But let's go back to the work of Johannes Charlier. At that time Johannes was focussing on parasites in lactating cattle. He wanted to make a tool for farmers and their advisors to calculate the costs of parasites in dairy cattle, so they can think about proper measures (or not) in case the economic losses are large. The result was a programme called ParaCalc®.
Recently the scientific paper associated with this calculation tool was published in the journal Veterinary Parasitology. Besides a description of the tool, default calculations are provided, based on input parameters from 93 Belgian dairy herds. For those herds, the estimated median cost per year per cow was € 46 [25th-75th percentile: € 29 - € 58] for gastrointesitnal nematode infections. For liver fluke infections the median costs were € 6 [25th-75th percentile: € 0 - € 19] per cow pwer year. The most important components of these costs are milk production losses.
Six veterinarians evaluated the programme and thought it was a useful tool to raise the farmer's awareness with regard to worm infections.