Occurrence Of Necrotic Enteritis Research Articles

Evaluation the efficacy of oral immunization of broiler chickens with a recombinant Lactobacillus casei vaccine vector expressing the Carboxy-terminal fragment of α-toxin from Clostridium perfringens

BackgroundClostridium perfringens (C. perfringens) is a serious anaerobic enteric pathogen causing necrotic enteritis (NE) in broiler chickens. Following the ban on antibiotics as growth promoters in animal feedstuffs, there has been a remarkable rise in occurrence of NE which resulted in considering alternative approaches, particularly vaccination. The objective of this work was to evaluate the recombinant Lactobacillus casei (L. casei) expressing the C-terminal domain of α-toxin from C. perfringens as a potential probiotic-based vaccine candidate to immunize the broiler chickens against NE.ResultsThe broiler chickens immunized orally with recombinant vaccine strain were significantly protected against experimental NE challenge, and developed specific serum anti-α antibodies. Additionally, the immunized birds showed higher body weight gains compared with control groups during the challenge experiment.ConclusionsThe current study showed that oral immunization of broiler chickens with a safe probiotic-based vector vaccine expressing α-toxin from C. perfringens could provide protective immunity against NE in birds.

Occurrence of Necrotic Enteritis (NE) Among Local Chickens Slaughtered at Muda Lawal Market in Bauchi Metropolis, Bauchi State, Nigeria

Occurrence of Necrotic Enteritis (NE) Among Local Chickens Slaughtered at Muda Lawal Market in Bauchi Metropolis, Bauchi State, Nigeria

Incidence and associated risk factors of necrotic enteritis in Belgian layer pullet flocks

ABSTRACT Necrotic enteritis (NE) caused by Clostridium perfringens is commonly reported in broilers. Recently, increased NE prevalence in layer breeds was reported in the Indian subcontinent. NE is also frequently observed by veterinary practitioners in Europe, mainly during the pullet rearing phase. In this study, data from layer pullet flocks in Belgium over a 5-year period (2013–2017) were used to assess the incidence of NE and identify potential risk factors for NE in layer pullets. NE was observed in 26% of the layer pullet flocks receiving veterinary intervention. This accounts for an overall estimated NE incidence of 12.3% in Belgian layer pullet flocks. Occurrence of NE was significantly associated with coccidiosis, with flocks being diagnosed with coccidiosis being two-fold more likely to develop NE. Additionally, birds kept in aviary houses were less prone to NE than flocks reared in floor systems or enriched cages. At necropsy, necrotic lesions in the small intestine were comparable to NE in broilers. A single strain of C. perfringens was isolated from the necrotic lesions of three different birds from the same flock; however, no NetB could be detected.

The netB-positive Clostridium perfringens in the experimental induction of necrotic enteritis with or without predisposing factors

The netB-positive Clostridium perfringens has been considered as the requisite to consistently induce necrotic enteritis (NE). However, use of a netB-positive strain did not guarantee consistent NE reproduction unless high protein diets or Eimeria, conceived as 2 major predisposing factors, was incorporated. To establish a refined model, the roles of dietary fishmeal inclusion, Eimeria inoculation, and netB-positive C. perfringens challenge in NE induction and the confounding effects of Eimeria infection on NE were examined. The results showed that the use of netB-positive C. perfringens without a predisposing factor failed to induce NE. Fishmeal incorporation promoted the occurrence of NE but did not significantly affect the incidence of the disease in conjunction with challenge of netB-positive C. perfringens. However, the additional participation of Eimeria infection in the same induction procedure produced significantly higher numbers of NE cases and promoted more severe lesions in chickens (P < 0.05). Inoculation of Eimeria resulted in a significant higher incidence of NE compared to the non-Eimeria treated group (P < 0.05). The results demonstrated that both netB-positive C. perfringens and predisposing factors were required for the reproduction of disease. Mild-to-moderate coccidial infection (coccidial lesion score ≤ 2) was noted in NE cases in this model but severe coccidial infection did not correlate with the occurrence of NE, indicating mild coccidial infection may be beneficial for the development of NE. If multiple species infection of Eimeria precedes the challenge of C. perfringens, days 19 to 21 (1 to 3 D after the last clostridial challenge) was the time period favorable for observations of NE lesions. The time after this period may be subject to bias of severity, incidence, or mortality of NE owing to the profound coccidial lesions in the intestinal region. This study demonstrated that the co-infection with netB-positive C. perfringens and Eimeria species under fishmeal incorporation produced a desirable NE model, being of value in studying the effectiveness of novel feed additives and alternative mitigation strategies to prevent NE.

