Levels of serum IgE in response to gastrointestinal nematodes in cattle

Serum IgE concentration has been considered a valuable measurement in parasitic infections, yet little has been reported regarding cattle. This study examines the association of IgE levels of nematode-na?ve Holstein steer calves and the level of gastrointestinal parasitism acquired by grazing irrigated pasture for 30 days. Total IgE levels were determined by enzyme-linked immunosorbent assay (ELISA) specific for bovine IgE on serum collected both before and after exposure to parasite-infected pastures. Following necropsy, parasite loads were determined by direct count from the contents of the abomasum, small intestine, cecum and large intestine; species of Ostertagia and Cooperia being the most common helminths found. Significant increases of IgE in the serum of calves with light infestations were seen, whereas calves with moderate to heavy infestations showed only mild IgE increases. With increased parasite burden, the frequency of increased IgE levels was reduced. Additionally, there appeared to be a seasonal correlation relating the level of serum IgE detected to the number of worms counted and to the course of parasite development.     

Efficacy of moxidectin against gastrointestinal nematodes of cattle.

Three groups of 11 naturally infected crossbred beef calves were injected subcutaneously with moxidectin 1 per cent injectable at 0.2 or 0.3 mg moxidectin/kg bodyweight or with the unmedicated vehicle. Nematode infections had been acquired during grazing from December to April. Based on the faecal egg counts and total worm counts of the control calves at necropsy (11 to 13 days after treatment) most of the calves had heavy parasitic burdens. Ostertagia ostertagi was predominant and the mean numbers of adults, developing fourth stage larvae (L4) and inhibited early L4 were 45,906, 10,061 and 68,918, respectively. Haemonchus placei and Trichostrongylus axei were also present in the abomasa. Three species of Cooperia, Oesophagostomum radiatum L4 and T colubriformis adults were found in the intestinal tract. Both dosages of moxidectin were equally effective (P < 0.05) against all the abomasal nematodes (99.9 to 100 per cent) and the intestinal tract nematodes (99.4 to 100 per cent). No adverse reactions to the moxidectin treatment were observed. Abomasal pathology characteristic of heavy O ostertagi infection was observed in the control calves, but not in the treated calves.     

Observations on the free-living stages of cattle gastrointestinal nematodes

A 4-year study on the free-living stages of cattle gastrointestinal nematodes was conducted to determine (a) the development time from egg to infective larvae (L3) inside the faecal pats, (b) the pasture infectivity levels over time, and (c) the survival of L3 on pasture. Naturally infected calves were allowed to contaminate 16 plots on monthly basis. Weekly monitoring of eggs per gram of faeces (epg) values and faecal cultures from these animals provided data for the contamination patterns and the relative nematode population composition. At the same time, faecal pats were shaped and deposited monthly onto herbage and sampled weekly to determine the development time from egg to L3. Herbage samples were collected fortnightly over a 16-month period after deposition to evaluate the pasture larval infectivity and survival of L3 over time. The development time from egg to L3 was 1-2 weeks in summer, 3-5 weeks in autumn, 4-6 weeks in winter, and 1-4 weeks in spring. The levels of contamination and pasture infectivity showed a clear seasonality during autumn-winter and spring, whilst a high mortality of larvae on pasture occurred in summer. Ostertagia spp., Cooperia spp. and Trichostrongylus spp. were predominant and a survival of L3 on pasture over a 1-year period was recorded in this study.     

Effects of ivermectin on control of gastrointestinal nematodes and weight gain in weaner-yearling beef cattle

Four groups of 16 crossbred beef calves were used in evaluating different anthelmintic treatment schedules: group 1 was given ivermectin (IVM) at weaning only (October 31) and grazed on initially safe pasture; group 2 was given IVM at weaning, on January 28, and on April 22, and grazed on contaminated pasture; and group 3 was given IVM at weaning and on April 22, and grazed on contaminated pasture; and group-4 was group treated with fenbendazole (FBZ) at weaning only, with provision for individual salvage treatment, and grazed on contaminated pasture. The investigation was from Oct 31, 1984, to Oct 9, 1985. Initially high fecal egg counts at weaning were more effectively reduced by IVM than by FBZ, and the effect of safe pasture was evident in minimal worm burdens in tracer calves grazed with group-1 cattle during November and least amount of weight loss in group-1 yearlings during winter. Fecal egg counts, pasture larval counts, and plasma pepsinogen concentrations remained low in group 2 after the January treatment. Fecal egg counts of the other groups increased substantially during late winter and spring, but pasture larval counts increased only on group-1 and group-4 pastures. During spring, highest worm burdens were found in group-1 and group-4 tracer calves (grazed in April) and in group-3 and group-4 yearlings (slaughtered in early April). Six cattle of group 4 were salvage treated with FBZ in February and April. Greatest gains were observed from March through June, with group-2 and group-1 cattle gaining the most.(ABSTRACT TRUNCATED AT 250 WORDS)     

