Prevalence of internal parasites in beef cows in the United States: Results of the National Animal Health Monitoring System's (NAHMS) beef study, 2007-2008.

During the United States Department of Agriculture (USDA) National Animal Health Monitoring System's (NAHMS) 2007-2008 beef study, 567 producers from 24 US States were offered the opportunity to collect fecal samples from weaned beef calves and have them evaluated for the presence of parasite eggs (Phase 1). Participating producers were provided with instructions and materials for sample collection. Up to 20 fresh fecal samples were collected from each of the 99 participating operations. Fresh fecal samples were submitted to one of 3 randomly assigned laboratories for evaluation. Upon arrival at the laboratories, all samples were processed for the enumeration of strongyle, Nematodirus, and Trichuris eggs using the modified Wisconsin technique. The presence or absence of coccidian oocysts and tapeworm eggs was also noted. In submissions where the strongyle eggs per gram exceeded 30, aliquots from 2 to 6 animals were pooled for DNA extraction. Extracted DNA was subjected to genus level polymerase chain reaction (PCR) identification for the presence of Ostertagia, Cooperia, Haemonchus, Oesophagostomum, and Trichostrongylus. In this study, 85.6% of the samples had strongyle type, Nematodirus, and Trichuris eggs. Among the samples evaluated, 91% had Cooperia, 79% Ostertagia, 53% Haemonchus, 38% Oesophagostomum, 18% Nematodirus, 7% Trichuris, and 3% Trichostrongylus. The prevalence of coccidia and tapeworm eggs was 59.9% and 13.7%, respectively.

Pendant l'étude de 2007­2008 chez les bovins effectuée par le Système national de surveillance des maladies animales (NAHMS) du Département de l'agriculture des États-Unis (USDA), 567 producteurs provenant de 24 états américains se sont vus offrir l'opportunité de prélever des échantillons de fèces de veaux sevrés et de les faire analyser pour la présence d'oeufs de parasite (Phase 1). On a fourni aux producteurs participants les instructions et le matériel pour le prélèvement d'échantillon. Jusqu'à 20 échantillons de fèces fraiches furent prélevés de chacune des 99 opérations participantes. Les échantillons de fèces fraiches furent soumis de manière aléatoire pour évaluation à l'un des trois laboratoires participants. Suite à l'arrivée au laboratoire, tous les échantillons étaient traités pour énumération des strongles, de Nematodirus, et d'oeufs de Trichuris en utilisant la technique de Wisconsin modifiée. La présence ou l'absence d'ookystes de coccidie et d'oeufs de vers plats furent également notées. Dans les échantillons soumis et dont le nombre d'oeufs de strongles par gramme dépassait 30, des aliquots de 2 à 6 animaux étaient regroupés pour extraction de l'ADN. L'ADN extrait était soumis à une réaction d'amplification en chaine par la polymérase (PCR) pour une identification au genre de la présence d'Ostertagia, de Cooperia, d'Haemonchus, d'Oesophagostomum, et de Trichostrongylus. Dans la présente étude, 85,6 % des échantillons avaient des strongles, du Nematodirus, et des oeufs de Trichuris. Parmi les échantillons évalués, 91 % avaient du Cooperia, 79 % de l'Ostertagia, 53 % de l'Haemoncus, 38 % de l'Oesophagostomum, 18 % du Nematodirus, 7 % du Trichuris, et 3 % du Trichostrongylus. Les prévalences de coccidies et d'oeufs de vers plats étaient respectivement de 59,9 % et 13,7 %.(Traduit par Docteur Serge Messier).

Effectiveness of current anthelmintic treatment programs on reducing fecal egg counts in United States cow-calf operations.

