Microorganisms Involved in Hydrogen Sink in the Gastrointestinal Tract of Chickens.

Hydrogen sink is a beneficial process, which has never been properly examined in chickens. Therefore, the aim of this study was to assess the quantity and quality of microbiota involved in hydrogen uptake with the use of real-time PCR and metagenome sequencing. Analyses were carried out in 50 free-range chickens, 50 commercial broilers, and 54 experimental chickens isolated from external factors. The median values of acetogens, methanogens, sulfate-reducing bacteria (SRB), and [NiFe]-hydrogenase utilizers measured in the cecum were approx. 7.6, 0, 0, and 3.2 log10/gram of wet weight, respectively. For the excreta samples, these values were 5.9, 4.8, 4, and 3 log10/gram of wet weight, respectively. Our results showed that the acetogens were dominant over the other tested groups of hydrogen consumers. The quantities of methanogens, SRB, and the [NiFe]-hydrogenase utilizers were dependent on the overall rearing conditions, being the result of diet, environment, agrotechnical measures, and other factors combined. By sequencing of the 16S rRNA gene, archaea of the genus Methanomassiliicoccus (Candidatus Methanomassiliicoccus) were discovered in chickens for the first time. This study provides some indication that in chickens, acetogenesis may be the main metabolic pathway responsible for hydrogen sink.

Chicken embryo lethality assay for determining the lethal dose, tissue distribution and pathogenicity of clinical Enterococcus cecorum isolates from poultry.

Enterococcus cecorum is a well-known component of the normal poultry intestinal microbiota and an important bacterial pathogen. Infections caused by E. cecorum have negative effects on the poultry production worldwide. In this study we used the SPF-chicken embryo lethality assay (ELA) to assess the pathogenic potential of E. cecorum. A total of 23 isolates were used: 19 clinical isolates from field outbreaks in different poultry groups (CB - broiler chickens, BB - broiler breeders, CL - layers, T- turkeys, W - waterfowl) and 4 commensal isolates. The cumulative mortality caused by all clinical isolates was higher (53.4%) than that of the commensals (38.9%). The highest mortality was induced by CB isolates (68.9%), followed by CL (60.4%), all chicken isolates (59.2%; CB, BB, CL), BB (45.8%), T (41.7%), non-chicken isolates (40.7%; T, W), and W isolates (39.8%). Most of the embryos that died, did die on the 1st day post-infection (dpi), except those infected with CB, CL (on 2 dpi). The median lethal dose (LD50) of E. cecorum ranged from 6.07 × 102 cfu/ml (CB isolates) and 1.42 × 104 cfu/ml (all clinical isolates) to 4.8 × 105 cfu/ml (commensal isolates). This study provides the first evidence of a wide tissue distribution and multiplication of E. cecorum in embryos. Dead embryos showed scattered petechiae, hemorrhages, aggregates of bacteria in blood vessels, multiple organ necrosis, and encephalomalacia. Our data indicate that surviving embryos were able to elicit innate immune response to infection. On the other hand, reisolation of viable bacteria from surviving embryos may suggest that E. cecorum could evade or resist immune mechanisms in order to persist in organs. Furthermore, body mass of surviving embryos was affected by the strain type, not the dose (bacterial concentration) used, and was lower for the infection with clinical strains. The results indicated the highest pathogenicity of clinical E. cecorum isolates from CB and CL flocks.

Review on skeletal disorders caused by Staphylococcus spp. in poultry.

Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.

Analysis of genomes of bacterial isolates from lameness outbreaks in broilers.

