Cattle besnoitiosis due to
Besnoitia besnoiti
is spreading across Europe and is responsible for severe economic losses in newly infected herds. Experimentally speaking, rabbits have been found to be ...susceptible to this parasite. The adaptation of
B. besnoiti
to rabbits may offer a new, easier and cheaper model of investigation for this disease. This study compared the virulence between tachyzoites and bradyzoites of
B. besnoiti
in rabbits. Eighteen New Zealand rabbits were allocated into three groups of six animals each. The rabbits from the control (group C), “tachyzoite” (group T) and “bradyzoite” (group B) groups were subcutaneously injected in the right flank with 66 μg of ovalbumin, 6.10
6
tachyzoites (125th passage on Vero cells) and 6.10
6
bradyzoites (collected from a natural infected cow) of
B. besnoiti
, respectively. Clinical follow-up and blood sampling for serological survey and qPCR were performed during 10 weeks until euthanasia. Molecular and immunohistochemistry examination was achieved on 25 samples of tissue per rabbit. Seroconversion occurred in group T without any clinical signs. Rabbits of group B exhibited a febrile condition (temperature above 40 °C from day 8 to day 11 following injection) with positive qPCR in blood. Cysts of
B. besnoiti
were found on skin samples and organs of rabbits from group B in tissue explored with threshold cycle (Ct) values below 30. These results suggest a higher virulence of bradyzoites in rabbits than Vero cell-cultivated tachyzoites. The proposed model could be used to assess the in vivo effectiveness of vaccine or drugs against cattle besnoitiosis.
Bovine besnoitiosis (BB) is a chronic and debilitating parasitic disease in cattle caused by the protozoan parasite Besnoitia besnoiti. South European countries are affected and have reported ...clinical cases of BB. However, BB is considered as emerging in other countries/regions of central, eastern and northern Europe. Yet, data on drivers of emergence of BB in Europe are scarce. In this study, fifty possible drivers of emergence of BB in cattle were identified. A scoring system was developed per driver. Then, the scoring was elicited from eleven recognized European experts to: (i) allocate a score to each driver, (ii) weight the score of drivers within each domain and (iii) weight the different domains among themselves. An overall weighted score was calculated per driver, and drivers were ranked in decreasing order of importance. Regression tree analysis was used to group drivers with comparable likelihoods to play a role in the emergence of BB in cattle in Europe. Finally, robustness testing of expert elicitation was performed for the seven drivers having the highest probability to play a key role in the emergence of BB: i.e., (i) legal/illegal movements of live animals from neighbouring/European Union member states or (ii) from third countries, (iii) risk of showing no clinical sign and silent spread during infection and post infection, (iv) as a consequence, difficulty to detect the emergence, (v) existence of vectors and their potential spread, (vi) European geographical proximity of the pathogen/disease to the country, and (vii) animal density of farms. Provided the limited scientific knowledge on the topic, expert elicitation of knowledge, multi-criteria decision analysis, cluster and sensitivity analyses are very important to prioritize future studies, e.g., the need for quantitative import risk assessment and estimation of the burden of BB to evidence and influence policymaking towards changing (or not) its status as a reportable disease, with prevention and control activities targeting, firstly, the top seven drivers. The present methodology could be applied to other emerging animal diseases.
An outbreak of trypanosomosis was observed for the first time in metropolitan France in October 2006, when five camels were proved to be infected by Trypanosoma evansi using parasitological methods. ...The parasite was isolated and used to produce a soluble antigen for antibody–enzyme linked immunosorbent assay (ELISA) in a protocol derived from a method previously developed for sheep and humans but using protein A conjugate. The animals were treated on three instances, alternatively with melarsomine hydrochloride and quinapyramine and followed up on a monthly basis for 2 years with various diagnostic techniques including parasitological, serological and DNA-based methods. Initially, five animals were detected as being positive using ELISA with 83.3% concordance to parasitological tests. Immediately after the first treatment, parasites and DNA disappeared in all animals; antibody levels decreased regularly until ELISA became negative 3–4 months later. Ten months after the first treatment, parasites and antibodies were detected again in one of the camels previously found to be infected. A retrospective study indicated that the weight of this animal had been underestimated; consequently, it had received underdosages of both trypanocides. However, since hypotheses of re-infection or relapse could not be fully substantiated, it is not known whether the ELISA results for this animal were true- or false-negative over a 7-month period. The study confirmed the value of this ELISA using protein A conjugate to detect antibodies directed against T. evansi in camels and the need to use several diagnostic techniques to optimize detection of infected animals. A warning is raised on surra, a potentially emerging disease in Europe.
