Comparative evaluation of efficiency of various immunologic reactions with Candida antigens in detecting immediate hypersensitivity

In the dynamic survey of 577 persons having had contacts with yeast-like fungi of the genus Candida the effectiveness of tests for the diagnosis of mycogenic sensitization was made with the use of a number of immunological methods. The basophil degranulation test was shown to have higher sensitivity and specificity in the detection of hypersensitivity to microbial strains used in the production processes of microbiological synthesis, while the use of polysaccharide antigens is more expedient in immunological reactions, such as the precipitation test with the finished product obtained by these processes and with C. albicans. Some prevalence of the level of sensitization in the presence of Candida carriership was established in persons having had contacts with these fungi.     

Epidemiological significance of carriers of hyaluronidase-active meningococci

To find out the epidemiological role of the carriers of hyaluronidase-positive meningococcal strains, their spread in the foci of meningococcal infection, as well as outside these foci, was studied. For this purpose, altogether 5059 persons from 40 family foci of infection and 40 organized groups were examined. The number of carriers of hyaluronidase-active meningococci, detected among those of them who had contacts with sick persons, was 13 times greater than among the persons having no such contacts. In preschool institutions with unfavorable morbidity situation this number was 16 times greater than in those with favorable situation. In the family foci carriers of hyaluronidase-active meningococci constituted 80-88 %. The percentage of the carriers of hyaluronidase-active meningococci causing cases of the generalized form of meningococcal infection varied in different groups. According to the results obtained in this study, the threshold percentage of such carriers constituted 30 in preschool institutions, 36 in boarding schools and 50 in common school and in hostels for adults.     

Aerosolized MMR vaccine: evaluating potential transmission of components to vaccine administrators and contacts of vaccinees

Although numerous operative and immunological advantages accompany aerosol immunization, potential vaccine virus transmission from the aerosol device to vaccine administrators or from aerosol vaccinees to their contacts requires further study. We conducted a clinical and serological follow-up study of vaccine administrators and matched classroom or household contacts of young adults who received the MMR vaccines by aerosol or injection. Differences in incidence of clinical adverse events between vaccinees and contacts were not statistically significant. No seroresponses to any components of MMR vaccine were noted among 25 matched contacts of persons receiving injected vaccines, and only one equivocal seroresponse was noted among 25 matched contacts of aerosol recipients. No seroresponses were observed in 3 persons who administered aerosol vaccine. The composite findings of this study provide additional evidence of the safety of this approach.     

Oxidative Stress and Metabolic Perturbations in Wooden Breast Disorder in Chickens

This study was conducted to characterize metabolic features of the breast muscle (pectoralis major) in chickens affected with the Wooden Breast myopathy. Live birds from two purebred chicken lines and one crossbred commercial broiler population were clinically examined by manual palpation of the breast muscle (pectoralis major) at 47–48 days of age. Metabolite abundance was determined by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using breast muscle tissue samples from 16 affected and 16 unaffected chickens. Muscle glycogen content was also quantified in breast muscle tissue samples from affected and unaffected chickens. In total, levels of 140 biochemicals were significantly different (FDR < 0.1 and fold-change A/U > 1.3 or < 0.77) between affected and unaffected chickens. Glycogen content measurements were considerably lower (1.7-fold) in samples taken from Wooden Breast affected birds when compared with samples from unaffected birds. Affected tissues exhibited biomarkers related to increased oxidative stress, elevated protein levels, muscle degradation, and altered glucose utilization. Affected muscle also showed elevated levels of hypoxanthine, xanthine, and urate molecules, the generation of which can contribute to altered redox homeostasis. In conclusion, our findings show that Wooden Breast affected tissues possess a unique metabolic signature. This unique profile may identify candidate biomarkers for diagnostic utilization and provide mechanistic insight into altered biochemical processes contributing to tissue hardening associated with the Wooden Breast myopathy in commercial chickens.     