During the United States Department of Agriculture (USDA) National Animal Health Monitoring System's (NAHMS) 2007-2008 beef study, producers from 24 states were offered the opportunity to evaluate their animals for internal parasites and for overall responses to treatment with anthelmintics. A lapse of 45 d was required between initial sampling and any previous treatments. Choice of anthelmintic (oral benzimidazoles, and both injectable and pour-on endectocides) was at the discretion of the producer so as not to alter the local control programs. Fresh fecal samples were collected from 20 animals, or from the entire group if less than 20, then randomly assigned to 1 of 3 participating laboratories for examination. Analyses consisted of double centrifugation flotation followed by enumeration of strongyle, Nematodirus, and Trichuris eggs (the presence of coccidian oocysts and tapeworm eggs was also noted). Where strongyle eggs per gram (epg) exceeded 30, aliquots from 2 to 6 animals were pooled for egg isolation and polymerase chain reaction (PCR) analysis for the presence of Ostertagia, Cooperia, Haemonchus, Oesophagostomum, and Trichostrongylus. Results from 72 producers (19 States) indicated that fecal egg count reductions were < 90% in 1/3 of the operations. All operations exhibiting less than a 90% reduction had used pour-on macrocyclic lactones as the anthelmintic treatment. While some of these less than expected reductions could have been the result of improper drug application, PCR analyses of the parasite populations surviving treatment, coupled with follow-up studies at a limited number of sites, indicated that less than expected reductions were most likely due to anthelmintic resistance in Cooperia spp. and possibly Haemonchus spp.

Pendant l'étude de 2007­2008 chez les bovins effectuée par le Système national de surveillance des maladies animales (NAHMS) du Département de l'agriculture des États-Unis (USDA), des producteurs provenant de 24 états américains se sont vus offrir l'opportunité de faire évaluer leurs animaux pour la présence de parasites internes et pour leur réponse globale à un traitement avec des anthelminthiques. Un délai de 45 j était requis entre l'échantillonnage initial et un traitement antérieur. Le choix d'un anthelminthique (benzimidazole oral, et des endectocides injectables et en solution à verser) était à la discrétion du producteur afin de ne pas altérer les programmes de contrôle locaux. Des échantillons de fèces fraiches ont été prélevés de 20 animaux, ou de tout le groupe si moins de 20, puis ils ont été acheminés de manière aléatoire à un des trois laboratoires participants pour fin d'examen. L'analyse consistait en une double centrifugation par flottaison suivie d'une énumération des strongles, de Nematodirus, et d'oeufs de Trichuris (la présence d'ookystes de coccidie et d'oeufs de vers plats fut également notée). Lorsque le nombre d'oeufs de strongles par gramme dépassait 30, des aliquots de 2 à 6 animaux étaient regroupés pour isolement des oeufs et et soumis à une réaction d'amplification en chaine par la polymérase (PCR) pour détecter la présence d'Ostertagia, de Cooperia, d'Haemonchus, d'Oesophagostomum, et de Trichostrongylus. Les résultats provenant de 72 producteurs (19 états) indiquent que les réductions dans le dénombrement des oeufs dans les fèces étaient de < 90 % dans le tiers des opérations. Toutes les opérations montrant une réduction de moins de 90 % avaient utilisé des lactones macrocycliques en solution à verser comme traitement anthelminthique. Alors que certaines de ces réductions moindres que prévues puissent être le résultat d'une mauvaise application du produit, les analyses par PCR des populations de parasites survivantes au traitement, combinées aux études de suivis à un nombre limité de sites, indiquent que les réductions moindres que prévues étaient fort probablement dues à la résistance aux anthelminthiques chez Cooperia spp. et possiblement Haemonchus spp.(Traduit par Docteur Serge Messier).

Outbreak of Trichinella spiralis infections associated with a wild boar hunted at a game farm in Iowa.

BACKGROUND: Rates of trichinellosis have declined significantly in the United States due to improved pork production practices and public awareness of the danger of eating raw or undercooked pork. In April 2011, the Minnesota Department of Health received a report of presumptive trichinellosis in a 50-year-old man with a history of wild boar consumption. A public health investigation was initiated. METHODS: Medical record reviews and patient and family interviews were conducted. Trichinella species serology was performed on patient and family serum samples, and larval identification was attempted on clinical specimens and meat samples. RESULTS: The index patient harvested a wild boar from an Iowa game farm; he processed the meat after returning home and developed gastrointestinal symptoms 2 days later. Four days after his illness onset, all 5 family members consumed a roast from the boar. The index patient sought healthcare 4 times after illness onset before being definitively diagnosed with trichinellosis. Following initiation of albendazole therapy, the index patient developed atrial fibrillation. One additional family member who processed the raw meat was diagnosed with trichinellosis. Trichinella spiralis larvae were identified in wild boar meat samples. CONCLUSIONS: Trichinellosis has long been recognized as a potential hazard of consuming undercooked wild carnivore meat, and historically has been associated with consumption of pork from domestic swine, but may be unfamiliar to practicing clinicians in the United States. Education of hunters and the broader population on the potential for trichinellosis and the importance of proper handling and cooking meat from wild or free-range animals needs to be reinforced.