Update on the emergence and pathogenesis of necrotic enteritis in broiler chickens

Necrotic enteritis (NE) is a disease of broiler chickens, which is caused by Clostridiumperfringens type A or C and is characterized by high mortality and severe intestinal lesions. NE is described as a disease of high economical importance which affects health and welfare of broilers and also may pose a threat to public health. Although NE was known as a disease since 1930, it did not cause serious problems to the poultry industry. The emergence of the disease occurred after 1986 in Scandinavia and 2000 in the European Union and was related with the ban of in-feed antimicrobial growth promoter. Furthermore, the ban of meat meal and bone meal from the feed of broiler chickens and their replacement by fishmeal increased further the occurrence of NE. NE breaks the Koch's postulate, which supports that "a disease-causing organism should not be present in healthy individuals", because C perfringens may be detected in high populations in the gut of birds with no visible signs of NE. Moreover, challenge of birds with C perfringens does not \eadperse to the development of the disease. It is very well accepted that NE is a multi-factorialdisease in which a number of co-factors are usually required for the proliferation and toxinogenesis of C. perfringens and manifestation of the disease. Toxin -a, since 2006, has been proposed to be the main virulence factor for NE in poultry. The origin of this assumption seems to lie to observation that crude supernatant from C perfringens type A cultures induced necrotic lesions in broilers. Moreover, the development of NE lesions prevented partially by antibodies against C. perfringens toxin -a. The interpretation of these early studies is not clear, because they used crude supernatant and the assumption was made that the effects were caused by the dominant protein present (i.e. toxin -a). However, many other proteins are also present in the supernatant ofC perfringens cultures. The most convincing evidence, that toxin -a is not essential virulence factor for the pathogenesis of NE, comes from studies using a toxin -a negative mutant (epa mutant) of a C perfringens strain from NE outbreak, which was able to produce characteristic NE lesions. Recently, netB, a novel toxin that is associated with broiler NE, has been described. A netB mutant of C perfringens was unable to cause necrotic lesions in the gut of experimentally infected broilers, but a complemented netB mutant was virulent, like the wild-type strain. However, netB per se, might not be an essential component of virulence factor for the pathogenesis of NE, because not all strains isolated from diseased birds carry the netB gene. The presence of the toxin -β2, although it has been linked with increased incidence of bovine enterotoxaemia, intestinal disorders in human, horses and diarrhea in piglets, does not seem to be involved in the pathogenesis of NE in broiler. Most C. perfringens strains isolated from cases of NE do not carry the gene (cpb2) which is responsible for the production of toxin -β2. The efficacy of antitoxin -a toxoid vaccines, the high concentration of toxin-a at the supernatant of C. perfringens culture and feces of diseased birds, as well as the high titer of antibodies against toxin-a in birds with NE, indicate that toxin -a definitely play a role, major or minor, on the pathogenesis of NE in broilers.

Occurrence of necrotic enteritis in a commercial layer flock

Necrotic enteritis (NE), cause by Clostridium perfringens, is one of the leading diseases in poultry industry, which primarily affects the young chicks. The present case reports the incidence of NE in layer birds (42 weeks). The carcass was submitted for detail postmortem examination. The gross examination revealed petechial haemorrhages on intestinal mucosa and congestion in visceral organs. Microscopic observations showed degeneration and disruption of villi with haemorrhages in lamina propria and severe necrosis with submucosal haemorrhages and leucocytic infiltration in the intestine. The intestinal scrapings were collected and subsequently cultured for the isolation of causative agent. The isolates were identified as Clostridium spp. based on colony and staining characteristics, and further confirmed by detection of alpha toxin gene (402bp) using PCR.

Isolation, identification, and antimicrobial susceptibility of Clostridium perfringens isolates from acute necrotic enteritis of broiler chickens

The aim of this study was to isolate, identify and determine the antimicrobial susceptibility of Clostridium perfringens (CP) isolates from acute necrotic enteritis of broiler chickens. All broiler carcasses diagnosed as necrotic enteritis (NE) were sampled, subjected to microbial tests and 40 isolates were identified according to standard procedures. The antimicrobial susceptibility of CP isolates to 20 antibacterial agents was then determined. The results show widespread resistance among CP isolates. The most frequent resistance was observed to neomycin sulfate (87.5%), and then to lincomycin and tetracycline (both 80%). No isolate was resistant to chloramphenicol and the least frequency of resistance was observed to vancomycin (10%), sulfamethoxazole+trimethoprim (17.5%), and penicillin (20%). All isolates were multiple drug resistant types. There were 39 resistant patterns among the CP isolates, 95% of which were distributed in 38 resistant patterns. These multiple and variable resistance patterns observed among the CP isolates, even among different isolates from one farm, demonstrate a challenge for veterinarians in the field to choose the correct compound to combat the occurrence of NE.

