Nematode Infections In Cattle Research Articles

Epidemiological survey of gastrointestinal infections by gastrointestinal nematodes and coccidia in cattle in the semiarid region of Northeastern Brazil

The aim of the present study was to carry out an epidemiological survey on gastrointestinal infections by nematodes and coccidia in cattle herds in the semiarid region of Paraíba, northeastern Brazil. A total of 832 cattle were sampled, of both sexes and different ages, on 21 farms in 21 municipalities in the state of Paraíba, Brazil. Fecal samples were collected individually to perform eggs per gram (EPG) and oocysts per gram (OoPG) counts in feces, and to perform fecal cultures. To assess factors associated with nematode and coccidia infections, epidemiological survey forms were applied to the farmers. The total frequency of infections by nematodes was 59.6% (496/832) and it was 36.9% (307/832) for coccidia. The levels of infection by nematodes and coccidia were most frequently low (EPG < 300; OoPG < 1,000), in 72.4% (359/496) and 75.2% (231/307), respectively. The most frequent nematode genera was Haemonchus spp. (78.8%). The risk factors for nematode infections in cattle were beef production trait (odds ratio = 2.99) and extensive rearing system (odds ratio = 3.8); the factors for coccidia were age ≤ 12 months (odds ratio = 2.9) and body score between 1 and 2 (odds ratio = 5.2). These results prove that there are high frequencies of gastrointestinal infections by nematodes and coccidia in cattle herds in the semiarid region of Paraíba, with predominantly low levels of infection. However, given the importance of subclinical infections, adjustments to sanitary management measures can contribute to reduction of parasite indices and better performance among the animals, thus generating greater profitability for farmers.

Studies on prevalence of GI nematodes in cattle in Udaipur, district (Rajasthan)

A study was conducted from Sept. 2020 to January 2021 in and around Udaipur district and the overall prevalence of for gastrointestinal nematode in the cattle of Udaipur district was reported. The Overall prevalence of GI nematode infection in cattle was (64.28%). Among various GI nematode infections reported in the present study, Strongyles (44.55%) were the most prevalent gastrointestinal nematode followed by Trichuris, Toxocara and Strongyloides. In cattle seasonal analysis revealed highest prevalence in rainy season (72.61%) and lowest in winter (39.62%). Sex wise observations that the females (67.39% and 58.33%) were more infected with GI nematode infection than the males cattle, respectively. The age wise prevalence of GI nematode infection reported highest prevalence in age group below 3 years (82.79%) followed by 3-5 years age group (55.07%) and above 5 years age group (41.66%) in cattle. Month wise GI nematode infection showed higher prevalence in September Month (75.92%) in cattle.

Anthelmintic Drugs: Their Efficacy and Cost-Effectiveness in Different Parity Cattle.

Gastrointestinal nematodes are responsible for economic losses in bovines and are characterized by reduced milk production, decreased working efficiency, and even death. In our study, the effect of different anthelmintic treatments on nematode control in different parity cattle (Friesian crossbreds) at calving and their effect on milk yield were evaluated. The economics of anthelmintics and farm benefits in terms of increased milk production after deworming was also calculated. We screened cattle of first and second parity for nematodes. Animals were randomly selected in each group. In first parity animals, there were 23 positive cattle found, which were divided into 3 different groups, while in second parity animals there were 20 positive cattle which were also divided into 3 groups. For treatment of gastrointestinal nematodes, we used albendazole (velbazine) at 10 mg/kg body weight and levamisole (Nilverm®) at 7.5 mg/kg. In this study, both drugs were found effective in controlling nematode infections in cattle. Percentage reduction of eggs per gram (EPG) by albendazole was 48.20, 85.34, and 93.90% and 51.54, 81.43, 91.74% on day 7, 14, and 21 in first and second parity animals, respectively. Percentage reduction of EPG by levamisole was 44.45, 76.92, and 88.03% and 46.60, 73.78, 85.43% on day 7, 14, and 21 in first and second parity animals, respectively. The average increase in milk production in albendazole-treated groups was 0.39 and 0.92 L per day while increases in levamisole treated groups were 0.27 and 0.55 L per day in first and second parity cattle, respectively. After treatment, albendazole increased the milk fat by 0.07 and 0.1% while levamisole decreased by 0.02 and 0.05% in first and second parity cattle, respectively. It is concluded that anthelmintic treatments of recently calved cattle have a significant effect on milk production due to the nematode control. Milk production increased significantly in second parity cattle following anthelmintic treatment as compared to first parity animals. Levamisole had a negative effect on fat concentration in cattle while albendazole-treated cattle showed a positive effect. Albendazole has been found more efficient in reducing EPG of helminths in both parity animals as compared to levamisole-treated animals while the cost-benefit ratio of levamisole was greater than albendazole.

