern USA.

Molecular diagnosis and characterization of Cryptosporidium spp. in turkeys and chickens in Germany reveals evidence for previously undetected parasite species

A total of 256 fecal specimens were randomly collected from farmed poultry in Germany and screened for the presence of Cryptosporidium spp. by PCR and further characterized by direct automated DNA sequencing. Using a nested PCR amplifying approximately 830 bp 18S rDNA fragment, 7.03% (n = 18) of the samples were Cryptosporidium-positive. In detail, Cryptosporidium was detected in 9.3% (8/86) of turkeys, 5.7% (9/158) of broilers and 8.3% (1/12) of layers. After DNA sequencing, Cryptosporidium parvum the most frequently observed species was identified in 5.1% (13/256) of all poultry species, including 8.1% (7/86) of turkeys, 3.2% (5/158) of broilers and 8.3% (1/12) of layers. Cryptosporidium baileyi was detected in 1.3% (2/256) of the broilers only. Three novel unclassified Cryptosporidium spp. were detected in 1.2% (1/86) of turkeys and 1.3% (2/158) of broilers. The infection rate was high in 13-20 week old turkeys, 1-6 weeks old broilers and >20 weeks old layers but differences between age groups were not significant. This is the first study in Germany uses molecular methods for the detection of Cryptosporidium in poultry. The results indicate that Cryptosporidium parasites are common among broilers and turkeys in Germany. Considering the large size of the poultry industry, the large amount of poultry meat that is consumed and the fact that C. parvum is also the most common Cryptosporidium parasite in humans, poultry might also be a source of human infections.

Attenuation of a drug-sensitive strain of a turkey protozoan parasite Eimeria meleagrimitis by selection for precocious development

An attenuated line of Eimeria meleagrimitis was established by repeated propagation of the parasite in 9-day old turkey poults and subsequent selection for precocious development. Following 20 passages, the prepatent period decreased from 120 to 104h. A series of experiments were conducted to evaluate the pathogenicity, immunogenicity and fecundity of the newly selected line. Judged by body weight gain, feed consumption and feed efficiency following infection, the attenuated line had appreciably reduced pathogenicity. Immunogenicity of the attenuated line was examined by infecting poults successively with incremental doses of 10(2), 10(3) and 10(4) oocysts at 0, 7, and 14 days of age respectively. No oocysts were detected following challenge with 5×10(2) oocysts, indicating that the attenuated line had retained immunogenicity. Fecundity was assessed by infecting two-week old birds with 5×10(2) oocysts of either parent or attenuated line. Oocyst production from 96 to 240h post-infection showed that the patent period of the attenuated line commenced earlier and was of shorter duration than the parent line.

An unusual outbreak of histomonosis in a commercial turkey flock

In the past histomonosis was very well controlled with Dimetridazole as a treatment and/or Nifursol as feed additive. In the European Union both products were banned in 1995 and 2003, respectively. This was followed by the re-emergence of the disease in the recent years. In the present case a farm with two houses was affected by the disease. In each house 2620 hens and 2620 toms were kept, separated by wire mesh. At the 53rd day of age the toms in house 1 showed general clinical symptoms, accompanied by a slightly raised mortality, which sharply increased in the following days. At necropsy all dead birds showed lesions typical for histomonosis in caeca and liver. Histomonosis was diagnosed by histopathology and PCR. Within five days cumulative mortality was 25.1%.The hens kept at the same house didn't show any symptoms. At day 57 two toms, which were kept in house 2, died and showed similar symptoms and lesions. Within the next three days 48 more birds died. Again the hens in house 2 showed neither clinical signs nor mortality. Treatment trials using herbal products and a change of litter directly after the onset of clinical signs did not reduce the mortality. On day 62 the toms of both houses were euthanized by CO2 in closed containers. The hens were kept until they were slaughtered in week 16 and did not show any evidence of histomonosis.

Assessment of the antihistomonal effect of paromomycin and tiamulin

Histomonosis, a parasitic disease of galliformes and sporadically of other birds caused by Histomonas meleagridis, can result in very high mortality, especially in turkeys. The ban on the last antihistomonal drug prompted an urgent search for alternative prevention and treatment strategies. As both paromomycin and tiamulin have been reported to have antihistomonal activity, these antibiotics were investigated in vitro by adding two-fold serial dilutions ranging from 12.5 to 400 microg/mL to cultures of H. meleagridis. Controls (no antibiotics, or 12.5 microg or 400 microg/mL dimetridazole) were included. Parasites were counted after 3, 20, 28, 44, 51, and 71 hours of incubation. Tiamulin did not have a clear antihistomonal effect, but paromomycin had an inhibitory effect at all concentrations tested. The latter antibiotic was subsequently examined in an in vivo study. Five groups of 20 1-day-old poults, matched by weight and sex, were either not treated (infected and uninfected control groups) or treated with paromomycin (100, 200, or 400 ppm) added to their feed. After 2 weeks all groups, except for the uninfected control group, were intracloacally inoculated with 200,000 histomonads per bird. A clear dose-response effect was found for paromomycin. In the 100-ppm paromomycin group, mortality was similar to that in the untreated control group, whereas about half of the birds died in the 200-ppm paromomycin group; almost complete protection against histomonosis was seen in the 400-ppm paromomycin group. This study shows that paromomycin supplied in feed at 400 ppm is a potentially preventive strategy against H. meleagridis.

[Reoccurrence of histomonosis in turkey breeder farm]

Histomonosis is a severe disease caused by the protozoan parasite Histomonas (H.) meleagridis, which can lead to high losses in turkeys. The present report describes the reoccurrence of histomonosis in a turkey breeder farm. The first outbreak occurred in 2005 in 17 weeks old hens, the second in 2009 in 8 weeks old hens. The disease remained restricted in one house and one compartment, respectively. Mortality rose to 26 and 65% respectively within few days in spite of therapy with various compounds. Both flocks had to be euthanized. In both cases H. meleagridis belonging to genotype A was detected. The source of infection remained unclear in both cases.