Diffusion of Clostridium perfringens NetB positive strains in healthy and diseased chickens

For over 30 years α toxin was considered the key virulence factor responsible for the appearance of necrotic enteritis (NE) in chickens but, recently, a new toxin related to the occurrence of NE, called NetB, has been described. The aim of this work was to evaluate the CP toxin-type and the NetB gene presence in strains collected from chickens affected or not by enteric diseases. 107 strains were tested: 30 isolated from chickens affected by NE, 54 from subjects affected by other enteric pathologies and 22 from healthy animals. All strains resulted toxin-type A and 26.17% of these was positive also for β2 toxin gene. No strains were positive for cpe gene. 27% (29/107) of CP was NetB positive and 93% (27/29) of these was isolated from birds affected by intestinal disorders. 16 NetB positive strains were obtained from chickens affected by NE (16/30), 9 from animals affected by other intestinal disorders (9/54) and 4 from healthy animals (4/22). A significant difference between the number of NetB positive strains isolated from animals affected by NE and healthy chickens has been observed (P=0.014). However, the finding that the 17.4% of strains isolated from healthy chickens was also positive for NetB, confirm that other virulence factors could play an important role on NE appearance.

Recombinant AttenuatedSalmonella entericaSerovar Typhimurium Expressing the Carboxy-Terminal Domain of Alpha Toxin fromClostridium perfringensInduces Protective Responses against Necrotic Enteritis in Chickens

Clostridium perfringens-induced necrotic enteritis (NE) is a widespread disease in chickens that causes high mortality and reduced growth performance. Traditionally, NE was controlled by the routine application of antimicrobials in the feed, a practice that currently is unpopular. Consequently, there has been an increase in the occurrence of NE, and it has become a threat to the current objective of antimicrobial-free farming. The pathogenesis of NE is associated with the proliferation of C. perfringens in the small intestine and the secretion of large amounts of alpha toxin, the major virulence factor. Since there is no vaccine for NE, we have developed a candidate live oral recombinant attenuated Salmonella enterica serovar Typhimurium vaccine (RASV) that delivers a nontoxic fragment of alpha toxin. The 3' end of the plc gene, encoding the C-terminal domain of alpha toxin (PlcC), was cloned into plasmids that enable the expression and secretion of PlcC fused to a signal peptide. Plasmids were inserted into Salmonella enterica serovar Typhimurium host strain chi8914, which has attenuating pabA and pabB deletion mutations. Three-day-old broiler chicks were orally immunized with 10(9) CFU of the vaccine strain and developed alpha toxin-neutralizing serum antibodies. When serum from these chickens was added into C. perfringens broth cultures, bacterial growth was suppressed. In addition, immunofluorescent microscopy showed that serum antibodies bind to the bacterial surface. The immunoglobulin G (IgG) and IgA titers in RASV-immunized chickens were low; however, when the chickens were given a parenteral boost injection with a purified recombinant PlcC protein (rPlcC), the RASV-immunized chickens mounted rapid high serum IgG and bile IgA titers exceeding those primed by rPlcC injection. RASV-immunized chickens had reduced intestinal mucosal pathology after challenge with virulent C. perfringens. These results indicate that oral RASV expressing an alpha toxin C-terminal peptide induces protective immunity against NE.

Risk factors for the use of prescription antibiotics on UK broiler farms

Despite growing concerns about the emergence of antibiotic-resistant strains of bacteria, little work has been carried out to investigate reasons for prescription antibiotic use in UK farming systems. We carried out a nationwide survey of broiler farms to determine risk factors for the use of prescription antibiotics. A cross-sectional questionnaire-based survey of UK broiler farms was undertaken covering flock placement dates from July 2002 until July 2003 and was based on information concerning 54% of the national broiler population reared on 497 farms. Data were collected on all aspects of broiler production and multivariable logistic regression analyses were performed to determine risk factors for two dependent variables; therapeutic and preventive use of antibiotics. The major indications for the use of antibiotics for therapeutic purposes were enteric and respiratory disease, the strongest association being with the occurrence of necrotic enteritis. No direct association was found between the use of antibiotics for preventive purposes and disease. Multivariable logistic regression analysis indicated that the main drivers for the use of antibiotics for disease prevention may be poultry company disease prevention policies and farm management practices. With increasing restrictions on the use of antibiotics in food-producing animals, research efforts need to be focused on the epidemiology of enteric and respiratory disease in poultry. The cost of disease to the broiler industry is great, resulting in the use of antibiotics for preventive purposes to safeguard against large financial losses. More research into alternative disease control measures is required.

