Laboratory evidence that dinotefuran, pyriproxyfen and permethrin combination abrogates Leishmania infantum transmissibility by sick dogs

Dogs are reservoir hosts of leishmaniasis caused by Leishmania infantum and transmitted by phlebotomine vectors. The effect of dinotefuran, pyriproxyfen and permethrin spot-on solution (Vectra®3D, Ceva Santé Animale, Libourne, France) on Leishmania transmissibility by naturally infected dogs via reared Phlebotomus perniciosus, was assessed. Dogs affected by leishmaniasis were submitted to xenodiagnosis and 6 infecting >10% of insects were treated topically on day 0. Antifeeding, insecticidal and anti-transmissibility effects were evaluated through xenodiagnoses performed on days 1, 7 and 28, using individual pre-treatment parameters as control. Feeding and mortality rates were assessed at 24 h, whereas promastigote infection, maturation and burden were assessed up to 96 h post blood meal (potentially infectious rate). On day 1, the anti-feeding efficacy was >95% in 4 dogs, insecticidal efficacy 100% in 4 dogs, and anti-transmissibility effect 100% in 6 dogs. Efficacy rates recorded on day 7 were very similar to day 1. On day 28, anti-feeding and insecticidal efficacy values were much broader, ranging 32.6–100% and 7.7–94.4%, respectively. Potentially infectious insects were recorded from two dogs, with sharp decrease in transmissibility rate as compared with pre-treatment condition. Altogether, Vectra®3D abrogated by >98% the potential Leishmania transmissibility by the examined pool of infected dogs over 1 month

Effect of a moderate dietary fat supplementation on the digestive function in the horse

Supplementing athletic horses with fat to meet their high energy requirements may have a detrimental impact on the digestibility of fibre when fat was supplemented at the expense of an iso-energetic amount of non-structural carbohydrates (Jansen et al., 2000, 2002, 2007). The objective of this study was to determine the effect of a moderate fat supplementation on the total tract apparent digestibility and the colonic bacterial ecosystem. Six fistulated horses (449 +/- 33 kg) used in a double (3x3) Latin square experiment received a diet consisting of a forage-to-concentrate ratio of 67:33 on DM basis. Three fat concentrations were tested in the concentrate: 4.0, 7.0 and 8.8 % DM, respectively. Mean daily DM intake was 1.7% BW divided in two equal meals of hay and concentrate. The apparent digestibility (DM, TDF, NDF, ADF, Fat) was measured by total collection of faeces during 5 days. The anaerobic flora (total, cellulolytic, amylololytic, lacticolytic) and VFA concentrations and pH were determined in the colonic content collected 4 hours after the morning meal. The total fat intake 42, 59 and 69 g/100 kg BW for the rations composed of 4.0, 7.0 and 8.8% of fat in the concentrate. The digestibilities of DM, fat, TDF, NDF and ADF were not altered by the fat supplementation. In agreement with Jansen et al. (2007), the pH, total and cellulolytic bacterial concentrations in the content of the hindgut were not modified. Consequently, a moderate fat supplementation increased the energetic supply without any adverse effects on the hindgut ecosystem.vo

New molecular approach for the detection of Kinetoplastida parasites of medical and veterinary interest

Kinetoplastids are protozoa containing a range of ubiquitous free_living species-pathogens of invertebrates, vertebrates and even some plants. Some of them are causative agents of canine vector-borne diseases. Their diagnosis is often missing in a gold standard. Here, we proposed a molecular approach for the diagnosis and study of Kinetoplastida. The TaqMan qPCR assays target the following genes: 24Sa LSU of Kinetoplastida, 28S LSU of Leishmania/Trypanosoma spp., 5.8S rRNA of Trypanosoma spp., 18S SSU of Leishmania spp., kinetoplast minicircle DNA (kDNA) of L. donovani complex and kDNA of L. infantum, were designed, validated for their sensitivity (Se) and specificity (Sp) in silico and in vitro using a panel of known DNAs. They were then used to screen 369 blood samples (358 dogs, 2 equids, 9 monkeys). In addition, new 28S LSU primer sets are presented to use for Kinetoplastida's identification by PCR/sequencing. All qPCRs showed consistently high analytical sensitivities and reproducibility. They detect approximately 0.01 parasite/mL blood for the kDNA based-qPCRs and at least a single cell-equivalent of rDNA for the other systems. Based on the sequencing results, after screening, Se and Sp were: 0. 919 and 0.971, 0.853 and 0.979, 1.00 and 0.987, 0.826 and 0.995 for all of Kinetoplastida, Leishmania/Trypanosoma, Trypanosoma, Leishmania spp. specific qPCRs, respectively. kDNA based qPCRs were more sensitive and specific (Se: 1.00; Sp: 0.997). PCR/sequencing allowed the detection of Kinetoplastids in animal blood samples such as L. infantum, L. guyanensis, T. congolense, T. evansi and Bodo spp. The molecular approach proposed here is useful for epidemiological studies, fundamental research such as screening for new Kinetoplastida species, diagnosis and therapeutic follow-up. In addition, researchers are free to choose the molecular tools adapted to their aims

