First report of eprinomectin-resistant isolates of Haemonchus contortus in 5 dairy sheep farms from the Pyrénées Atlantiques département in France.

Infection of sheep by gastrointestinal nematodes (GIN) in pastoral systems such as those found in the South Western area of France, the Pyrénées Atlantiques, is one of the main reasons for economic loss and degradation of their welfare. In the present study, the efficacy of eprinomectin (EPN) was monitored on farms from this area following suspicion of lack of anthelmintic efficacy. Suspicions were raised by veterinarians, based on clinical signs ranging from milk and body condition loss, to anaemia, and mortality. Resistance was evaluated according to the World Association for the Advancement for Veterinary Parasitology (WAAVP) guidelines using fecal egg count reduction tests reinforced by individual analysis of drug concentration in the serum of all treated ewes by high-performance liquid chromatography (HPLC). EPN was administered by subcutaneous (SC) and topical (T) route according to manufacturer's requirements, as well as by the oral route (O) with the topical solution according to off-labelled practices in the field. For the first time in France, the presence of resistant isolates of Haemonchus contortus to EPN was observed in 5 dairy sheep farms. The HPLC dosages showed exposure of worms to concentrations compatible with anthelmintic activity for animals treated by the SC and O routes. By contrast, they showed under exposure to the drug of most individuals treated by the T route. EPN is the only null milk withdrawal anthelmintic molecule currently available. The presence of resistant isolates of the pathogenic H. contortus to EPN in this important dairy region requires an urgent change in grazing, and sometimes production, systems.

Stomoxys calcitrans, mechanical vector of virulent Besnoitia besnoiti from chronically infected cattle to susceptible rabbit.

Cattle besnoitiosis caused by Besnoitia besnoiti (Eucoccidiorida: Sarcocystidae) is a re-emerging disease in Europe. Its mechanical transmission by biting flies has not been investigated since the 1960s. The aim of this study was to re-examine the ability of Stomoxys calcitrans (Diptera: Muscidae) to transmit virulent B. besnoiti bradyzoites from chronically infected cows to susceptible rabbits. Three batches of 300 stable flies were allowed to take an interrupted bloodmeal on chronically infected cows, followed by an immediate bloodmeal on three rabbits (Group B). A control group of rabbits and a group exposed to the bites of non-infected S. calcitrans were included in the study. Blood quantitative polymerase chain reaction (qPCR) analyses, and clinical, serological and haematological surveys were performed in the three groups over 152 days until the rabbits were killed. Quantitative PCR analyses and histological examinations were performed in 24 tissue samples per rabbit. Only one rabbit in Group B exhibited clinical signs of the acute phase of besnoitiosis (hyperthermia, weight loss, regenerative anaemia and transient positive qPCR in blood) and was seroconverted. Parasite DNA was detected in four tissue samples from this rabbit, but no cysts were observed on histological examination. These findings indicate that S. calcitrans may act as a mechanical vector of B. besnoiti more efficiently than was previously considered.

Divergent selection on milk somatic cell count in goats improves udder health and milk quality with no effect on nematode resistance.

