Expert voice: Lawsonia intracellularis on German pig farms, performance losses may even not be known!

Interview of Prof. Michael Wendt from University of Veterinary Medicine Hannover, Germany for Phileo’s knowledge center

By Caroline Brückmann, Technical Sales Phileo by Lesaffre Germany

How high is the prevalence of Lawsonia intracellularis in Germany?

“Infections with Lawsonia intracellularis are very common in Germany, as they are worldwide. Both earlier and current investigations in Germany show that 80-90% of the farms examined have animals that excrete Lawsonia intracellularis or have developed antibodies against it. While the pathogen is more frequently found in faecal samples from younger animals, particularly in the pre-fattening period, antibodies are most frequently detected in older pigs towards the end of the fattening period. Serological testing of old sows shows that up to 100 % of farms have positive reactants.”

Lawsonia intracellularis causes ileitis. What type of ileitis do you encounter most frequently in Germany? Where do you think most problems occur?

“Subclinical infections are the most common, i.e., the farmer does not initially recognise that the pigs are infected. On closer inspection, however, it can often be seen that a few animals are not developing as usual, have lower weight gains and feed conversion is poorer than usual. In more severely affected herds, a chronic form of the disease with the occurrence of diarrhoea is more likely to be observed. However, deaths are rare. Such courses are particularly noticeable in the pre-fattening period but can also extend into the main fattening period on some farms. Clinical diseases are less common in the rearing area, where isolated piglets that have developed antibodies usually only appear towards the end of the flat deck phase. Suckling piglets, on the other hand, almost never fall ill as they are protected by the colostrum.

Acute forms are much less common. Sudden deaths can occur without the farmer noticing any abnormalities beforehand. The event becomes clear when massive bloody diarrhoea appears in the barn. Affected pigs die within hours due to heavy blood loss. However, this form of the disease only occurs in older pigs towards the end of fattening or in gilts. Old sows, on the other hand, are almost never affected.”

What are the first signs in a herd that suggest the presence of Lawsonia intracellularis? How do you diagnose and monitor the presence of Lawsonia intracellularis on a farm?

“The farmer should regularly check the pigs for signs of diarrhoea. However, this does not provide a definitive diagnosis, as other pathogens may also be the cause of the diarrhoea. Reduced weight gain, poorer feed conversion and groups growing apart can also be initial indications of a Lawsonia intracellularis infection. If diarrhoea occurs, faecal samples should be taken and sent in to be examined for possible diarrhoea pathogens. Detection of the pathogen helps to initiate the correct treatment.

If a subclinical infection with Lawsonia intracellularis is suspected, blood samples are suitable for a serological screening test to determine whether the pigs have had contact with the pathogen. Animals from different age groups should be sampled to see when antibodies appear.

On sow farms, newly purchased gilts may develop bloody diarrhoea or even die some time after stabling. This is usually due to the fact that these animals have had no contact with Lawsonia intracellularis in the herd of origin and become acutely infected on the new farm. It can be helpful to carry out serological tests on new gilts in quarantine to see whether they are protected by antibodies. If this is not the case, they should be vaccinated so that they do not become sick.”

How useful / successful are biosecurity measures?

“The usual biosecurity measures should generally be standard on every farm, but cannot usually prevent a Lawsonia infection, as most farms are already infected, and it is almost impossible to eliminate the pathogen from the herd. The most common route of introduction is through the purchase of subclinically infected pigs, but Lawsonia intracellularis can also be transmitted by rodents and other animals such as birds and insects, as well as through personal contact and equipment. Problems can be minimised if there is strict spatial and hygienic separation between the age groups so that the pathogen is not transmitted from older, infected pigs to younger animals. Careful cleaning and disinfection are also important in order to reduce the pressure of the pathogen.”

If a farm is diagnosed with Lawsonia intracellularis problems, what would be your strategy to get the farm back on track?

“If there is a current diarrhoea problem on the farm caused by Lawsonia intracellularis, antibiotic treatment should be initiated to control the symptoms. However, as group treatment is usually carried out, it is important to realise that animals that are not yet infected at the time of treatment will not develop antibodies. This can lead to such animals becoming infected at a later stage and showing diarrhoea, as the pathogen is not eliminated from the herd. For example, the acute form of Lawsonia intracellularis infection with bloody diarrhoea and deaths can occur towards the end of fattening.

In the event of recurring problems and subclinical infections, long-term vaccination is recommended, as this protects the animals throughout the entire rearing and fattening period and reduces antibiotic consumption and prevents the development of resistance. Purchased gilts without antibodies should also be vaccinated while still in quarantine.”

What experience have you had with the two vaccines currently on the market against Lawsonia intracellularis?

“There are currently two vaccines on the market – a live vaccine and an inactivated vaccine. Neither can prevent infection of the animals, but they largely reduce the occurrence of clinical diseases and growth disorders, as they significantly reduce the development of intestinal lesions. With the live vaccine, it should be noted that it is administered orally and that no antibiotics should be administered 3 days before to 3 days after vaccination, as these could potentially kill the vaccine pathogen. The inactivated vaccine can be administered intramuscularly or intradermally but still require animal handling and individual administration.

First, consideration should be given to vaccinating gilts if they do not yet have antibodies against Lawsonia intracellularis when they arrive on the farm.

On farrow-to-finish farms, vaccination is recommended as early as possible after weaning so that the piglets are already protected in the rearing area. On fattening farms, vaccination should take place when the animals arrive. However, as animals may be brought in already infected, it is not always possible to prevent illness. If pigs repeatedly show problems with Lawsonia intracellularis despite vaccination, vaccination should be implemented in the farm of piglet origin if possible.”

Subclinical ileitis in particular causes economic and performance losses. To what extent are these performance losses accepted and when would you recommend an intervention such as vaccination?

“Many farms are not even aware that subclinical infections by Lawsonia in their herd lead to performance losses, as daily weight gains and feed conversion are not always checked regularly. However, this is a prerequisite for recognising reductions in performance and being able to monitor the success of treatment and vaccination. Data in the literature varies greatly, reduced daily weight gains can be between 3 and 30 %, feed conversion can be reduced by 2 to 35 %. As the loss of performance can vary from farm to farm depending on the infection rate, and the management of the herd also has an important influence on this, the benefits of an intervention such as vaccination on the farm must be discussed with the farmer. If in doubt, the intervention can be trialled to see whether the performance parameters improve significantly.”

How high do you estimate the economic damage caused by Lawsonia intracellularis on a farm? How do farmers view this economic damage?

“Estimates from the literature indicate economic losses of between €3 and €5 per fattening pig. In the case of subclinical infections, the costs can also be lower. However, as already discussed, this depends very much on the individual farm situation. Farmers are naturally more likely to be persuaded to intervene, especially if there is a significant drop in performance.”