Impact of barley form on equine total tract fibre digestibility and colonic microbiota

International audienceThis study aimed at assessing the impact of four barley forms on total tract apparent digestibility of dietary fibre in horses fed a large amount of starch in the morning meal (0.27% BW). Processed barley forms had a greater pre-caecal starch digestibility than the whole form. Based on this result, we hypothesised that using barley-processing methods would limit the potential dumping of undegraded starch in the hindgut of horses and, consequently, the potential negative effect on fibre degradation in the hindgut. In a 4×4 latin square design, four mature geldings fitted with a right ventral colon-fistula were fed a meadow hay : concentrate (62 : 38; dry matter (DM) basis) diet at 1.7% BW. The concentrate was made of 80% barley distributed either as whole grain or as processed forms: 2.5 mm ground, pelleted or steam-flaked. For each period, total tract apparent digestibilities of DM, NDF and ADF were determined over 3 consecutive days by total faecal collection, whereas pH, volatile fatty acids (VFA) concentrations and cultural functional bacteria counts (total anaerobic, cellulolytic bacteria, lactic acid producers, amylolytic bacteria and lactic acid utilisers) in colonic content were evaluated on 1 day 4 h after the morning meal. Total tract apparent digestibility of DM and dietary fibre was influenced (P<0.05) by barley form. Diets including thermo-mechanically treated barley forms led to a higher (P<0.05) total tract apparent digestibility of NDF than those constituted of ground barley and also led to a greater (P<0.05) total tract apparent digestibility of ADF than those made of whole or ground barley forms. However, no significant difference was observed in colonic pH, VFA concentrations and cultural bacteria concentrations. Owing to a high starch supply in the morning meal, the concentration of the functional bacteria in the colonic content averaged 7.8 log CFU/ml, 5.9 NPM/ml, 6.9 and 7.3 CFU/ml for total anaerobic, cellulolytic, amylolytic and lactic acid-utilising bacteria, respectively. Consequently, providing horses with pelleted or steam-flaked instead of ground barley forms may limit the negative impact of starch on fibre digestibility in horses fed a high level of starch in the morning meal (0.27% BW). Moreover, the fibre-to-starch ratio fed in this experiment did not cause any digestive upset

Assessment of the anti-feeding and insecticidal effects of the combination of dinotefuran, permethrin and pyriproxyfen (Vectra\textregistered 3D) against Triatoma infestans on rats

International audienceno abstrac

Assessment of the anti-feeding and insecticidal effects of the combination of dinotefuran, permethrin and pyriproxyfen (Vectra((R)) 3D) against Triatoma infestans on rats

International audienceThis study, based on the rat model, was designed to explore the anti-feeding and insecticidal efficacy of a topical ectoparasiticide, dinotefuran-permethrin-pyriproxyfen (DPP), against Triatoma infestans (Hemiptera: Reduviidae), a vector of Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae), for which dogs are domestic reservoir hosts. Twenty rats were divided into two equal groups: untreated and treated. Each rat was exposed under sedation to 16 T.infestans of mixed life stages for 1h on days 1, 7, 14, 21 and 28 post-treatment. The anti-feeding and insecticidal effects of DPP were estimated after 1h of exposure. Insecticidal efficacy was also assessed after incubation of the insects for 24h post-exposure. Anti-feeding efficacy was 96.7, 84.7, 80.5, 81.5 and 42.6% on days 1, 7, 14, 21 and 28, respectively. Insecticidal efficacy evaluated at 1 and 24h after exposure on days 1, 7, 14, 21 and 28 was 100, 91.2, 82.5, 80.0 and 29.1, and 100, 100, 100, 96.0 and 49.9%, respectively. This study demonstrates that a single administration of DPP spot-on treatment at a dose equivalent to the minimal recommended dose in rats has a powerful effect against T.infestans starting from day1 that lasts for at least 3weeks