Milk somatic cell count (SCC) is commonly higher in goats than in cattle and sheep. Furthermore, the ability of milk SCC to predict mastitis is considered lower in goats than in cattle and sheep, and the relevance of somatic cell score (SCS)-based selection in this species has been questioned. To address this issue, we created 2 divergent lines of Alpine goats using artificially inseminated bucks with extreme estimated breeding values for SCS. A total of 287 goats, 158 in high- and 129 in low-SCS lines, were scrutinized for mastitis infections. We subjected 2,688 milk samples to conventional bacteriological analyses on agarose and bacterial counts were estimated for positive samples. The SCS, milk yield, fat content, and protein content were recorded every 3 wk. Clinical mastitis was systematically noted. A subset of 40 goats (20 from each line) was subsequently challenged with Haemonchus contortus and monitored for anemia (blood packed cell volume) and fecal egg counts to see if SCS-based selection had an indirect effect on resistance to gastrointestinal nematodes. Milk production traits, including milk quantity, fat content, and protein content, were similar in both goat lines. In contrast, the raw milk SCC almost doubled between the lines, with 1,542,000 versus 855,000 cells/mL in the high- and low-SCS lines, respectively. The difference in breeding value for SCS between lines was 1.65 genetic standard deviation equivalents. The Staphylococcus spp. most frequently isolated from milk were S. xylosus, S. caprae, S. epidermidis, and S. aureus. The frequency of positive bacteriology samples was significantly higher in the high-SCS line (49%) than in the low-SCS line (33%). The highest odds ratio was 3.49 (95% confidence interval: 11.95-6.25) for S. aureus. The distribution of bacterial species in positive samples between lines was comparable. The average quantity of bacteria in positive samples was also significantly higher in high-SCS goats (69 ± 80 growing colonies) than in low-SCS goats (38 ± 62 growing colonies). Clinical cases were rare and equally distributed between high- (n = 4; 2.5%) and low-SCS (n = 3; 2.3%) lines. Furthermore, the larger the amounts of bacteria in milk the higher the SCS level. Conversely, goats with repeatedly culture-negative udders exhibited the lowest SCC levels, with an average of below 300,000 cells/mL. We therefore confirmed that SCS is a relevant predictor of intramammary infection and hygienic quality of milk in goats and can be used for prophylactic purposes. After challenge with H. contortus, goats were anemic with high fecal egg counts but we found no difference between the genetic lines. This result provides initial evidence that resistance to mastitis or to gastrointestinal nematodes infections is under independent genetic regulation. Altogether, this monitoring of the goat lines indicated that SCS-based selection helps to improve udder health by decreasing milk cell counts and reducing the incidence of infection and related bacterial shedding in milk. Selection for low SCC should not affect a goat's ability to cope with gastrointestinal nematodes.

A real-time PCR approach to identify anthelmintic-resistant nematodes in sheep farms.

Resistance to fenbendazole, ivermectin, and moxidectin was explored by a fecal egg count reduction test in four meat sheep flocks in southwestern France where anthelmintic resistance was suspected. The FECR test results of the present study confirmed the presence of benzimidazole resistance in three out of the four farms and the presence of ivermectin resistance in one flock. In addition, a suspicion of moxidectin resistance was shown in this latter farm. Both conventional morphological and molecular identifications were performed on larval cultures before and after the treatment in the studied farms. A high positive correlation was found between the number of larvae counted under binocular microscope and the number of larvae estimated by the qPCR analysis (R 2 = 0.88) and a high Cohen's Kappa value (0.91) in the detection of strongylid larvae in larval cultures. According to qPCR results, Trichostrongylus species demonstrated high levels of BZ resistance and Teladorsagia circumcincta was involved in the IVM resistance in one farm. The molecular procedures used in this study have the potential to be beneficial for anthelmintic resistance surveillance in sheep industry.

Storage of gastrointestinal nematode infective larvae for species preservation and experimental infections.

Techniques to preserve the infective third-stage larvae (L3) of gastrointestinal nematodes are of considerable interest to preserve rare species and to maintain a stable source for routine experimental infections. This study compares the relative pros and cons of the two most common techniques, cryopreservation and refrigeration by comparing how they influence consequent infection outcome parameters in terms of life-history traits and fitness as a function of time using the gastrointestinal nematode of sheep Haemonchus contortus as a study species. Establishment capacity was found to be significantly reduced in cryopreserved stocks of L3 compared to refrigerated stocks, but this was followed by significant increases in their fecundity. Refrigeration did not affect L3 stocks consequent fitness by 16 months (the maximum examined) although they did incur a significant reduction in establishment, followed once again by an augmentation in fecundity. The study highlights potential areas for bias in comparing studies using L3 larvae maintained for different periods of time under different techniques.

