Campylobacter is a Gram-negative bacterium that is present in the gastrointestinal tract of birds and it is known to affect humans.
The importance of Campylobacter in the poultry industry is largely related to human campylobacteriosis and the role of poultry as a vector and reservoir for this zoonosis.
The annual cost of campylobacteriosis to public health systems, including the loss of individual health and productivity is estimated at:
- over €2.4 billion in the EU
- US$1.2 to $4 billion in the United States
The impact of campylobacteriosis in humans is well known. It usually results in severe abdominal pains and diarrhea, which can lead to hospitalization. But it is worth remembering that it can lead to death and, in some cases, lead to serious complications, such as Guillain-Barre syndrome, reactive arthritis, bacteremia, inflammatory bowel disease and irritable bowel syndrome.
There are an estimated 9 million cases of campylobacteriosis in the EU alone each year.
Campylobacter jejuni is often considered as one of the most important causes of human food borne disease in developed countries with an estimate of 2.5 million cases of human campylobacteriosis in the USA per year (1020 cases/100000 people/year).
Approximately, 100 people die due to Campylobacter infections in the USA every year being most cases reported in infants, elderly, or immunocompromised patients (Mead et al., 1999).
Consequently, it is important to control this pathogen in poultry production.
Campylobacterspp. are part of the microflora present in the digestive tracts of many wild and domestic animals including pigs, cattle and poultry, without inducing clinical signs. However, scientists around the world widely agree that poultry products, including meat, are the primary source of campylobacteriosis in humans.
Poultry species are considered to be an important vector for human campylobacteriosis. For example, 83 % of broiler chickens sampled in a live poultry market in New York City carried Campylobacter jejuni in their intestines (Grant et al., 1980). Using retrospective epidemiological studies, chicken meat manipulation and chicken meat consumption (especially raw or undercooked) were strongly related with increased risk of developing Campylobacter-associated diarrhea in humans (Harris et al., 1986).
According to the European Food Safety Authority (EFSA), in 2017, 37.4% of 13445 sampling units (single and batch samples) of fresh broiler meat were found to be positive for Campylobacter spp. This number for turkey birds were 31.5% (in 1028 sampling units tested for campylobacter). The proportion of positive units in poultry birds, other than broilers and turkeys were 27.7% (in 1425 sample units).
In light of the economic and health problems associated with campylobacteriosis, serious discussions between government officials in different countries about the possibility of imposing obligatory controls for reducing Campylobacter spp. in poultry operations have been started.
It is important to remember that Campylobacter spp are not necessarily commensal bacteria but have been shown to have the potential to cause disease in poultry: diarrhea and reductions in feed efficiency.In the UK, for example, estimates suggest that the costs to the industry are up to US$29.16 per thousand broilers. Controlling the situation on farm is of benefit to poultry producers, and not just meeting contamination levels for poultry leaving the processing plant.
Why Campylobacter spp. is hard to control
Campylobacter bacteria do not proliferate outside the alimentary tract of warm-blooded animals. They can survive up to several weeks in food products, particularly those stored at low temperatures. Campylobacter spp. colonize the mucosa of the cecum and cloaca crypts of infected chickens. They may also infect the spleen and liver, and circulate in the blood.
A single gram of infected chicken feces can contain up to one hundred billion Campylobacter. Even this level of infection may not cause changes in cecal mucosa. In commercial production, birds carry high levels of Campylobacterspp. in the intestine as part of their normal microflora without showing any signs of clinical disease. In addition, there is no change in mortality or feed conversion rates in infected flocks.
When and how Campylobacter infect poultry
The prevalence of Campylobacter-positive poultry flocks is generally high, though this varies by region, season and production type (intensive, free range, organic, etc.). In some cases, the contamination is as little as 2% of the flock, and in other cases, contamination can reach 100%.
It is rare to find Campylobacter in birds younger than three weeks old. Scientists believe that this may relate to the presence of maternal antibodies and the rapid development of a chick’s gastrointestinal tract and microbiota. However, after three weeks, even if one bird in the flock becomes infected, the whole flock can be infected in less than four days.
Vectors of Campylobacter transmission include:
Isolates of Campylobacter jejuni obtained from human patients have been used to produce experimental diarrhea in young chickens. Oral gavage with C jejuni (9 x 107) induced diarrhea in 88 % of 3-day old chickens. The authors determined that diarrhea could be consistently induced in young chicks using as little as 90 CFU (Ruiz-Palacios et al., 1981).