An automated, multiplex-tandem PCR platform for the diagnosis of gastrointestinal nematode infections in cattle: An Australian-European validation study

Detecting the genera and species of gastrointestinal (GI) nematode infections in faecal samples obtained from cattle requires the incubation of faeces (‘larval culture’) followed by identification of the third-stage larvae that are harvested after 10–14days. Substantial research in the development of PCR-based methods for the rapid and specific identification GI nematodes has been conducted for small ruminants, whilst only few such assays have been developed for cattle. In the present paper we describe the development of an automated, robotic PCR platform for the detection and genus and/or species-specific identification of GI nematodes from bovine faecal samples. This test was then validated using samples from different regions of three countries (Australia, Belgium and Scotland). The PCR platform was found to be highly sensitive and specific for the identification of the important GI nematodes in naturally infected cattle (both estimates >90%). The PCR platform can also estimate the percentage of genera or species present in a mixed-species infection, and was found superior to larval culture in terms of speed (1–2days versus 1–2 weeks for culture), sensitivity and specificity. The PCR was simple to use and the operator requires no knowledge or experience to identify the nematodes present, compared to larval culture where even experienced operators can make substantial errors due to considerable overlap in the published characteristics of key species.

FAUNA OF GASTROINTESTINAL STRONGYLATES OF SHEEP AND GOATS ON THE TERRITORY OF THE CHECHEN REPUBLIC

Abstract . Aim. Livestock is one of the main sources of protein human nutrition. Helminthiases infections are one of the limiting factors in animal husbandry. The most prevalent helminths of sheep and goats OF gastrointestinal tract are Strongylatoses. Studies on helminthiasis are absent during the last twenty years in the Chechen Republic. This paper analyzes the state of nematode infections of cattle in farms and private land plots of the Chechen Republic. The aim of the work is study of Strongylata infections of gastrointestinal tract of sheeps and goats: taxonomic composition, identification of extensiveness and intensity of infestation of strongylate invasions in the Chechen Republic. Material and methods. Tripes, intestines and lungs of 235 sheep 1-2-3-4-5-6-7-8-9-10-11-12-months of age, 1–2 years sheeps, 2–3 years sheeps and older than 3 years sheeps were studied. The follows methods were used: the method of opening full helminthological autopsy by Scryabin, the method of Fulleborn, helminthological research method by Berman-Orlov. Results. Livestock is infected by 14 species of nematodes of the suborder Strongylata, that are parasitic in the gastrointestinal tract. The most common nematodes are of genera Chabertia , Nematodirus , Haemonchus , Trichostrongylus , Ostertagia , Cooperia , Bunostomum . Conclusions. The results will allow to plan the most optimal anthelmintic activities.

Activity of ivermectin long-acting injectable (IVOMEC(®) GOLD) in first-season grazing cattle exposed to natural challenge conditions in Germany.