Prevalence and pathology of the nematode Heterakis gallinarum, the trematode Paratanaisia bragai, and the protozoan Histomonas meleagridis in the turkey, Meleagris gallopavo

The prevalence of infection and associated pathology induced by two helminth and one protozoan species infecting Brazilian turkeys are reported. The intestinal nematode Heterakis gallinarum appeared with a prevalence of 70% in the infected birds, without gross lesions when not associated to the protozoan Histomonas meleagridis. Histological findings in the ceca were represented by the presence of H. gallinarum worms, intense chronic diffuse inflammatory processes with mononuclear and polymorphonuclear (heterophils) leucocyte infiltrations. The prevalence of the protozoan H. meleagridis associated to H. gallinarum was of 2.5% and microscopic examination revealed a severe inflammatory process in the liver and cecum with the presence of small clear areas with round eosinophilic parasites. Gross lesions were absent in turkeys infected with the renal digenetic trematode Paratanaisia bragai; the parasite was prevalent in 20% of the cases and cross-sections of the kidneys showed a remarkable distension of the collecting ducts with several worms in the lumen. The walls of the ducts presented a discrete heterophilic infiltrate among mononuclear cells.

Selection for Early (Precocious) Development of Eimeria meleagridis in the Turkey

A precocious line of Eimeria meleagridis was developed by repeated propagation of the parasite in young turkeys and collection of the very first oocysts produced following infection. After 20 generations of selection, the prepatent period was reduced by 4-8 hr. Weight gain of poults given this line, from days 0-3 after infection, was significantly greater than that of poults given the parental strain, indicating that selection resulted in a loss of pathogenicity. Poults immunized with the precocious line produced no oocysts following challenge with the parental strain, indicating that immunogenicity was retained following selection. This is the first published report of the selection of a precocious line of Eimeria in the turkey.

Characterization of a strain of Eimeria meleagridis from the turkey

An isolate of Eimeria meleagridis Tyzzer, 1927 was obtained by harvesting oocysts from the ceca of a turkey from northwest Arkansas and a pure line was established by infecting birds with a single oocyst. Oocysts were first produced in the ceca of infected birds from 102 to 108 hr after inoculation and were of similar size (mean length X width, 24.9 X 17.0 microm) to those of Eimeria adenoeides Moore and Brown, 1951 and Eimeria gallopavonis Hawkins, 1952. The line was identified as E. meleagridis based upon the development of large schizonts in the midintestine, and small schizonts in the ceca. Two generations of large schizonts were found 48 and 72 hr after infection, and at least two generations of small schizonts were found from 60 to 108 hr after infection. An inoculum of 2 X 10(5) oocysts was found to cause a significant reduction in weight gain from days 0-3 and 0-6 after infection, suggesting that the significance of this species of Eimeria as a pathogen of turkeys should be reassessed.

Phylogeny of spironucleus (eopharyngia: diplomonadida: hexamitinae)

Diplomonad flagellates from the genera Spironucleus and Hexamita (Hexamitinae) inhabit the digestive tract of a variety of animal hosts, some as important pathogens, and others as commensals. Species descriptions of many diplomonads have been based on light microscopy only, causing many taxa to be misidentified. Presently, electron microscopy is considered the appropriate tool for description of diplomonads. The existence of morphologically very similar genotypes/species has in addition prompted the need for molecular tools to resolve the true identity of many diplomonad taxa. To further explore the relationship within the Hexamitinae we have sequenced most of the SSU rRNA gene from Spironucleus torosa isolated from Atlantic cod, Spironucleus meleagridis isolated from turkey, Spironucleus vortens isolated from ide and Hexamita nelsoni isolated from oyster. Phylogenetic analyses recovered three non-monophyletic Spironucleus clades that may have originated separately in the sea, in freshwater or on land. Spironucleus torosa was identified as a sister taxon to Spironucleus barkhanus and Spironucleus salmonicida. Spironucleus vortens from ide appeared to be genetically very different from Spironucleus vortens isolated from angelfish.

Rapid transmission of the protozoan parasite Histomonas meleagridis in turkeys and specific pathogen free chickens following cloacal infection with a mono-eukaryotic culture

In the present investigation, the pathogenicity and transmission of a mono-eukaryotic culture of Histomonas meleagridis for commercial turkeys and specific pathogen free (SPF) chickens is described for the first time. Two separate trials with the same kind of experimental design were performed, one with commercial turkeys and one with SPF chickens. In each experiment, two different groups were included, which were housed in separate rooms. The first group contained four control birds, whereas the second group consisted of 10 infected and four in-contact birds. The birds were infected via the cloaca at 14 days of age with 380,000 cells of a mono-eukaryotic culture of H. meleagridis consisting of a cloned isolate (Turkey/Austria/2922-66/04). Reisolation of the parasite from turkeys and chickens under experimental conditions was performed for the first time. The infected birds started to excrete the parasite as soon as 2 days post infection. Rapid spread of the parasite to in-contact turkeys and chickens was noticed, based on reisolation of live parasites. Reisolation of the pathogen was impossible from two of the four in-contact SPF chickens at any time, whereas all of the infected turkeys were found positive. Intermittent shedding of the parasite was noticed in infected turkeys and SPF chickens, but the phenomenon was much more severe in the SPF chickens as these birds survived the infection. All of the infected and in-contact turkeys died between days 11 and 14 post infection, whereas no death was recorded in the SPF chickens, which were killed 6 weeks after the infection. Typical lesions were recorded in the caeca and livers of the infected turkeys. In addition, a heavy destruction of the bursa of Fabricius was seen in all of the infected and one of the in-contact turkeys. Altogether, the present investigations are of importance for an understanding of the pathogenicity and transmission of H. meleagridis in poultry.

