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-Cattle hypodermosis, due to insect larvae, is widely spread over the northern hemisphere. Very efficient insecticides are available and their use in most countries are done on an individual level but never cover the whole cattle population of a country. Untreated animals remain the reservoir of the disease and annually re-infest the cattle population. The economic effects of this disease on animal production (meat, milk and the leather industry) but also on the general cattle health status, have led many European countries to launch organised control programs. The first example of definitive hypodermosis control goes back one hundred years ago when Danish farmers eradicated hypodermosis from the Danish islands by manual elimination of the warbles. Since then, more and more European countries have considered the feasibility and economic returns of such programs. The various factors which foster these programs are related to (i) biological factors, (parasite cattle specificity, synchronous biological cycles of both species of insects involved), (ii) the development of more and more efficient insecticides used only once a year by systemic application, with high efficiency at very low dosages against the first larval stage of Hypoderma spp., (iii) the development of acute techniques of detection of the disease for the monitoring of hypodermosis free countries and (iv) the durable successful results obtained in more and more European countries. Although the programs were imposed by different partners of the livestock channel production (farmers, dairy industry, leather industry) and have been engaged within the last 50 years in many European countries (Denmark, the Netherlands, Ireland, the United Kingdom, the Czech Republic, Germany, France and Switzerland) common features have emerged among these different eradication programs. They all need a preliminary statement of the economic impact of this pest and the farmers' awareness of the economic returns of such programs. The programs'efficacy depends: (i) on a good knowledge of the epidemiology of the parasites, (ii) on the simultaneous implementation of the control program on the whole national cattle population whatever the structure monitoring the treatments (veterinary services, farmers association), (iii) on a national Warble fly legislation making the treatments compulsory and (iv) on an acute epidemiological survey as soon as the status of a hypodermosis free country is reached and the treatments are suspended. The sanitary and financial returns of such programs are a benefit to all the partners of livestock production, to the quality of the environment and to the consumers.hypodermosis / organised-control program / cattle / myiasis 455 Vet.

The collagenase from the larvae Hypoderma lineaturn, with a molecular weight of 24000 and isoelectric point of 4.1, was obtained in homogeneous form by ion-exchange chromatography. It is stoichiometrically inhibited by diisopropylfluorophosphate. On the other hand it is unaffected by ethylenediaminetetraacetate, p-chloromercuribenzoate, dithiothreitol, N-tosyllysine chloromethyl ketone, N-tosylphenylalanine chloromethyl ketone and ovomucoid trypsin inhibitor. The enzyme which degrades native collagen in its helical parts, has a specific activity on thermally reconstituted collagen fibrils of 150 pg collagen degraded x min-' x (mg enzyme)-' at 37 "C. It hydrolyses casein but has no esterolytic activity characteristic of trypsin, chymotrypsin nor elastase. It has no action on the synthetic peptide 4-phenylazobenzyloxycarbonyl-~-prolyl-~-leucyl-glycyl-~-prolyl-~-arginine. The amino acid composition of Hypoderma collagenase indicates a distinct similarity with the serine proteinases of the trypsin family and with another athropode serine collagenase, that of the fiddler crab Uca pugilator. This suggests that eucaryotic collagenases with digestive rather than morphogenic function represent a new category of members of the trypsin family.Since the occurence of a collagenase from a eucaryote was first described in tadpole skin culture media [l], a number of collagenases from various animal and human tissues have been isolated and characterized [2-51. Little is known, however, about the collagenases from eucaryotes which do not play a role in the physiological remodelling of connective tissues. Such collagenases functioning as digestive enzymes have been demonstrated in the hepatopancreas from the fiddler crab, Ucapugilator [6,7], and in the pyloric caeca from a fish, Seriola quinquecadiata [8]. Many years ago, collagenolytic enzymes were also reported in parasites which enter through the skin of their host [9 -131. The demonstration of a collagenolytic enzyme in the midgut of the first instar migrating larvae from and migrate during eight months while digesting its connective tissues, helped by the enzymic secretion of their salivary glands. As they migrate, the larvae partially reabsorb their salivary enzymes together with the degradation products of the connective tissue of their host and stock them in their midgut which is closed in its hind end and can thus act as a reservoir In a previous biochemical study, the collagenase from H. lineatum was purified and partially characterized [16]. Its mode of attack on collagen was shown to be similar to that of vertebrate tissue collagenases in that it cleaves native collagen, at neutral pH and under non-denaturing conditions, at a site located three-quarters of the length of the molecule from the N terminus. H. lineatum collagenase differs however from vertebrate collagenases in regard to its behaviour to various inhibitors, particularily EDTA. Although this agent completely blocks the action of most tissues collagenases, which are metalloenzymes, it was without effect on t...

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Cattle and yak hypodermosis in China is caused by Hypoderma bovis and H. lineatum, with a prevalence reaching up to 98-100% of the animals and maximum intensities exceeding 400 warbles for each animal. A third species, H. sinense, is also considered by Chinese researchers to affect livestock. The molecular characterization of the most variable region of the mitochondrial cytochrome oxidase I gene and of the ribosomal 28S gene has been performed for the third-stage larvae collected from cattle and yaks in China and identified (on the basis of the spinulation on the ventral side of the 10th segment) as H. bovis, H. lineatum, and H. sinense. Amplicons were digested with the HinfI and BfaI restriction enzymes, which provided diagnostic profiles to simultaneously differentiate the 3 Hypoderma species. Third-stage larvae of H. sinense were also examined by scanning electron microscopy, which revealed proper morphological characteristics different from those of H. bovis and H. lineatum. The molecular and morphological evidence herein reported support the existence of a third species of Hypoderma affecting cattle and yaks in China, and the results provide new tools for unequivocal identification of this species and present key components for the evaluation of its endogenous cycle and pathogenicity in animals and humans.