Salmonella typhimurium outbreak in broiler chicken flocks in Mexico

A Salmonella typhimurium outbreak in 1-to-2-week-old broiler flocks in Mexico is reported. Clinical signs were growth retardation, blindness, twisted necks, and lameness. Gross lesions consisted of hypopyon, panophthalmitis, hepatomegaly with necrotic foci, enlarged spleen, pericarditis, coagulated and unabsorbed yolks, and purulent arthritis. Mortality and cull rates in different flocks ranged from 1.7% to 10.6% during the first two weeks of age. All internal organs, eyes, and hock joints of diseased chickens that were cultured were Salmonella-positive. The bacteria were also isolated from the breeder source flock. Disease was thought to be transmitted through eggs at hatch.     

Prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in broiler chicken and turkey flocks slaughtered in Quebec, Canada

We conducted an observational study to estimate prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in poultry. Eighty-one broiler chicken and 59 turkey flocks selected among flocks slaughtered in the province of Quebec, Canada, were included in the study. Flock status was evaluated by culturing pooled caecal contents from about 30 birds per flock. Exposure to potential risk factors was evaluated with a questionnaire. Odds ratios were computed using multivariable logistic regression.

The prevalence of Salmonella-positive flocks was 50% (95% CI: 37, 64) for chickens and 54% (95% CI: 39, 70) for turkeys, respectively. Odds of Salmonella colonization were 2.6 times greater for chicken flocks which failed to lock the chicken house permanently. In turkeys, odds of Salmonella colonization were 4.8–7.7 times greater for flocks which failed to be raised by ≤2 producers with no other visitors allowed onto the premises, or origin from a hatchery.

The prevalence of Campylobacter-positive flocks was 35% (95% CI: 22, 49) for chickens and 46% (95% CI: 30, 62) for turkeys. Odds of colonization were 4.1 times higher for chicken flocks raised on farms with professional rodent control and 5.2 times higher for flocks with manure heap >200 m from the poultry house, and also increased with the number of birds raised per year on the farm and with the age at slaughter. For turkeys, odds of Campylobacter flock colonization were 3.2 times greater in flocks having a manure heap at ≤200 m from poultry house and 4.2 times greater in flocks drinking unchlorinated water.     

Identification of risk factors for the prevalence and persistence of Salmonella in Belgian broiler chicken flocks

According to the European Food Safety Authority, salmonellosis is still one of the main causes of infectious foodborne gastroenteritis in humans. Broilers are an important source of salmonellosis after eggs and pork. Between 1987 and 1999 the trend of human salmonellosis incidence in Belgium increased constantly. However, from 2000 until 2005 a decrease in human cases was observed, probably following the sanitary measures implemented in the poultry breeder and laying sector. In order to decrease human infections it is essential to tackle the problem at the farm level to minimize cross-contamination from farm to fork. This paper seeks to answer two questions: (i) given the Salmonella status of the farm at a certain occasion (equal to the sampling time of the flock), what are the risk factors that the farm will be Salmonella positive at a following occasion? And (ii) what are the risk factors for a farm to be persistently positive for two consecutive flocks? We used surveillance data on 6824 broiler flocks studied for Salmonella infectivity from 2005 to 2006 in Belgium. The farms were tested regularly (3 weeks before slaughter of each broiler flock) for the presence of Salmonella based on multiple faecal samples per flock on a farm yielding clustered data. Generalized estimating equations, alternating logistic regression models, and random-intercept logistic regression models were employed to analyse these correlated binary data. Our results indicated that there are many factors that influence Salmonella risk in broiler flocks, and that they interact. Accounting for interactions between risk factors leads to an improved determination of those risk factors that increase infection with Salmonella. For the conditional analysis, the risk factors found to increase the risk of Salmonella infection on a farm at a current occasion given the previous Salmonella status included: Salmonella infection of day-old chicks (of the current flock); a previously infected flock even though the farm was equipped with a hygiene place to change clothes prior to entering the broiler house; having temporary workmen when there was a separation between birds of different species; and separating birds of different species in the Walloon region relative to the Flanders region. Sanitary measures such as a cleaning and disinfecting procedure conducted by an external cleaning firm, applying the all-in all-out procedure, and hand washing decreased the risk despite their interaction with other factors. From the joint analysis, the most important factors identified for increased risk for persistent Salmonella on a farm involved the interaction between having temporary workmen when there were poultry or farmers in contact with foreign poultry or persons, and the interaction between having temporary workmen when there were poultry or farmers in contact with external poultry or persons.     

