E. COLI OR COLIBACILLOSIS INFECTIONS IN POULTRY
By Dr MN Bharati,Technical manager, Srinivasa group.ex Tech. manager Venkys
Colibacillosis is caused by bacterial infection with avian pathogenic Escherichia coli (APEC) and is found in poultry flocks worldwide. E.coli is a gram-negative, rod-shaped bacterium which is normally found in the intestine of poultry and most other animals. Although most serotypes are non-pathogenic, a limited number produce extra intestinal infections. These can be primary or secondary (in response to an earlier infection such as Mycoplasma infections, ND, IBD, wounds, parasites etc.).
Although a high number of E.coli is maintained in the poultry house environment through faecal contamination, the initial exposure to APEC may occur in the hatchery from infected or contaminated eggs.
• Colibacillosis is a localized or systemic infection caused by avian pathogenic Escherichia coli bacteria characterized by septicemia, drop in production and mortality.
• Colisepticaemia, egg peritonitis, yolk sac infection(“mushy chick disease” and “omphalitis’), and coligranuloma (Hjarre’s disease) are the well recognized results of E.coli infection. These conditions are collectively grouped under the heading “Colibacillosis”.
Causes:
• Escherichia coli is a normal inhabitant of the digestive tract and wild birds, which are source of infection for poultry flocks and spread is by direct or indirect contacts.
• Organisms are susceptible to common physical and chemical disinfectants. They can survive in freezing and can remain viable for long period at low temperatures.
• In litter, high ammonia concentration can inactivate rapidly and survive at 370C for 1-2 days.
• Trachea, caeca and oviduct of recovered birds can harbor E.coli for several weeks.
• Organisms are not transmitted through eggs.
• Beetles can transmit the bacteria and birds consuming these beetles get the infection.
• Large numbers of E. coli are maintained in the poultry house environment through fecal contamination.
• Initial exposure to pathogenic E. coli may occur in the hatchery from infected or contaminated eggs, but systemic infection usually requires predisposing environmental factors or infectious causes.
• Mycoplasmosis, infectious bronchitis, Newcastle disease, hemorrhagic enteritis, and turkey bordetellosis precede colibacillosis.
• Poor air quality and other environmental stresses may also predispose to E coli infections.
• A hatching environment that is not sufficiently humid is often associated with a high incidence of yolk sac infection. E.coli multiplies rapidly in the intestines of newly hatched chicks and infection spreads rapidly from chick to chick in the hatchery and brooders.
Predisposing factors —
During peaking period:-
• Multi-age complexes • Exposure to endemic mycoplasmas (M. gallisepticum or M. synoviae) and/or infectious bronchitis virus (IBV) • Poor ventilation with high levels of dust and/or ammonia • Stress of production in a young developing bird • High levels of circulating endogenous hormones (especially estrogen)
Predisposing factors during late lay period:–
• Vent trauma, non-lethal vent cannibalism, and/or partial prolapse • Too much light intensity • Small-framed birds • Excessively large egg size • Excessive fat pad
Cause E. coli with poultry?
The source of infection of E. coli is in the parent stock. They transfer E. coli through the eggs to the hatcheries and from hatcheries it is possibly transferred to the broilers and layers.
