Most common bacterial UK gastrointestinal disease.
The two species Campylobacter jejuni and C. coli are most often associated with disease. Grows best in reduced oxygen atmospheres and only at temperatures exceeding room temperature.
Loves meat slicers. While the 2011 FSA Guidance focussed on E. coli, EHOs had identified howling Campy counts on complex equipment – one of the principal reasons you now need separate complex equipment for raw and cooked.
Growth and Control
Temperature: Optimum 42°C, range 30.5 to 45°C. Is comparatively slow growing (fastest generation time approximately 1 hour) even under optimum conditions.
pH: Optimum 6.5 to 7.5, range 4.9 to 9
Atmosphere: Normally requires reduced levels of oxygen – optimum growth at 3-5% oxygen and 2-10% carbon dioxide. Can be adapted to aerobic growth, although the significance of this in transmission of the disease is unclear.
Water Activity: Optimum growth is at aw = 0.997 (≡0.5% NaCl), minimum aw ≥0.987 (≡2.0% NaCl)
Temperature: Survival in food is better under refrigeration than at room temperature, up to 15 times as long at 2°C than at 20°C. Can survive up to an hour on hands and moist surfaces. Numbers decline slowly at normal freezing temperatures after an initial reduction. Freezing therefore does not instantly inactivate the organism in food.
Atmosphere: Survives well in modified atmosphere and vacuum packaging. Usually survives poorly at atmospheric oxygen concentrations.
Viable but Non-Culturable (VNC) Cells: Under adverse conditions Campylobacter can undergo a transition to a ‘VNC’ state. The ability for Campylobacter to produce VNC cells is becoming widely accepted.
Inactivation (CCPs and Hurdles):
Temperature: Rapidly inactivated by heating at 55°C and above.
D50C = 1-6.3 min. D55C = 0.6-2.3 min. D60C = 0.2-0.3 min.
pH: Growth inhibited in foods at less than pH 4.9 and above pH 9. Rapid death in foods at pH <4.0 especially at above refrigeration temperatures.
Water Activity: Thought to be sensitive to drying but under certain refrigeration conditions can remain viable for several weeks.
Preservatives: Sensitive to NaCl concentrations above 1%, and death occurs slowly at 2% (D time is 5-10 hours). Ascorbic acid and several spices inhibit growth.
Sanitisers/Disinfectants: Sensitive to most sanitisers, e.g. chlorine and QACs. See here for guidance.
Radiation: Sensitive to γ irradiation. An estimated 6 D reduction would result from exposure to 2 kGy, 10 D would result from 2.5 kGy. A 2-3 kGy dose is sufficient to decontaminate meat. D values reported are 0.18 kGy in refrigerated product, 0.24 kGy in frozen product. More sensitive to ultraviolet radiation than E. coli and commercial UV water treatment units producing 30 mWs/cm2 are considered adequate.
Incubation: 1 to 10 days (usually between 2 and 5 days) following ingestion of the bacteria.
Symptoms: Typically muscle pain, headache and fever (known as the “febrile prodrome”) followed by watery or bloody diarrhoea, abdominal pain and nausea. Symptoms may last 1 day to 1 week or longer (usually 5 days). Excretion of the organism in stools occurs on average for 2 to 3 weeks and is mostly self-limiting. Hospitalisation has been reported in 10% of cases. The attack rate is around 45%.
Condition: Campylobacteriosis. Campylobacter colonises the gut and damages the intestine. The exact mechanisms of this remain unclear.
Toxins: Toxins are not produced in foods.
At Risk Groups: Can affect any age group but most often isolated from infants (< 1 year) and young (twenties) adults. Incidence higher in males (up to 45 years of age).
Long Term Effects: Infection may occasionally be followed by arthritis (e.g. Reiter’s syndrome) or Guillain-Barré Syndrome (GBS). 1% of cases suffer reactive arthritis 7-10 days after onset. 0.1% of cases develop GBS 1-3 weeks after infection, and of these 15% recover completely, 3-8% die and the rest recover with varying degrees of impairment. A number of other less common non-enteric diseases can occur. Invasion of the bloodstream may occur in 1.5 per 100,000 cases, especially in the elderly. US data suggests a case-fatality rate of around 3 per 100,000 outbreak associated illnesses.
Dose: Consumption of 800 cells causes infection on approximately 50% of occasions, but many are subclinical (the proportion of people showing symptoms is not as high). Dose response information for numbers less than this is not available. Modelling has indicated an “optimum” dose for becoming ill is 1,000-10,000 cells.
Treatment: Supportive. Fluids may be given. Some cases warrant treatment with antibiotics. Erythromycin is the drug of choice, although resistant strains are emerging.
Reservoirs / Sources
Human: Campylobacter is not one of the organisms normally found in the human intestine. Faeco-oral person-to-person transmission (in some cases by asymptomatic carriers) has been reported.
Animal: Commonly found at high numbers in the guts of ruminant animals. Some non-ruminant animals (e.g. dogs and cats) are infected with the organism and may, or may not, show signs of disease. Flies have been implicated as vectors. Birds are considered to be a reservoir.
Food: Raw poultry is frequently contaminated, cooked chicken is rarely contaminated. Raw milk, offal, red meat, mushrooms, garlic butter, salads and shellfish have all yielded Campylobacter.
Environment: Excreta from infected animals may contaminate soil or water. Environmental survival is conventionally considered to be poor but newer information suggests it may be better than currently acknowledged. For example Campylobacter has been detected in dry beach sand. Survival in cold water is good, but reduced at temperatures above 10°C. Campylobacter is present in water and sediments more frequently and at higher numbers in the winter months. Environmental survival appears to be the opposite to human cases, i.e. survival is poorer in the warmer months.
Transmission Routes: The importance of undercooked chicken as a source of a proportion of cases of campylobacteriosis recognised, but the relative importance of other routes, e.g. other foods, recreational water, occupational exposure is unknown.
Plague and Pestilence
Outbreaks: Most cases of disease are sporadic and outbreaks relatively rare. Most outbreaks are caused by cross contamination – especially in retail butchery – or inadequate cooking. Correct refrigeration serves to aid the survival of the organism.
Associations include occupational exposure to raw meat, having a household pet with diarrhoea, ingesting untreated water from lakes, rivers and streams, travel abroad, consumption of poultry liver, consumption of poultry, consumption of sausages at a barbecue, and eating poultry that was brought into the house raw.