Broad dissemination of Histomonas meleagridis determined by the detection of nucleic acid in different organs after experimental infection of turkeys and specified pathogen-free chickens using a mono-eukaryotic culture of the parasite

Histomonas meleagridis, a flagellated protozoan parasite, is the causative agent of histomonosis (syn. histomoniasis, blackhead) in turkeys and chickens. The organs primarily affected by the parasite are the caeca and the liver. Until now, only few reports exist in which the parasite has been diagnosed in tissues other than those mentioned above. Hence, the aim of this study was to perform a systematic investigation of various organs of turkeys and specified pathogen-free chickens following an experimental infection with a mono-eukaryotic culture of Histomonas meleagridis in order to determine the dissemination of the flagellate in infected birds. Molecular methods like PCR and in situ hybridization were used for this purpose. For the first time, the DNA of the parasite could be detected in 13 different organs of infected turkeys by PCR including the proventriculus, duodenum, jejunum, caeca, pancreas, bursa of Fabricius, liver, kidney, spleen, heart, lung, thymus and the brain. Most of these findings were further confirmed by in situ hybridization. In contrast to the turkeys that all died shortly after the infection, all of the chickens survived without displaying any clinical symptoms. Even at necropsy, only mild pathological changes were observed in the caeca. Nevertheless, the parasite could also be detected in various organs of these birds, namely the caeca, bursa of Fabricius, kidney, heart and the brain.

PCR for the identification and differentiation of Histomonas meleagridis, Tetratrichomonas gallinarum and Blastocystis spp

In the present investigation PCR assays were developed for the rapid detection and differentiation of two poultry flagellates: Histomonas meleagridis and Tetratrichomonas gallinarum as well as the protozoan microorganism: Blastocystis spp. The nucleotide sequences of the small subunit ribosomal RNAs were used for primer construction obtaining fragments which vary in size for each microorganism. The established PCRs were able to detect DNA obtained from one microorganism of T. gallinarum and Blastocystis spp. propagated in vitro, proving the high analytical sensitivity of the method. DNA isolated from 10 protozoa was sufficient to detect H. meleagridis. To assess specificity, each PCR assay was performed with DNA from either H. meleagridis and/or T. gallinarum and/or Blastocystis spp. as well as with DNA from several other protozoan parasites (Eimeria tenella, Toxoplasma gondii, Cryptosporidia spp., Trichomonas gallinae, Entamoeba invadens, Entamoeba ranarum), fungi (Aspergillus fumigatus, Candida albicans), bacteria (Staphylococcae, Streptococcae, E. coli, Clostridium perfringens, Camplyobacter jejuni, Proteus) and viruses (fowl adenovirus serotype 4, avian reovirus) as well as livers and caecal samples from turkeys and specified pathogen free (spf) chickens. No cross-reactions with any of these samples were observed with the primer sets for the detection of H. meleagridis and Blastocystis spp. The primers designed for the identification of T. gallinarum yielded a PCR product with DNA of Trichomonas gallinae that had the identical size as the amplicon obtained with DNA from T. gallinarum. However, no PCR products resulted from any of the other samples tested with these primers. Liver and caecal samples from turkeys and chickens from flocks with outbreaks of histomonosis also named as "histomoniasis" originating from geographically distinct regions were investigated with the established PCRs. This is also the first report about the detection of the nucleic acid of H. meleagridis, T. gallinarum and Blastocystis spp. nucleic acid in the livers and/or caeca of laying hens and turkeys obtained from field outbreaks. Hence, the established PCR assays proved to be a rapid and sensitive diagnostic tool for the direct detection and differentiation of H. meleagridis, T. gallinarum and Blastocystis spp. nucleic acid in organ samples of infected turkeys and chickens regardless of the geographic origin.

Clonal cultures of Histomonas meleagridis, Tetratrichomonas gallinarum and a Blastocystis sp. established through micromanipulation

Clonal cultures of Histomonas meleagridis, Tetratrichomonas gallinarum and a Blastocystis sp. were established for the first time. Single microbes were successfully isolated from a mixture of micro-organisms obtained from caecal contents of turkeys, using a micromanipulation approach. The cloned parasites were propagated in vitro and maintained through continuous passages multiplying to high numbers. Identification of the protists was done by morphological investigation identifying various forms of each parasite. PCR and partial sequencing of the small subunit rRNA were used to confirm clonality and to determine the relationship of the cloned parasites with known protozoan parasites. The clonal cultures established by this technique will be useful to gain more insight into the biological repertoire of the organisms. In addition, refined infection experiments in different poultry species can now be performed to elucidate the pathological pathways of the respective protozoa.

Histomonas meleagridis in Turkeys: Dissemination Kinetics in Host Tissues After Cloacal Infection

Histomonas meleagridis is a flagellated protozoa causing histomoniasis, a disease of gallinaceous fowl. This disease is characterized by necrotic typhlitis, hepatitis, and high mortality, especially in turkeys. In an attempt to detect the progression of H. meleagridis in the turkey, birds were infected via the cloaca. Between d 0 and 19, a group of 4 turkeys was killed and autopsied every 3 d. Cecal and hepatic lesion scores were used to measure severity of infection. For each turkey, 15 tissue samples were taken. Another group of 3 infected turkeys were placed separately, and samples of cecal and intestinal stool were collected every 3 d. Samples were analyzed by PCR. For samples of cecal droppings, cecum, cecal content, rectum, proventriculus, and bursa of Fabricius, the number of birds detected as positive by PCR followed the evolution of the lesion scores. Within the liver, the parasite DNA was detected only in some severe lesions. The parasite DNA was also detected in duodenum, jejuno-ileum, spleen, heart, lungs, and brain samples. The parasite DNA was not detected in the blood, kidneys, pancreas, or muscle of the thigh. Results of the PCR were in agreement with the evolution of the clinical signs and of the cecal and liver lesions.