In case of other problems, a massive growth of the E. coli bacteria occurs, such as:
• in the case of secondary infections
• a weakened immune system
• a weakened intestinal wall
• weakened air pockets
• skin lesions
Characteristics with dams
• Peritonitis is the most common symptom, this is caused by intestinal penetration and airway penetration
• Fallopian tube inflammation
• Airway inflammation
Infestation route E. coli parent stock / laying hens:
• 1. Cloaca: the orbicular muscle between the vagina and cloaca can relax too much, so that fertilizer particles with E. coli can reach the vagina and fallopian tube
• 2. Intestinal wall: E. coli can get into the abdominal cavity via the intestinal tract and the intestinal wall
• 3. Airways: E. coli bacteria can get in the fallopian tubes and abdominal cavity via the air bags
Characteristics with broilers
• Yolk rest inflammation in the first week of life. The mortality can get as high as 15%
• Intestinal problems cause reduced digestion and provide poorer technical results
• Blood infection leads to an increased mortality
Infestation route E. coli broilers:
• 1. Airways: E. coli bacteria can get in the fallopian tubes and abdominal cavity via the air bags
• 2. Intestinal wall: E. coli can get into the abdominal cavity via the intestinal tract and the intestinal wall
• 3. Via the parent stock: in the egg through contaminated fallopian tubes or contaminated shell (cloaca, contaminated manure)
Consequences E. coli with poultry
• Reduced lay
• Increased mortality
INCUBATION PERIOD—
The time between infection and onset of clinical signs (the incubation period) usually varies between 1 to 3 days depending on the specific type of disease produced by the E. coli bacteria
Clinical symptoms
• Affected birds will have respiratory symptoms, depression, loss of appetite and disinclination to move.
• Soiling of vent with pasty diarrhoeic faeces will be seen.
• In Coliform omphalitis/yolk sac infection causes mortality in a batch of chicks in the first week of life after hatching. Affected chicks exhibit depression, sleepiness with tendency to huddle together around heat sources with distended abdomen and swelling of naval.
• Swollen Head Syndrome (SHS) causes swelling of head.
Gross lesions
• Birds with Colisepticaemia develop airsacculitis, perihepatitis and pericarditis with cloudiness of pericardial sac and light coloured fibrinous exudates.
• In Coliform omphalitis/yolk sac infection, unabsorbed yolk will have abnormal volume, colour, consistency and smell.
• Salphingitis (inflammation of oviduct) causes peritonitis, abdominal cavity containing abnormal egg or yolk mass, impaction of oviduct, distortion of ovaries and produce foul smelling pus like material.
• Coligranuloma (Hjarre’s disease) causes millet sized multiple projected granulomas are found on the surface of liver, caeca and mesentery.
• Air sac disease (Chronic Respiratory Disease) causes thickened air sac and will have caseous exudates.
A whole or partly formed egg may be seen in the abdominal cavity known as impaction of oviduct which was firm and adhered to peritoneum and visceral organs.
Prevention of E. coli with poultry
It is of great importance to minimalize the risk factors of E. coli. The hygiene and drinking water quality should be in great condition. There should be an optimal digestion and intestinal health. The stress level must be minimized.
Treatment—–
Historically, antimicrobial drugs have been used to treat and control colibacillosis; however, the availability of effective antimicrobials has decreased due to threat of antimicrobial resistance and lack of new drug development in the poultry sector. It is important to determine susceptibility of the bacterial isolate involved when selecting an antimicrobial therapy in order to avoid ineffective treatment and propagation of resistance profiles. The following is a list of currently approved feed additive antimicrobial drugs available for treatment of colibacillosis in both pullets and layers. If there is high mortality due to E. coli infection, the live E. coli vaccine can be used as a treatment and is efficacious in 50% of cases. Consult a poultry veterinarian before commencing any treatment plan. Availability of drugs and local regulations may vary
Treatment now involves supportive measures to aid in reducing the level of infection for the remaining flock members as follows:—–
• Vaccination with the live E. coli vaccine;(Till now not available in India)
• Fogging (nebulizing) disinfectants such as VirkonS or chlorine dioxide;
• Sanitizing water with five to 10 ppm chlorine or six to 12 ounces of iodine disinfectant per a gallon of stock solution metered at one ounce per gallon drinking water;
• Collecting dead birds more frequently to remove them as a source of infection in an the attempt to decrease the disease cycle;
• Replacing wet litter with dry in floor houses;
• Adding an intestinal health aid such as Diamond V Original XPC will give some immediate boost of the immune system while prolonged use will aid in improving the microflora makeup.
Prevention of E. coli infections is, therefore, the main control measure used. Several preventative practices are available as follows:—
• Treatment strategies include attempts to control predisposing infections or environmental factors and early use of antibacterials indicated by susceptibility tests.
• Maintain adequate hygiene and bio security to minimize transmission through faecal contamination of eggs.