No detection of Besnoitia besnoiti DNA in the semen of chronically infected bulls.

Bovine besnoitiosis is a chronic and debilitating disease observed in many European countries that may cause important economic losses in cattle. The recent widespread of the parasite in Europe had led the European Food Safety Authority to declare bovine besnoitiosis as a re-emerging disease in Europe. Many aspects of the epidemiology of bovine besnoitiosis such as the main routes of transmission are still unclear and need to be further studied. Among the different hypotheses, a sexual transmission has not yet been investigated. Therefore, the aim of this study was to evaluate the presence of Besnoitia besnoiti DNA in the semen of naturally infected bulls by using a highly sensitive method (real-time qPCR). Both pre-sperm and sperm fractions of 40 bulls, including seronegative (n = 11), seropositive subclinically (n = 17), and seropositive clinically (n = 12) infected animals, were collected by electroejaculation and analyzed by real-time qPCR. No B. besnoiti DNA was detected in 27 pre-sperm and 28 sperm fractions of the 40 examined bulls, suggesting that the transmission of B. besnoiti infection by the semen of chronically infected bulls is very unlikely.

Efficacy of dinotefuran, permethrin and pyriproxyfen combination spot-on on dogs against Phlebotomus perniciosus and Ctenocephalides canis.

This study was conducted to evaluate the efficacy of a new topical ectoparasiticidal spot-on containing 4.95% dinotefuran (w/w), 36.08% permethrin (w/w) and 0.44% pyriproxyfen (w/w) (Vectra 3D, Ceva, Libourne, France) against Portuguese strain of Phlebotomus perniciosus and a French strain of Ctenocephalides canis in dogs. Twelve beagle dogs were exposed for 1 h to 100 P. perniciosus on day 6 for allocation in two groups. One group was treated on day 0, and the other group was the control group. The dogs were exposed for 1 h to 100 P. perniciosus on days 1, 7, 14, 21 and 28. After each sandfly challenge, the same dogs were infested with 100 C. canis. Counts of living fleas were determined 48 h after infestation on days 4, 3, 9, 16, 23 and 30. For sandflies, the anti-feeding effect was 96.9, 99.7, 98.7, 83.5 and 87.0 % on days 1, 7, 14, 21 and 28, respectively. The mortality effect was 97.8, 99.8, 73.7, 27.5 and 39.6% on days 1, 7, 14, 21 and 28, respectively. At each challenge point, the mortality and anti-feeding effects on sandflies were significantly different between the control and treatment groups (p < 0.05). The adulticidal effect on C. canis remained above 99% throughout the study period. The results indicate that a combination with dinotefuran, permethrin and pyriproxyfen may be used as an effective part of an overall flea and sandfly control strategy in dogs for monthly use.

Development of a protocol testing the ability of Stomoxys calcitrans (Linnaeus, 1758) (Diptera: Muscidae) to transmit Besnoitia besnoiti (Henry, 1913) (Apicomplexa: Sarcocystidae).

Cattle besnoitiosis due to the cyst-forming coccidian parasite Besnoitia besnoiti has recently been reported in expansion in Europe since the end of the twentieth century. The B. besnoiti life cycle and many epidemiological traits are still poorly known. Hematophagous flies, including the worldwide-distributed Stomoxys calcitrans, could be mechanical vectors in the contamination of mouthparts after the puncture of cutaneous cysts or ingestion of infected blood. In this study, a protocol is presented to assess more deeply the role of S. calcitrans, reared in laboratory conditions, in parasite transmission. A preliminary trial showed that stable flies could transmit tachyzoites from bovine artificially parasite-enriched blood to B. besnoiti-free blood using glass feeders. Evidence of transmission was provided by the detection of parasite DNA with Ct values ranging between 32 and 37 in the blood recipient. In a second time, a B. besnoiti-infected heifer harboring many cysts in its dermis was used as a donor of B. besnoiti. An interruption of the blood meal taken by 300 stable flies from this heifer was performed. Immediately after the blood meal was interrupted, they were transferred to a glass feeder containing B. besnoiti-free blood from a non-infected heifer. Quantitative PCR and modified direct fluorescence antibody test (dFAT) were used to detect B. besnoiti DNA and entire parasites, respectively, in the blood recipient, the mouthparts, and the gut contents of S. calcitrans at two time intervals: 1 and 24 h after the interrupted blood meal. Parasite DNA was detected at both time intervals (1 and 24 h) in all samples (blood recipient, mouthparts, and gut contents of stable flies) while entire parasites by dFAT were only found in the abdominal compartment 1 h after the interrupted blood meal. Then, S. calcitrans were able to carry B. besnoiti from chronically infected cattle to an artificial recipient in the conditions of the protocol.