Identification of new morphological and life-cycle stages of Cochlosoma anatis and experimental transmission using pseudocyst

Cochlosoma anatis is a flagellated intestinal parasite that infects a variety of avian species. C. anatis infections have been associated with decreased weight gain and increased morbidity and mortality. Conditions favoring the growth of this organism in birds are current pathogenic intestinal infections and/or young age. There is little data describing the life cycle of this parasite. In this study, electron microscopy images are presented that document longitudinal binary fission of the trophozoite stage and outline the events of pseudocyst formation, which includes a rounding stage. Evidence provided here indicates that the pseudocyst stage may be a mechanism for transmission of this organism. The observations reported here provide additional evidence of homology between Cochlosoma and members of the trichomonad order.

Detection of Histomonas meleagridis DNA in Different Organs After Natural and Experimental Infections of Meat Turkeys

Histomonas meleagridis infection of turkeys is usually accompanied by a severe disease with unspecific clinical symptoms but with distinct pathological lesions in the ceca and liver. In the literature some macro- and microscopic evidence of the spread of histomonads to the other organs has been provided. The aim of the present investigations was to use real-time polymerase chain reaction (PCR) to demonstrate the dissemination of H. meleagridis DNA to different organs after natural and experimental infection of meat turkeys. Samples from several organs were collected from a meat-turkey flock, which proved to be naturally infected with histomoniasis, and examined for histomonad DNA by real-time PCR. Histomonad DNA was detected in all investigated ceca, livers, spleens, kidneys, and pooled brain swabs. Additionally it was found in 75% of investigated samples from bursae of Fabricius, in 50% of investigated duodenums, and in 40% of investigated jejunum samples. After experimental intracloacal infection of 3-wk-old turkey poults with 147,500 histomonads, similar samples were collected from all turkeys that died. After a 3-wk observation period the surviving birds, as well as the noninfected control group, were euthanatized and samples were taken. During the entire experimental period, 10 birds out the 20 infected birds died. Histomonad DNA was detected in all investigated ceca, livers, lungs, and hearts (100%) and almost all kidneys (90%) and bursae of Fabricius (80%). On the other hand, only 30% of examined spleens and 10% of brain samples revealed positive results. Surviving infected birds were euthanatized and necropsied; histomonad DNA was found in one out of 10 livers but not in any ceca. Also, histomonad DNA could not be detected in examined cecal and lung samples from the noninfected control group.

Evaluation of dietary Natustat for control of Histomonas meleagridis in male turkeys on infected litter

Histomoniasis (histomonosis, infectious enterohepatitis, or blackhead) is a disease of turkeys on litter or range caused by the protozoan Histomonas meleagridis, a parasite of worms, primarily spread in feces, in Heterakis gallinarum (cecal worm) eggs, or in Eisenia foetida (earthworms). In this trial, Natustat (Alltech, Inc., Nicholasville, KY), a proprietary plant-derived product, was used at 1.925 kg/tonne and compared with nitarsone in male hybrid turkey diets to 42 days of age on histomonad infected litter (day 7) from broiler breeders. Infected nonsupplemented and uninfected nonsupplemented control groups were also included. Natustat and nitarsone significantly improved 28- and 42-day feed conversion ratios and lowered 28- and 35-day cecal and liver lesion scores compared with infected nonsupplemented turkeys. The body weight at 42 days was greater in the Natustat and nitarsone supplemented groups than in the infected nonsupplemented group.

Blackhead Disease in Turkeys: Direct Transmission of Histomonas meleagridis from Bird to Bird in a Laboratory Model

The spread of Histomonas meleagridis infections through groups of turkeys in the absence of the cecal worm vector (Heterakis gallinarum) was studied in a battery cage model. Battery-reared poults were exposed at 2 wk of age by commingling with infected birds into cages that had the floor lined with paper. One treatment received no exposure, whereas other birds were commingled with two, three, or four birds/cage (25%, 37.5%, or 50%) inoculated per cloaca with cultured H. meleagridis (200,000/bird). Inoculated birds died at 7-13 days postinoculation (DPI) showing typical liver and cecal lesions of histomoniasis. By 14 DPI, 87.5% of the directly inoculated birds died or had severe lesions of histomoniasis. Turkeys commingled with two, three, or four infected birds became infected at the rate of 72%, 80%, or 75%, respectively. In another experiment, two birds/cage (25%) were inoculated with Histomonas from culture and allowed to commingle with other birds for 1, 2, 3, or 4 days. Two of 12 (16.7%) birds had minor cecal lesions after contact with inoculated birds for 1 day, but 87.5%-100% became infected if inoculated birds remained in the cage for 2-4 days. Contemporaneous inoculation with cecal coccidia (Eimeria adenoeides) as a predisposing factor in blackhead infections was studied using the model. Turkey poults directly inoculated with Histomonas were allowed to commingle for 5 days with uninoculated birds that had received inoculation with 0, 10(3), or 10(4) sporulated oocysts. The coccidian infection appeared to interfere with transmission of blackhead infection by 7 DPI, as suggested by lessened severity of cecal lesions and a lower percentage of infected birds. These studies confirm that histomoniasis is transmitted readily from directly exposed young turkeys to others in the absence of the cecal worm vector, and that this phenomenon can be reproduced in battery cages as an experimental model.

Molecular assay for the detection of Cochlosoma anatis in house flies and turkey specimens by polymerase chain reaction

A 1520 bp region of Cochlosoma anatis mtDNA 16S gene was subjected to DNA sequencing and a 466 bp portion was compared with other protozoan 16S sequences to develop PCR primers specific for C. anatis. This PCR diagnostic method allowed identification of C. anatis from house flies, Musca domestica L., turkey gut, and fecal samples within 6 h after field-collected samples reached the laboratory. House flies detected carrying C. anatis using the diagnostic 374 bp amplicons represented the first record of this protozoan in house flies.