Attempts to reproduce vacuolar myelinopathy in domestic swine and chickens

Avian vacuolar myelinopathy (AVM) was first recognized as a cause of bald eagle (Haliaeetus leucocephalus) mortality in 1994 in Arkansas (USA) and has since caused over 90 bald eagle and numerous American coot (Fulica americana) mortalities in five southeastern states. The cause of AVM remains undetermined but is suspected to be a biotoxin. Naturally occurring AVM has been limited to wild waterbirds, raptors, and one species of shorebird, and has been reproduced experimentally in red-tailed hawks (Buteo jamaicensis). In this study, chickens and swine were evaluated for susceptibility to vacuolar myelinopathy with the intent of developing animal models for research and to identify specific tissues in affected coots that contain the causative agent. Additionally, submerged, aquatic vegetation, primarily hydrilla (Hydrilla verticillata), and associated material collected from a reservoir during an AVM outbreak was fed to chickens in an effort to reproduce the disease. In two separate experiments, six 4-wk-old leghorn chickens and ten 5-wk-old leghorn chickens were fed coot tissues. In a third experiment, five 3-mo-old domestic swine and one red-tailed hawk, serving as a positive control, were fed coot tissues. In these experiments, treatment animals received tissues (brain, fat, intestinal tract, kidney, liver, and/or muscle) from coots with AVM lesions collected at a lake during an AVM outbreak. Negative control chickens and one pig received tissues from coots without AVM lesions that had been collected at a lake where AVM has never been documented. In a fourth experiment, eight 3-wk-old leghorn chickens were fed aquatic vegetation material. Four chickens received material from the same lake from which coots with AVM lesions were collected for the previous experiments, and four control chickens were fed material from the lake where AVM has never been documented. Blood was collected and physical and neurologic exams were conducted on animals before and once per week during the trials. All animals were sacrificed and necropsies were performed on Day 29 of feeding, with the exception of one treated chicken that was sacrificed and necropsied on Day 15 of feeding. Microscopic lesions of vacuolar myelinopathy were present in the red-tailed hawk and five chickens that received a mixture of all tissues and two chickens that received only gastrointestinal tissues of coots with AVM lesions. Three of four treated chickens in the aquatic vegetation trial developed vacuolar lesions. None of four treatment pigs or any of the negative control animals developed vacuolar lesions. Chickens are susceptible to AVM and may serve as a useful animal model for future studies. Swine may be refractory to AVM or not affected by AVM at the same dose as are chickens and red-tailed hawks. The causative agent of AVM in affected coots is associated with the gastrointestinal tissues. Furthermore, AVM can be reproduced in chickens via ingestion of aquatic vegetation and associated materials collected from a lake during an AVM outbreak. The cause of AVM is most likely present in the materials associated with submerged vegetation because the vegetation itself (hydrilla) was the same at our AVM-positive and AVM-negative sites.     

Salmonella carrier state and biological characteristics of the infectious agent

Salmonella carrier state (42.6%-S. enteritidis and 34.4%-S. dublin) was demonstrated in subjects after acute salmonellosis as well as in healthy persons infected with salmonella as a result of occupational exposure to poultry (8.8% in humans exposed to chickens and 6.1% in those exposed to ducks) and sheep (2.8%). The carrier state was accompanied by intermittent pain in the epigastrium, diminished appetite, diarrhoea etc. Most of the carrier subjects with a history of salmonellosis exhibited, upon rectoromanoscopy, a varying degree of proctosigmoiditsi. The etiological role of S. typhimurium was proved beyond doubt, as well as its ability to cause salmonellosis outbursts, sporadic cases of the disease and the carrier state. When large industrial facilities specializing in poultry processing were investigated, the salmonella carrier state was revealed in practically healthy poultry--in 16% of chickens and 12% of ducks. The salmonella organisms isolated from carrier persons had, with some exceptions, typical properties, being virulent in that they caused death of experimental animals, seeded their internal organs and induced pathogenicity-associated enzymes. Multiple resistance to antibiotics was demonstrated in salmonella isolated from poultry; also determined was its plasmid nature. Pronounced resistance of the above salmonella subtypes to tetracycline-related antibiotics and streptomycin may be due to the fact that these drugs are used in poultry raising.     

Outbreak of Food-poisoning Caused by Salmonella Virchow in Spit-roasted Chicken

Salmonella virchow food-poisoning acquired from eating chicken caused illness in at least 50 people who attended a tennis club function in Liverpool, and in many other people in the Merseyside area. In some cases the illness was severe, with positive blood cultures, and 35 people were admitted to hospital.The source of infection was a retail shop which received deep-frozen chickens already contaminated with S. virchow from a packing-station in Cheshire. These chickens were spit-roasted after inadequate thawing and subsequently handled under unhygienic conditions. The result was a massive build-up of salmonella contamination in the shop and in the chicken portions sold.S. virchow was isolated from over 160 patients and contacts in the Merseyside area during the outbreak and many continued to excrete the organism in the faeces after four months. Antibiotic treatment was not recomended because there was no evidence that it shortened the duration of excretion.A high rate of contamination of chickens from a packing-station by a salmonella type capable of causing serious disease in man is clearly a public health problem which cannot be ignored.The use of rotary spits for roasting chickens requires thorough investigation and appraisal, because as operated at present they evidently constitute a public health hazard.     

