ENTERIC COLIBACILLOSIS
Enteric colibacillosis is a gastrointestinal illness resulting in significant financial losses. The main clinical manifestation is episodes of acute diarrhea.
Depending on when it happens, there are two main classifications:
- Neonatal diarrhea: Before weaning.
- Post-weaning diarrhea: After weaning, often in the first two weeks.
Risk factors of neonatal diarrhea and post-weaning diarrhea
There are many factors that cause enteric colibacillosis and its exact origin is hard to pin down precisely. However, there are a series of factors that make animals more susceptible to this disease:
Facility hygiene
Causative pathogens in the pigs’ environment put the animals at risk of developing diarrhea because some bacteria can survive in the environment for up to six months.
Temperature
Cold weather can slow down intestinal motility, making it easier for pathogens to adhere to the intestinal surfaces.
Stress
Things like parturition, weaning, new eating habits and overcrowding can put stress on piglets, compromising their intestinal health.
Animal density
With more animals in the same space, their immune systems have to work harder to fight new pathogens and generate herd immunity
Viral infections
Viral infections can lead to enteric colibacillosis, mainly due to decreased immune function.
Post-weaning diet
The abrupt change in diet can cause fasting in the beginning, which can decrease the length of the intestinal villi, making it difficult to absorb nutrients. Ingredients like soy or overeating can also contribute to post-weaning diarrhea.
Genetics
Some pigs have genetic immunity to the pathogens involved in this disease.
Passive immunity
Maternal antibodies passed on to piglets can help them fight the disease.
Weaning age
The earlier pigs are weaned, the greater the risk of infection.
Main causes
Although there can be several causes, the main pathogenic agent involved in colibacillosis diarrhea is Escherichia coli. Most E. coli strains are commensal, meaning they can inhabit the gut without harming the host. Only a minority are pathogenic, of which the ones responsible for enteric colibacillosis are generally classified as enterotoxigenic E. coli (ETEC) or enteropathogenic E. coli (EPEC).
These bacteria adhere to the intestinal lining and produce toxins, called enterotoxins, that affect the permeability of intestinal cells, increasing secretion into the lumen and the resulting loss of electrolytes. This leaves a lot of food undigested in the large intestine, increasing fermentation and leading to metabolic acidosis, which causes diarrhea that can quickly result in dehydration and malnutrition.
These bacteria are often found in sows’ feces in the farrowing room and, although they don’t affect healthy adult pigs, the piglets still have immature immune systems and are more susceptible to infection, both before and after weaning.
Incorrect transition from easily digested liquid food to dry solid food without the right adaptation period can leave the intestine vulnerable to ETEC, triggering post-weaning diarrhea.
Enteric colibacillosis is often caused by multiple factors, meaning that they interact with other agents that can trigger the disease or make it worse. These agents include viruses like rotavirus or coronavirus and parasites like coccidia.
After ingestion from the pig’s environment (1), ETEC attaches to and colonizes the mucosa of the small intestine with fimbrial adhesins (2) and produces enterotoxins that trigger secretion of water and electrolytes into the intestinal lumen (3), causing diarrhea and possibly death (4).
Signs and symptoms
- Moderate to severe diarrhea
- Dehydration
- Weight loss
- Higher respiratory rate
- Death (sudden in some cases before other symptoms appear)
Financial losses
How to fight enteric colibacillosis
Prevention
Prevention is key to stopping enteric colibacillosis, reducing financial losses and mitigating the consequences for animals. So, it is important to do several things on the farm to help keep E. coli levels low and ensure the pigs’ wellbeing:
- Control dampness and temperature: Keep weaning area between 28°C and 32°C initially, without abrupt temperature changes or drafts.
- Hygiene: Clean and disinfect the spaces meticulously between batches and clean out feces daily.
- Vaccinate pregnant sows and/or piglets.
- Increase weaning age or weight.
- Genetic selection: Raising resistant swine can be an effective, affordable strategy in the long term.
- Food: Make sure the sucklings get enough high-quality colostrum from their mothers to be protected against post-natal infections. Weaning diets should be easily digestible, without much soy flour and preferably based on dairy proteins. Other effective measures include keeping an eye on how much the animals eat to make sure it isn’t too little or too much, promoting feed consumption early in maternity and using fiber rich diets. Other options include adding organic acids to drinking water or weaning diets to decrease stomach acid and make it harder for E. coli ingested to survive, and using prebiotics and probiotics to promote balanced gut microbiota, making it harder for pathogenic bacteria to proliferate.
Diagnosis
Enteric colibacillosis is diagnosed using a combined analysis of clinical symptoms, macroscopic lesions and microbiological analyses. This comprehensive assessment allows you to distinguish this disease from others and establish a suitable treatment plan.
Multiple PCR can be useful for detecting the genes of the pathogens associated with the enteric colibacillosis diarrhea. If the test is positive, we recommend doing a histological test of the small intestine to confirm the diagnosis.
While waiting for the lab results, given that these outbreaks are highly contagious, a therapeutic plan should be implemented after consulting with the veterinarian. The plan should treat sick animals and contain the illness on the farm, as well as monitoring the situation over time.
Treatment
Effective treatment for enteric colibacillosis requires a combination of measures, including a rigorous cleaning and hygiene program, complementary feed to reduce loose stool and a course of the right antibiotics.
For years, zinc oxide (ZnO) has been a widely used feed additive for piglets because it helps prevent diarrhea. However, the European Union banned this additive in 2017 given the risk of it contaminating the environment and granted farmers a 5 year grace period to find appropriate alternatives.
It is essential to apply treatments properly. Right now, the most complete, effective therapeutic approach is to:
- Begin treatment with electrolytes, which can be administered orally or parenterally. We recommend using oral rehydration solutions as the cells remain intact and retain their absorption capacity.
- Then, antimicrobials can be added to feed or water. It is essential to choose antibiotics that reach the intestinal lumen, like apramycin or neomycin, among others.
- For post-weaning diarrhea, we recommend adding complementary feed to reinforce the immune system.
BIBLIOGRAPHY
- Fairbrother, J.M., Nadeau, E., Gyles, C.L. (2005) Escherichia coli in postweaning diarrhea in pigs: an update on bacterial types, pathogenesis, and prevention strategies. Anim Health Res Rev. 6(1):17-39. doi: 10.1079/ahr2005105. PMID: 16164007.
- Fairbrother J.M., Nadeau E. (2006) Escherichia coli: on-farm contamination of animals. Rev Sci Tech. 25(2):555-69. PMID: 17094697.
- Luppi, A. (2017) Swine enteric colibacillosis: diagnosis, therapy and antimicrobial resistance. Porcine Health Management. 8;3:16. doi: 10.1186/s40813-017-0063-4.
- Moennighoff C., Thomas N., Nienhaus F., Hartmann M., Menrath A., Merkel J., Detlefsen H., Kreienbrock L., Hennig-Pauka I. (2020) Phenotypic antimicrobial resistance in Escherichia coli strains isolated from swine husbandries in North Western Germany – temporal patterns in samples from laboratory practice from 2006 to 2017. BMC Vet Res. 16(1):37. doi: 10.1186/s12917-020-2268-z.
- Sjölund, Marie & Zoric, Mate & Wallgren, Per. (2014). Financial impact on pig production: III. Gastrointestinal disorders.
