Avian colibacillosis is an infectious disease caused by the bacteria Escherichia coli, which can affect any avian species. Although it can be considered a primary disease, in most cases it is a secondary disease caused by a state of immunosuppression due to other viral or bacterial diseases. The most important clinical characteristic of avian colibacillosis is the development of septicemia or colisepticemia characterized by the appearance of clinical signs and variable lesions depending on the affected organs.
What is avian colibacillosis?
Avian colibacillosis is an infection caused by the bacterium Escherichia coli, which can affect any species of bird, so colibacillosis is common in canaries, pigeons, parrots… Although it can be a primary infection (initially caused by this bacterium), it is usually a secondary infection that occurs as a complication of other respiratory processes in birds.
Colibacillosis in birds can occur in an acute form, with a septicemic picture of high morbidity and mortality, or in a chronic form, with less severity and mortality.
Etiology of avian colibacillosis
As we have already mentioned, the etiological agent of avian colibacillosis is E. coli. This bacterium can be found:
- In the digestive tract: it is a common inhabitant of the intestinal tract of birds, although many strains are not pathogenic and therefore Therefore, they do not cause disease. As it is usually found in the intestine, it is also often present in bird droppings.
- On skin and feathers: as a result of contamination by contact with faeces.
- In the upper respiratory tract: not usually as in the intestine, but in cases of infection.
Colibacillosis can be a primary disease, although in most cases it is considered a secondary disease caused by a state of immunosuppression due to other viral or bacterial diseases. The lesions caused by these primary pathogens facilitate the entry, colonization, and secondary spread of E.coli. In this other article we talk about the most common diseases in birds.
Transmission of avian colibacillosis
Transmission of colibacillosis in birds can be:
- Vertical: is the transmission that occurs from the parents to their offspring. Infected mothers can contaminate the eggshell, which, being semi-permeable, allows E. coli to enter the interior. The infection can also occur at the time of hatching the egg or through the parents during the stuffing.
- Horizontal: is the transmission that occurs between individuals who are not mother-child. Generally, it is transmitted directly by the respiratory route (aerosols that are formed from contaminated feces), although in some cases it can be transmitted by the digestive route.
Avian colibacillosis symptoms
Clinical signs of colibacillosis in birds may vary depending on:
- The specific strain of E. coli and its pathogenicity.
- The location of the infection.
- The immune status of infected birds.
The most important clinical characteristic of avian colibacillosis is the development of septicemia or colisepticemia (serious systemic response of the organism to a generalized infection), in which lesions such as perihepatitis, peritonitis, pericarditis, airsacculitis, salpingitis and omphalitis. In very acute cases, the main sign observed in birds is an increased mortality In less acute cases, the following are observed:
- Typical clinical signs of septicemia: fever, ruffling of feathers, poor appearance, apathy, anorexia.
- Respiratory signs: airsacculitis (inflammation of the air sacs) usually develops accompanied by clinical signs such as dyspnea or respiratory distress and rales.
- Digestive signs: enteritis that can become hemorrhagic.
- Reproductive disorders: infection of the oviduct leads to a slight drop in laying in poultry.
- In colibacillosis in canaries, song cessation is characteristic.
Diagnosis of avian colibacillosis
The clinical diagnosis of colibacillosis in birds is complicated because the picture it produces is common to many other pathologies. For this reason, laboratory diagnosis is usually resorted to by isolation and identification of the causal agent to confirm the infection.
However, we must remember that the isolation of E.coli does not necessarily imply that it is responsible for the condition, since it is a common inhabitant of the digestive tract of birds. Therefore, in addition to identifying the bacteria, it is necessary to analyze the virulence of the strain by detecting somatic (O) and capsular (K) antigens to check whether or not it is responsible for the clinical picture. Strains with somatic antigen 1, 2, 35 and 78 are the most associated with avian colibacillosis.
Prevention of avian colibacillosis
Avian colibacillosis prevention measures include:
- Hygiene of pens or aviaries: Adequate cleaning and disinfection programs must be maintained to maintain a good degree of hygiene in the installations. E. coli is a desiccation-sensitive organism, so drying surfaces after washing is a good way to reduce bacterial load. In addition to the facilities, the litter, drinkers and feeders must also be kept clean of feces and organic matter. Facilities should be kept well ventilated and protected from pests and wild birds.
- Reduce stress levels: especially maintaining a level of animal density appropriate to the space and the behavioral needs of each species. Stressful situations will trigger immunosuppression and, therefore, greater susceptibility to infections.
- Water and feed control: It must be ensured that both the water supply and the food are free of pathogens. Chlorine is very efficient for treating and disinfecting water.
- Vaccination: Although there are vaccines against colibacillosis, they are not highly effective. In fact, it is a vaccine that does not fall within the usual vaccination programs for birds.
It is important to remember that birds should not live in small spaces that deprive them of their freedom. Like all animals, they deserve to have a good quality of life, so if you live with one or more birds, it is essential that they can move freely and not remain confined to a cage 24 hours a day. Similarly, adequate environmental enrichment for birds is essential.
Treatment of avian colibacillosis
The first thing to consider when treating colibacillosis in birds is whether E. coli is acting as a primary or secondary agent. If it is causing a secondary infection, it will be necessary to also treat the primary agent, since only in this way will we be able to resolve the disease.
The aetiological treatment of colibacillosis in birds requires an antibiogram to select an antibiotic that is effective against the strain causing the infection infection. In this way, we will ensure that the causal agent is sensitive to the prescribed antibiotic and we will avoid the development of antimicrobial resistance. The most commonly used antibiotics are: enrofloxacin, doxycycline and ampicillin.
In addition, it is advisable to support the antibiotic treatment with vitamin complexes, amino acids and probiotics, in order to restore the intestinal flora and favor the recovery of the birds.