2- to 3-day old chickens challenged with human derived strains of C jejuni consistently developed diarrhea and the inoculated number of Campylobacter was amplified by 3 to 4 logs throughout the intestine. In addition, systemic infection was suggested after isolation of Campylobacter from spleen, liver, and blood withdrawn from the heart (Sanyal et al., 1984).
Effective vaccine lacking
Work to develop vaccines against campylobacteriosis both in animal and human health sectors is already well established. Within the human sector, no vaccine to prevent Campylobacter-associated illness has been approved by a regulatory authority anywhere in the world. The main problem likely stems from an incomplete understanding of Campylobacter jejuni pathogenesis and antigenic diversity, as well as its association with some post-infectious syndromes.
Within the poultry industry, numerous strategies have been developed and experimentally checked in attempts to create an effective vaccine. However, no efficient vaccine against Campylobacter is currently available.
Why antibiotics are not effective against campylobacter infection in poultry
Campylobacterspp. is not recognized as a specific pathogen under commercial conditions. Therefore, treatment of the flock is not a consideration. One must be cautious of the zoonotic risk associated with C. jejuni and its ability to rapidly develop antibiotic resistance. In reality, an antibiotic control strategy would not be a practical choice for management of Campylobacter on commercial poultry farms.
Scandinavian experiences point to a preventive approach
Scandinavian countries have historically had a much lower prevalence of campylobacteriosis compared to elsewhere. The approach to Campylobacter control in Scandinavia is based on prevention. A preventative approach spans the entire broiler meat production chain from farm to fork.
A preventative approach to Campylobacter focuses on three main risk factors:
- Poultry flock prevalence
- Carcass contamination
- Kitchen hygiene
Among these three, flock prevalence is likely the most important one. Poultry flock prevalence can be addressed in two ways, namely by 1) preventing birds from being infected by Campylobacter and 2) reducing the concentration of Campylobacter within birds’ gastrointestinal tracts. Biosecurity plays a role in both types of prevention.
There is still no definitive solution to control Campylobacter in poultry flocks. Yet, there are several strategies that can reduce its incidence, so improving food safety and enhancing farm profits.
Broiler producers need to apply a series of measures to reduce Campylobacter contamination levels. A mixed approach starts with improved biosecurity, changes to management practices, proven feed or water intervention with additives and, finally, intervention measures during slaughter.
Table 1 provides an overview of management strategies to counter Campylobacter. These management methods, however, are not all applicable universally, for example within the EU there are restrictions due either to availability legislation or consumer demand for carcass size. In addition to management strategies, there is also the option to use feed additives or water treatments, which can further reduce the level of Campylobacter contamination, as shown in Table 2. Of these, probiotics may be the most promising approach for controlling Campylobacter through nutritional interventions.
Table 1. Management strategies to counteract Campylobacter contamination in broilers. Source: BIOMIN
|Measure||Success and implementation status|
|Vaccine||Does not exist|
|Extreme temperature intervention||Claims to reduces rate of carcass contamination by up to 90%.|
Does not eliminate risk to humans.
|Chlorine wash||Not permitted in the EU due to concerns over carcinogenic residues|
|Stringent biosecurity||May reduce rate of carcass contamination by 50% to 70%,|
though difficult to attain under commercial conditions.
|Stop thinning||Single out-loading of flocks can reduce contamination by 80%.|
Puts pressure on production and introduces short-term challenges.
|Slaughter at 28 days||Dramatic reduction in contamination levels.|
Impractical due to market requirements.
Table 2. Nutritional strategies to counteract Campylobacter contamination in broilers. Source: BIOMIN
|Measure||Success and implementation status|
|Bacteriocins||Some effect in scientific trials showing reductions of contamination in the caeca. More investigative work required.|
|Bacteriophages||In vivo us tends to be therapeutic. Considered for in slaughterhouse treatment of carcasses but problems may occur in registration.|
|Organic acids||Mixture of acids needed. The pH of drinking water has to be lowered to between 4.0 and 4.5 for optimum resulsts. Varied results obtained.|
|Phytogenic feed additives||In vitro trials not replicated in vivo to date. More work required.|
|Probiotics||Several trials show significant reduction of Campylobacter colonization.|
Perhaps the most promising for commercial purposes.