Patients with chronic viral hepatitis as sources of infection

Dynamic observation on 126 foci of infection formed by patients with manifest forms of chronic hepatitis B, 41 foci of chronic hepatitis of unknown etiology, and 37 foci formed by chronic "healthy" carriers was made. In the foci of type 1 the epidemic process developed intensively and was manifested mainly by HBsAg carriership in persons having had contacts with the patients. During the period of observation 43.0% of new cases of infection were detected. In the foci of types 2 and 3 the frequency of contacting infection was not different from that in the control group of the population.     

Effect of serum from chickens treated with clenbuterol on myosin accumulation, β-adrenergic receptor population, and cyclic AMP synthesis in embryonic chicken skeletal muscle cell cultures

Broiler chickens at 35 d of age were fed 1 ppm clenbuterol for 14 d. This level of dietary clenbuterol led to 5-7% increases in the weights of leg and breast muscle tissue. At the end of the 14-d period, serum was prepared from both control and clenbuterol-treated chickens, and was then employed as a component of cell culture media at a final concentration of 20% (v/v). Muscle cell cultures were prepared from both the leg and the breast muscle groups of 12-d chick embryos. Treatment groups included control chicken serum to which 10 nM, 50 nM, and 1 microM clenbuterol had been added, as well as cells grown in media containing 10% horse serum. Cultures were subjected to each treatment for 3 d, beginning on the seventh d in culture. Neither the percent fusion nor the number of nuclei in myotubes was significantly affected by any of the treatments. The quantity of myosin heavy chains (MHCs) was not increased by serum from clenbuterol-treated chickens in either breast or leg muscle cultures; however, the MHC quantity was 50-150% higher in cultures grown in control chicken serum to which 10 and 50 nM clenbuterol had also been added. The beta-adrenergic receptor (betaAR) population was 4000-7000 betaARs per cell in cultures grown in chicken serum, with leg muscle cultures having approximately 25-30% more receptors than breast muscle cultures. Receptor population was not significantly affected by the presence of clenbuterol or by the presence of serum from clenbuterol-treated chickens. In contrast, the betaAR population in leg and breast muscle cultures grown in the presence of 10% horse serum was 16,000-18,000 betaARs per cell. Basal concentration of cyclic adenosine 3':5'monophosphate (cAMP) was not significantly affected by the treatments. When cultures grown in chicken serum were stimulated for 10 min with 1 microM isoproterenol, limited increases of 12-20% in cAMP concentration above the basal levels were observed. However, when cultures grown in the presence of horse serum were stimulated with 1 microM isoproterenol, cAMP concentration was stimulated 5- to 9-fold above the basal levels. Thus, not only did cells grown in horse serum have a higher betaAR population, but also each receptor had a higher capacity for cAMP synthesis following isoproterenol stimulation. Finally, the hypothesis that clenbuterol exerts its action on muscle protein content by changes in cAMP concentration was tested. No correlation was apparent between basal cAMP concentration and MHC content.     

Prior Infection of Chickens with H1N1 or H1N2 Avian Influenza Elicits Partial Heterologous Protection against Highly Pathogenic H5N1