The persistent activity of ivermectin long-acting injection (IVM LAI; IVOMEC® GOLD, Merial; 3.15% ivermectin w/v) against nematode infections of cattle was evaluated under natural challenge conditions. Seventy nematode-free Brown Swiss calves were blocked by pre-treatment bodyweight and allocated randomly to seven groups of 10 animals each: saline (control) at 1 mL/50 kg bodyweight once on day 0 or IVM LAI at 1 mL/50 kg bodyweight (630 mcg IVM/kg) on either days 0, 7, 14, 21, 28, or 35. After housing until day 35, calves were grazed as one herd on a naturally contaminated pasture for 42 days. Calves were then weighed and housed for 4 weeks before being necropsied for parasite counting. Treatment with IVM LAI prevented the establishment (>90%, p < 0.05) of Dictyocaulus viviparus (100%), Bunostomum phlebotomum (100 %), Haemonchus contortus (98.6%), Ostertagia ostertagi/lyrata (94.9%), and Oesophagostomum radiatum (93.3%) for at least 77 days; Ostertagia leptospicularis (99.1%) for 63 days; Cooperia punctata (97.7%), Trichostrongylus axei (96.5%), and Ostertagia spp. inhibited larvae 4 (93.3%) for 56 days; Cooperia oncophora/surnabada (96.9%), Trichuris discolor (93.6%), and Cooperia spp. inhibited larvae 4 (98.8%); and Nematodirus spp. inhibited larvae 4 (97.1%) for 42 days. Calves of groups treated with IVM LAI had significantly (p < 0.001) higher days 0 to 77 weight gains than the saline-treated controls (28.40-39.25 vs 2.60 kg); the weight gains of the IVM LAI-treated groups, however, were not different from one another (p > 0.3). This study demonstrated a very high efficacy of IVOMEC® GOLD in preventing the establishment of a wide range of bovine nematodes for extended periods of time which was associated with a significant benefit to productivity in terms of weight gain.

A Simple and Efficient Protocol for the Treatment of Zebrafish Colonies Infected with Parasitic Nematodes

Abstract Our zebrafish colony experienced a period of increased mortality rate of 6.5 times more deaths per month in a colony of over 13,000 zebrafish (Danio rerio), which developed over 3 months. We observed that before death, affected fish appeared emaciated, often with an abdominal bulge. We performed dissection on 18 fish that had this appearance and found in 15 that their gut was infected with a nematode that closely resembled Pseudocapillaria tomentosa. We devised a treatment protocol for this nematode infection, which involved addition of fenbendazole, a drug used to treat nematode infections in cattle and sheep, to the fish feed. Fenbendazole produced no severe side effects in the fish and several treatments have effectively eradicated the parasite from our colony. The mortality rate of our fish has decreased to a value of 0.7%/month (p<0.001, equal to that before the infection). We propose this protocol as an inexpensive alternative to having to rederive an entire colony from bleached eggs, and as a prophylactic measure used in quarantine facilities on a regular basis.

Predicting the effect of anthelmintic treatment on milk production of dairy cattle in Canada using an Ostertagia ostertagi ELISA from individual milk samples

Gastrointestinal nematodes, such as Ostertagia ostertagi and several species of Cooperia, are ubiquitous in temperate climates and have been shown to have detrimental effects on production in adult dairy cattle. A published meta-analysis demonstrated that overall, producers lose approximately 0.35kg of milk per parasitized cow per day. Enzyme-linked immunosorbent assays (ELISAs) have the ability to quantify nematode infections in cattle, and thus, could be used to estimate the amount of milk production loss due to differing levels of parasitism at the individual cow level.ELISA results from individual cow milk samples were used to predict milk production response following a randomized anthelmintic treatment in a large field trial. To increase statistical power, the data collected from this field trial was pooled with data from two other published field trials to form an individual patient data meta-analysis (IPDMA).The ability to predict the effect of anthelmintic treatment on milk production depends on the level of parasitism quantified by an ELISA measuring milk antibodies against O. ostertagi, and reported as optical density ratios (ODRs). Therefore, the estimates from the interaction between ODR and treatment on milk production were used to determine how well the ODR predicted the response of the treatment. It was anticipated that the relationship between milk production and ODR was unlikely to be linear, so fractional polynomials were applied to the continuous ODR values.The interaction in the field trial showed a trend (p=0.138) toward a beneficial treatment effect when the individual ODR values, measured in late lactation and using Svanovir®, were greater than 0.12. When individual data from two other similar studies were included in an IPDMA, the interaction terms became statistically significant (p=0.009) indicating that there is a beneficial treatment effect when ODR values are slightly elevated. A graph was used to demonstrate the treatment effect (the estimated difference of kg/cow/day of milk yield between the treated and placebo cows), with 95% confidence intervals, as the ODR values increase. It is important to note that the methods of quantifying the ODR values differed between the three studies in the IPDMA, therefore some caution should be used when using these final estimated values. However, the shape and magnitude of the treatment effects, as well as the other fixed model estimates, were very similar between the field trial and the IPDMA suggesting that any bias would likely be minimal.