We investigated lameness outbreaks at 3 commercial broiler farms in Arkansas. We isolated several distinct bacterial species from Bacterial Chondronecrosis with Osteomyelitis (BCO) lesions from these 3 farms. The results show that BCO-lameness pathogens on particular farms can differ significantly. We characterized genomes for isolates of the 2 most prevalent species, Escherichia coli and Staphylococcus aureus. Genomes assembled for E. coli isolates from all 3 farms were quite different between farms, and most similar to genomes from different geographical locations and hosts. The E. coli phylogenomics suggests frequent host shifts for this species. Genomes for S. aureus isolates from one farm were highly related to those from chicken isolates from Europe. Highly related isolates have also been characterized from chickens in the Arkansas area for at least a decade. Phylogenomics suggest that this S. aureus has been restricted to poultry for more than 40 y. Detailed analysis of genomes from 2 neighboring clades of S. aureus human and chicken isolates, identifies the acquisition of a specific pathogenicity island in the transition from human to chicken pathogen and that pathogenesis for this clade in chickens may depend on this mobile element. Investigation of the evolution of this chicken-restricted clade from 1980 in Ireland, Poland in 2008, Oklahoma in 2010 and Arkansas in 2019, reveals the acquisition of additional virulence determinants including pathogenicity islands. Isolate-specific genome characterizations will help further our understanding of the disease mechanisms of BCO-lameness, a significant animal welfare issue.

Pigeons as Carriers of Clinically Relevant Multidrug-Resistant Pathogens-A Clinical Case Report and Literature Review.

Pigeons are widespread bird species in urban regions (Columba livia forma urbana) and may carry pathogens with zoonotic potential. In recent years, more and more data indicate that these zoonotic pathogens are multidrug resistant. Our results confirmed that global trend. Three different multidrug-resistant pathogens were isolated from an oral cavity of a racing pigeon with lesions typical for pigeon pox virus infection. Staphylococcus aureus was recognized as methicillin resistant, thus resistant to all beta-lactams. Additionally, it was also resistant to many other classes of antibiotics, namely: aminoglycosides, tetracyclines, phenicols, lincosamides, and macrolides. Escherichia coli showed resistance to all antimicrobials tested, and it was classified as intermediate to amikacin. Moreover, Candida albicans resistant to clotrimazole, natamycin, flucytosine, and amphotericin and intermediate to ketoconazole, nystatin, and econazole was also isolated. This raises the question how pigeons acquire such highly resistant strains. Therefore, more data are needed concerning the resistance to antibiotics in strains from domestic and wild pigeons in Poland. Until the problem is fully understood, it will be challenging to implement adequate planning of any control measures and check their effectiveness.

Comparative Effects of Using New Multi-Strain Synbiotics on Chicken Growth Performance, Hematology, Serum Biochemistry and Immunity.

In this study, the influence of new multi-strain synbiotics on chicken growth performance, hematology, serum biochemistry and immunity was explored. Each synbiotic preparation (A, B and C) comprised three, four or five strains of Lactobacillus sp., respectively, as well as S. cerevisiae and inulin. All strains used in the synbiotics originated from wild-type strains from animal farms in Poland. Six groups of chickens, ROSS 308 line, were fed with three different synbiotics at a dose of 0.5 g/1 kg of feed. Body weight, as well as the biochemical and hematological parameters of the animals in each study group, were determined on the 7th, 14th, 28th and 42nd day of life. Body weight on day 42 differed between groups and was the highest in control group. This group also had the highestfeed conversion ratio (FCR) value. All measured biochemical parameters were in the normal ranges for poultry; however, we observed a lower alkaline phosphatase (AP) concentration on day 7 in the groups fed with synbiotics, which correlated with a lower level of triglycerides in those groups. The aspartate transaminase (AST) concentration was significantly lower in all groups on day 42 in comparison with the control. On day 7, the control group showed the highest concentration of Ca, K and P. Other parameters did not differ significantly throughout the experiment. All groups showed a similar tendency of increase in the red blood cells (RBC) count according to the age of the birds. Every white blood cells (WBC) population showed differences in the proportions between T and B lymphocytes. The T cell and monocyte counts increased until day 28 in all groups. The results showed that our newly developed synbiotic formulas do not have any unfavorable influence on chicken health and may modulate immune response and biochemical parameters. However, this hypothesis needs to be evaluated in future experiments.

A Review of Current Knowledge on Staphylococcus agnetis in Poultry.