Feeding and breeding aspects of Stomoxys calcitrans (Diptera: Muscidae) under laboratory conditions.

Bionomic aspects of Stomoxys calcitrans (Linnaeus, 1758) (Diptera: Muscidae) were studied under laboratory conditions. For this reason, laboratory-rearing techniques were optimized at the National Veterinary School of Toulouse. The colony was maintained at 25±2°C, 50±10% RH under a 12-hour light cycle and observed daily. The size of each adult cage is 30x30x30 cm and designed to house about 500-1,000 flies. The average cycle from egg to adult was 19.2±1.7 days. The mean longevity of imagos was 9.3±5.8 days and not significantly different between sexes. Stable flies were split into two groups; the first was fed with blood, honey and water, and the second was fed only with honey and water. The mean weight of a blood meal was 11.1±3.8 mg with no significant differences between males and females. The mean longevity of non-blood fed flies was found to be significantly higher (10.4±3.9 days) than those fed with blood. The maximum lifespan was shorter for non-blood fed males (17 days) and females (18 days) than for those fed with blood (females: 24 days, males: 23 days). Under these laboratory conditions, S. calcitrans rearing was successfully established. In the end, the number of expected generations of S. calcitrans and the net reproduction rate were estimated to be 11.8 generations/year and 16.2 living females per female respectively.

Sheep and goat immune responses to nose bot infestation: a review.

Oestrus ovis L. (Diptera: Oestridae) is a cosmopolitan agent of myiasis in sheep and goats. The parasitic phase begins after adult females deposit first-stage larvae (L1) into the nostrils of hosts; these larvae develop into L2 and L3 in the nasal and sinus horn cavities. Sneezing and nasal discharges are the major clinical signs in infected animals. The pathogenesis of O. ovis infection is caused by: (a) the trauma resulting from the mechanical action of spines and hooks during larval movement on mucosal membranes, and, more importantly, (b) an allergenic reaction provoked by molecules excreted/secreted by larvae, of which salivary antigens are those mainly recognized by the host's immune system. The recruitment of immune reactive cells increases gradually from the nasal to sinus cavities in infected hosts. Mast cells, eosinophils, macrophages and lymphocytes are always more numerous in infected than non-infected animals. Humoral (antibody) systemic response of immunoglobulin G (IgG) usually reaches seroconversion 2-4 weeks post-first infection and the highest levels are observed during the development of L2 and L3 larvae. Local antibody responses include specific IgG, which has been found to negatively correlate with larval survival and development. Hypersensitivity reaction, immunomodulation, immunization trials and mixed infections of O. ovis and helminths are discussed.

Risk factors associated with observed clinical lumpy skin disease in Ethiopia.

