Michel Franc

Insecticide and acaricide molecules and/or combinations to prevent pet infestation by ectoparasites.

External antiparasitic drugs used in cats and dogs have evolved in terms of active ingredients but also regarding formulations. Old chemical groups have been supplanted by phenylpyrazoles, neonicotinoids, oxadiazines, spinosyns or others which are entering the veterinary market. In addition to insecticides-acaricides, insect and mite growth inhibitors (IGRs) have emerged. These IGRs are used in animals or in the environment, either alone or in combination with insecticides-acaricides. The notion of antiparasitic treatment has evolved to the concept of prevention of ectoparasite infestation but also of transmitted diseases through the introduction of formulations providing long-lasting activity. At the same time, ease-of-use has been improved with the development of spot-on formulations. Progress has also been achieved through the development of antiparasitic drugs providing control of both external and internal parasites.

Bovine besnoitiosis: Epidemiological and clinical aspects

Bovine besnoitiosis, due to the cyst-forming apicomplexan Besnoitia besnoiti, is widespread in Africa, in Asia and in the south of Europe. This infection leads to major economic losses in cattle production with a decrease in milk production, transient of definitive sterility of bulls and mortality. Since its emergence in Europe (Germany, Spain and Centre of France), more attention has been given to this infection during the last 10 years, including the recent development of serological methods for diagnosis. The life cycle of B. besnoiti remains a mystery: the definitive host is unknown and the transmission routes are poorly understood. B. besnoiti is thought to be transmitted mainly by hematophagous insects. This paper presents a review of what is currently known of the epidemiology of bovine besnoitiosis and the key manifestations of the disease. It highlights the urgent need for research programs to improve efficient and sustainable control methods.

A longitudinal study of Besnoitia besnoiti infections and seasonal abundance of Stomoxys calcitrans in a dairy cattle farm of southwest France

Bovine besnoitiosis, caused by the cyst-forming apicomplexan Besnoitia besnoiti, is commonly reported in some restricted regions of South-Western Europe, and in larger regions of Africa and Asia. This infection is thought to be transmitted by blood feeding insects and is responsible for major economic losses in cattle production. A recent emergence in Europe, notified in the Centre of France, Spain and Germany, has attracted more attention to this disease. Clinical signs could appear in some animals; however, many infected cattle remain asymptomatic or show scleral-conjunctival cysts (SCC) only. Recent development of serological methods allows carrying out seroepidemiological field studies. In this respect, a long-term investigation was performed in a dairy cattle farm localized in an enzootic area of besnoitiosis of South-western France between March 2008 and May 2009. The objective was to estimate the seasonal pattern of B. besnoiti infections based on the presence of SCC and serology (ELISA and Western blot). In parallel, an entomological survey was conducted to describe population dynamics of Stomoxys calcitrans and Tabanidae species. The seroprevalence determined by Western blot in a cohort of 57 animals continuously present during the whole survey increased from 30% in March 2008 to 89.5% in May 2009 and was always higher than the prevalence based on clinically assessed SCC. New positive B. besnoitia seroconversions occurred throughout the year with the highest number in spring. In addition, many seroconversions were reported in the two months before turn-out and could be associated with a high indoors activity of S. calcitrans during this period.

Personal protection against biting insects and ticks.

Recent events with the first cases of local transmission of chikungunya and dengue fever virus in southern France by Aedes albopictus, adding to the nuisance and potential vectors that can be encountered when traveling in tropical or sub-tropical countries, has shown the value of a reflection on the Personal protection against vectors (PPAV). It is seen during an outbreak of vector-borne disease, or simply because of nuisance arthropods, that our fellow citizens try to protect themselves individually by using an arsenal of resources available on the market. Yet most of these means have been neither checked for effectiveness or safety tests, however, essential. Travellers, staff on mission or assignment, are looking for specific information on how to protect themselves or their families. Health workers had at their disposal so far indications that vary widely from one source to another. Therefore it seemed important to the Society of Travel Medicine (SMV) and the French Society of Parasitology (SFP) to initiate a reflection on this theme. This reflection took the form of recommendations for good practice, following the outline established by the French High Health Authority (HAS). The aim was to gather all relevant information, verified and validated and the format to be used not only by health personnel (doctors, pharmacists, nurses), but also by travel agents and individuals. This document highlights the need to take into account the risk of vector-borne diseases, some deadly, and the benefit of various methods of personal protection. The choice of methods is clearly oriented towards those whose effectiveness has been proven and potential risks assessed. The paper finally proposes two decision trees based on the transmission type (day or night) and kind of stay (short or roaming, long and steady). It concerns travellers, but also expatriates, residents and nomads.