This review aims to summarize recent discoveries and advancements regarding the characteristics of Staphylococcus agnetis (S. agnetis) and its role in poultry pathology. S. agnetis is an emerging pathogen that was primarily associated with mastitis in dairy cattle. After a presumed host jump from cattle to poultry, it was identified as a pathological agent in broiler chickens (Gallus gallus domesticus), causing lameness induced by bacterial chondronecrosis with osteomyelitis (BCO), septicemia, and valvular endocarditis. Economic and welfare losses caused by lameness are global problems in the poultry industry, and S. agnetis has been shown to have a potential to induce high incidences of lameness in broiler chickens. S. agnetis exhibits a distinct repertoire of virulence factors found in many different staphylococci. It is closely related to S. hyicus and S. chromogenes, hence infections caused by S. agnetis may be misdiagnosed or even undiagnosed. As there are very few reports on S. agnetis in poultry, many facts about its pathogenesis, epidemiology, routes of transmission, and the potential impacts on the poultry industry remain unknown.

The Use of Bacteriophages in the Poultry Industry.

The emergence of multidrug-resistant infections and antibiotic failures have raised concerns over human and veterinary medicine worldwide. Poultry production has had to confront the problems of an alarming increase in bacterial resistance, including zoonotic pathogens. According to the European Food Safety Authority (EFSA), campylobacteriosis and salmonellosis have been the most frequently reported human foodborne diseases linked to poultry. This situation has strongly stimulated a renewal of scientists' interest in bacteriophages (phages) since the beginning of the 21st century. Bacteriophages are the viruses of bacteria. They are abundant in nature, and accompany bacteria in each environment they colonize, including human microbiota. In this review, we focused on the use of bacteriophages as therapeutic agents to treat infections and reduce counts of pathogenic bacteria in poultry, as biocontrol agents to eliminate foodborne pathogens on/in food, and also as disinfectants to reduce contamination on food-contact surfaces or poultry carcasses in industrial conditions. Most of the phage-based products are targeted against the main foodborne pathogens, such as Campylobacter jejuni, Salmonella spp., Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Clostridium perfringens. Phages are currently addressed at all stages of the poultry production "from farm to fork", however, their implementation into live birds and food products still provokes discussions especially in the context of the current legal framework, limitations, as well as public health and safety.

Prevalence, antibiotic susceptibility and virulence factors of Enterococcus species in racing pigeons (Columba livia f. domestica).

BACKGROUND: This study was aimed to investigate the intestinal microbiota in racing pigeons with regard to Enterococcus species distribution, virulence factors and antibiotic susceptibility. Three methods (API, Multiplex sodA-PCR, 16S rRNA sequencing) were compared for Enterococcus species identification. Cloacal samples from 179 apparently healthy pigeons of 13 different flocks were tested. RESULTS: Multiplex sodA-PCR and 16S rRNA gene sequencing showed almost perfect agreement in Enterococcus species identification. Isolates were identified as Enterococcus columbae (34.5%), Enterococcus hirae (20.7%), Enterococcus faecalis (11.7%), Enterococcus faecium (11.7%), Enterococcus gallinarum (9%), Enterococcus mundtii (4.8%), Enterococcus casseliflavus (3.4%), Enterococcus cecorum (2.1%), Enterococcus durans (2.1%). More Enterococcus species were found after the race season than before. The study showed differences between Enterococcus species in relation to 68.8% (22/32) biochemical parameters. Six out of seven virulence genes were detected: gelE (43.5%), asa1 (42.1%), efaA (30.3%), ace (30.3%), cylA (27.6%), and esp (9%). None of the isolates harboured hyl gene. Overall 15.2% of Enterococcus isolates produced gelatinase, but 66.7% gelE genes were silent. Enterococcus faecalis showed the most often efaA, ace and gelatinase activity than other enterococcal species. Nearly all isolates (93.1%) were resistant to at least one antibiotic. The most frequent resistance was to enrofloxacin (80%), doxycycline with teicoplanin (73.1%), erythromycin (49.7%). The study revealed significant differences between some enterococcal species in the antibiotic susceptibility to different antibiotics. Enterococcus columbae and E. cecorum showed significantly more frequent resistance to chloramphenicol than other enterococci. The presence of VRE (19.3%), HLGR (2.8%) and no LRE were found. Overall 30.3% of isolates were positive for vancomycin resistance genes, where vanC1 (E. gallinarum), vanC2-C3 (E. hirae, E. casseliflavus), vanB (E. columbae) predominated. CONCLUSIONS: We conclude, that intestinal microbiota in racing pigeons is composed by 9 different Enterococcus species. Given that racing pigeons are kept in close contact with humans and backyard animals, combined with their long-distance flight abilities, they can serve as potential source of virulent and antibiotic resistant Enterococcus spp. in the environment.