Control, prevention and eradication of Salmonella enteritidis infection in broiler and broiler breeder flocks

Salmonella enteritidis was identified by serological and bacteriological techniques in two clinically normal breeder flocks in an integrated broiler organisation in Northern Ireland. The organism was transmitted vertically to clinically affected progeny flocks. The infected breeder flocks were slaughtered and the infection throughout the organisation controlled and subsequently eradicated. A working group, consisting of the senior management of the broiler organisation and veterinary staff from the Veterinary Research Laboratories at Stormont, was formed to establish procedures to minimise the risk of the reintroduction of salmonella infection, by preventing vertical transmission from grandparent flocks, or lateral transmission from personnel, other animal species and fomites, or transmission through the feed. All feed was heated to a minimum of 70 degrees C for 12 minutes immediately before it was pelleted and subsequently transported to the flocks through a dedicated system of conveyor belts, bins and lorries. A comprehensive system for monitoring the efficacy of the preventive procedures was established and is now used throughout the poultry industry of Northern Ireland.     

Epidemiological associations between characteristics of registered broiler chicken flocks in Canada and the Salmonella culture status of floor litter and drinking water

A Canada-wide flock management survey of 294 randomly selected commercial broiler chicken flocks was conducted during 1989-1990. The prevalence of flocks that yielded Salmonella from cultures of floor litter or drinking water, and the prevalence of floor litter samples that yielded Salmonella, were significantly associated (p < 0.05) with the age of the flock and the region of Canda in which the flock was located. Culture of Salmonella from the drinking water was significantly associated (p < 0.05) with the type of drinker used, the dead bird disposal method, and the region of Canada in which the flock was located. There was a significantly greater risk (p < 0.05) of contamination of drinking water with Salmonella from trough drinkers (odds ratio = 7.99) and plastic bell drinkers (odds ratio = 6.10) than from nipple drinkers. No significant associations were found between pest control, restrictions on visitors, clean-out methods, or water sanitization and the culture of salmonellae from floor litter or drinking water.     

Development and application of an ELISA for detecting antibodies to Salmonella enteritidis in chicken flocks.

Enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of IgG antibody to Salmonella enteritidis in poultry flocks. A lipopolysaccharide (LPS) and heat-extracted (HE) antigen for use in the ELISA were evaluated together with the rapid slide test (RST), microagglutination test (MT) and the microantiglobulin (MAG) test. In experimentally infected specific pathogen free chickens, good correlation was seen between all tests although, generally, the MT and MAG detected antibody earlier and titres peaked earlier than the ELISAs. The LPS antigen detected antibody earlier than the HE antigen but the latter gave higher titres in the later stages of infection. Cross reactions were seen between S enteritidis and S typhimurium in the ELISAs although homologous reactions were always much higher. Antisera to S montevideo or S senftenberg gave weak positive reactions in both S enteritidis ELISAs. Serological and bacteriological examinations of representative samples from two commercial chicken flocks were carried out. In flock A the HE-ELISA and MAG test detected antibody in nearly all birds. The LPS-ELISA detected antibody in over 60 per cent of birds, while the MT and RST detected few seropositive birds. The whole blood test using the stained S pullorum antigen on the farm detected antibody in just under 25 per cent of the birds. S enteritidis was isolated from the organs of 25 per cent of the birds. All birds in flock B were seronegative by all tests; no salmonellae were isolated from the organs of these birds.     

Introduction and spread of thermophilic campylobacters in broiler flocks.

Campylobacteriosis is the most commonly reported infectious cause of human gastroenteritis in developed countries and broiler chickens are considered to be the major food-borne source of the infection. The control of the infection in man depends upon its control in broiler flocks but the epidemiology in poultry is poorly understood. Up to 50 per cent of broiler flocks may be infected and most of the birds in an infected flock carry the organisms until slaughter. Vertical transmission through the egg appears unlikely but there are many other potential sources of the infection for the chicks; direct contact with infected animals or birds has been proposed and there is also evidence for indirect transmission through drinking water or insect vectors. It is suggested that the cross-sectional studies discussed in this review should be followed by well designed case-control studies to test the aetiological hypotheses put forward.     

Diseases diagnosed in broiler chicken flocks in Victoria, Australia, 1977 to 1984

During the period July 1977 to June 1984, specimens from 1402 broiler chicken flocks were submitted to the Veterinary Research Institute, Victoria, Australia for investigation of morbidity, mortality and, or, poor performance. A total of 19,450 post mortem examinations, as well as numerous ancillary tests, were performed. The findings on these flocks are presented and the consequences of some particular diseases noted.     