A cross-sectional study based on a questionnaire survey was conducted to determine the distribution of lumpy skin disease (LSD) and associated risk factors in three main agro-climatic zones of Ethiopia. A total of 330 questionnaire surveys were collected from 44 peasant associations (PA) distributed in 15 districts. Across agro-climate zones, herd-level LSD prevalence in the midland agro-climate was significantly higher 55.2% [95% confidence interval (CI) 47.5-62.6] than in highland and lowland agro-climate zones. Overall observed LSD prevalence at animal-level was 8.1% (95% CI 7.3-8.9) and observed mortality was 2.12% (95% CI 1.73-2.6). The odds ratio (OR) of LSD occurrence in midland vs. highland and lowland vs. highland zones was 3.86 (95% CI 2.61-5.11) and 4.85 (95% CI 2.59-7.1), respectively. Significantly high risk of LSD occurrence was associated with communal grazing and watering management (OR 4.1, 95% CI 2.02-6.18) and introduction of new cattle (OR 8.5, 95% CI 6.0-11.0). Our findings describe the distribution of LSD in different agro-climates in Ethiopia along with associated risk factors, and can help shed light on the epidemiology of LSD in other African countries suffering from the disease.

Cell grazing and Haemonchus contortus control in sheep: lessons from a two-year study in temperate Western Europe.

Managing infections of sheep with anthelmintic resistant gastrointestinal nematodes (GIN) is a major challenge for sheep producers in Western Europe. New methods of grazing management have been poorly explored as a component of an integrated and sustainable control of these parasites. Therefore, the purpose of this study was to evaluate the effect of two different types of grazing systems of sheep (intensive cell grazing versus conventional rotational grazing) on GIN infections over two years in a farm located in a temperate environment of Western France. When considering the whole study, the type of grazing system did not influence significantly the intensity of egg excretions of adult ewes even if the proportion of ewes excreting high numbers of GIN eggs was higher in cell grazing system than in rotational grazing system. The most striking result of this survey was the effect of grazing system on the GIN species composition harbored by ewes and by their lambs: with time, the proportions of H. contortus infections were lower in cell grazing system than in rotational grazing system. In conclusion, the cell grazing system, as implemented in this study, could limit the importance of this highly pathogenic nematode species in sheep.

Specific IgG antibody responses in Oestrus ovis L. (Diptera: Oestridae) infected sheep: associations with intensity of infection and larval development.

Larvae of Oestrus ovis (Diptera: Oestridae) are ubiquitous parasites of nasal and sinusal cavities of sheep and goats. According to the chronobiology of O. ovis infections in Sardinia and the seasonal pattern of the IgG response, the optimal period to investigate the relationships between O. ovis larval populations and intensity of local and systemic IgG antibody responses was mid-July in the summer season. Sarda x Lacaune ewes (n=186), divided into three ram-families were used in the study. Systemic and local IgG responses were measured by ELISA tests using second stage larval crude extracts (L2CE) and L2 (L2SGC) and L3 (L3SGC) salivary gland contents as coating antigens. The number of larval instars, larval length of L1, L2 and L3 larvae, and larval weight of L2 and L3 larvae were individually recorded after ewe necropsy. Negative correlations among larval establishment and/or larval development on the one hand and intensity of local or systemic IgG responses on the other hand were found in two out of three studied ram-families.

First outbreak of Trypanosoma evansi in camels in metropolitan France.

The first outbreak of trypanosomosis caused by Trypanosoma evansi in camels in France was reported on a farm in the Aveyron Department. Five camels were imported from the Canary Islands to the farm in early July 2006, and trypanosomes were observed on a stained blood smear from one of them, which died in October. On further investigations, trypanosomes were observed in the blood of five camels, three of them indigenous to the farm and two that had been imported. On the basis of microscopical examination (morphological criteria and measurements) and serological results based on the card agglutination T evansi test and PCR typing, the parasites were identified as T evansi. After treatment with melarsomine, the infected camels rapidly became negative by parasitological tests and were negative two to four months later by serological tests. The parasite was probably transmitted by tabanids and Stomoxys calcitrans, which were abundant in July to September 2006. No parasites were observed in other animals on the farm or on neighbouring farms, but some of the sheep on these farms were positive by PCR or serology.