There is a critical need to have vaccines that can protect against emerging pandemic influenza viruses. Commonly used influenza vaccines are killed whole virus that protect against homologous and not heterologous virus. Using chickens we have explored the possibility of using live low pathogenic avian influenza (LPAI) A/goose/AB/223/2005 H1N1 or A/WBS/MB/325/2006 H1N2 to induce immunity against heterologous highly pathogenic avian influenza (HPAI) A/chicken/Vietnam/14/2005 H5N1. H1N1 and H1N2 replicated in chickens but did not cause clinical disease. Following infection, chickens developed nucleoprotein and H1 specific antibodies, and reduced H5N1 plaque size in vitro in the absence of H5 neutralizing antibodies at 21 days post infection (DPI). In addition, heterologous cell mediated immunity (CMI) was demonstrated by antigen-specific proliferation and IFN-γ secretion in PBMCs re-stimulated with H5N1 antigen. Following H5N1 challenge of both pre-infected and naïve controls chickens housed together, all naïve chickens developed acute disease and died while H1N1 or H1N2 pre-infected chickens had reduced clinical disease and 70–80% survived. H1N1 or H1N2 pre-infected chickens were also challenged with H5N1 and naïve chickens placed in the same room one day later. All pre-infected birds were protected from H5N1 challenge but shed infectious virus to naïve contact chickens. However, disease onset, severity and mortality was reduced and delayed in the naïve contacts compared to directly inoculated naïve controls. These results indicate that prior infection with LPAI virus can generate heterologous protection against HPAI H5N1 in the absence of specific H5 antibody.     

Gene expression profiling of hereditary exencephaly in chickens

In this preliminary study, differentially expressed genes were investigated in cranial tissues from chickens with hereditary exencephaly using cDNA microarrays containing 1,152 genes and expressed sequence tags (ESTs). Genes showing twofold or greater differences at P < 0.05 between affected and normal cranial cells were considered to be candidates for hereditary exencephaly in chicken. Eighteen ESTs (11 known genes/homologues) were upregulated and 108 ESTs (51 known genes/homologues) were downregulated. The EST AL584231 (ROS006C9), orthologous to human MTHFD1, a known candidate gene for human neural tube defects (NTDs), was expressed at the same level both in normal and affected chicken cranial tissues. ESTs AL584253 (ROS006F7, thioredoxin reductase 1) and AL585511 (ROS024H9, thioredoxin), both involved in NTD pathogenic pathways in mice, were downregulated and had mean ratios of 0.41 and 0.04 for expression in affected vs. normal cells respectively. Expression differences of these two ESTs were confirmed by quantitative real-time polymerase chain reaction. These data indicate that ESTs AL584253 and AL585511 are candidates for hereditary exencephaly in chickens.     

Detection and isolation of a 30 kDa abnormal protein in avian dystrophic muscle

We have studied the protein composition of the pectoralis superficialis muscle of genetically dystrophic (New Hampshire line 413) and normal control (line 412) chickens by one- and two-dimensional gel electrophoresis. A protein, referred to hereafter as the 30 kDa abnormal protein, was specifically detected in the affected muscle. It was purified to homogeneity, and its molecular properties were studied. It is a monomer with a molecular mass of approximately 30 kDa and an isoelectric point of about pI 8.4. We have screened by Western blotting a variety of muscles from line 412 and line 413 chickens for the presence of the 30 kDa protein. While the pattern of total protein is very similar in all cases, the 30 kDa protein was not detected in the pectoralis superficialis muscle of line 412 chickens. However, the immunoreactive bands were detected in the sartorius muscle and the tensor fasciae latae muscle from dystrophic and normal chickens. Interestingly, the immunoreactive bands of normal skeletal muscles are smaller in molecular weight than those of dystrophic skeletal muscles. To determine the early time sequence of the appearance of the abnormal protein, we studied muscles from embryos and post-hatched chickens at various ages. The abnormal protein was detected in dystrophic muscles as early as 15 days ex ovo and occurred throughout development up to six months ex ovo. Although the implication of the dystrophy-associated appearance of the 30 kDa protein in the affected muscle is not clear at present, it would be of particular interest to elucidate the biochemical functions of the 30 kDa protein in the affected muscle (pectoralis superficialis muscle) of genetically dystrophic chicken.     

Campylobacter enteritis: a "new" disease.

By selective culture campylobacters (C jejuni and C coli) were isolated from the faeces of 57 (7-1%) out of 803 unselected patients with diarrhoea; none were isolated from 194 people who had not got diarrhoea. Specific agglutinins were found in the sera of 31 out of 38 patients with campylobacter enteritis and 10 of them had a rising titre. Half the patients were aged 15 to 44 years, but the incidence was highest in young children. All the patients with campylobacters had a distinctive clinical illness with severe abdominal pain. Campylobacters are a relatively unrecognised cause of acute enteritis, but these findings suggest that they may be a common cause. Spread of infection was observed within 12 out of 29 households, and in these cases children were usually implicated. Several patients were apparently infected from chickens, both live and dressed, and poultry may be the primary source of the organism. In two cases dogs with diarrhoea were found to be infected with strains indistinguishable from their human contacts. Ten patients acquired their infections while travelling abroad.     