Salivary IgA: a suitable measure of immunity to gastrointestinal nematodes in sheep

Infection with gastrointestinal nematodes (GIN) is a major constraint on the productivity of grazing livestock. The development of selection methods to quickly and accurately identify animals capable of developing an effective natural immunity to infection would contribute to the development of sustainable worm control programs. A carbohydrate larval surface antigen (CarLA), present on the infective-stage larvae (L3) of all trichostrongylid nematodes, is a target antigen for host antibody (Ab). The levels of various Ab isotypes in serum and/or saliva of field-grazed lambs were assessed by ELISA, and Ab titres compared with parasite faecal egg counts (FECs) and a range of animal productivity parameters. Levels of anti-CarLA IgA in saliva proved to be the most heritable (h(2)=0.3), and had the closest genetic correlation with FEC (r=-0.5). Those animals identified as having 'high levels' of anti-CarLA IgA typically have 20-30% lower FEC than animals with low or undetectable titres. Furthermore, animals with 'high levels' of anti-CarLA IgA tend to have improved growth rates post-weaning, and have no tendency for increased breech-soiling. The assay performed well regardless of parasite genera present on pasture. The saliva assay has a number of key practical advantages over the use of FEC for selection purposes: animals can be identified without a requirement to withhold anthelmintic treatment; sampling is rapid and easy and there is a significantly reduced barrier to adoption within the farming community. Measurement of anti-CarLA IgA in saliva by ELISA offers a practical, rapid and easy method of selecting for natural immunity to GIN in sheep.     

Efficacy of febantel paste against naturally acquired gastrointestinal nematodes of cattle

Twenty calves with naturally acquired gastrointestinal nematode infections were assigned to 10 replicates of 2 calves each and were treated with febantel paste (5 mg/kg of body weight, PO) or an equivalent volume of paste vehicle (control calves). Adverse reactions were not observed after febantel treatment. At necropsy, gastrointestinal nematode counts in febantel-treated calves, compared with control calves, were reduced by over 99% for all major species except Trichuris discolor, counts of which were reduced by only 69%. Counts of gastrointestinal nematode eggs in feces of febantel-treated calves were reduced by 100% after treatment.     

Persistent efficacy of abamectin and doramectin against gastrointestinal nematodes of cattle

Objective To assess the persistent activity of injectable formulations of abamectin and doramectin against gastrointestinal nematodes of cattle.
Design Controlled slaughter study assessing residual efficacy.
Procedure Nematode-free calves were treated with abamectin or doramectin (each at a dose of 200 μg/kg) and infections then induced with repeated doses of infective larvae of Trichostrongylus axei, Haemonchus placei, Ostertagia ostertagi and Cooperia species. The duration of challenge ranged from 14 to 28 days. The calves were slaughtered at either 38/39 or 45/46 days after the treatments and nematodes recovered from the gastro-intestinal tract.
Results Significant reductions in numbers of O ostertagi occurred for both abamectin and doramectin treatments (> 93%) relative to counts in untreated calves, when challenge was administered up to 21 days after treatment. For T axei and Cooperia spp significant reductions occurred when the challenge occurred for 14 days after treatment (99%). Although differences from untreated animals were not significant, the results for H placei suggested high efficacy (> 85%) for up to 21 days for doramectin and up to 28 days for abamectin.
Conclusion There was no significant difference between abamectin and doramectin for any parasite at any challenge point, indicating that there is equivalent persistent activity of doramectin and abamectin against important gastrointestinal nematodes of cattle.     

Use of copper oxide wire particles to control gastrointestinal nematodes in goats

