In Europe, Post-weaning Multisystemic Wasting Syndrome (PMWS) has been with us for several years, since 1999. The acute disease with high mortality has largely passed and we are now living with the chronic form of the disease, with varying degrees of severity in the late grower or finishing herd. In some countries, the chronic form is considered relatively low grade, following the implementation of challenge reduction guidelines (Madec's principles) and changing breeds to less susceptible ones, like the Pietrain. However, in others countries, such as the UK, it is still seen as a major cause of mortality in finishing pigs and exerts a continuing, depressing effect on the overall health and productivity of a herd.

The main cause of the disease and its effects is clearly associated with Porcine Circovirus type 2 (PCV-2) infection and this is also supported by the response to the PCV-2 vaccines, which are being used successfully in both the USA and Canada. There are thought to be other associated trigger/complicating factors such as Mycoplasma hyopneumoniae, PRRSV (Porcine Reproductive and Respiratory Syndrome Virus) and even Salmonella spp, which exacerbate the clinical problem but in Europe we are fortunate that the US PRRSV strains are not so widespread or so virulent. Currently, there are four PCV-2 vaccines in N. America, with one introduced for sows, which is also available in a few countries in Europe, and three for use in young pigs of three weeks of age. An early trial report, given at the recent AASV meeting using a killed vaccine (Ingelvac CircoFLEX - Boehringer Vetmedica) in young piglets has shown mortality figures in finishers dropping to almost pre-PCV-2 infection levels, by as much as 7% (Desrosiers and others, 2007). The vaccine was given to groups of weaners and growers, which were free from PRRSV and M. hyopneumoniae, so the effect was just against PCV-2 infection.

Using these figures and data from our own production trials and costs in the UK to develop a model, the approximate cost of a severe case of the disease can be calculated (see Table 1) and the benefits from piglet vaccination extrapolated (see Table 2).

Table 1. Example - Calculating the cost of a severe, chronic PCV-2 infection in finishing pigs

The potential cost of a severe chronic form of PCV-2 infection causing a 7% increase in mortality could be as much as 16.19 Euros/pig or US$ 21.37 (Exchange rate: US$1.32 = 1€, Other Currencies)

An approximate cost of PCV-2 disease in finishers can be based on associated extra mortality and its effects on reducing growth rate and FCE, according to the severity of the condition.

 

Table 2. Cost of PCV-2 associated disease in finishers by severity and cost/benefit of piglet vaccination

Even a mild form of the disease with a relatively low mortality of 1% can cause a reduced margin/pig of 2.31 Euros or $3.05. Taking into account the cost of piglet vaccination there is still a potential extra margin of 1.14 Euros or $1.50 (see Graph 1). As the severity increases, the cost and potential additional margin resulting from PCV-2 vaccination soars, giving a very substantial cost/benefit result.

Graph 1. Cost of disease (US$) based on PCVD associated mortality and vaccination costs

In Europe, it is likely that the piglet vaccines will not be available for some time. However, if their initial promise in N. America is reflected in the European situation, they will be most welcome, even after such a long wait.

 

Reference:
Desrosiers, R., Clark, E., Tremblay, D. and Tremblay, R. (2007) Proceedings of the American Association of Swine practitioners Conference, Orlando, USA, pp 143-145

 

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Pig Diseases & Medication:  Pig Technical Reviews

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