A review of the epidemiology and control of gastrointestinal nematode infections in cattle in Zimbabwe

In this review, the main gastrointestinal nematodes infecting cattle in Zimbabwe and the epidemiological factors influencing their occurrence are reviewed and discussed. Nineteen gastrointestinal nematode species that belong to seven families have been found to occur in cattle in Zimbabwe. The main genera reported to date are Cooperia, Haemonchus, Trichostrongylus and Oesophagostomum and the dominant species are Cooperia pectinata, Cooperia punctata, Haemonchus placei and Trichostrongylus axei. The mixed infection by several species from the genera is the cause of parasitic gastroenteritis in cattle in Zimbabwe. Production and husbandry practices, season, host age and environment are considered to be the main factors that influence gastrointestinal nematode infection in cattle. The geographical distribution of the gastrointestinal nematodes is also reviewed in relation to the climatic conditions of the country. Various control options are discussed and how they are applicable to the Zimbabwean situation. Based on reports and existing data on the epidemiological features of the gastrointestinal nematode infection in cattle, practical control measures are critically reviewed and recommendations are made for a national control programme.

The Effect of Ivermectin Pour-On Administration Against Natural Trichostrongylus colubriformis Infestations and Prevalence Rate of that in Cattle

These days one of the real problems that cause the prejudice economic in animal farms yearly is parasitic diseases. For that reason to prevent these problems the use of antiparasitic drugs is necessary. Ivermectin is a broad spectrum antiparasitic agent and different dosage forms such as injection, oral and pour-on used. The aims of this study was evaluation of the efficacy of ivermectin pour-on administration against natural Trichostrongylus colubriformis nematode infections in cattle and also determine the prevalence rate of this parasite in Tabriz area. In this study in 120 heads of male and female hybrid cattle were carried out LPG (larves per gram of feces) feces test. Willis method was applied for feces test and Stoll method was used for counting nematode larves (LPG). After confirm worm contamination and counting Trichostrongylus colubriformis nematode larves in feces, in infected animals, ivermectin (0.5 mg/kg) pour-on was administered. Feces test was repeated in 1, 7, 21 and 28 day after treatment. Results showed that total prevalence of Trichostrongylus colubriformis nematode infections was 20% in cattle’s of Tabriz area. The effects of ivermectin pour-on on trichostrongylus colubriformis nematode were 40, 79.23, 93.84 and 99.23 % in 1, 7, 21 and 28 day respectively. In conclusion, because the effect of this drug against trichostrongylus colubriformis nematode was >99% (p<0.05), so in cattle can use this drug in antiparasitic program. Of course the effect of this drug on other nematodes and parasitic infections are needed to be more investigated.

English

&nbsp; These days one of the real problems that cause the prejudice-economy in animal farms yearly is parasitic disease. For that reason and to prevent these problems the use of antiparasitic drugs is necessary. Ivermectin is a broad spectrum antiparasitic agent and is in different dosage forms such as injection, oral and pour-on.&nbsp;The aims of this study was to evaluate the efficacy of ivermectin pour-on administration against natural&nbsp;Nematodirus spathiger&nbsp;nematode infections in cattle and also to determine the prevalent rate of this parasite in Tabriz area.&nbsp;In this study, 120 heads of male and female hybrid cattle were used for LPG (larves per gram of feces) feces test. Willis method was applied for feces test and Stoll method was used for counting nematode larvae (LPG). After confirming worm contamination and counting&nbsp;N. spathiger&nbsp;nematode larves in feces in infected animals, ivermectin (0.5 mg/kg) pour-on was administrated. Feces test was repeated in 1, 7, 21 and 28 days after treatment.&nbsp;Results showed that total prevalence of&nbsp;N.&nbsp;spathigernematode infections was 33.33% in cattle of Tabriz area.&nbsp;The effects of ivermectin pour-on on&nbsp;N.&nbsp;spathiger&nbsp;nematode were 13.37, 44.96, 83.69 and 99.1% in 1, 7, 21 and 28 days respectively. In conclusion, because the effect of this drug against&nbsp;N. spathiger&nbsp;nematode was &gt;99% (p&lt;0.05), cattle can use this drug in anti-parasitic programme. Of course, the effect of this drug on other nematodes and parasitic infections need more investigation. &nbsp; Key words:&nbsp;Ivermectin, pouron administration,&nbsp;Nematodirus&nbsp;spathiger, cattle.