L’extension de la résistance des nématodes gastro-intestinaux aux anthelminthiques, récemment observée pour Haemonchus contortus, représente un réel problème et rend urgente la recherche de solutions ...alternatives comme la sélection d’animaux résistants aux helminthes. Tous les cas d’infestations expérimentales mettent en évidence une variabilité individuelle importante dans les excrétions d’oeufs, discriminant bien les individus résistants et les individus sensibles, ce qui permet d’envisager la sélection d’individus résistants dans les races étudiées. Toutefois, la méconnaissance des mécanismes de la réponse immunitaire des ovins vis-à-vis de ces strongles reste un obstacle au développement de cette sélection. Il est acquis que le niveau d’excrétion d’oeufs de parasites dans les matières fécales représente un indicateur pertinent pour évaluer la résistance d’un animal aux strongles. Ce critère a été examiné lors de la présente étude, réalisée avec deux races ovines françaises, la Martinik Black Belly (résistante) et la Lacaune (sensible). Les animaux ont été infestés par voie orale avec une seule dose de 10 000 larves L3 d’H. contortus. La réponse des ovins a fait l’objet d’un suivi lors d’examens ante mortem et post mortem. Les résultats ont montré clairement qu’au cours d’une primo-infestation par H. contortus il y avait une différence significative entre les populations parasitaires (intensité parasitaire et production d’oeufs) et entre certains paramètres physiopathologiques (éosinophilie sanguine et tissulaire) observés chez ces deux races ovines.
Culex pipiens is an important vector of pathogens of substantial medical and veterinary importance such as Dirofilaria immitis and Dirofilaria repens or the West Nile Virus. The control of these ...mosquitoes is therefore essential to control the transmission of mosquito-borne agents to humans and animals. A combination of dinotefuran, permethrin and pyriproxyfen (Vectra® 3D) has already shown its efficacy against Aedes aegypti. The aim of this study was to confirm the efficacy of this combination in repelling and killing another species of mosquito, Culex pipiens, after a single topical application to dogs.
Twelve adult Beagle dogs with an equal receptivity to mosquitoes were included in the study and divided in two groups of six dogs: an untreated control group and a group treated with a combination containing 54mg/mL dinotefuran +4.84mg/mL pyriproxyfen +397mg/mL permethrin (Vectra® 3D). All dogs were challenged with 80 Culex pipiens females for 90±5min on Days - 28, 1, 7, 14, 21 and 28. The treatment was applied once topically on Day 0. Count and engorgement determination of dead and live mosquitoes were performed after each exposure to treated and untreated dogs.
Compared to control dogs, the spot-on formulation provided a repellent efficacy (anti-feeding effect) against mosquitoes of 98.9%, 98.8%, 98.6%, 96.7% and 97.9% on Days 1, 7, 14, 21 and 28 respectively. There was a significant difference (p≤0.05) between the treated and controlled groups on every assessment day. The insecticidal efficacy on treated dogs at 90min was 34.7%, 50.3%, 39.7%, 22.8% and 11.4% on Days 1, 7, 14, 21 and 28 respectively. There was a significant difference between the treated and controlled groups for live mosquitoes for all assessment days (p<0.05).
A single topical application of a combination of dinotefuran, permethrin and pyriproxyfen showed a significant repellent effect (i.e. >96%) against Culex pipiens which lasted for 28days. The results suggest that the Vectra® 3D spot-on solution could be used as an effective mosquito control strategy in dogs and is therefore recommended for use in a dirofilariosis prevention programme.
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•Dung beetles’ phoretic mites may act as predators of Haemonchus contortus larvae.•In vitro, these mites can reduce the development of this pathogenic nematode.•Controlling the ...nematode Haemonchus contortus through its free living stages.
Worldwide increasing levels of anthelmintic resistance are pushing farmers and health advisors towards a more sustainable management of gastrointestinal nematodes (GIN), one of the greatest threats to the viability of grazing small ruminant production systems, and to these animals’ welfare. These Strongyloidea develop freely in livestock dung, where they are exposed to predatory organisms that can eventually break their cycle. The aim of this study was to investigate the effect of phoretic mites of dung beetles Macrocheles sp. (Macrochelidae) on the gastrointestinal nematode Haemonchus contortus (Rudolphi, 1803) that has a free-living larval stage that evolves in sheep feces. Direct observations under a stereomicroscope confirmed that the studied Macrocheles mites may have an active predatory behavior on the third-stage (L3) larvae of H. contortus. In order to quantify the effects of the mites’ predation on the survival of L3 nematode larvae, we designed experimental units, replicated across five trials, and containing free-living stages of the nematode either in the presence or absence of mites. The number of H. contortus larvae that reached the third-stage was significantly reduced in the presence of mites, despite a variable intensity of the predatory effects between trials. This is the first report of a predatory activity of phoretic mites of dung beetles’ on a livestock gastrointestinal nematode. This first step encourages further studies in order to have a better quantification of this interaction, and to investigate to which extent the phoretic mites of dung beetles can impact H. contortus populations in natural conditions.