Cooperia punctata: effect on cattle productivity?

Cooperia spp. have become the most prevalent parasites in United States cow/calf operations as observed in the USDA NAHMS (National Animal Health Monitoring System) Beef Cow/Calf survey in 2008. This is at least in part due to the widespread use of macrocyclic lactones that have recently been shown to have a reduced activity against these parasites. The effects of Cooperia spp. on cattle productivity are largely unknown. This study was conducted to assess their effect upon cattle housed under conditions found in American feedlots. Two hundred yearling calves (average weight 460 lb/209 kg) were acquired from northwestern Arkansas and northeastern Oklahoma and were vaccinated and dewormed upon arrival at the feedlot. Animals were comingled and preconditioned for approximately one month, and were fed a standard growing ration throughout the study. Calves were randomly divided into two groups (n=80, infected and control) and each group was further divided into two replicate pens (n=40). Calves from the two infected pens were orally inoculated with a gavage of 1 × 10(5) and 0.825 × 10(5) infective larvae of a recent isolate of Cooperia punctata on day 0 and 14, respectively, with the two control pens receiving a similar volume of tap water. Data collected included biweekly fecal egg counts, daily individual feed consumption and weight gain over the 60-day test period. The presence of C. punctata (>99% of recovered worms) was confirmed by necropsy and recovery from the small intestine on days 35 and 60 post infection (PI) in a subset of animals. Egg counts were positive by day 14 PI and remained at numbers similar to values seen in field studies. The control group gained weight 7.5% more rapidly (p=0.02) than infected animals (3.24 lb/1.47 kg per day vs. 3.0 lb/1.36 kg per day, respectively). The Cooperia-infected calves also consumed 1.5 lb (0.68 kg) less dry feed per day than the control animals (p=0.02). These data suggest that C. punctata has a deleterious effect on both appetite and nutrient uptake or utilization. At necropsy (days 35 and 60), the draining mesenteric lymph nodes of infected animals were increased in size and the small intestinal mucosa was thickened and covered with a thick layer of mucus in the infected animals. The most prominent histological changes in the Cooperia- infected animals included a moderate increase in the number of intraepithelial lymphocytes and globule leukocytes, as well as aggregates of eosinophils within the lower lamina propria. The only significant difference was an increase in the goblet cell density at day 60. Anthelmintic sensitivity/resistance of the Cooperia isolate used was determined by treatment of one pen of infected calves with a macrocyclic lactone and the other pen with a benzimidazole at the completion of the study. The macrocyclic lactone treatment (n=40) did not remove the parasites (FECRT=8.8%), while treatment with a benzimidazole was very effective (FECRT=98.1%). This study demonstrated that C. punctata has a significant effect on cattle productivity, both reduced weight gain and decreased feed intake compared to controls.

Pulmonary trematodosis (Pharyngostomoides sp.) in a juvenile raccoon (Procyon lotor).

A lethargic, wild, juvenile raccoon died and was subsequently presented for necropsy. The lungs had widely disseminated, finely granular, yellow-tan foci with moderate pulmonary, as well as, thoracic lymphadenopathy. Histopathology revealed numerous cross-sections of larval trematodes morphologically consistent with diplostomid mesocercariae and metacercariae as well as moderate alveolointerstitial pneumonia with a mixed population of eosinophils, macrophages, lymphocytes, and plasma cells. The presence of larval trematodes within lymphatics in multiple organs indicates a route of fluke migration. Live specimens of mesocercariae and metacercariae recovered from refrigerated lung tissue after 7 days were identified as Pharyngostomoides sp., an intestinal diplostomid parasite (trematode) of raccoons and other mammals that is similar in appearance and life cycle to Alaria spp.

Veterinarians in biomedical research: building national capacity.

This Executive Summary provides the conclusions from the presentations and discussions at the conference Veterinarians in Biomedical Research-Building National Capacity, a meeting coordinated by the AAVMC and held at the National Institutes of Health (NIH), Bethesda, MD, August 1-4, 2007.

Parasite control in calves and growing heifers.

Parasite control in calves and growing heifers results in animals that grow faster and remain healthier. Control programs revolve around reducing the parasites (infective stages) in the environment. In confinement, sanitation removes or reduces the number of infective stages (oocysts, cysts, and infective larvae) and the infection rate. On pasture one must resort to pasture management and parasite removal. The mites and lice are generally controlled by reducing or removing the populations on the animals, preventing the spread. Environmental control and manure management impact the fly populations.