Prevalence and risk factors of Campylobacter infection in broiler flocks from southern Spain

An extensive epidemiological study was performed to determine the prevalence and risk factors of Campylobacter infection in broiler farms in Andalusia (southern Spain). A total of 2221 cloacal swabs and 747 environmental swabs from 291 broiler flocks were screened between April 2010 and May 2012. The prevalence of Campylobacter in individual animals was 38.1%, and the flock prevalence was 62.9%. Flocks were predominantly infected by C. jejuni and C. coli but were also infected by untyped Campylobacter spp., and mixed-species infection could be found. Risk factors for Campylobacter infection were assessed from direct interview of the farmers. The number of positive samples by flock was modelled assuming a binomial distribution. Analysis indicated five factors associated with increased intra-flock prevalence: presence of dogs or cats on the farm, older age of the broiler flock, the application of thinning of flocks, the presence of windows with canvas blinds, and the presence of rodents in the poultry house. Two factors were associated with decreased intra-flock prevalence: the treatment of drinking water and having an entrance room for access into the poultry house. This is the first study performed on broilers farms from Spain reporting the risk factors of Campylobacter infection and is the largest study on the prevalence of Campylobacter infection.     

Prevalence of Alcaligenes faecalis in North Carolina broiler flocks and its relationship to respiratory disease

In order to assess the role of Alcaligenes faecalis in respiratory disease of broilers, a study was conducted to determine the prevalence of this bacterium in North Carolina broilers and to determine the relationship of A. faecalis infection to clinical disease. Our studies showed that A. faecalis is prevalent in North Carolina commercial broilers during the winter months. Bacteriological examination of turbinates and tracheas revealed that almost 40% of individual birds between 35 and 45 days of age yielded positive cultures; 62% of tested flocks were infected. When present, A. faecalis was usually the predominant bacterium isolated. Furthermore, because of a higher frequency of A. faecalis isolation in broiler flocks with respiratory disease (75% vs. 29% in flocks without respiratory diseases), these studies suggest a causal relationship between this bacterium and clinical respiratory disease.     

Prevalence of wet litter and the associated risk factors in broiler flocks in the United Kingdom

A postal questionnaire was sent to the managers of 857 broiler farms in the UK to determine the prevalence and risk factors for wet litter. The response rate was 75 per cent. Wet litter was reported by 75 per cent (95 per cent confidence interval [CI] 71.3 to 78.3) of the respondents in at least one flock during the year 2001 and 56.1 per cent (95 per cent CI 52.0 to 60.0) of them reported that they had an outbreak of wet litter in their most recently reared flock. Wet litter occurred more often during the winter months and farms using side ventilation systems were at an increased risk (odds ratio 1.74; 95 per cent CI 1.09 to 2.76). A multivariable analysis was carried out using two different definitions of wet litter as outcome variables - all cases of wet litter, and cases of wet litter associated with disease. Consistent risk factors for both outcomes were coccidiosis, feed equipment failures and the availability of separate farm clothing for each house. Cases of wet litter associated with disease were reported by 33.7 per cent (95 per cent CI 28.8 to 39.1) of the managers in their last flock and were associated with the use of hand sanitisers and broiler houses with walls made of concrete.     

Characterization of Salmonella spp. isolated from an integrated broiler chicken operation in Korea

The purpose of this study was to investigate the biological and genetic characterization of persistent Salmonella isolates in an integrated broiler chicken operation, in an attempt to elucidate the source of contamination. From the breeder farm, the hatchery, the broiler farm and the chicken slaughter house of an integrated broiler chicken operation, a total of 6 serotypes were observed. Although S. Heidelberg was not detected in the broiler farm, it was consistently found in the breeder farm, the hatchery and the chicken slaughter house. Also, S. Enteritidis and S. Senftenberg were found in the hatchery and the chicken slaughter house, and the hatchery and the broiler farm, respectively. S. Gallinarum and S. Blockley were found only in the broiler farm, and S. Virchow was only recovered in the chicken slaughter house. Isolated S. Heidelberg, S. Enteritidis and S. Senftenberg strains were divided into 3, 5 and 7 types, respectively, on the basis of all properties. Especially, S. Senftenberg isolates, divided into four types by their antimicrobial resistance patterns, were all obviously the XbaI PFGE pattern. Also, four S. Enteritidis isolates resistant to nalidixic acid showed a difference in phage type and PFGE pattern. Such a different pattern was shown despite Salmonella isolates originating from an integrated broiler operation, suggesting that further epidemiological studies on many integrated chicken companies in Korea are needed.     

Tenosynovitis in broilers and broiler breeder flocks

Tenosynovitis in commercial broiler breeder flocks, characterised by severe lameness, resulted in malnutrition and eventual culling of these chickens. Histologically there was metaplasia of tendons, tendon sheaths, connective tissues and infiltration with heterophils. Although Staph. aureus was isolated from some specimens, it is probable that the condition is of viral origin: the virus has not yet been isolated.     