Multiple-resistance to ivermectin and benzimidazole of a Haemonchus contortus population in a sheep flock from mainland France, first report.

Anthelmintic resistance was explored by fecal egg count reduction test in a sheep flock from the French Pyrenees at the request of the veterinary practitioner after a poor response to anthelmintics was noted. The FECRT confirmed the suspicion with a mean percentage of reduction in egg excretions of 45% (CI 95%: - 40 to 78.5) and 0% (CI95%: - 162 to 49) within the ivermectin and the benzimidazole groups respectively. Haemonchus contortus was shown to be the IVM and BZ resistant species after morphological and molecular characterizations whereas Teladorsagia circumcincta was probably resistant to BZ only. The H. contortus population was still susceptible to moxidectin, closantel and levamisole. As this sheep flock is a transhumant flock, the spread of this multiple-resistant Haemonchus contortus population to the other sheep flocks sharing the same pastures in Pyrenean Mountains is highly likely. From the knowledge of the authors, this is the first report of multi-resistance to ivermectin and benzimidazole of a Haemonchus contortus population in mainland France.

Resistance to gastrointestinal nematodes in dairy sheep: Genetic variability and relevance of artificial infection of nucleus rams to select for resistant ewes on farms.

Breeding sheep for enhanced resistance to gastrointestinal parasites is a promising strategy to limit the use of anthelmintics due to the now widespread resistance of parasites to these molecules. This paper reports the genetic parameters estimated for parasite resistance and resilience traits in the Blond-faced Manech dairy sheep breed and the putative impacts of the selection for resistance to gastrointestinal nematodes (GIN) on farms. Two datasets were used. First, the rams of the selection scheme were artificially infected twice with L3 Haemonchus contortus larvae. Faecal egg counts (FEC) and packed cell volume (PCV) loss were measured 30 days after each infection. Secondly, the FEC, PCV and body condition score (BCS) (1-6 measures per ewe) of naturally infected ewes on farms were measured in the spring, summer and autumn over a two-year period. Genetic parameters were estimated for each dataset independently but also globally based on the pedigree connections between the two datasets. For the experimentally infected sires, the FEC following the second infection was moderately heritable (heritability: 0.35) and strongly correlated with FEC after the first infection (genetic correlation: 0.92). For the naturally infected ewes, FEC was also heritable (0.18). Using the two datasets together, a genetic correlation of 0.56-0.71 was estimated between the FEC values of the experimentally infected rams and naturally infected ewes. Consequently, the genetic variability of parasite resistance is similar whatever the physiological status (males or milking/pregnant ewes) and the infection conditions (experimental infection with one parasite or natural infection with several parasites). In practice, when the sire population is divided into two groups based on their genetic value, the FEC of the ewes born to the 50% most resistant sires is half that of the ewes born to the 50% most susceptible sires. Our study shows the feasibility and efficiency of genetic selection for parasitism resistance based on the sires' FEC records to improve parasite resistance in naturally grazing ewes. For breed improvement, and to increase the selection pressure on parasite resistance, it seems more appropriate to measure FEC values on rams after experimental infection rather than on ewes in natural infection conditions because this limits the number and standardizes the conditions of FEC measurements.

Proteolytic activity in salivary gland products of sheep bot fly (Oestrus ovis) larvae.

This study identified and characterized hydrolytic enzymes in salivary gland products of Oestrus ovis larvae. Third instars were collected from the heads of slaughtered goats. Salivary glands were extracted, their products obtained by centrifugation and the enzymatic profile determined. Optimum pH, temperature of maximum proteolytic activity, thermal stability, and resistance of salivary gland products were determined on collagen and subclasses of proteases were identified using protease inhibitors. Zymograms were used to determine the molecular weight of proteases. Antigenic protein bands were revealed by immunoblotting using sera obtained from experimentally infested goats. Seven positive enzymatic activities were detected in salivary gland products: acid phosphatase, naphthol-AS-BI-phosphohydrolase, esterase (C4), esterase lipase (C8), leucine arylamidase, alpha-glucosidase and N-acetyl-beta-glucosaminidase. Optimum pH for proteolytic activity was 8.0; proteolytic activity increased with temperature (10-50 degrees C) then drastically decreased at 60 degrees C. Proteases in O. ovis salivary gland products belong to the serine subclass. In Zymograms, bands of proteolytic activity were detected in the 20-63 kDa range; the immunoblot showed three antigenic bands, one of them related to a protease band (63 kDa). Serine proteases in O. ovis salivary gland products are most likely involved in larval nutrition and host immuno-modulation.