The objectives of these experiments were to determine the optimal dose of copper oxide wire particles (COWP) necessary to reduce gastrointestinal nematode (GIN) infection in young and mature goats naturally infected with Haemonchus contortus or a mixed infection and to determine whether the effectiveness could be enhanced through feeding management. Two experiments were conducted during cooler months in Georgia, and 4 experiments were conducted during warmer spring or summer months in Arkansas. Meat goats received 0 up to 10 g of COWP under a variety of management conditions. In all experiments, blood and feces were collected every 3 or 7 d from 6 to 42 d to determine blood packed cell volume (PCV) and fecal egg counts (FEC) to estimate the degree of GIN infection. In mature goats grazing fall pasture, mean FEC of 0 g of COWP-treated goats increased, and those of 4 g of COWP-treated goats remained low on d 0, 7, and 14 (COWP x d, P < 0.03), and FEC decreased on these days (P < 0.001). In 5 and 10 g of COWP-treated goats, PCV increased (P < 0.001), but FEC and PCV remained unchanged over time in control goats. Fecal egg counts were similar among all low doses (0.5, 1, 2, 4 g) of COWP administered to weaned kids for all dates examined (P > 0.10), which were lower on d 7 through 21 (COWP x date, P < 0.05) but similar by d 28, compared with FEC of 0 g of COWP-treated kids. Packed cell volume was lower in 0 g compared with all COWP-treated kids by d 14 (COWP x date, P < 0.05). Feeding management in combination with COWP for GIN control had little effect compared with COWP alone for these short-term studies. In conclusion, a dose of COWP as low as 0.5 g, which was considered optimal to reduce the risk of copper toxicity, was effective in reducing FEC in young goats, and 5 g of COWP was effective in older goats. Copper oxide does not appear to be effective in controlling newly acquired L4 stage (preadult) larvae, which also feed on blood, leading to decreased PCV in newly infected goats.     

Efficacy of ivermectin administered via sustained-release bolus against gastrointestinal nematodes in cattle

Twelve calves (mean weight, 175.5 kg) were used to confirm efficacy of ivermectin delivered from a prototype sustained-release bolus against naturally acquired gastrointestinal nematodes including early fourth-stage (inhibited) larvae of Ostertagia ostertagi. The calves were allocated by restricted randomization on weight to 1 of 2 groups: controls, to which a placebo bolus was given orally, and treated calves, to which a sustained-release bolus designed to deliver 8 mg of ivermectin/day at a steady rate was given orally. After treatment, the 2 groups were housed in separate pens with concrete flooring. Twenty-eight days after treatment, all calves were euthanatized and necropsied. The ivermectin-treated calves had no larval or adult Ostertagia spp and significantly (P less than 0.01) fewer adult Trichostrongylus axei and adult Cooperia (C oncophora, C punctata and C surnabada) than control calves. Efficacy of ivermectin was greater than 99% for Cooperia spp, and 100% for other parasites. Drug-related adverse reactions were not observed.     

Efficacy of combined chemotherapy against gastrointestinal nematodes and Fasciola hepatica in cattle

Direct blood smear examination (using 0.05 ml of whole blood) detected 168 (80.9%) of 204 microfilaremic canine blood samples as determined by the modified Knott test for microfilariae (mff) of Dirofilaria immitis (using 1 ml of whole blood). Direct smear examination detected all of 134 microfilaremias greater than 50 mff ml(-1), but only 31 of 70 (44.3%) microfilaremias having less than 50 mff ml(-1). In a separate retrospective query of a database of 963 dogs with necropsy-confirmed heartworm infections, 834 (86.6%) were positive by the DiroCHEK heartworm antigen test, and 504 (52.3%) were microfilaremic by the modified Knott test. Only 2 (0.4%) of the microfilaremic dogs were DiroCHEK negative and another 18 (3.6%) were very weak positives. Although these microfilaremic dogs were not tested by direct smear, only one of the two DiroCHEK-negative and six of 18 weakly DiroCHEK-positive dogs had microfilaremias so low that a direct smear may have given a false negative result. Significant adverse reactions to either diethylcarbamazine or the macrolide endectocides have not been reported for microfilaremias less than 500 mff ml(-1), thus substitution of the direct smear for a concentration test for mff, such as the modified Knott test or membrane filtration, does not appear to increase the risk of an unexpected adverse reaction to heartworm prophylactic drugs. Such a substitution results in only a very slight decrease (on the order of 0.1%) in the overall sensitivity of heartworm screening, provided a test for mff is run concurrently with an antigen test. If a test for mff is the only screening test used, then substitution of a direct smear for a concentration test may decrease the sensitivity of heartworm screening by nearly 20%, depending on the prevalence of low level microfilaremias in the population of dogs tested.     

The seasonal epidemiology of gastrointestinal nematodes in N'Dama cattle in The Gambia

From June 1987 to June 1988, a total of 180 N'Dama cattle were necropsied to identify and enumerate parasites present, including 39 sick calves and 25 dead calves from local village herds, and 116 adult cattle from a local abattoir. Of 175 animals infected with one or more helminths (97%), Haemonchus contortus was found in 67% of all necropsied animals, Cooperia punctata in 75%, Cooperia pectinata in 55%, Oesophagostomum radiatum in 71% and Bunostomum phlebotomum in 21%. There was a wide range of worm burdens (0-22 925) and a pronounced seasonal pattern occurred. Eighty-two percent of the total adult Haemonchus burden occurred during the rainy season (June-October). By the end of the rainy season, almost 100% of the Haemonchus burden was present as inhibited larvae. By contrast, a different survival strategy appeared to occur in Cooperia spp.; Oesophagostomum spp. and Bunostomum spp., which were found as adults throughout the year. Results indicated that, apart from malnutrition during the dry season, gastrointestinal nematode infections, especially haemonchosis, represent a major constraint on the health and productivity of N'Dama cattle under West African savanna conditions.     