10 tips for maintaining high levels of biosecurity and keeping Campylobacter at bay
It is important to highlight prevention and good gut performance management to control Campylobacter. These 10 tips are meant to help you maintain high levels of biosecurity in your poultry houses in order to ensure food safety and profitability.
Tip 1: Segregate the clean and dirty areas of the poultry house entrance with a physical barrier (dwarf wall)
A dwarf wall represents a small investment, though they are widely appreciated on farms that have them because they help stop the cross contamination of Campylobacter and other pathogens.
- Use dedicated footwear and overalls in the clean area for the entire growing cycle.
- Have one disinfectant bath inside the clean area and one disinfectant bath outside the clean area directly in front of the actual chicken house door.
- Better to permanently keep clean footwear in the disinfectant bath when not in use. Change the content of the disinfectant baths every three days.
- Clean the area within the wall boundary regularly with a dedicated dustpan and broom that stay within the clean area and is not used anywhere else.
Tip 2: Keep equipment in the poultry house for the whole cycle
Things such as stepladders, buckets, catching bird fences, brooms, etc. should stay in the poultry house for an entire cycle. Avoid transporting these items from one house to another to reduce the risk of contamination.
Tip 3: Practice regular hand hygiene
Equip the entrance of each poultry house with a sink or wash basin with warm water, soap, paper towels, and hand sanitizer. If the full list is cost prohibitive, be sure to stock up on hand sanitizer, which can still be a big help.
Tip 4: Wear disposable overalls
Disposable overalls are a cheap and practical way to greatly reduce cross contamination. Be sure to dispose of them after each house visit.
Tip 5: Apply rodent control
Most farmers are familiar with the process of rodent control. It is important to follow through with the opening, cleaning, and placing of new bait in rat bait stations at the beginning of each crop. Remember to record rodent observations and dates. Rodent bait suppliers are able to provide more education and training as required.
Tip 6: Ensure good water quality
Regardless of the quality of water coming to your farm, the drinking water system should be properly cleaned and maintained to prevent it becoming a vector for pathogens. It is common to wash and clean lines at the beginning and end of each crop, but this overlooks hygiene measures that can be taken during the growing period. Chlorine, hydrogen peroxide and acidifiers are commonly used to ensure proper water sanitation, control water hardness and acid levels, and prevent biofilm.
Tip 7: Withdraw feed between 8 and 12 hours prior to slaughter
Broilers’ gastrointestinal tract is emptied and flattened with relatively mild sloughing after 8 to 12 hours of fasting. The extent of cross-contamination will be considerably decreased if birds experience a correct feed withdrawal period before their transport to the slaughterhouse. Birds that have had a proper feed withdrawal period prior to their entry to the slaughterhouse may carry less contamination on their feathers and feet, etc., because they excrete much less fecal material during transport.
Also, cleaner birds going into scalding tanks may cause less contamination to the water which is largely recycled during the operation. Do not withdraw feed too early. As withdrawal time increases over 14 hours, intestinal integrity will decrease and the probability of intestinal breakage and subsequent contamination will increase.
Tip 8: Educate catching and transport teams
Catching teams are one of the main sources of Campylobacter cross-contamination between farms. Stress makes birds more susceptible to pathogens as well. Ensure that all visitors and staff adhere to your biosecurity protocols, and follow proper catch and transport procedures in order to keep stress and disease to a minimum.
Tip 9: Discuss lairage and slaughterhouse practices
Cross-contamination between slaughterhouse and farms is another major cause of Campylobacter occurrence in farms. Catching vehicles contaminated during transport may travel to three or four farms every day. Catching crates should be properly cleaned and disinfected after each delivery. Birds may be kept in lairage (I.e the factory yard) or even in the transport vehicle for up to six hours.
In such conditions, birds shed a considerable number of microorganisms present in their gut, including Campylobacter. Speak to your slaughterhouse manager regularly to see that the necessary steps are followed and that everyone involved understands their roles and responsibilities.
Tip 10: Control contamination within the birds’ gut
Certain feed additives that support gut health and integrity can play a role in limiting Campylobacter growth and colonization. Look for poultry probiotics that support beneficial bacteria: these competitively exclude harmful or unwanted bacteria in the birds’ gastrointestinal tracts by colonizing the gut and using up nutrients before problems arise; a microbial solution to a microbial problem.