Interactive effects of turkeypox virus and Plasmodium hermani on Turkey poults

Two experiments were conducted to examine the interactive effects of two disease agents of wild turkeys (Meleagris gallopavo), turkeypox virus and the malarial organism, Plasmodium hermani, on the health of turkey poults. Groups of domestic broad-breasted white turkey poults of 1 and 10 wk of age were infected with either turkeypox virus, P. hermani, both turkeypox virus and P. hermani, or were maintained as uninfected controls. The strains of turkeypox virus and P. hermani had been isolated from wild turkeys in southern Florida (USA). The goals of these experiments were two-fold and included both an examination of age differences in response to infections, and an examination of the effects of dual versus singular infections with the two agents. Both singular and concomitant infections of turkeypox virus and P. hermani were more detrimental to poults infected at 1 wk of age than to those infected at 10 wk, based on mortality, weight gain, and parasitemia. Dual infections of turkeypox virus and P. hermani were found to be slightly more harmful to 1-wk-old poults than were singular infections. No such interactive effects were noted in the poults infected at 10 wk of age.

Infection of turkeys with Histomonas meleagridis by the cloacal drop method

The infection of turkeys with Histomonas meleagridis was attempted in the absence of its normal vector Heterakis gallinarum, using several experimental techniques. Battery-reared poults were inoculated at 2 wk of age with histomonads cultured in vitro, by several routes, including (a) per os (PO), (b) intradoacal (CI), and (c) cloacal drop (CD). Feed restriction was also studied as a predisposing factor. Intracloacal inoculation (CI) consistently produced severe infections in all experiments. In several experiments, turkeys did not become infected after inoculation PO with 1 x 10(5) cultured histomonads. Feed restriction prior to inoculation did not make turkeys susceptible to infection inoculated PO. However, when liquid cultures containing histomonads were applied to the vent (CD) and the dorsal lip stimulated to initiate cloacal drinking, the histomonads were taken into the cloaca and transported to the ceca by retrograde peristalsis. Heavy infections were produced by this method, with severe liver and cecal lesions recorded when birds were necropsied 12 days later. These results suggest that CD may provide ready entry into the lower intestinal tract for these parasites and may facilitate spread of infection through flocks.

A Mathematical Model of the Population Dynamics of Heterakis Gallinarum in Turkeys (Meleagridis Gallopavo)

Heterakis gallinarum is a relatively nonpathogenic organism, but it is important as the transport host for the pathogenic protozoan Histomonas meleagridis. A mathematical model was developed to describe the population dynamics of Heterakis gallinarum in a turkey flock to study its kinetics in a number of hosts. The model includes quantitative (parasite burden) and qualitative (number of hosts without mature parasite) descriptions of these dynamics. To understand the role of Heterakis as a transport host, the various elements that delay the beginning of development of the parasite population (e.g., necessary delay of larval stage, the probability of having a male and female in the same host) were taken into account. From published data, the negative binomial distribution parameter k = 0.24, which described the aggregated distribution of the Heterakis among the hosts, was calculated. The sensibility study showed that when the k parameter decreased (i.e., when the population was more aggregated), infestation increased quantitatively (mean parasite burden increased) but not qualitatively (the number of host without mature parasite increased). The model demonstrated that the population dynamics of Heterakis takes time; for instance, with an aggregated population of Heterakis at d 90, the host is mainly free of adult parasite. These results may be used in the future to test the role of Heterakis in the spread of Histomonas.

Control of Coccidiosis in Turkeys with Diclazuril and Monensin: Effects upon Performance and Development of Immunity toEimeriaSpecies

The effects of diclazuril and monensin, when included in the feed of turkeys from 0 to 10 wk, upon performance and development of immunity to Eimeria species was investigated. Birds were initially inoculated with a low dose of oocysts of three species of Eimeria at 3, 5, 7, and 9 days of age in order to simulate a natural infection. Weight gain and feed intake from 0 to 6 wk of age was significantly greater in medicated birds compared with those that received no anticoccidial medication. Weight gain and feed intake from 6 to 10 wk was greater in birds that received diclazuril than in unmedicated birds. No differences in performance were evident after drug withdrawal from 10 to 16 wk. Immunity to Eimeria species developed by 10 wk in birds that received no anticoccidial medication but did not develop in those given diclazuril or monensin.

Epizootiology of Plasmodium hermani in Florida: Chronicity of Experimental Infections in Domestic Turkeys and Northern Bobwhites

A pen-reared northern bobwhite and a domestic turkey were infected with a strain of Plasmodium hermani obtained originally from a wild turkey in southern Florida. Blood films from these 2 birds were positive microscopically for 188 and 370 days postinfection (PI), respectively. Culicine mosquitoes (Culex nigripalpus and C. salinarius) were blood fed on the bobwhite and the turkey at different times during the infection and used to transmit the malaria to other bobwhites and turkeys up to days 298 and 473 PI, respectively. It was concluded that in nature, P. hermani could remain in a chronic phase in avian hosts for a year, or longer, allowing survival of the parasite between seasons of mosquito transmission.

Enteric helminths of juvenile and adult wild turkeys (Meleagris gallopavo) in eastern Kansas

Viscera of 49 wild turkeys (Meleagris gallopavo) collected in the spring of 2001 and 23 wild turkeys collected in the fall and winter of 2001-02 from 12 counties in eastern Kansas were examined for enteric helminths. Four cestode species, two trematode species, one nematode species, and one acanthocephalan species were identified. Two cestode and two trematode species present in the spring sample also were present in the fall and winter sample. Parasite prevalence was similar to previous studies of enteric helminths of wild turkeys except for the low numbers of nematode species and individuals recovered in the present study.

Identification of tissue-embedded ascarid larvae by ribosomal DNA sequencing

Polymerase chain reaction (PCR) was applied to identify tissue-embedded ascarid nematode larvae. Two sequences of the internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA), ITS1 and ITS2, of the ascarid parasites were amplified and compared with those of ascarid-nematodes registered in a DNA database (GenBank). The ITS sequences of the PCR products obtained from the ascarid parasite specimen in our laboratory were compatible with those of registered adult Ascaris and Toxocara parasites. PCR amplification of the ITS regions was sensitive enough to detect a single larva of Ascaris suum mixed with porcine liver tissue. Using this method, ascarid larvae embedded in the liver of a naturally infected turkey were identified as Toxocara canis. These results suggest that even a single larva embedded in tissues from patients with larva migrans could be identified by sequencing the ITS regions.

