Resistance Is No Fluke
The statistics are frightening: economic losses due to liver fluke stand at an annual $2 billion worldwide, just 150 fluke can kill a sheep and there is a dearth of effective treatments. The situation could unfortunately get worse. The market leading treatment triclabendazole has been so widely used that resistant fluke populations have started to appear in Australia, the Netherlands, Ireland and now the UK.
Resistant parasites have long been the scourge of the animal health industry and they are not about to go away overnight. What concerns many experts is that currently this is a burgeoning problem they can't contain.
Mr Nigel Underwood is Livestock Marketing Manager at Janssen Animal Health, "Resistance to flukicides is an issue that could have major productivity implications for the sheep industry: Increased mortality, reduced lambing percentages and liveweight gain In severe cases good pasture may be lost because sheep are unable to graze infected land and wore still, some producers will ultimately go out of sheep production. Despite wide acceptance of the fact that the same flukicide should not be used year on year, it's clear that many farmers have previously been advised to do just that. This has resulted in what have so far been sporadic reports of resistance to triclabendazole but leading figures in the industry acknowledge that by the time we have detected resistance through rising faecal egg counts or overt fluke outbreaks, the problem could already be widespread. Of course, from a commercial point of view pharmaceutical companies would love their products to be used exclusively but when it comes to parasite control that's just not a responsible message.
We need to remember that we have only a few options if we want to treat immature and adult flukes: closantel (FlukiverTM), nitroxynil and triclabendazole."
To make matters worse, fluke is "on the move" in the UK, with the traditionally safe drier areas in the east also becoming infected. While it is acknowledged that there is a real need to collect more data for analysis so that this problem can be better evaluated, there are several strategies that experts recommend:
1. Do not use the same flukicide year on year – a strategic rotation programme alternating closantel and triclabendazole year on year is a good option.
2. Do not under-dose when using flukicides, either in volume or frequency.
3. Check faecal egg counts post treatment to identify if resistance is occurring and consider also checking poor doers as failure to thrive may be due to fluke.
4. If triclabendazole resistance is detected, closantel is the drug of choice as it is in a different chemical group and kills triclabendazole resistant fluke.