The application of the loop-mediated isothermal amplification (LAMP) method for diagnosing Enterococcus hirae-associated endocarditis outbreaks in chickens.

BACKGROUND: Enterococcus hirae is considered a part of the normal intestinal biota of several domestic animals, including poultry. However, this species is also associated with infective endocarditis in chickens, a disease that leads to unexpected deaths and serious economical losses. Enterococcus hirae is identified predominantly with the use of conventional bacteriological methods, biochemical tests and PCR. Rapid, sensitive and specific methods for detecting E. hirae in clinical samples are required in poultry production. The aim of this study was to use the Loop-Mediated Isothermal Amplification (LAMP) for the identification and quantification of E. hirae in heart samples from broiler chickens. RESULTS: The specificity of the LAMP method was confirmed for 7 enterococcal strains and 3 non-enterococcal strains. E. hirae was detected in all of the 22 analyzed clinical bacterial isolates and in all of the 9 heart samples. Three sets of primers supported the detection of E. hirae with high sensitivity and specificity within one hour. The highest detection rate of a LAMP product was approximately 7 min for an E. hirae strain and 12 min for a positive heart sample. The detection limit for the E. hirae ATCC 10541 standard was 1.3 × 102 CFU (43.4 fg) or 13.8 copies of the E. hirae genome equivalent per reaction. The reaction was 10-fold more sensitive than conventional species-specific PCR. The LAMP assay supported the determination of the E. hirae load in chicken hearts with endocarditis in field cases. The average number of E. hirae cells in hearts was 5.19 × 107 CFU/g of tissue, and the average number of E. hirae genome equivalents in hearts was 5.51× 106 copies/g of tissue. Bacterial counts were significantly higher in the LAMP assay than in the standard plate count. CONCLUSIONS: The LAMP assay is a useful diagnostic tool and an effective alternative to conventional methods for the detection of this enterococcal species. The sodA-based LAMP assay supported direct identification of E. hirae from pure cultures and heart samples without previous bacterial cultivation. This is the first study to apply the LAMP method for the purpose of diagnosing E. hirae-associated endocarditis in poultry.

Characterization of pathogenic Enterococcus cecorum from different poultry groups: Broiler chickens, layers, turkeys, and waterfowl.

Enterococcus cecorum (EC) is known as a commensal in the intestines of mammals and birds. However, it has been described as an emerging pathogen in poultry industry worldwide. The aim of this study was to analyze and compare EC isolated from clinical material collected from poultry groups with different production purposes. The genetic diversity among pathogenic EC in relation to each specific poultry type was examined. In total, 148 isolates from independent infection outbreaks (2011-2016) were used: 76 broiler chickens (CB), 37 broiler breeders (BB), 23 layers (CL), 7 waterfowl (W) and 5 turkey (T) flocks (1 isolate/1 flock). We provided age ranges at diagnosis of EC-infection for 5 poultry groups. Isolates obtained from CB were significantly more frequently retrieved from bone marrow, joints, spine, and contrary to BB, CL less frequently retrieved from respiratory system. The study showed differences between EC of various poultry types in relation to 10/32 (31.3%) biochemical parameters. EC isolates from CB were significantly more often positive for ßGAL, ßNAG, MLZ, and less often positive for PAL and ßMAN than isolates from other poultry types. However, BB and W isolates showed higher ability to metabolise mannitol than CB, CL, and T. CB isolates showed lower ability to survive at 60°C. Only chicken EC-isolates harbored virulence genes: CB (8.1%) > BB (3.4%) > CL (2%). No specific pulsotype of EC was associated with a specific poultry. One or several various (up to 6) genetic types of EC may be involved in outbreaks in CB flocks within one year in one region. Outbreaks reported in following years in the same region were usually caused by a distinct set of EC-genetic types. PFGE results indicated at the genetic heterogeneity among pathogenic isolates involved in outbreaks in relation to each poultry type. To our best knowledge, this is the first study which provides a comparison between clinical EC from 5 poultry groups. The study provides a new insight into EC as pathogen of different bird species. The obtained data may be useful in further studies on EC-infections more focused on a specific type of poultry.