Effects of immunization of Pelibuey lambs with Oestrus ovis digestive tract protein extracts on larval establishment and development.

Larval midgut proteins of hematophagous parasites contain strong antigens that can be used for host immunization. This concept has been applied for immunization of Pelibuey sheep against Oestrus ovis L. (Diptera: Oestridae). The aim of this study was to examine the effect of immunization on larval establishment (LE) and development. Immunized lambs (I, n = 6) received two injections of crude gut membrane protein extracts (GMPE) from third instar larvae with Freund's incomplete adjuvant (FIA) on days 0 (Day of first immunization) and 21 (0.4 and 0.45 mg GMPE/lamb, respectively). The control group (C, n = 5) received physiological saline with FIA. Lambs were challenged with first instars on Day 29 (20 larvae) and Day 43 (25 larvae). Blood samples were collected biweekly and IgG titers were analyzed by ELISA. All lambs were slaughtered on Day 90 and number of larvae recovered, larval stage and larval weight were recorded at necropsy. No significant effect of immunization on LE (C = 28.9%; I = 31.0% P > 0.05) was observed. Antibody titers were higher in the immunized group on Day 28 (P < 0.05), but subsequently similar in both groups. Larval physiological age and weight were also significantly (P < 0.05) affected by immunization. Immunization of Pelibuey lambs with GMPE did not affect LE but did delay O. ovis larval development.

Trends and challenges in the effective and sustainable control of Haemonchus contortus infection in sheep. Review.

Haemonchosis, with its very wide distribution, has become a very important production constraint in sheep farms in tropical, subtropical and temperate regions worldwide. Various intrinsic and extrinsic factors determine the survival of Haemonchus contortus and hence the development of the disease in the animal. In general, control of gastrointestinal nematode infestation in sheep relies heavily on anthelmintic treatments. However, the indiscriminate use of these drugs has led to the widespread emergence of drug resistant strains of parasites, that has necessitated the development and use of various parasite control methods such as grazing management, biological agents and vaccines and the selection of resistant breeds of animals, with or without moderate use of anthelmintics. The ultimate goal of such control programs is to enhance productivity, while minimising risks regarding drug resistance and consumer and environmental concerns. This review attempts to highlight the different methods employed in the control of haemonchosis in sheep and the practical limitations associated with both control programs and the internal and external factors associated with the parasite and its microenvironment.

[Does 2003 summer heat wave modified prevalence of bovine helminthosis in southwestern France?]. / La prevalence des helminthoses bovines a-t-elle été modifite par la canicule de l'éit 2003 dans le sud-ouest de la France?

The heat wave of 2003 summer had serious consequences on helminths prevalence and epidemiology. Comparison of 1917 cattle epg counts in southwestern France for years before and after showed that prevalence and mean numbers of Fasciola hepatica, paramphistomids, Dicroccelium lanceolatum and gastrointestinal strongyles eggs were significantly reduced. Nevertheless, the next year the epg counts were quickly increasing. Several factors may have induced a more or less long modification: strains of helminths may become adapted, a new spreading of intermediate hosts may occur with a modified ecology and finally moving of hosts and reservoirs may be amongst causes of epidemiological changes. Finally, after a heat wave the anthelmintic pressure may be maintained, as parasites seem quickly become adapted to a novel and modified environment.