Pharmacokinetics of Selamectin in Dogs after Topical Application

Some pharmacokinetic parameters of selamectin were determined in male (n = 5) and female (n = 5) Beagle dogs following a topical application at a dose rate of 6 mg/kg. The plasma concentration versus time data for the drug were analysed using a one-compartment model. The maximum plasma concentrations of 12.72±5.13 ng/ml for males and 22.65±11.95 ng/ml for females occurred around 5 days after administration. The area under the concentration–time curve (AUC) was 192.08±63.85 ng.day/ml for males and 370.97±146.87 ng.day/ml for females. The mean residence time was the same in males and females (12.55 days). This study reveals a sex-influence on the disposition of selamectin in the plasma of dogs, which implies that further information will be needed for correlation with efficacy studies in dogs.

The repellency of lemongrass oil against stable flies, tested using video tracking

Lemongrass oil (Cymbopogon citratus) is an effective repellent against mosquitoes (Diptera: Culicidae) and house flies (Diptera: Muscidae). In this study, its effectiveness was assessed on stable flies (Diptera: Muscidae) in laboratory conditions. First, we demonstrated that lemongrass oil is an active substance for antennal olfactory receptor cells of Stomoxys calcitrans as indicated by a significant increase in the electroantennogram responses to increasing doses of lemongrass oil. Feeding-choice tests in a flight cage with stable flies having access to two blood-soaked sanitary pads, one of which was treated with lemongrass oil, showed that stable flies (n = 24) spent significantly more time in the untreated zone (median value = 218.4 s) than in the treated zone (median value = 63.7 s). No stable flies fed on the treated pad, whereas nine fed on the untreated pad. These results suggest that lemongrass oil could be used as an effective repellent against stable flies. Additional studies to confirm its spatial repellent and feeding deterrent effects are warranted.

Efficacy of a new combination of fipronil and permethrin (Effitix®) against Phlebotomus perniciosus in dogs.

Two controlled clinical trials were carried out to assess the anti-feeding and adulticidal effects of a spot-on combining fipronil and permethrin (Effitix(®), Virbac, Carros, France) against Phlebotomus perniciosus in dogs. The first study (Exp. A) was a dose-determination study in which 3 doses of permethrin (30 mg/kg, 60 mg/kg and 120 mg/kg) were compared. The second study (Exp. B) was an efficacy study using commercial dose of permethrin contained in Effitix(®) (the minimum dose of permethrin applied to dogs was 60 mg/kg). Twenty four and twelve Beagle dogs with equal sensitivity to sandflies were included in Exp. A and in Exp. B, respectively. Dogs were challenged with female sandflies (50 per dogs in Exp. A and 80 in Exp. B) for 60±5 min on Days - 7, 1, 7, 14, 21 and 28 (Day 0 being treatment day). Counts and engorgement determination of dead and alive sandflies were performed after each exposure to treated and untreated dogs. Dead sandflies were also counted 24 h after exposure. In Exp. A, the repellency induced by an administration of 30 mg/kg of permethrin to dogs was above 91% for the first two weeks and then dropped to 82.2, 83.1 and 81.1% on Days 14, 21 and 28, respectively. For dogs receiving 60 mg/kg of permethrin, the repellency was a bit higher with 95.8, 97.6, 92.1, 91.4, and 86.8%, for Days 1, 7, 14, 21 and 28, respectively. The repellency induced by 120 mg/kg of permethrin was significantly higher than that induced by 60 mg/kg of permethrin on Day 14 only. In Exp. B the anti-feeding effect of the spot-on formulation was 94.1, 97.8, 96.3, 90.8 and 87% on Days 1, 7, 14, 21 and 28, respectively. The mortality effect was 98.9, 99.1, 99.8, 97.0 and 89.7% 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 control and treatment group (p<0.05). The results indicate that a monthly administration of this new combination of permethrin and fipronil could be used as an effective sandfly control strategy in dogs and therefore recommended for use in an integrated leishmaniosis prevention program.

Evolutions épidémiologiques et nouvelles contraintes dans la lutte contre les myiases ovines

Une myiase naso-sinusale à Oestrus ovis et deux myiases cutanées à Lucilia sericata et Wohlfahrtia magnifica constituent toujours une dominante pathologique des ovins au pâturage. De plus, la myiase naso-sinusale à Oestrus ovis est responsable de cas sporadiques d’ophtalmomyiase externe chez l’homme. Dans les dernières décennies, ces affections parasitaires ont connu des évolutions épidémiologiques importantes, gagnant de nouveaux territoires en France métropolitaine. Leur contrôle reste tout à fait réalisable en élevage ovin allaitant même s’il est contraignant, mais il s’est considérablement compliqué en élevage ovin laitier en raison d’interdictions réglementaires de l’utilisation de nombreuses molécules actives. En parallèle, les méthodes alternatives au traitement chimique restent très limitées. L’information des éleveurs et des vétérinaires est donc essentielle pour la détection précoce des cas et la surveillance de ces parasitoses.