Trial shows Butox SWISH effective against bluetongue midge

Treating cattle with Butox^® SWISH this summer will give four weeks’ control of midges, the insects responsible for carrying the bluetongue virus (BTV-8), according to recent German trial results.

“Butox SWISH showed a rapid killing effect even after a brief contact time between midges and hair on treated animals,” says trial director Professor Heinz Mehlhorn from the Heinrich-Heine University in Dusseldorf. “The work also showed that the product spreads to the areas prone to midge bites - the underside of the belly and other exposed areas such as the legs.”

The recommended monthly application of the pour-on insecticide for midge control coupled with starting midge control early in the season, should reduce the number of females able to lay eggs. Combining vector control with vaccination will reduce the overall threat of infection to all stock. “We have to do several things at once – vector control starting early in the season, adapting stock management and vaccination – to reduce the risk of infection,” states Prof Mehlhorn.

This is particularly important given that evidence from Germany, France and Holland shows BTV-8 is more aggressive in its second year. The Dutch livestock sector alone reported losses of more than 80 million Euros in 2007, due to weight loss, lower milk yields, plus fertility problems and an increase in secondary infections.

The virus causes fever, nasal discharge, swelling and ulceration of the mouth. Swollen teats, runny eyes, lethargy, drooling saliva, and swelling of the head and neck are also seen. Symptoms and deaths tend to be greater in sheep; infection in cattle is often subclinical however they play an important role in keeping the disease in circulation.

The culicoides midge is responsible for transmitting BTV-8 and Butox SWISH is the only pour-on proven to be effective against this midge. By applying at the standard dose along the lower neck and mid-line of the animal, it easily spreads over the entire surface.

Last summer’s trial treated six heifers (each around 400kg) with 30ml Butox SWISH (the standard adult dose for fly control). Untreated heifers were also kept with the group to provide comparative results. Samples were taken weekly from all the animals over the next five weeks, from areas prone to midge bites.

“At each sampling point, immediate paralysis of the midges occurred in the treated group and they then went on to die at varying intervals, depending on contact time and the number of days after treatment with Butox SWISH,” says Prof Mehlhorn.

Importantly, however, for up to 28 days after treatment with Butox SWISH, all midges were killed, meaning the bluetongue virus would not have had time to replicate within them before they could go on and infect other animals. In the control group, all midges survived.

“Doubtless, many farmers will be concerned about midge control and bluetongue as we head towards warmer days,” says Intervet vet adviser Rosemary Booth. “Monthly applications of SWISH on all stock will reduce the overall threat of midges capable of spreading the bluetongue virus and should be used in conjunction with vaccinating with Bovilis^® BTV8, as well as good management practices which may reduce exposure to midges.”