• Infected excreta and litter should be disposed properly to avoid contamination of natural water sources and spread in the farm.
• Avoid stress and overcrowding in the flocks which favors outbreaks.
• Birds should be procured from sources tested free of ND, IB, and Mycoplasma.
• Diet with protein, selenium, and vitamin E may be favorable in control of colibacillosis.
• Chlorination of drinking water inactivates the bacteria.
• Intestinal health aids. Several research-backed products are on the market. Diamond V Original XPC has been shown to reduce E. coli levels in the cecum when fed at recommended levels and would aid in reducing contamination levels in the birds’ environment and improve their response to invading bacteria.
• Water sanitation. Routine sanitation of water with either chlorine or iodine can be very effective in reducing bacterial infections.
• Vaccination. The live E. coli vaccine has been a very useful tool in egg layers and is being evaluated in broiler and turkey flocks. In egg layers, two to three doses are applied by spray during the growing period prior to housing. Booster applications are given to some flocks prior to molting.
• Ventilation practices. Reducing ammonia levels by providing the proper ventilation rates and temperatures throughout grow for broilers will keep litter dry and reduce the release of ammonia from the litter. Keeping the stored manure dry in high-rise layer houses is also important in reducing ammonia. The use of manure drying fans in the pits of highrise houses has been a great aid in reducing the moisture of the manure piles.
• Moving age of egg layers. Moving egg layer pullets at least one to two weeks prior to the onset of production will aid in getting the birds’ microflora stabilized and the birds exposed to pathogens in the new layer house environment prior to the stress of egg production. Spreading out these stressors appears to reduce the problems with early lay E. coli problems in egg layers.
Vaccination ——
There are two main types of vaccines used in pullets and layers – inactivated and modified-live vaccines. Regardless of type of vaccine used, clinical disease attributable to E. coli infection tends to less severe in vaccinated compared to unvaccinated birds. Type of Vaccine Description Results Autogenous inactivated (killed) • Provides protection against homologous E. coli strains • No cross protection • Breast injection • Reduced morbidity and mortality due to E. coli infection Commercial modified-live • Poulvac E. coli 078 (by Zoetis) • Cross protection against serotypes O1, O2 and O18 • Spray • Reduced morbidity and mortality due to E. coli infection • Enhanced bird productivity
INTERVENTION STRATEGIES –
Management Procedures
Effective control and prevention of colibacillosis depends on identifying and eliminating predisposing causes of the disease. Maintaining flock biosecurity is critical in the control and prevention. The goal is to reduce the level of E. coli exposure by improving biosecurity, sanitation, ventilation, nutrition, and flock immunity.
Biosecurity—-
• Reduce exposure to E. coli and prevent introduction of other infectious agents • Improve sanitation of environment (e.g. hatchery, house) • Clean chick source • Reduce fecal contamination of eggs, clean nest boxes and reduce number of floor eggs • Treatment of feed with products to lower bacterial levels (e.g. pelleting, formaldehyde, organic acids) • Collect dead birds more frequently
Nutrition —
• Feed additives that support healthy immune systems and improve survivability • Proper protein ratios • Increase selenium • Increase vitamins A and E • Probiotics to promote competitive exclusion
Ventilation —-
• Improve air quality and ventilation to reduce dust and ammonia levels • Minimize use of leaf blowers and mowers to reduce environmental spread
Immune System —-
• Protect immune systems by preventing introduction of immunosuppressive diseases (e.g. IBD/ Gumboro) and other bacterial and viral infections (e.g. IB, M. gallisepticum, etc.) • Effective vaccination program matching vaccines to field strains • Manage any respiratory vaccine reactions • Maintain healthy gut flora (e.g. coccidiosis control) • Routine serological surveillance • Reduce stress (e.g. proper stocking density, no temperature extremes, etc.)
Surveillance —–
• Monitor prevalence by routine posting of birds every few months • Early diagnosis and treatment
References:On request.
COLIBACILLOSIS IN LAYERS: A DISEASE OF ECONOMIC IMPORTANCE IN POULTRY FARMING
