Using anthelmintics
The first of these strategies is the use of anthelmintics, based on the epidemiology of the disease. This makes it possible to determine the time of the year when the maximum effect can be achieved with the fewest possible treatments. The correct time for anthelmintic treatment depends mainly on climatic conditions and weather data. Timing is basically similar across districts, with only small adjustments required in south–eastern Australia. Figures 2–4 suggest timing of strategic treatments for the Central Tablelands, the Northern Tablelands and the North Coast. Fewer treatments than indicated may be required. The weather pattern of the Central Tablelands (Figure 2) is similar to that of the Southern Tablelands. The North Coast pattern (Figure 4), apart from higher rainfall, is similar to conditions on the south coast.
In the irrigation areas a similar program is recommended where the epidemiology of fasciolosis depends mainly on temperature. Treatments are essential when clinical disease is apparent, even though it may be too late to prevent economic losses. Treat according to the charts in order to prevent the disease and reduce the problem of liver fluke disease to a manageable level.
Drugs play an important role in the control of fasciolosis. An efficient strategic control program relying on a minimum number of treatments per year and aimed at long–term elimination of pasture contamination requires drugs that are effective against both mature and early immature flukes. More frequent treatments are necessary if you use drugs that are only effective against advanced mature fluke aged 12–16 weeks or older.
Drug resistance has been reported against triclabendazole and closantel but is not yet widespread. When found it is usually first seen as
Table 1. Comparative anthelmintic efficiency and safety of drenches suitable for the treatment of fasciolosis in sheep and cattle.
Active Ingredient
Safety index* at recommended dose
Over 90% efficiency at recommended dose
Age of fluke (weeks)
2
4
6
8
10
12
14
Triclabendazole (oral; pour-on formulations are also available)
20
+
+
+
+
+
+
+
Closantelt
5.3
-
-
-
+
+
+
+
Closantelt plus oxfendazole
5.3
-
-
+
+
+
+
+
Closantelt plus albendazole
5.3
-
-
-
+
+
+
+
Nitroxynil§
4.0
-
-
-
-
+
+
+
Albendazole
6.0
-
-
-
-
-
+
+
Oxyclozanide** plus levamisole
4.0
-
-
-
-
-
+
+
Clorsulon§ plus ivermectin
20
-
-
-
-
-
+
+
* Safety Index = Maximum tolerated dose divided by the recommended dose rate. § Registered as a subcutaneous injection for cattle ± At 12 weeks is less effective in cattle than in sheep t Not registered for cattle ** Registered for lactating cows PRIMEFACT 446,