Escherichia Coli (Colibacillosis )


Various serotypes of enterotoxigenic Escherichia coli can cause either diarrhoea or septicaemia in very young calves first 4 days of life.

The main risk factors for ETEC infection in young calves are:

• Inadequate or unsuccessful passive immune transfer of antibodies from the dam to calf

• Exposure to the pathogen before colostrum was ingested, immediately after birth

• Inclement weather

• Use of milk replacers as opposed to whole milk

• Poor hygiene, especially in calving pens ETEC cause diarrhoea in very young calves, less than 3-4 days of age (typically less than 48 hours of age).

Calves are depressed, do not drink or suckle, become dehydrated, and die rapidly. Very profuse and watery diarrhoea is typical of ETEC scours. ETEC diarrhoea in calves has also been associated with the presence of viral scour pathogens, rotavirus and coronavirus Septicaemic colibacillosis, caused by another serotype of ETEC, is an acute disease with very few diagnostic signs and is the most common cause of acute, fatal illness in neo-natal calves.

Depressed, weak animals initially have a fever but become hypothermic rapidly. Mortality rates are high and survivors are often affected by post-septicaemic localisation of infection in the form of arthritis, meningitis or pneumonia. Inadequate transfer of passive immunity from the dam is considered the main risk factor for colibacillosis.

ESCHERICHIA COLI TREATMENT:  


This disease requires an immediate response, centred on isolation and rehydration therapy. Parental antibiotics can be useful if given early, but not without rehydration therapy. In calves with diarrhoea and no systemic illness (normal appetite and no fever) antimicrobials are not recommended. Multi-resistant (to antibiotics) strains of E. colihave been identified, and antibiotics should not be the main approach to treatment.

One study has suggested that use of dried oregano leaves, which provides essential oils, may be effective as an oral treatment against colibacillosis. However, this is only experimental work and is, as yet not a commercial option. The isolation of affected calves, effective treatment with rehydration solutions and the provision of dry and warm conditions are vital in the treatment of calf scours, in order to avoid further suffering. There is evidence to suggest that the addition of antibiotics to the rehydration solution does not improve recovery.

The use of oral antibiotics should be carefully avoided in the case of undiagnosed outbreaks of calf scours to avoid further disruption of gut flora. If the calf is incapable of drinking the dehydration solution, parenteral rehydration has to be provided. Septicaemic colibacillosis is a major cause of early calf deaths. The condition is often fatal or leads to post-septicaemic infections that are often non-responsive to treatment. If an outbreak occurs, every effort should be made to isolate the affected calves immediately. If the cause of the condition is known, systemic antibiotic and anti-inflammatory therapy can be helpful.

PREVENTION:


The passive immunity acquired from the colostrum and absorbed into the circulation from the gut is the calf’s main defence mechanism against E. coli diarrhoea. Inadequate amounts of antibodies in the colostrum, inadequate intake of the colostrum and inadequate absorption of antibodies from the gut render very young calves susceptible to infection. Additionally, among calves aged 1-4 months old, carriage of VTEC E. coli O157 was reduced if the calf had suckled colostrum from the mother or if the calf had stayed more than 2 days with the mother after calving. For herd where a known infection is present an improvement in colostrum feeding in the first 6-9 hours of life and dam immunisation against ETEC E. coli F5 (K99) adhesin are the main ways of controlling disease.

The disease can be reduced by the use of dam vaccine before calving, improved hygiene around calving and improved colostrum administration. Where the disease is absent from the herd, the prevention should concentrate on keeping it out by good herd biosecurity.


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