Assessment of ivermectin efficacy against gastrointestinal nematodes in cattle on four Scottish farms

CURRENT control strategies targeted against gastrointestinal nematode infections in cattle rely heavily on the use of anthelmintics. Three drug classes are licensed for this purpose in the UK: benzimidazoles, imidazothiazoles...

Serum pepsinogen levels to monitor gastrointestinal nematode infections in cattle revisited

The serum pepsinogen level is widely accepted as a useful parameter for monitoring gastrointestinal nematode infections in first-season grazing calves. However, several aspects, with possible implications for its practicality and the way to use the pepsinogen test, have received little attention to date. The objectives of this study were to evaluate (1) the reproducibility of a pepsinogen assay; (2) the required sample size for a reliable diagnosis and (3) the compliance to and effect of advice based on pepsinogen levels determined in year one on the nematode infection levels in the next generation of calves. Despite a high repeatability of the pepsinogen assay within the reference lab, the reproducibility between different labs was poor. There was more variation in pepsinogen levels between herds than between animals within a herd, suggesting that it is most useful to make a herd level diagnosis. Sample size calculation indicated that sampling seven animals sufficed to obtain a reliable indication of calf groups of up to 40 animals. Eighty-two herds were followed-up over two consecutive years and 39 (48%) had followed the advice that was formulated based on pepsinogen levels. Thirty-nine percent of the herds were advised to reduce the intensity of chemoprophylaxis. Samples from animals of those herds showed a higher pepsinogen level in the second year, but none of them had a mean pepsinogen level that is considered excessive. It is concluded that pepsinogen determination at housing from a limited number of animals can contribute to the design of the anthelmintic control strategy in the next year and a more targeted use of anthelmintics. However, more efforts are needed to harmonize the assay between veterinary diagnostic labs.

Clinical Forum: Bovine lungworm

Parasitic bronchitis, caused by the nematode Dictyocaulus viviparus. is a serious disease of cattle. For over 40 years, a radiation-attenuated larval vaccine (Bovilis® Huskvac, Intervet UK Ltd) has been used successfully to contol this parasite in the UK. Once vaccinated, animals require further boosting via field challenge to remain immune however there have been virtually no reports of vaccine breakdown. Despite this, sales of the vaccine decreased steadily in the 1980s and 90s; this was probably due to farmers' increased reliance on long-acting anthelmintics to control nematode infection in cattle. This method of lungworm control can be unreliable in stimulating protective immunity, as it may not allow sufficient exposure to the nematode. Such animals remain susceptible to disease when subsequently exposed to D. viviparus larval challenge. Evidence of this phenomenon has been provided by the documented increase in the numbers of parastitc bronchitis outbreaks in the UK in the last 20 years, especially ...

Efficacy of moxidectin 0.5% pour-on against naturally acquired nematode infections in cattle in the Mexican tropics

The efficacy of 0.5% moxidectin pour-on in cows with naturally acquired nematode infections was evaluated. The study was carried out in a ranch in Veracruz, Mexico. Four groups of 15 cows were randomly allocated. Animals in the treated group received 0.5% moxidectin pour-on at a dose of 0.5 mg/kg body weight on a single occasion. The other two groups remained as untreated controls. Fecal samples from all cattle were taken on days 0 (pre-treatment), 7, 14, 28 and 60 (post-treatment, PT). Fecal egg-counts were determined using a modified McMaster technique and fecal cultures were performed to identify gastrointestinal nematodes infected larvae (L 3). Treatment with moxidectin was associated with a significant reduction in fecal trichostrongyle egg-counts compared with the controls; efficacy was 100% at 28 days PT. Haemonchus spp. and Strongyloides spp. were the two genera identified from coprocultures.