Geographical variants in the immunological structure of the population in combined foci of tick-borne encephalitis and endemic rickettsiosis in the European part of the USSR

The zonal study of the immunological structure of the population revealed an increase in the number of infective agents with which the population comes into contact in the southern regions. In the medial boreal forest zone contacts of low intensity only with tick-borne encephalitis virus were detected (the immune stratum was found to be 5.5%, 2,178 persons were examined); in the southern boreal forest zone the foci of tick-borne encephalitis actively manifested (the immune stratum reached 38.9%, 2,854 persons were examined), and Q fever was constantly detected (1.6%). In the forest-steppe zone the population was found to have contacts with the causative agent of tick-borne encephalitis (the immune stratum was found to be 13.3%, 2,056 persons were examined), Q fever (1.2%) and tick-borne rickettsiosis (1.1%).     

Pathological changes in chickens inoculated with reticuloendotheliosis-virus-contaminated Marek's disease vaccine.

A disease characterized by delayed growth, anemia, abnormal feathers, and leg paralysis occurred among chickens inoculated with Marek's disease vaccine over a period from spring to fall in 1974. These chickens were recognized among flocks inoculated with the vaccine produced by two vaccine makers. The affected ones were examined pathologically. Gross examination revealed a slight enlargement of peripheral nerves and atrophy of the spleen, thymus, and bursa of Fabricius. Histopathologically, the peripheral nerves had a mild cell infiltration of lymphoid and plasma cells, edema, degeneration of nerve fibers with Schwann's cell proliferation. Perivascular cuffings consisting mainly of lymphoid cells were seen in the brain and spinal cord. Atrophic changes displayed by prominent reduction of lymphocytes were recognized in the spleen, thymus, and bursa of Fabricius. Etiological examination suggested that most of the chickens examined might have been infected with reticuloendotheliosis virus and not with Marek's disease virus. The pathological changes observed in the peripheral nerves and central nervous system, however, were not distinguishable from those of Marek's disease.     

Characterization of cecal microbiota and response to an orally administered lactobacillus probiotic strain in the broiler chicken

A probiotic Lactobacillus strain was given in drinking water to young broiler chickens from 1 to 19 days of age. Cecal contents were collected from 4- and 19-day-old chickens in treated and control groups. Enumeration of bacteria by culture on selective media showed a decrease in Clostridium perfringens carriage in the 4-day-old treated chickens, whereas coliforms and Lactobacillus populations were not significantly affected by the treatment. Fluorescent in situ hybridization analysis with 7 phylogenetic probes targeting the major groups of intestinal bacteria revealed that the Clostridium coccoides group accounted for more than 50% of the total bacteria in the cecum of 4-day-old chickens, whereas the bacterial community of 19-day-old chickens evolved towards a more diverse microbiota with Faecalibacterium prausnitzii (36%) and C. coccoides (22%) groups representing the predominant bacteria. No effect of the Lactobacillus strain supplementation was observed in the composition of the cecal microbiota assessed by fluorescent in situ hybridization with the 7 probes. Nevertheless, profiling of the cecal microbiota using temporal temperature gradient gel electrophoresis in combination with principal component analysis demonstrated an impact of the probiotic treatment on the overall bacterial community as well as on the Lactobacillus population.     

Effect of silver nanoparticles on growth performance, metabolism and microbial profile of broiler chickens

This study evaluated the potential of silver nanoparticles (AgNano) as an antimicrobial growth-promoting supplement for broiler chickens. One hundred forty-four seven-day-old broiler chicks were distributed randomly to AgNano treatments at 0, 10 and 20 mg/kg (Control, Group AgNano10, and Group AgNano20, respectively) provided via the drinking water from day 7 to 36 post-hatching. Body weight and feed consumption were measured weekly. In addition, balance and respiration experiments were carried out to determine nitrogen (N) utilisation and energy retention. At days 22 and 36, blood samples and intestinal content were collected to evaluate the effects of AgNano on plasma concentration of immunoglobulins and the intestinal microflora, respectively. The provision of water solutions containing different concentrations of AgNano had no effect on postnatal growth performance and the energy metabolism of broiler chickens. However, in Group AgNano10 N intake (p = 0.05) and retention (p = 0.03) was increased, but N excretion and efficiency of utilisation was not affected. The populations of bacteria in the intestinal samples were not affected by AgNano supplementation. The concentration of immunoglobulin (IgG) in the blood plasma of broilers supplemented with AgNano decreased at day 36 (p = 0.012). The results demonstrated that AgNano affects N utilisation and plasma IgG concentration; however, it does not influence the microbial populations in the digestive tract, the energy metabolism and growth performance of chickens.     

