Toxicity of dimetridazole in waterfowl

Dimetridazole at a concentration of 1.0 g/l in drinking water caused mortality in both ducklings and goslings. When given to goslings at a concentration of 0.5 g/l, the drug caused growth depression and nervous signs characterized by excess activity, abnormal head attitudes, and ataxia.     

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.     

A virulent mono-eukaryotic culture of Histomonas meleagridis is capable of inducing fatal histomonosis in different aged turkeys of both sexes, regardless of the infective dose

Histomonosis (syn. histomoniasis) is a parasitic disease which affects predominately turkeys but also other avian species. Concurrent with the ban of therapeutic and prophylactic substances, the disease, caused by the flagellated protozoon Histomonas meleagridis, is more frequently reported. Due to somewhat diverse results reported in the past, a well-characterized culture was used in the present study to investigate the possible influence of certain parameters on the outcome of the disease. For this study, turkeys were infected with different doses of the mono-eukaryotic culture Histomonas meleagridis/Turkey/Austria/2922-C6/04 using birds of both sexes at various ages. All study groups consisted of 14 birds, of which 10 birds were directly infected via the cloacal route and four birds were kept as in-contact birds. This scheme was used to investigate the pathogenicity of the cloned isolate in 1-day-old and 14-day-old turkeys. In 8-week-old turkeys, only eight birds out of 12 were infected. When 1-day-old and 8-week-old turkeys were infected with 10(4) histomonads per bird, all turkeys died between 11 and 21 days postinfection or had to be euthanatized due to their poor condition. In a group of 14 poults, infective doses of either 10 histomonads (100 histomonads among 10 birds) or 10(3) histomonads per bird had hardly any influence on the first notification of clinical signs. However, even though the onset of clinical signs and mortality was delayed with the lower dose, none of the birds survived the infection. As a consequence, no differences were noticed between male and female turkeys using the mono-eukaryotic culture of Histomonas meleagrigis/Turkey/Austria/2922-C6/04 in the current experimental setting.     

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.     

Pasteurella multocida recovered from live turkeys: prevalence and virulence in turkeys

Swabs of the oropharynges of 801 live turkeys (621 meat birds and 180 breeders), collected from 15 flocks that had experienced an outbreak of fowl cholera and from 12 non-outbreak flocks, were screened for the presence of Pasteurella multocida. Turkeys from outbreak flocks were sampled within 2 to 9 weeks of the outbreak. Forty-nine isolates of P. multocida were recovered from turkeys in 11 of the outbreak flocks, and none were recovered from turkeys in non-outbreak flocks. Isolation rates varied from 0 to 72% of turkeys sampled in a flock. Nineteen isolates were tested for virulence by injecting them intravenously into turkeys, and 14 were lethal. Results demonstrated that for purposes of disease control, meat birds in fowl-cholera-outbreak flocks should be considered carriers of potentially virulent P. multocida for the life of the flock.     

Neoplasms in the oviducts of turkeys

The reproductive tracts of turkey breeder hens from five flocks were examined grossly and histologically. Hens from one flock had a normal reproductive history, but hens from the four other flocks had poor records in both egg production and hatchability. Nodular growths occurred in the oviducts of birds in all five flocks. The incidence of lesions varied from flock to flock and from bird to bird. In four flocks, lesions were small and consisted of areas of dysplasia with adenomatous change. Histologically, the lesions in some birds in the fifth flock were adenocarcinomas. No metastases were observed.     

Respiratory disease (rhinotracheitis) of turkeys in Brittany, France. III. Interaction of multiple infecting agents

A candidate breeder flock of turkeys was studied during and after an outbreak of rhinotracheitis. Laboratory studies revealed the presence of three pathogens during the acute phase of the disease. These agents were hemorrhagic enteritis virus (HEV), paramyxovirus type 2 (PMV2), and chlamydia. Twenty-five turkeys in the flock were individually identified, and blood samples from these birds were collected for serological studies each week for 21 weeks. The serological results revealed high titers for HEV and chlamydia but very low titers for PMV2.     

Residues of dimetridazole in eggs after treatment of laying hens

Laying hens were dosed orally with dimetridazole (DMZ) (50 and 250 mg/kg) for 3 days or intramuscularly (50 mg/kg), also for 3 days, and the residues were determined by liquid chromatography in albumen and yolk. The sensitivity of the whole procedure was 2 ng/g. The drug was excreted preferentially into the yolk (about 57% of the total) and the elimination period lasted for 4–6 days after treatment.Abbreviations AUC area under the plasma concentration-time curve - depletion time the time needed for the DMZ concentration to fall below 0.01 g/g - elimination rate constant - Cl clearance - DMZ demetridazole     

Cryptosporidia in the respiratory tract of turkeys

Cryptosporidia were found in the respiratory tract of turkeys in eight flocks on five different farms over a 4-month period. Turkeys ranged in age from 2 1/2 weeks to 11 weeks of age. All had respiratory signs. Diagnoses were made by examining wet smears and confirmed by histopathological examinations.