Effect of strategic deworming of village cattle in Uganda with moxidectin pour-on on faecal egg count and pasture larval counts : short communication

Strategic application of moxidectin pour-on (Cydectin) was evaluated in Uganda for its effect on pasture larval counts and gastrointestinal nematode faecal egg counts in village cattle kept under tethering (semi-intensive) grazing management. The strategic deworming schedule involved treating cattle twice at an interval of 2 months, at the end of the 1st wet season and during the 2nd wet season. Two groups of 30 cattle, each consisting of a treated and a control group, were examined for nematode infections every 4 weeks from June 1999 to January 2000. The treated group had significantly lower mean faecal egg counts than the untreated groups (t-value = 2.47, P < 0.05). Generally, the pasture larval counts on treated farms were lower than on untreated ones, but not significantly so (t-value = 2.22, P = 0.068). Pasture larval counts with different nematode species on treated farms were lower than on untreated ones, but the differences were not significant for Haemonchus spp. (t-value = 1.68, P = 0.145), Oesophagostomum spp. (t-value = 1.87, P = 0.111), Trichostrongylus spp. (t-value = 1.93, P = 0.102), Dictyocaulus spp. (t-value = -0.74, P = 0.485) and Cooperia spp. (t-value = -1.00, P = 0.356). Treated farms did, however, have significantly lower pasture larval counts of Bunostomum spp. (t-value = 4.64, P < 0.05). This study has revealed that the application of moxidectin pour-on on cattle has an effect on faecal egg count and pasture contamination under the tethering grazing system. Moxidectin pour-on and the strategic deworming schedule evaluated here could be used for the control of gastrointestinal nematode infections in cattle by small-scale farmers who practise tethering or semi-intensive grazing management in Uganda and other tropical countries, especially where there is a bimodal rainfall pattern.

Probable multigeneric resistance to macrocyclic lactone anthelmintics in cattle in New Zealand

AIM: To establish the efficacy of topical formulations of eprinomectin and abamectin against naturally acquired abomasal and small intestinal nematode infections in cattle purchased from a North Island bull-beef property. METHODS: A controlled slaughter trial, involving eighteen 6–8-month-old mixed breed calves, was conducted in May 2002. The animals were randomly allocated on the basis of faecal egg count to one of three equal-sized groups (n=6), consisting of an untreated control group and two treatment groups. One of the treatment groups was treated with a topical formulation of eprinomectin, the other with abamectin. Both anthelmintics were administered as a single topical treatment on an individual liveweight basis, at the manufacturer's recommended dose rates of 0.5 mg/kg. All calves were housed in separate groups with no access to pasture throughout the entire trial and were slaughtered 7–10 days after treatment. RESULTS: Both anthelmintic treatments were highly effective (worm count reduction >98%) against Ostertagia ostertagi, Trichostrongylus axei and Cooperia punctata, but were not effective at reducing worm counts significantly of either Cooperia oncophora or Trichostrongylus longispicularis. Against these latter two parasites, worm count reductions of only 72% and 79%, and 81% and 76%, respectively, were recorded following treatment with eprinomectin or abamectin, respectively (all p>0.05). CONCLUSIONS: These results demonstrate evidence of resistance to macrocyclic lactone anthelmintics by C. oncophora and probably T. longispicularis also. CLINICAL RELEVANCE: As well as perhaps providing the first record of resistance to any anthelmintic by T. longispicularis, the present findings may also represent the first case of resistance to macrocyclic lactone anthelmintics exhibited by more than one parasite species at a time in cattle in New Zealand.