A questionnaire-based,retrospective field study of persistence of Salmonella Enteritidis and Salmonella Typhimurium in Danish broiler houses

A questionnaire-based, retrospective field study was conducted in 78 Danish broiler houses (analytical units) on 42 farms. In spring 1997, all these broiler houses had been infected with Salmonella Enteritidis, phage type 8, and/or Salmonella Typhimurium, definitive-type 66, by day-old chicks delivered from the same hatchery. Because these two salmonella types had not been detected in the Danish broiler sector before and the broiler houses were infected in a period of low salmonella prevalence, the study could focus on farm-related factors, without being distorted by other salmonella infections.

The same person visited all 78 broiler houses, and farm-related factors were listed both from personal observations and by interrogating the person in charge of attending to the broilers. Additional factors (noted at the visits) were recorded in a later telephone interview. Altogether, 187 variables were analyzed.

Broiler houses were divided into single-infection houses (which had one or both of the salmonella types in only one crop), and multiple-infection houses (where infection occurred in multiple crops). This was done both generally and separately for each of the salmonella types.

Factors associated with house status—but that were beyond the control of the farmer—were the salmonella type and the percentage of salmonella positive samples in the first crop. Factors which could be controlled by the farmer and which were associated with reduced prevalence of multiple-infection houses included antiseptic soap and water for washing hands in the anteroom, hygiene barriers when removing dead broilers, gravel alongside the broiler house, systematic checks of indoor rodent-bait depots, and combined surface and pulse-fogging disinfection.     

Risk factors for cumulative mortality in broiler chicken flocks in the first week of life in Taiwan

(1) Factors influencing the survival of chickens in the first week of life in Taiwan were identified by modelling data from 63% of the annual national broiler production database (4769 broiler flocks). (2) Broiler chicks raised in rooms with open-curtain ventilation had the lowest mean first week cumulative mortality (CM), 1.30%, relative to those raised in rooms with negative pressure ventilation (1.42%) and water-cooled ventilation (1.37%). Increasing flock size reduced the CM. Broiler chicks shipped distances within 50 km had the lowest CM (1.22%), while broiler chicks raised in mountain areas showed the highest CM (1.65%). (3) Multiple regression analysis results indicate that ventilation type, flock size, shipping distance and delivery route influence CM in broiler chickens. Broiler chicks kept in rooms with negative pressure ventilation have an 11.22% greater CM compared to those in rooms with open-curtain ventilation. For each 1000-chicken increase in flock size, CM is reduced by 0.12%. For each kilometre increase in shipping distance, CM increases by 0.05%. Broiler chicks delivered via mountain routes show a 9.48% increase in CM compared to delivery via flat terrain. (4) Negative pressure ventilation and delivery via mountain routes are the most critical factors affecting the survival of chicks up to one week old.     

Subclinical infectious bursal disease in commercial broiler flocks in Saskatchewan.

Five commercial broiler flocks, not vaccinated for infectious bursal disease virus, derived from infectious bursal disease virus-vaccinated breeder flocks were surveyed for evidence of bursal damage and infectious bursal disease virus infection. They were compared with two groups of birds raised in isolation. Serum samples from one day old chicks contained maternal anti-infectious bursal disease virus antibodies which declined to undetectable levels by four weeks of age. Serum antibody levels remained undetectable in both control groups and one commercial flock, whereas four of the five commercial flocks had actively produced anti-infectious bursal disease virus antibodies by slaughter age. The weight of bursae from infectious bursal disease virus-positive flocks declined as compared to controls after four weeks of age. The decline in weight correlated with the appearance of histopathological lesions. Infectious bursal disease virus antigen was demonstrated in selected infected bursae and infectious bursal disease bursae and infectious bursal disease virus was isolated from some of these damaged bursae. Clinical infectious bursal disease was not observed in any of the commercial flocks. The importance of subclinical bursal damage and immunosuppression is discussed.     

Seroprevalence and identification of Ornithobacterium rhinotracheale from broiler and broiler breeder flocks in Thailand

Ornithobacteriosis is an infectious disease of avian species that has been reported in almost all countries around the world, except Thailand. The objectives of this study were to determine the seroprevalence of Ornithobacterium rhinotracheale (ORT) and to isolate and identify ORT in broilers and broiler breeders in Thailand. Chicken antibodies had been randomly checked from 17 farms (19 flocks) of broilers and 23 farms (28 flocks) of broiler breeders. The seropositive flocks were 63% and 100% in broilers and broiler breeders, respectively. The sera analysis showed that the individual 280 broiler sera antibody responses were 67.5% negative, 12.9% suspect, and 19.6% positive. The individual antibody responses of 510 broiler breeder sera revealed 12.2% negative, 38.0% suspect, and 49.8% positive samples. The bacteria were isolated and identified by polymerase chain reaction (PCR). Bacterial isolation and identification revealed that nine isolates of the 12 PCR analysis samples showed positive results to PCR analysis. All the positive PCR samples were collected from the broiler breeder farms.