A multiplex PCR assay for differentiating economically important gastrointestinal nematodes of cattle

A multiplex polymerase chain reaction (PCR) test was developed for identifying gastrointestinal (GI) nematodes that commonly infect cattle. This assay was developed using adult-derived genomic DNA and shown capable of discriminating parasite eggs from the feces of experimentally-infected animals at both the species and genus levels. Sequence data from internal (ITS) and external (ETS) transcribed spacers of the ribosomal DNA (rDNA) repeats as well as the 3'-end of the small subunit rDNA and 5'-end of the large subunit rDNA were used to generate five primer sets which, when used simultaneously in a multiplex PCR, produce a unique electrophoretic DNA banding pattern characterized by a single DNA fragment for Ostertagia ostertagi (257bp), Haemonchus placei (176bp), Oesophagostomum radiatum (329bp), Trichostrongylus colubriformis (243bp) and Cooperia oncophora (151bp). In a similar manner, the constructed primer sets amplified DNA from Ostertagia lyrata, Haemonchus contortus, Trichostrongylus axei, Cooperia surnabada and Cooperia punctata. With respect to H. contortus, a closely migrating doublet was generated suggesting size heterogeneity in the ETS which is consistent with multiple rDNA repeat units within this species. PCR analyses using mixtures of monospecifically-purified nematode eggs indicated a sensitivity of less than 0.5 egg-DNA equivalent per species. Although, not designed as a quantitative technique, relative PCR signal intensities corresponded to relative egg burdens within the DNA samples from mixed species of eggs.     

Occurrence and seasonal behavior of gastrointestinal nematodes infecting Maine dairy cattle.

Gastrointestinal tracts of 48 yearling Maine dairy cattle were examined (8 animals every 2 months) for 1 year. Adult and immature nematodes were identified and counted. Species recovered were Bunostomum phlebotomum, Cooperia mcmasteri, Cooperia oncophora, Cooperia pectinata, Cooperia punctata, Haemonchus placei, Nematodirus helvetianus, Oesophagostomum radiatum, Ostertagia circumcincta, Ostertagia lyrata, Ostertagia ostertagi, Trichostongylus axei, and Trichuris ovis. Strongyle parasitism was observed during every sampling period and the overall incidence was 93.7%. The most commonly encountered genera were Ostertagia spp (85.4%) and Cooperia spp (81.2%). Seasonal fluctuations in the worm burden of various nematodes were observed, with largest numbers seen in the fall. The incidence and degree of parasitism appeared to be related to environmental conditions. Proportions of adult and immature worms were shown to fluctuate with the time of year. Greatest numbers of immature worms were observed during the fall and winter.     

Epidemiology and effect of gastrointestinal nematodes on beef cattle from tropical Argentina

The aim of this work was to study the epidemiology and the harmful effect of gastrointestinal nematodes (GINs) on beef cattle in the piedmont forest and grassland region of northwestern Argentina, between March 2015 and March 2016. Sixty weaned female calves were divided into three groups: STG—calves treated systematically with 200 mcg/kg moxidectin every 40–50 days; LTG—calves treated as usually locally implemented, with 200 mcg/kg ivermectin on May 4 and August 5; and UTG—calves not receiving treatment. Moreover, a group of 20 untreated first-calving cows was monitored. Eggs per gram of faeces (epg) and faeces cultures were performed. Live weight gain (LWG) was recorded. Differences among groups were compared using analysis of variance and Tukey test. At the start of the experiment, mean epg was from moderate to high (595?±?480); therefore, this group was treated in May. Mean UTG epg peaked (907?±?754) in mid-winter, decreasing toward spring. LTG epg only decreased partially after treatment, showing 54.2% of ivermectin efficacy. Epg values of STG were always negligible values (95.8% of moxidectin efficacy). The dominant nematode genus was Cooperia (81.9%), followed by Haemonchus (15.5%). The effect of treatments was evident from middle autumn, with STG showing a significantly (p?<?0.002) higher LWG than the other groups. Toward the end of the trial, LWG of STG and LTG increased by 27.2 and 8.2%, respectively, to those of UTG. This preliminary study showed a winter epg peak and a negative effect of GINs on LWG, even in moderately infected calves.