Effet de traitement par injection de moxidectine sur la prévalence et la production d’oeufs de strongles chez des bovins dans un système de pâturage communal en Ouganda

L’effet de la moxidectine sur la prévalence des infections par les nématodes chez les bovins, ainsi que sur la production d’oeufs des fèces et la contamination sur des pâturages collectifs a été évalué dans le district de Tororo en Ouganda. Dans le premier essai, un groupe traité et un autre non traité de 40 bovins chacun ont été suivis pendant une période de 12 semaines, alors que dans le deuxième essai un groupe traité et un autre non traité de 30 bovins chacun ont été suivis pendant sept mois. Dans le premier essai, la prévalence d’infection par les nématodes ainsi que le nombre moyen d’oeufs des fèces du groupe traité sont restés significativement (p &lt; 0,05) moins importants que ceux du groupe non traité du 7e au 84e jour. Dans le deuxième essai, les traitements stratégiques ont d’abord entraîné une réduction du nombre d’oeufs de 100 p. 100 chez les bovins traités, alors que cette réduction a été de 82 p. 100 chez les bovins non traités. Par la suite, le nombre moyen d’oeufs des fèces du groupe traité est resté en dessous de 60 pendant six mois, alors que celui du groupe non traité a fluctué en fonction de la pluviométrie entre 63 et 400. De plus, la contamination au pâturage par des larves infestantes des bovins traités a été significativement (p &lt; 0,05) plus faible que celle du groupe non traité pendant la saison humide. Les infestations au pâturage par Haemonchus spp., Bunostomum spp., Oesophagostomum spp. et Trichostrongylus spp. ont été respectivement trois fois, cinq fois, quatre fois et deux fois moins importantes chez les bovins traités que chez les bovins non traités. La moxidectine pourrait être utilisée dans la lutte stratégique contre les parasites dans les conditions de gestion communale des pâturages en Afrique tropicale par le traitement sélectif des groupes d’âges de bovins les plus affectés à la mi- et à la fin de la saison des pluies pour réduire la contamination au pâturage.

The effect of simulated rainfall on the efficacy of doramectin pour-on against nematode parasites of cattle

Two studies were conducted with doramectin topically administered at 500 μg/kg body weight to assess retention of therapeutic efficacy against nematode infections of cattle before, and after, simulated rainfall. In the first study, 50 heifers, with patent nematode infections, were allocated to one of five treatment groups. An untreated control group and one doramectin-treated group were not exposed to simulated rainfall. Simulated rainfall was applied at a rate of 25.4 mm of water in 35 min to three of the five groups: one group immediately before treatment, the second group 90 min after treatment, and the third group 24 h after treatment. Fecal samples were collected for determining egg counts 14 days after treatment. Percentage efficacy ranged from 97.3% to 100% in all treated calves, regardless of exposure to simulated rainfall. The second study involved 40 mixed-sex cattle that were allocated to one of four treatment groups (one saline control and three doramectin-treated groups). All cattle were confirmed to be free of nematode infections prior to oral gavage with infective larvae of Dictyocaulus viviparus, Cooperia oncophora, and Ostertagia ostertagi. Twenty-six days after infection, three groups were treated with doramectin pour-on and exposed to 20 mm of simulated rainfall over 40 min: one group 60 min before treatment, the second 20 min after treatment, and the third 40 min after treatment. Approximately two weeks after treatment, all cattle were necropsied for worm counts. In all treated groups, the percentage efficacy against O. ostertagi and D. viviparus was >99% to 100%. Percentage efficacy against Cooperia ranged from 97% to 98%. Results indicated that doramectin pour-on remains efficacious against nematodes of cattle when administered immediately before or after rainfall.

Integrated control of nematode infections in cattle: A reality? A need? A future?

Helminth infections are a major cause of production loss in cattle. Great progress has been achieved in the design of control strategies for these infections. Control is based mainly on the use of anthelmintics, and these have become more potent and easier to administer. However, the most effective control is possible only through the integration of different approaches. Moreover, an increasing number of disadvantages of chemotherapy/prophylaxis—biological, economical and environmental—have been suggested. In sheep, the high incidence of anthelmintic resistance has simply forced veterinarians/producers to adopt alternative control strategies; in cattle, no real need for deviation from the actual control programmes seems to exist. Therefore, the following questions are discussed: (1) Based on the distribution of cattle worldwide, what are the target parasites? (2) Can we continue to rely on control based mainly on the use of (highly effective) anthelmintics? (3) What are the prospects for non-chemical control? (4) Who will develop and implement integrated control systems? (5) In the case of parasite control in Western Europe, has it been effcient and can/need it be changed? (6) How can we integrate helminth control in the general design of herd disease control?