Direct lateral transmission of Histomonas meleagridis in turkeys

The lateral transmission of Histomonas meleagridis in turkeys was studied in floor pens without the presence of Heterakis gallinarum. Battery-reared poults (120) were transferred at 2 wk of age to concrete-floored floor pens with fresh pine shavings litter (40/group). One group received no exposure. In other groups, either 10% or 25% of the birds were inoculated per cloaca with cultured H. meleagridis (200,000/bird) and placed in the pens as seeder birds. Inoculated birds died at 10-18 days postinfection (PI) showing typical liver and cecal lesions of histomoniasis. Birds in the high-exposure group died of histomoniasis beginning 16 days PI and continuing to 100% mortality by day 23 PI. Birds in the low-exposure (LE) group died beginning on day 19 PI and continuing through day 31 PI. All but one LE bird alive on day 31 PI had severe liver and cecal lesions of histomoniasis at necropsy. There was no evidence of histomoniasis in unexposed birds. No cecal worms (H. gallinarum) were found at necropsy of dead birds or in unexposed birds at the end of the experiment. Even though H. gallinarum is the only known reservoir for H. meleagridis, these results suggest that lateral transmission of histomoniasis through a flock can occur readily through normal contact between uninfected birds and infected birds and their droppings in the total absence of cecal worms.

Elevation of muscle and plasma 3-methylhistidine as a result of turkey coccidiosis

To assess muscle breakdown during avian coccidiosis, the level of the non-metabolizable amino acid 3-methylhistidine (3MH) was determined in muscle and plasma from turkey poults that received an infection with a field isolate containing a mixture of Eimeria species. The effect of increased levels of parasitism was evaluated at 6 days postinoculation (DPI) in birds receiving 2.5 x 10(4), 1 x 10(5), or 2 x 10(5) oocysts each. The changes in 3MH levels during recovery from acute infection were assessed at 6-29 DPI in animals given 1.9 x 10(5) oocysts per bird. In some experiments, uninoculated birds given the same amount of feed as infected birds (pair fed) were used to determine the impact of feed deprivation on weight loss and 3MH levels. Infected birds had significantly elevated plasma and muscle 3MH at 6 DPI after a single dose of Eimeria oocysts. The plasma and muscle 3MH returned to control levels after 14 DPI. The 3MH levels increased with increased dose of oocysts. Plasma and muscle 3MH levels were well correlated, and an inverse curvilinear relationship between weight gain and plasma 3MH concentrations levels was observed. Plasma and muscle 3MH levels were significantly elevated in pair-fed birds, but 3MH levels in infected birds were increased by 30% over pair-fed birds. The results suggested that muscle breakdown, as assessed by plasma and muscle levels of 3MH, increased during the acute stage of Eimeria infection in turkey poults.

Phylogenetic position of the trichomonad parasite of turkeys, Histomonas meleagridis (Smith) Tyzzer, inferred from small subunit rRNA sequence

The phylogenetic position of the trichomonad, Histomonas meleagridis was determined by analysis of small subunit rRNAs. Molecular trees including all identified parabasalid sequences available in data bases were inferred by distance, parsimony, and likelihood methods. All reveal a close relationship between H. meleagridis, and Dientamoeba fragilis. Moreover, small subunit rRNAs of both amoeboid species have a reduced G + C content and increased chain length relative to other parabasalids. Finally, the rRNA genes from H. meleagridis and D. fragilis share a recent common ancestor with Tritrichomonasfoetus, which exhibits a more developed cytoskeleton. This indicates that Histomonas and Dientamoeba secondarily lost most of the typical trichomonad cytoskeletal structures and hence, do not represent primitive morphologies. A global phylogeny of parabasalids revealed significant discrepancies with morphology-based classifications, such as the polyphyly of most of the parabasalid families and classes included in our study.

Presence and recovery of Ascaridia dissimilis ova on the external shell surface of turkey eggs

Ascaridia dissimilis, a roundworm in turkeys, has been noted with increased frequency in commercial turkeys. Because infected turkeys can shed A. dissimilis ova in their feces, the potential exists for the external surface of turkey eggshells to be contaminated with A. dissimilis ova. The objectives of this study were to determine the presence of and recover A. dissimilis ova on the external surface of the turkey egg. In Experiment 1, turkey eggs were collected from naturally infected flocks, and eggs were processed by a sodium hydroxide procedure to recover any A. dissimilis ova on the external egg surface. In Experiment 2, the external surface of the turkey eggs was inoculated with 116 A. dissimilis ova/g feces, and eggshells were sampled every 3 days until 28 days of incubation to assess the recovery of A. dissimilis ova from the eggshell. In Experiment 1, of the 36 eggs examined from a flock naturally infected with A. dissimilis, one egg had an A. dissimilis ovum on its external eggshell surface. Experiment 2 demonstrated that A. dissimilis ova can be recovered from the external egg surface after a 28-day incubation period in the incubator. Ova recovery declined from an average of 62 A. dissimilis ova/turkey egg at day 2 of incubation to an average of 3 A. dissimilis ova/turkey egg at day 28 of incubation.