Disseminated hyaline ring granuloma in the omentum of a dog.

BACKGROUND: Hyaline ring granuloma (HRG) is an uncommon histopathologic finding of unsolved etiopathogenesis. According to the exogenous theory, HRG develops due to implantation of foreign material, most probably indigestible plant fragments. HRG is a comparatively rare condition in humans, mostly involving the oral cavity with very rare extraoral locations. CASE PRESENTATION: An 1-year-old mixed-breed dog in good condition was presented for routine ovariohysterectomy. Disseminated HGR were accidentally found in the omental adipose tissue during surgery. Histopathology revealed the presence of ring-like hyaline structures surrounded by granulomatous inflammation including foreign body-type multinucleated giant cells. The histochemical examinations indicated the exogenous plant origin of the foreign material. CONCLUSIONS: The lesions were similar to the findings in humans with HRG. The definitive diagnosis remains largely based on histopathological examination supported by special histochemical stains. To the best of our knowledge, this is the first case of hyaline ring granuloma reported in a non-human species. Moreover, the omentum is an uncommon location for this condition.

The response of mute swans (Cygnus olor, Gm. 1789) to vaccination against avian influenza with an inactivated H5N2 vaccine.

BACKGROUND: Recent epidemics of highly pathogenic avian influenza (HPAI) produced an unprecedented number of cases in mute swans (Cygnus olor) in European countries, which indicates that these birds are very sensitive to the H5N1 virus. The HPAI outbreaks stirred a debate on the controversial stamping-out policy in populations of protected bird species. After preventive vaccination had been approved in the European Union, several countries have introduced vaccination schemes to protect poultry, captive wild birds or exotic birds in zoos against HPAI. The aim of this study was to investigate the immune response of wild mute swans to immunization with an inactivated AI H5N2 vaccine approved for use in poultry. The serological responses of mute swans were assessed by comparison with racing pigeons (Columba livia), a species which is characterized by different susceptibility to infection with the H5N1 HPAI virus and plays a questionable role in the ecology of influenza (H5N1) viruses. RESULTS: Swans were vaccinated once or twice at an interval of 4 weeks. The humoral immune response was evaluated by hemagglutination inhibition (HI) and NP-ELISA. The lymphocyte blast transformation test was used to determine the cell-mediated immune response. Higher values of the geometric mean titer (GMT) and 100 % seroconversion (HI ≥32) were noted in double vaccinated swans (1448.2) than in single vaccinated swans (128.0) or in double vaccinated pigeons (215.3). Significant differences in HI titers were observed between swans and pigeons, but no variations in ELISA scores were noted after the booster dose. Immunization of swans had no effect on the proliferative activity of lymphocytes. CONCLUSIONS: The inactivated H5N2 vaccine was safe and immunogenic for mute swans and pigeons. Vaccination may have practical implications for swans kept in zoos, wildlife parks or rehabilitation centers. However, challenge studies are needed to prove the efficacy of the H5N2 AI vaccine.

Invasion of Flukes of the Echinostomatidae Family in Racing Pigeon ( Columba livia var. domestica) Lofts.

Over 4 years, only two known cases of fluke invasions were diagnosed in racing pigeons ( Columba livia ) originating from different regions of Poland. In both cases, the invasion was characterized by a very high mortality (approximately 70%), and the source of the infestation was snails of the Lymnaeidae family eaten by pigeons. Fluke invasions in pigeons are extremely rare and to date have not been described in Poland. Therefore, the occurrence of the symptoms of hemorrhagic diarrhea and sudden deaths of either adult pigeons or nestlings were suspected to be associated with poisoning. Autopsy revealed an invasion of flukes causing hemorrhagic enteritis. Renal failure and spleen atrophy were also found in the birds. Using molecular biology techniques, infestation with the fluke Echinostoma revolutum was determined in the second case.