Biochemical and physiological responses of growing chickens and ducklings to dietary aflatoxins

Two-week-old ducks and chickens were fed for a 14-day period diets containing either groundnut meal (GNM) or fish meal (FM) contaminated with the following aflatoxin (AF) levels: 0, 50, 100, 200 and 400 micrograms AF B1 equivalent per kg ration; nitrogen and energy balances were measured, liver lesions assessed, and various biochemical analyses in blood, livers and muscles were made. Both ducks and chickens fed diets containing GNM were more affected by dietary AF than those fed diets with FM. In ducks, in addition to the reduction in growth and utilization of protein, dietary AF caused liver damage and significantly affected most of the blood constituents; chickens were either not affected or affected to a lesser degree, but no liver damage was recorded. Individual blood tests or enzyme ratios did not provide a sufficiently precise diagnosis of aflatoxicosis. However, blood clotting time and De Riti's ratio, when used in a multivariate regression. allowed projection of a degree of liver damage caused by AF in ducks fed GNM diet with 83.6% of variance being accounted for.     

Identification of host genes linked with the survivability of chickens infected with recombinant viruses possessing H5N1 surface antigens from a highly pathogenic avian influenza virus

Seventeen recombinant viruses were generated by a reverse genetic technique to elucidate the pathogenicity of highly pathogenic avian influenza viruses (HPAIVs) in chickens. The recombinant viruses generated possessed hemagglutinin (HA) and neuraminidase (NA) genes from an HPAIV. Other segments were combinations of the genes from an HPAIV and two low-pathogenic avian influenza viruses (LPAIVs) derived from chicken (LP) and wild bird (WB). Exchange of whole internal genes from an HPAIV with those of an LPAIV resulted in a significant extension of the survival time following intranasal infection of the chickens with the recombinants. Survival analysis demonstrated that the exchange of a gene segment affected survivability of the chickens with statistical significance. The analysis revealed three groups of recombinants with various gene constellations that depended upon the survivability of the infected chickens. Recombinants where the PA gene was exchanged from LP to WB in the LP gene background, LP (W/PA), did not kill any chickens. LP (W/PA) replicated less efficiently both in vitro and in vivo, suggesting that the intrinsic replication ability of LP (W/PA) affects pathogenicity; however, such a correlation was not seen for the other recombinants. Microarray analysis of the infected chicken lungs indicated that the expression of 7 genes, CD274, RNF19B, OASL, ZC3HAV1 [corrected] , PLA2G6, GCH1, and USP18, correlated with the survivability of the chickens infected (P < 0.01). Further analysis of the functions of these genes in chickens would aid in the understanding of host gene responses following fatal infections by HPAIVs.     

Viability of preserved Cryptosporidium baileyi oocysts

The present study was undertaken to determine the viability and infectivity of oocysts of Cryptosporidium baileyi that had been stored from 1 to 40 months at 4 degrees C preserved in 2.5% potassium dichromate solution. Oocysts of C. baileyi were purified from the feces of experimentally infected chickens using discontinuous sucrose gradients. Subsequently, the purified oocysts were suspended in 2.5% potassium dichromate solution at a concentration of 1 x 10(7) organism/ml, and their viabilities were assessed by nucleic acid staining, histologic examination, and infectivity to 2-day-old chickens. All chickens inoculated with oocysts that had been stored for 1-18 months developed patent infections, while chickens infected with older oocysts remained uninfected. Between 5.8% and 82.2% of the oocysts, stored at 4 degrees C in 2.5% potassium dichromate solution, were found to be viable, as determined by nucleic acid staining. Parasite colonization in the bursa of Fabricius was detected in the microvillus border of bursal epithelium. The finding that C. baileyi oocysts remain infective to chickens for at least 18 months offers important time-saving advantages to investigators who frequently require large numbers of oocysts.