1. Clostridium perfringens-associates necrotic hepatitis in Swedish commercial broiler chickens flock.
Vet. Mohammed Abdel Fattah
National Food Agency, Sweden

2. Aetiology
C. perfringens is a spore forming, anaerobic, rod shaped, encapsulated and non-motile organism.
This organism is readily found in water, soil, sediment and also as a normal inhabitant of the intestinal tract of healthy poultry birds and humans.
It prefers to grow in conditions with very little or no oxygen, and under ideal conditions like high pH can multiply very rapidly.
Petit et al. (1999) divided C.perfringens into 5 toxinotypes (A, B, C, D
and E), based on production of four major toxins, alpha, beta, epsilon
and iota. Type A is considered to be the main causative factor for NE
in poultry.
Toxinotypes B, D and E do not play a role in poultry disease.

3. Necrotic enteritis and the subclinical form of C
Necrotic enteritis and the subclinical form of C. perfringens infection in poultry are caused by C. perfringens type A, producing the alpha toxin, and to a lesser extent type C, producing both alpha toxin and beta toxin.
Some strains of C. perfringens type A produce an enterotoxin at the moment of sporulation and are responsible for foodborne disease in humans.

4. Predisposing factors
It is generally accepted, however, that predisposing factors are required for these bacteria to colonize and cause disease in poultry. The best known predisposing factor is:
mucosal damage, caused by Coccidiosis due to low level of coccidiostats
Diets with high levels of indigestible, water-soluble non-starch polysaccharides, known to increase the viscosity of the intestinal contents
Diets with high protein
Stress, high levels of corticosteroids which lead to mucosal damage of the intestine
Immunosuppression
Hygiene

5. Pathogenesis
The pathogenesis of the disease is associate with the proliferation of Cl. perfringens in the large intestine and caecum and subsequent to the small intestine/hepatic and bile system where the toxin is produced. This is supported by an increase in the pH and reduced oxygen contents in the upper intestine.

6. Case history, house no. 1
A previous history of IBV (M41-like) and FAdV, D isolated from proventriculus and cecaltonsils.
During preparation and catching the birds by catching machine for transportation to the slaughterhouse which is localized nearby the farm (25 minutes) almost 450 birds (0,84%) died suddenly without showing any pervious symptoms.
At the slaughterhouse the number of birds which died during transport (DOA) was another 396 birds (0,90%).
There were no problems at all involving transportation (time, temperature and humidity) or waiting time at slaughterhouse before slaughtering (time, weather).
There was one transport crate (of 130 crates) which weighed 667kg/live birds instead for 600kg.

7. Mortality during rearingperiod
Week ,7 %
Three days before slaughtering ,0 %
Day 1 slaughtering, ,2 %
Day 2 slaughtering, ,1 %

8. Other relevant information
Parents group age Weekes
Slaughtering date /09/2014
Slaughtering age / 35 days
FCR/ Bird ,9kg
Avarge Slaughteringswieght g
Coccidiostats Narasin
Last date for using Narasin

9. Postmortem examination Uneven flock. Cyanosis of the Brest muscle.
Clinical signs
Impaired FCR
Weight loss
Reduced weight gain
Very stressed birds
Postmortem examination
Uneven flock.
Cyanosis of the Brest muscle.
Livers were greatly enlarged with a pale reticular pattern, sometimes with pale and stellate foci which had central pinpoint red spot. The gallbladder was enlarged and exceed the liver edges.
The spleens were greatly enlarged and had the same lesions as the livers.
Dilatation of the proventriculus and the gizzard with a very wide isthmus. There were haemorrhage in the mucosa of the proventriculus.
Black coloration and erosions on the mucosa of the gizzard.
Inflammation of the Bursa Fabricius.
Inflammation of the intestine.

10. Condemnations rate at slaughtering
Condemnations code
Day 1
Day 2
Liver necrosis
0,10 %
0,04 %
Hydropericardium
0,01 %
Ascites
0,45 %
0,41 %
Gastric dilatation
0,06 %
Yolk sack infection
0,03 %
0,02 %
Skin tumour
Synovitis
Skeletal malformation
Muscle degeneration
Cellulitis
0,2 %
Cyanosis
0,08 %
Cholangitis
0,086 %
0,11 %
DOA
0,90 %
0,09 %

17. Chose the right way not the easy way

18. Collect the evidence

20. The DNA sequences of polymerase chain reaction primers for the toxin genes of Clostridium perfringens.

21. Microscopic examination
Liver: in two samples from the liver there were acute multifocal necrosis and areas of degeneration of varied size. Around the blood vessels there were accumulations of heterophils granulocytes. In many blood vessels, and in one of the samples focally in parenchyma, was seen abundant short rod bacterium, including single cells contained the spores. In addition, there were moderate presences of eosinophil intranuclear inclusions bodies of the type seen in infection with FAdV.

22. Conclusions
Is it necessary that C. perfringens always cause necrotic enteritis?
Could a history of IBV (M41-like) and FAdV, D isolated from proventriculus and cecaltonsils from the pervious rearingperiod have played a negative (immunosuppressive) role despite cleaning and disinfection?
Stress due to catching (before, during and after) and transport to the slaughterhouse.
The impaction of the proventriculus and the gizzard and impairment of the intestinal motility may lead to increase the viscosity of the intestinal contents. Which could lead to reducing the oxygen level. The inflammation and the damage of the proventriculus could also lead to decreasing of the pepsinogen and gastric acid production resulting in high pH level in the intestinal tract.
In the event of damage in the proventriculus, this can be the result of extensive damage of the submucosal glands that produce hydrochloric acid, pepsinogen and thereby impair the ability to digest proteins.
Could early infection with FAdV from the previous rearingperiod be the reason that we could not isolate FAdV with PCR from samples at slaughtering despite the presence of eosinophil intranuclear inclusions bodies ?
Could the period between the last date for using Narasin and slaughtering day have played a negative role despite the normal level of Narasin in feedstuff?

23. Don’t Jump to Conclusions
It is important that the veterinary officer at the slaughterhouse to investigate, collect facts, do autopsy, and take samples to reveal the primary causative agents before taking further actions. Do not base your judgment on feelings nor on a gray zoned paragraph.

24. The “Farm to Fork” Approach
animals
husbandry
feed back
improvement
abattoir

25. Concerns regarding animal welfare
Birds that are considered dead on arrival(DOA) are those birds that have died between catching and the moment of slaughter.
The transportation of animals to processing facilities can be stressful, even under the best conditions. Death loss in that process can be expected.
Numerous factors can contribute to broiler processing plant DOA.
Factors, such as handling during catch, live-haul transport, yard time, and holding shed conditions historically have been shown to impact DOA at processing.
These unrecoverable birds present poultry companies with 3 challenges:
- Uncontrolled harm to birds.
- Understanding causes of DOA and corrective actions to reduce it.
- The economic impact of lost product.

26. Conclusions and Future Perspectives
It is believed that C. perfringens-associated necrotic enteritis and subclinical infection will emerge in broiler chickens after the ban of antimicrobial growth promoters in the EU.
Not only mortality due to necrotic enteritis, but also the sub-clinical form of the infection, leading to decreased weight gain and increased feed conversion, will have severe economic consequences for the poultry industry.
 Concerns arise on the high contamination rates of poultry by C. perfringens and the risk of transmission to the food chain which can cause public health problems.

27. Thank you