The disease is somewhat of an enigma because the organism can be identified both in normal animals and in those severely affected with disease. It is likely that Epe is very widespread and most sources of pigs examined (varying health status) have shown evidence of the bacteria.

In the majority herds where it has been identified there have been no clinical problems and the significance therefore of the organism in relation to infection in these cases must be in doubt. However, in the past two years a positive diagnosis associated with disease has become more common. Epe can cross the placenta and be responsible for poor pale pigs at birth and high pre-weaning mortality.

Clinical signs

Epe affects all classes of pigs from sows and piglets through to weaners and growers. Clinical pictures vary, particularly if there are secondary infections involved. It is useful however, to look at the clinical symptoms in acute and chronic disease. In piglets and weaners the acute disease is manifest by primary anaemia and secondary infections, whilst the more chronic picture appears related to slow growth, variable growth rate and poor-doing pigs. The chronic symptoms in sows are associated with reproductive failure and if there is stress at farrowing, fevers and agalactia may be experienced.

If pale anaemic pigs are evident during sucking or in the immediate post-weaning period and an injection of iron has been given, the possibility of Epe should be considered.

Diagnosis

The presence of the organism does not necessarily confirm disease. The following need to be considered to clarify the relationship between Epe and disease.

• The presence of pale and anaemic pigs.
• The identification of the organism in blood smears stained with Wright's stain. Fifty microscopic fields should be examined before a negative diagnosis is arrived at.
• The clinical picture on the farm should include lowered reproductive performance.
• Jaundice, particularly in young growing pigs from 7 to 21 days of age.
• Serological tests are being developed including an ELISA but at the time of writing they are still unreliable.
• Eliminate other causes of anaemia.
• Blood samples should be examined for packed cell volume (PCV) and haemoglobin levels. In normal pigs the mean PCV would be around 35% and in clinically affected pigs 24%. Haemoglobin levels would normally range from 9 to 14g per 100ml but in anaemic pigs they would be as low as 3 to 7g per 100ml.