Gastrointestinal nematode control programs with an emphasis on cattle.

Control strategies for nematode parasites rely on knowledge of the relationships between the parasites and their hosts. Specifically, these programs are based on identifying crucial points of interaction in the environment provided by the host, including genetics and the immune response, and critical periods in the physical environment in which the eggs and larval stages must develop. When these targets are identified and the interactions understood, cost-effective sustainable programs can be developed using currently available antiparasitic compounds. Resistance to the major classes of anthelmintic compounds requires consideration of new approaches, such as immunity or genetics of the host. Additionally, the efficacy of these compounds can be expanded with combined or concomitant use. Increased study of the use of novel approaches, including fungi, elements such as copper, and plant products, has also occurred. This article explores each of these areas to allow readers to appreciate how various approaches may be developed and incorporated into an effective parasite control program.

Evaluation of efficacy expectations for novel and non-chemical helminth control strategies in ruminants.

The interest in novel methods of controlling helminth infections in ruminants is driven primarily by the development of parasite resistance to currently available anthelmintics. While the purpose of anthelmintics is to achieve high efficacy, i.e. >90% reduction of adult and/or larval parasites in the target host animal, the purpose of novel parasite control methods is rather to assist in maintaining parasite infections below the economic threshold. The ability to maintain parasite levels below the economic threshold is related not only to the efficacy of the control method, but also to the epidemiology of the parasites, climatic conditions, the livestock management program, and integration in a sustainable parasite control program. Because of this fundamental difference, novel parasite control methods need to be evaluated using efficacy criteria different from that adopted for anthelmintics. Although the efficacy of novel parasite control methods may be demonstrated in classic dose-confirmation studies, the impact on livestock production parameters can only be evaluated when tested on-farm. In this paper, the rationale for evaluating novel methods differently from anthelmintics is reviewed, potential performance expectations are presented, and four novel parasite control methods (vaccines, nematophagous fungi, condensed tannins, and immunonutrition) are assessed based on the potential performance criteria.

Epidemiologic features of Campylobacter infection among cats in the upper midwestern United States.

OBJECTIVE: To describe the epidemiologic features of Campylobacter infection among cats in the Minneapolis-Saint Paul metropolitan area. DESIGN: Prevalence survey. ANIMALS: 152 cats examined at 3 private veterinary clinics and an animal humane society. PROCEDURES: Fecal samples were submitted for bacterial culture for Campylobacter spp. To determine the duration of Campylobacter carriage, follow-up fecal samples were collected from cats with positive Campylobacter culture results. RESULTS: Campylobacter organisms were cultured from 37 of the 152 (24%) fecal samples. Campylobacter isolates were identified as Campylobacter upsaliensis (29 cats), Campylobacter jejuni (2), and Campylobacter coli (1); species of the remaining 5 isolates could not be determined. Campylobacter organisms were isolated from 36 of the 122 (30%) cats that were < or = 1 year old but from only 1 of the 30 (3%) cats that were > 1 year old, and shedding was more common during the summer and fall months. No association between Campylobacter shedding and clinical signs of disease was identified. For 4 of 13 cats from which follow-up fecal samples were obtained, duration of Campylobacter carriage could not be determined because Campylobacter organisms were isolated from all follow-up samples. For the remaining 9 cats, median duration of Campylobacter carriage was 44 days. CONCLUSIONS AND CLINICAL RELEVANCE: C. upsaliensis can commonly be isolated from the feces of overtly healthy kittens in the Midwest United States. Because carriage may be prolonged, veterinarians should encourage good hand hygiene among owners of cats, especially among owners with new kittens in their household.

Teaching veterinary parasitology: the North American perspective.

The American Association of Veterinary Parasitologists (AAVP) initiated a study of parasitology curricula in veterinary schools in the US and Canada in November 1989. An ad hoc committee (Task Force) and then the Education Committee developed a position paper on teaching parasitology in veterinary colleges. In addition to confirming the importance of parasitology as a discipline they recommended a set of general learning objectives and proposed topic-specific titles rather than parasite-/group-specific titles. Another problem observed in teaching parasitology was a significant reduction in time available to teach parasitology. One way to compensate for the lost classroom time is to utilize some of the technological advances in presenting the material to students.