Prevalence and associated risk factors of necrotic enteritis on broiler farms in the United Kingdom; a cross-sectional survey

In order to determine the prevalence and risk factors for necrotic enteritis in broilers, a cross-sectional survey was conducted among 857 farms, rearing broilers for nine UK poultry companies. The main data collection tool was a postal questionnaire directed at farm managers. Additional information on disease occurrence on the farm was collected from veterinary postmortem reports. The response rate to the questionnaire was 75%, ranging from 54% to 90% within companies. During 2001, 32.8% of the respondents indicated that they had observed a case of necrotic enteritis (95% confidence interval, 29.1 to 36.8) in at least one flock. The disease was most often reported during the months October to February. The point prevalence (necrotic enteritis occurrence in the most recently reared flock) reported by farm managers was 12.3% (95% confidence interval, 9.8 to 15.2). Multilevel logistic regression was performed with the poultry company as the random effect, using the occurrence of necrotic enteritis in the farm's most recently reared flock as the dependent variable. Strong associations were found between the outcome variable and the occurrence of wet litter (odds ratio, 2.39; 95% confidence interval, 1.27 to 4.52; P = 0.007) and coccidiosis (odds ratio, 4.68; 95% confidence interval, 1.74 to 12.55; P = 0.002). In addition, the use of ammonia as a disinfectant for coccidial oocysts appeared to be an independent risk factor (odds ratio, 3.44; 95% confidence interval, 1.53 to 7.71; P = 0.003). Finally, the positive association between the use of plasterboard walls in poultry houses and the occurrence of necrotic enteritis might point to an important role of cleaning and disinfection in the epidemiology of this disease (odds ratio, 3.72; 1.38 to 10.00; P = 0.009).

Liver lesions seen at slaughter as an indicator of necrotic enteritis in broiler flocks.

Historical data of necrotic enteritis incidence and carcass condemnations owing to liver lesions in south-eastern Norway during 1978-1998 revealed covariance in the occurrence of the two variables. In histological examination during the first half of 1998, 33 of 45 sampled carcasses condemned owing to liver lesions showed histopathological changes consistent with earlier described Clostridium perfringens-associated hepatitis. The results suggest that the occurrence of necrotic enteritis in broiler flocks may be monitored by using meat inspection data on liver lesions.

Liver lesions seen at slaughter as an indicator of necrotic enteritis in broiler flocks

Historical data of necrotic enteritis incidence and carcass condemnations owing to liver lesions in south-eastern Norway during 1978–1998 revealed covariance in the occurrence of the two variables. In histological examination during the first half of 1998, 33 of 45 sampled carcasses condemned owing to liver lesions showed histopathological changes consistent with earlier described Clostridium perfringens-associated hepatitis. The results suggest that the occurrence of necrotic enteritis in broiler flocks may be monitored by using meat inspection data on liver lesions.

Isolation of &lt;i&gt;Clostridium perfringens&lt;/i&gt;, Causal agents of necrotic enteritis in chickens

The present study was conducted to isolate the causal agent of necrotic enteritis (NE) from broiler chickens. A total of 50 jejunal samples from necropsied broiler chickens were collected for isolation of Clostridium perfringens, the causal agent of NE. The novel method for isolation of Clostridium perfringens was stab culture in association with pouring of olive oil on the surface of the stab culture. The collected samples in nutrient broth were kept in a candle jar and incubated for 24 hrs at 37°C. For maintenance of anaerobic condition olive oil (2-3 cm) were poured on surface of culture broth in test tube. In Gram's staining, the morphology of the isolated bacteria was Gram-positive, rod-shaped, anaerobic, spore-forming single or paired in arrangement. The addition of olive oil on the surface of stab culture was effective for the growth of Clostridium perfringens. The characterization of Clostridium perfringens was then performed by other routine cultural study, staining procedure and different types of biochemical tests. The occurrence of necrotic enteritis was 8%. Keywords: Clostridium perfringens; Stab culture; Olive oil; Broiler chickens DOI: http://dx.doi.org/10.3329/jbau.v9i1.8751 JBAU 2011; 9(1): 97-102