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For many years, hypodermosis control - which started in the 1920's - was unsatisfactory, partly due to a lack of efficacy or a too high toxicity of the available products. An improved control became possible with the introduction (1957) of the organophosphate Metrifonate (Neguvon®, Bayer AG). Subsequent large-scale campaigns according to the Federal Ordinance on epizootic diseases (1967) quite reduced hypodermosis in Switzerland. However, due to a limited use of the product (only young and alpine-grazing cattle were allowed to be treated, administratively indicated maximum dose, side-effects) and its incomplete efficacy, a full control was not possible. The decision to maintain hypodermosis as a "notifiable" disease then allowed further epidemiological studies. In 2000/2001 a concerted action in close cooperation with the cantonal veterinarians allowed a consequent and systematic treatment of all cattle in all endemic areas by the large-scale use of Eprinomectin (Eprinex®, Merial Inc.) for dairy cattle and of Ivermectin (Merial Inc.) as microdose "off-label" for young cattle has led to a rapid and sustainable success.

In two test areas in Austria (Burgenland, Lower Austria) ivermectin has been used to control oestrinosis and hypodermosis in red- and roe deer since many years (1985 and 1987, respectively). The results until 1992, using the injectable solution Ivomec-injection 1% only, have been reported (Kutzer, 1994). In continuation of these tests Ivomec-Praemix 0.6% was examined and it turned out that the treatment was extremely successful. In practice Ivomec-Praemix 0.6% has to be given preference due to its stability. The most favourable dosage for red- and roe deer was 2 x 0.4 mg ivermectin/kg bodyweight administered at an interval of one week, although equally good results could be obtained with 1 x 0.3-0.4 mg ivermectin/kg bodyweight. With the above mentioned dosages against Pharyngomyia picta and Cephenemyia stimulator an up to 100% and against Hypoderma actaeon a 100% success of treatment could be achieved. The administration in two doses has the advantage to eradicate intestinal and lung nematodes at the same time if there are any. Finally, it was found that the controlling measures should not be interrupted for more than one year, if no treatment was done in the neighbouring hunting grounds.

The co-operation between G.D.R. and M.P.R. in the field of control of ectoparasites in farm animals is described. The problems under the specific conditions of the M.P.R. in the control of the principal parasitoses of economic importance such as hypodermosis, mange, tick infestations, oestrosis, vermipsyllosis, gasterophilosis and wohlfahrtiosis are analysed. The successfully applied hypodermosis control program represents the base for further systematic, state-directed strategic measures in controlling of ectoparasitoses.

Field trials in more than 3,000 head of cattle proved the efficacy and compatibility of the insecticide Trichlorphon 6%-"neu"--manufactured by the chemical works in Bitterfeld, German Democratic Republic, on the basis of domestic active ingredients--to be equal to the insecticides used until now. The inhibition of the activity of cholinesterase was moderate but longer lasting than with other preparations. The advantages of Trichlorphon 6%-"neu" are the substitution of imported substances by domestic products, prolonged efficacy, and--by a new formulation--its application at temperatures below zero.