Phenotypic and genotypic characterization of Enterococcus cecorum strains associated with infections in poultry.

BACKGROUND: From the beginning of the 21(st) century Enterococcus cecorum has emerged as a significant health problem for poultry raised under intensive production systems. To obtain new insights into this bacterial species, we investigated 82 clinical isolates originating from different poultry flocks in Poland between 2011 and 2014. RESULTS: Phenotypically, isolates from clinical cases showed ability to growth at low temperatures (4 °C, 10 °C), and differences in growth at 45 °C (74.4 %). Survival at high temperatures (60 °C, 70 °C) was observed for 15, 30 min. More than half of strains survived at 60 °C even after prolonged incubation (1 h), but none survived after 1 h at 70 °C. Total growth inhibition was observed on agar supplemented with tergitol or potassium tellurite. Relatively high number of isolates gave positive reactions for ß-galactosidase (ßGAL 80 %), Voges Proskauer test (60 %), less for ß-mannosidase (17 %), glycogen and mannitol (12 %). The metabolic fingerprinting for E. cecorum obtained in Biolog system revealed ability to metabolise 22 carbon sources. Only 27/82 strains contained ≥ 1 virulence genes of tested 7, however 2.4 % isolates carried 6. Increased antimicrobial resistance was observed to enrofloxacin (87 %), teicoplanin (85 %), doxycycline (83 %), erythromycin (46 %). Most strains (75/82) showed multidrug resistance. The single isolate was resistant to vancomycin (VRE) and high level gentamicin (HLGR). Linezolid resistance among clinical isolates was not found. PFGE revealed diversity of E. cecorum from cases. It could be assumed that transmission of pathogenic strains between flocks regardless of type of production or geographical region may be possible. CONCLUSIONS: Clinical infections in poultry caused by E. cecorum may indicated on new properties of this bacterial species, previously known as a commensal. Despite many common phenotypic features, differences were found among clinical isolates. Several, widely distributed pathogenic E. cecorum strains seemed to be responsible for infection cases found in different poultry types.

Draft Genome Sequences of Two Commensal Enterococcus cecorum Strains Isolated from Chickens in Belgium.

Here, we report the draft genome sequences of two commensal Enterococcus cecorum strains (1710s23 and 1711s24), cultivated from the ceca of healthy laying hens originating from different farms in Belgium.

Draft Genome Sequences of Five Clinical Enterococcus cecorum Strains Isolated from Different Poultry Species in Poland.

Here, we report five draft genome sequences of Enterococcus cecorum strains that were isolated from different bird species of affected poultry flocks (commercial broilers [CB], broiler breeders [BB], commercial layers [CL], ducks [D], and geese [G]) in Poland.

Histomonosis - an existing problem in chicken flocks in Poland.

Histomonosis (histomoniasis, blackhead), beside coccidiosis, belongs to the most important parasitic protozoan diseases in poultry. So far Histomonas meleagridis infections with varied mortality rates have been mainly diagnosed in young turkeys. Recently an increasing number of cases have been reported in chicken flocks in Europe resulting in economic losses. It is thought that this situation is predominantly caused by a complete withdrawal of the effective antihistomonals in the EU. Authors listed the selected outbreaks of histomonosis in 10 chicken flocks originated from different farms of 4 regions in Poland: 8 broiler breeder flocks (at mean age of 33 weeks) and 2 commercial layers flocks (at mean age of 38 weeks). This study reported here naturally occurring case of H.meleagridis infection in commercial broiler breeder (BB) flock line ROSS 308 at the age of 16 weeks. We showed acute form of infection with characteristic necrotic foci in the liver, and ulcerative typhilitis. Beside the liver and caeca, the multiple histomonads, lymphoid tissue depletion and heavy destruction in the bursa of Fabricius were observed. Additionally, the absence of systemic diffuse histomonads and lack of Heterakis gallinarum, caecal worm eggs in faecal samples were noted. PCR technique enabled to detect the presence of H.meleagridis genetic material in the investigated tissue samples. Authors indicate that histomonosis can be considered as re-emerging infectious diseases in chicken flocks of intensive production system.