Dicrocoeliosis is a common parasitic disease in European sheep farming. The prevalence of infection by this parasite can reach almost 70% in areas where the environment is favorable to intermediate ...hosts. In France, only one drug is currently available for the treatment of dicrocoeliosis: albendazole at a dose of 15 mg/kg in a single administration. However, a control coproscopy following a routine treatment led us to suspect that the efficacy of albendazole against Dicrocoelium dendriticum had diminished. Therefore, we carried out an efficacy test on 15 animals by treating them with albendazole at a dose of 15 mg/kg and performing a coproscopy on D0 and a control coproscopy 14 days later. We obtained a 39% reduction in the excretion of D. dendriticum eggs. This shows a reduction in the expected efficacy of albendazole, which is normally more than 90% in other studies involving this molecule at a dosage of 15 mg/kg. These results are of major concern as albendazole is currently the only drug available in France to treat dicrocoeliosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Mixed-grazing by sheep and cattle is the simultaneous or sequential grazing of a pasture by the two species. It is an agroecological practice known to improve lamb liveweight gains through parasite ...dilution (PD) and/or forage niche sharing (FNS).
We assessed the combined and relative strengths of the two mechanisms by developing a metabolic approach (French uplands context).
We used recently published equations to model the infection cost of gastrointestinal nematodes in metabolizable energy (ME), and crude protein (CP). By comparing infection levels in mixed and monospecific grazing, we quantified the gains of PD in ME and CP. We also used feed value tables to assess the gains in ME and CP resulting from FNS sheep diet improvement. We interpreted these gains in light of ME and CP requirements of lambs. We applied this approach to the dataset of a mixed-grazing experiment, involving sheep monospecific grazing and mixed sheep/cattle grazing, without veterinary treatment. We also applied it to a generic situation where we studied the relative gains in ME and CP, along gradients of increasing strength of PD and FNS.
The approach applied to our experimental data revealed that i) infection by gastrointestinal nematodes can represent 100% of ME and 57% of CP requirements in monospecific grazing, ii) mixed-grazing can reduce these costs to 23% and 12%, respectively and iii) PD was more important than FNS in terms of ME gains, whereas the opposite was true for CP. However, meeting CP requirements was less constraining than meeting ME requirements on the studied grassland type, which puts into perspective the importance of CP gains. With the generic approach, most of the modelled situations also identified PD as the main mechanisms of ME gain (79%), whereas it was FNS for CP (70%), with the same observation that CP requirements were less difficult to meet. Both approaches suggest that in our modelled context, PD matters more often than FNS in mixed-grazing, due to the greater difficulty in meeting ME requirements.
We proposed a novel approach to assess the roles of two biological mechanisms of contrasting nature, with the help of common metrics. This approach made it possible to evaluate their combined and relative strength. It has the potential to improve our understanding of the impact of interacting biological mechanisms involved in agroecological grazing systems, and identify prominent ones.
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•Sheep/cattle mixed grazing can improve lamb liveweight gain through forage niche sharing (FNS) and/or parasite dilution (PD).•We modelled the gains for lambs in terms of metabolizable energy (ME) and crude protein (CP) from PD and FNS.•Gains in ME from PD were often higher than those from FNS, whereas the opposite was true for CP.•ME requirements are the most difficult to cover, which suggests a prominent role of PD in sheep/cattle mixed-grazing.•Using common metabolic metrics helped assess the relative weights of biological mechanisms of contrasting nature.
•The majority of 38.6 million heads of one-humped camel (Camelus dromedarius) in the world occur in Africa.•Camels represent the first source of food and income for millions of pastoralists.•Surra in ...camels is one of the most important constraints in the economy of many African populations.•We argue that control of surra in Africa is affordable and recommend using the PCP approach.•We also propose that methods to control gastrointestinal parasitosis and sarcoptic mange will support improved surra control in camels.
With an increasing worldwide population that presently exceeds 38 million, camels are important source of meat, milk, and transportation of goods, in many regions of the world. Camels are particularly critical in the northern parts of Africa, above the tsetse belt. However, camel breeding areas are expanding into southern areas, under the pressures of global warming, leading to increasing risk of acquiring parasitic infections in these non-traditional ecotypes. Common biting flies (tabanids, stomoxyine flies, and Hippobosca camelina) act as mechanical vectors, resulting in exposure to trypanosomosis (Trypanosoma evansi; Surra) and high camel morbidity and mortality. In these regions, complicating infections with other Trypanosoma may also occur, particularly Trypanosoma vivax. In many modern camel-breeding areas, human populations are living under political upheaval (terrorism, riots), poverty, and precarity (drought, climate modification). Hence, control and/or elimination of Surra in camels would be beneficial to the economies of these populations. Due to the relatively straightforward epidemiology (single parasite with seasonal transmission in a single host species), control of Surra in Africa is affordable and should be based on implementing: (1) national veterinary services capabilities; (2) efficient diagnosis and control methods; (3) joint integrated control of Surra, gastrointestinal helminthoses (mainly haemonchosis), and sarcoptic mange. We propose that methods to control two economically-critical disease problems, gastrointestinal parasitosis and sarcoptic mange, will support improved Surra control in camels. Aided by decision-makers and donors, elimination of Surra could improve camel health and productivity, and stabilize camel-rearing in regions of the world that suffer from political instability and global warming pressures.
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.
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