Preliminary survey of ticks (Acari: Ixodidae) parasitizing wild turkeys (Aves: Phasianidae) in eastern Kansas

During the spring and fall turkey hunting seasons of 1999, hunters and Kansas Department of Wildlife and Parks field personnel examined wild turkeys, Meleagris gallopavo L., for ticks and submitted them to us for identification. From springtime hunting, we received 113 ticks from 12 turkeys killed in nine counties, all in the eastern one-third of Kansas. Collectors reported examining three additional wild turkeys on which no ticks were found. All ticks were nymphal lone star ticks, Amblyomma americanum (L.). Of 11 wild turkeys examined in seven counties during October, one was parasitized by 30 A. americanum larvae. Data from this study and accounts from the published literature suggest that parasitism of wild turkeys by immature lone star ticks is commonplace wherever this host and ectoparasite are sympatric. Our study suggests that M. gallopavo may be an important host that supports lone star tick populations.

[Distribution of lethal haemosporidoses pathogens in poultry]

Peculiarities of geographical distribution and distribution among hosts of the haemosporidian parasites, which cause lethal diseases in poultry, are specified. So far, 11 species of such parasites have been described. This represents about 5% of bird haemosporidian parasites. The haemosporidians cause the lethal epizooties in turkeys, chickens, ducks, geese, pigeons and domesticated ostriches. One species of parasites belongs to the family Haemoproteidae, six--to Plasmodiidae, and four--to Leucocytozoidae. The agents of lethal haemosporidioses have been recorded in domestic birds of the orders Galliformes, Anseriformes, Columbiformes and Struthiorniformes. The majority of these parasites (eight species of 73%) occurs in the galliform birds. Each other order obtaines only one species of parasites. Five species parasitize turkey, which is the main host of the agent of lethal haemosporidioses. The majority of highly virulent haemosporidian species have been recorded throughout a global territory, which includes the Holarctic, Ethiopian and Oriental zoogeorgaphical regions. Three species of these parasites have been found in the Neotropical region, while none species has been recorded in Australia. The majority of highly virulent haemosporidian species have quite clear outlined areas, that is important to know for the prophilactic purposes including the quarantine of bird introducing from endemic territories.

Systemic sarcocystosis in a wild turkey from Georgia

Acute sarcocystosis was diagnosed in an adult female wild turkey (Meleagris gallopavo) that was collected from Early County (Georgia, USA) in February of 1998. Marked inflammatory lesions were seen in the heart, lung, and liver and were associated with protozoal schizonts and merozoites. The organisms were identified as Sarcocystis sp. (Acomplexa: Sarcocystidae) based on structure and antigenicity. Protozoa divided by endopolygeny, merozoites lacked rhoptries, and the organisms did not react to anti-S. falcatula antibodies but reacted to anti-S. cruzi antibodies.

Isolation of Candida rugosa from turkeys

The present study describes the isolation of Candida rugosa from young turkeys that died 10 days after the end of a therapeutic treatment for a recent outbreak of coccidiosis. Candida rugosa was isolated from the digestive tract of all the birds examined. This isolation is the first in turkeys and corroborates the fact that C. rugosa is an opportunistic yeast which circumvents host defences when other predisposing factors are present.

Prevalence of Toxoplasma gondii antibodies in sera of turkeys, chickens, and ducks from Egypt

Sera from 173 turkeys, 108 chickens, and 48 ducks from Giza, Egypt, were tested for the presence of anti-Toxoplasma gondii antibodies by means of the modified agglutination test using mercaptoethanol and formalin-fixed tachyzoites. The prevalence of anti-T. gondii antibodies (>1:25) among turkeys, chickens, and ducks was 59.5%, 47.2%, and 50%, respectively.

Cryptosporidium meleagridis in an Indian ring-necked parrot (Psittacula krameri)

OBJECTIVE

To perform a morphological and genetic characterisation of a Cryptosporidium infection in an Indian ring-necked parrot (Psittacula krameri) and to compare this with C meleagridis from a turkey.

DESIGN

Tissue and intestinal sections from an Indian ring-necked parrot were examined microscopically for Cryptosporidium. The organism was also purified from the crop and intestine, the DNA extracted and a portion of the 18S rDNA gene amplified, sequenced and compared with sequence and biological information obtained for C meleagridis from a turkey as well as sequence information for other species of Cryptosporidium.

RESULTS

Morphological examination of tissue sections from an Indian ring-necked parrot revealed large numbers of Cryptosporidium oocysts attached to the apical border of enterocytes lining the intestinal tract. Purified Cryptosporidium oocysts measured about 5.1 x 4.5 microns, which conformed morphologically to C meleagridis. The sequence obtained from this isolate was identical to sequence information obtained from a C meleagridis isolate from a turkey.

CONCLUSION

Cryptosporidium meleagridis was detected in an Indian ring-necked parrot using morphological and molecular methods. This is the first time that this species of Cryptosporidium has been reported in a non-galliform host and extends the known host range of C meleagridis.

Morphologic, host specificity, and molecular characterization of a Hungarian Cryptosporidium meleagridis isolate

This study was undertaken in order to characterize Cryptosporidium meleagridis isolated from a turkey in Hungary and to compare the morphologies, host specificities, organ locations, and small-subunit RNA (SSU rRNA) gene sequences of this organism and other Cryptosporidium species. The phenotypic differences between C. meleagridis and Cryptosporidium parvum Hungarian calf isolate (zoonotic genotype) oocysts were small, although they were statistically significant. Oocysts of C. meleagridis were successfully passaged in turkeys and were transmitted from turkeys to immunosuppressed mice and from mice to chickens. The location of C. meleagridis was the small intestine, like the location of C. parvum. A comparison of sequence data for the variable region of the SSU rRNA gene of C. meleagridis isolated from turkeys with other Cryptosporidium sequence data in the GenBank database revealed that the Hungarian C. meleagridis sequence is identical to a C. meleagridis sequence recently described for a North Carolina isolate. Thus, C. meleagridis is a distinct species that occurs worldwide and has a broad host range, like the C. parvum zoonotic strain (also called the calf or bovine strain) and Cryptosporidium felis. Because birds are susceptible to C. meleagridis and to some zoonotic strains of C. parvum, these animals may play an active role in contamination of surface waters not only with Cryptosporidium baileyi but also with C. parvum-like parasites.

Experimental studies of interactions between wild turkeys and black-legged ticks

Wild turkeys are increasing in abundance and distribution in eastern North America, but their potential role as hosts for ticks, or as predators on ticks, is unknown. We performed two experiments, one to determine whether juvenile black-legged ticks (Ixodes scapularis) feed successfully on turkeys, and the other to determine if turkeys depredate adult black-legged ticks in forest habitats. Of 550 larval ticks placed directly on 5 captive wild turkeys, none engorged and only 7 (1.3%) were recovered; the remainder apparently were consumed during preening. Of 165 nymphal ticks placed on the turkeys, 5 engorged and 8 unengorged ticks were collected; 152 (93.3%) were apparently consumed. Of 250 adult ticks introduced into forest enclosures exposed to turkey foraging, 89.5% were recaptured, which was not significantly different from the 92.2% recaptured in control enclosures from which turkeys were excluded. We conclude that wild turkeys are unlikely to host juvenile black-legged ticks in nature, and that turkey foraging is unlikely to reduce local density of adult ticks.

Haemoglobinometry as a method to determine the blood meal size of two argasid tick species

A standardized clinical method for measuring haemoglobin has been applied to measure the quantity of blood ingested by Argas persicus and A. hermanni feeding on chicken and pigeons respectively. The blood fed ticks were added to a reagent which converts all haemoglobin to haemoglobincyanide (HiCN) which can be read spectrophotometrically. The validity of this method was established by comparing haemoglobin determination with the size of blood meals measured by weight. Linear relationships with high correlation coefficients were obtained for nymphs, males, and females of A. persicus and A. hermanni showing that both gravimetric (weighing) and HiCN methods gave similar estimates of ingested blood.

Experimental Cochlosoma anatis infections in poultry

Cochlosoma anatis [Kotlán, A., 1923. Zentralbl. Bakteriol. Parasitenkd. Infektienskr. Hyg. 90, pp. 24-28] is a flagellated protozoan parasite of birds. We have encountered C. anatis in turkeys with enteritis. Experimental oral inoculations of turkeys with 1 x 10(6) to 10 x 10(6) trophozoites consistently reproduced infections in recipients. Trophozoites were most numerous in the jejunum and ileum but could be observed in the duodenum, ceca, colon, and feces. When 12 naive turkeys were placed on contaminated litter vacated by excreting turkeys only one of 12 became infected. When eight naive turkeys were placed in boxes with birds currently excreting trophozoites, seven of eight became infected. Trophozoites could not survive exposure to water or to freezing. Attempts to culture trophozoites in modified Diamond's medium, Kiester's medium, RPMI 1640 medium with 10% fetal bovine serum, or on cultured bovine turbinate cells were not successful. Four of six bobwhite quail and one of eight chickens orally inoculated with 10 x 10(6) to 20 x 10(6) trophozoites had detectable infections. Trophozoites were observed only in the ilea of bobwhite quail and the ceca of the positive chicken. Trophozoites collected from chickens and bobwhite quail remained infectious for turkeys.

The effectiveness of benzimidazole derivatives for the treatment and prevention of histomonosis (blackhead) in turkeys

The benzimidazole derivatives, albendazole and fenbendazole were evaluated for their effectiveness in the treatment and prevention of histomonosis (blackhead) in turkeys. Histomonosis was produced in 5 week-old birds by placing them on broiler breeder litter known to be contaminated with Heterakis gallinae ova and the protozoan Histomonas meleagridis. In the first trial, at the onset of confirmed clinical disease, birds were treated orally with metronidazole, a compound known to be effective against Histomonas. Those receiving metronidazole had significantly greater mean body weight gains during the treatment period and the 2 weeks following treatment than untreated controls. Treated birds also had significantly lower caecal and liver lesion scores. These findings served to validate the method of disease reproduction and establish its suitability for testing the benzimidazoles. Similar trials were conducted to determine the therapeutic value of albendazole at 100.0 mg/kg of body weight and fenbendazole at 10.0 mg/kg body weight, administered orally twice a day for 5 consecutive days. Under these conditions, both drugs were found to be ineffective as treatments. A final trial was conducted to assess the prophylactic value of albendazole and fenbendazole administration. At the time of placement on contaminated litter, birds were medicated as previously described with the exception that treatment was continued for 14 consecutive days, the approximate incubation period for histomonosis. The trial was terminated on the 16th day. In the case of both albendazole and fenbendazole, treatment was associated with a significant increase in mean body weight gain and lower caecal and liver lesion scores. It is believed that the observed prophylactic effect may be attributed to the destruction of the transport vector e.g., Heterakis larvae, or to direct killing of the flagellated form of Histomonas which is normally found in the caecal lumen and is considered to be more sensitive to chemotherapeutic agents than the amoeboid form found in tissues.

Effects of different concentrations of monensin and monensin withdrawal upon the control of coccidiosis in the turkey

The efficacy of different concentrations of monensin in turkeys exposed to field isolates of Eimeria and the effect of the withdrawal of monensin from their diet were investigated. Results of a battery study indicated that 66 ppm monensin was effective against three species of Eimeria in the turkey. In floor pens in which poults were exposed to infection, use of 59.5, 79.4, and 99.2 ppm monensin resulted in reduced mortality and improved feed conversion at 3 wk of age compared with birds that had received no medication. Poults given 59.5 ppm monensin weighed more and had a better feed conversion at 3 wk than poults given 79.4 or 99.2 ppm monensin, but at 10 wk no differences in the body weight or feed conversion of poults given different concentrations of drug were apparent. At 14 wk (and from 10 to 14 wk), poults that had been given 99.2 ppm monensin had a lower feed intake and weighed less than birds that had been given 59.5 ppm of the drug but there were no significant differences in feed conversion. There was no significant difference in the weight gain or feed conversion of poults from 10 to 14 wk of age whether monensin was present in the feed or had been withdrawn. No evidence of compensatory growth was found in the present study.