The distribution of strongylid egg and lungworm (Dictyocaulus eckerti) larval counts in adult female farmed red deer (Cervus elaphus), and the implications for parasite control

Whilst healthy adult farmed red deer show little clinical indication of parasite infection, they may still be maintaining infection levels on the farm through low-level shedding of nematode eggs and lungworm larvae. This work was undertaken to establish the long-term distribution of parasite counts, to determine whether the higher counts seen in previous trials are repeatable across the same animals. All adult female red deer on a New Zealand North Island property were faecal sampled (n = 209), weighed, and body condition scored (BCS) on five sampling occasions from March - August 2021. Faecal samples were processed by modified Baermanns to recover, identify, and enumerate lungworm 1st stage larvae (FLC), and nematode faecal egg counts (FEC) were determined by mini-FLOTAC. Between animal variation for FEC was significant (p < 0.001); whilst many counts were low to zero, a few individuals were consistently shedding higher egg counts. Younger animals tended to have higher egg counts (p = 0.003), but there was no association between FEC and BCS (p = 0.22), and FEC and liveweight (p = 0.58). Modelling of the data indicated that 50% of the egg output resulted from 21% of the animals. Additionally, there was no significant association between the higher egg counts and the gastrointestinal nematode classification; 'long tails' (likely Oesophagostomum sp.) p = 0.76, and the Ostertagiinae complex p = 0.75. Lungworm counts tended to be very low (0 - 26 lpg); consistent with previous trials and literature in farmed adult deer. However, between animal differences were statistically significant (p < 0.001) indicating some animals were passing more larvae than others, and poorer conditioned animals (BCS 2.5) were significantly associated with higher larval count (p = 0.03). There was no relationship between larval count and age (p = 0.62) and larval count and liveweight (p = 0.22). Modelling indicates that 50% of pasture larval contamination was contributed by 15% of the animals. There was no correlation between nematode egg count and lungworm larvae count (p = 0.22). Adult deer may play an important role as a source of infection for young deer, therefore, an improved understanding of the distribution of infection is needed to improve parasite control.

in the faeces of beef cattle in northeastern Brazil

The lungworm Dictyocaulus viviparus has an important role in cattle health and productivity worldwide, since infections can lead to substantial economic losses. Despite its importance, few studies investigating the epidemiological aspects of infection by this parasite have been conducted. The aim of this study was to report the occurrence of lungworm infection in beef cattle herds reared in an area of livestock production in the northeastern region of Brazil. From September 2020 to August 2021, monthly fecal samples (n = 493) were collected from 46 beef cattle. Among all the animals assessed, lungworm larvae were detected in 8.7% (4/46). None of them presented any clinical sign suggestive of infection by lungworm parasites. Twenty larvae were retrieved, with the minimum number (n = 1) detected in October and December, and the maximum number (n = 13) in November. These presented a mean length of 363 μm (± 28.65 μm) and mean width of 19 μm (± 1.03 μm), and were morphologically similar to Dictyocaulus sp.. This study reports the occurrence of this parasite in this livestock production area. Lastly, local veterinarians need to be aware of inclusion of this parasite in the differential diagnosis of other respiratory infections in beef cattle.

Pasture rewetting in the context of nature conservation shows no long-term impact on endoparasite infections in sheep and cattle

BACKGROUND

Nature conservation with reduced drainage of pastures has been increasingly promoted in agriculture in recent years. However, moisture on pastures is a crucial factor for the development of free-living stages of many parasite species in ruminants. Hence, for the first time, we conducted a field study between 2015 and 2017 at the German North Sea coast to investigate the long-term effect of pasture rewetting (since 2004) on endoparasite infections in sheep and cattle.

METHODS

We examined faecal samples of 474 sheep and 646 cattle from five farms in spring, summer and autumn each year for the presence of endoparasite infections. Animals were kept on conventionally drained, undrained and rewetted pastures. The association between pasture rewetting and endoparasite infection probability was analysed in generalized linear mixed models and including further potential confounders.

RESULTS

Infection frequencies for gastrointestinal strongyles, Eimeria spp. and Strongyloides papillosus were significantly higher in sheep (62.9%, 31.7% and 16.7%) than in cattle (39.0%, 19.7% and 2.6%). Fasciola hepatica was detected with a frequency of 13.3% in sheep and 9.8% in cattle, while rumen fluke frequency was significantly higher in cattle (12.7%) than in sheep (3.8%). Nematodirus spp., lungworms (protostrongylids, Dictyocaulus viviparus), Moniezia spp., Trichuris spp. and Dicrocoelium dendriticum were identified in less than 7% of samples. Co-infection with more than three endoparasite taxa was present significantly more often in sheep than in cattle. We identified significant positive correlations above 0.2 for excretion intensities between S. papillosus with strongyles, Eimeria spp. and Nematodirus spp. in sheep and between strongyles and Nematodirus spp. in cattle. Pasture rewetting had no long-term effect on endoparasite infections, neither in sheep nor in cattle. Interestingly, F. hepatica infections decreased significantly in sheep and cattle from 2015 (10.9% and 13.9%) to 2017 (1.4% and 2.1%).

CONCLUSIONS

Pasture rewetting for nature conservation did not increase endoparasite infection probability in ruminants in the long term. This finding should be confirmed in ongoing studies aimed at further animal welfare parameters. The rapid decrease in F. hepatica infections over 3 years may suggest climatic impact or competition with rumen flukes in addition to potential anthelmintic treatment after feedback of the results to the farmers.

Effects of grazing undrenched weaner deer on chicory or perennial ryegrass/white clover pasture on the viability of gastrointestinal nematodes and lungworms

This study determined the in vitro effects on the viability of internal parasites of grazing undrenched weaner deer on either chicory (Cichorium intybus) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture. One experiment investigated the hatching and development of gastrointestinal nematode eggs and larvae, and the development and motility of L1 lungworm (Dictyocaulus eckerti) larvae, and a second experiment used larval migration inhibition assays to test the viability of L1 lungworm larvae extracted from the faeces of weaner deer grazed on either chicory or pasture when they were incubated with rumen and abomasal fluids from fistulated deer also grazing on chicory or pasture. The incubations were undertaken with and without added condensed tannins purified from chicory and with or without polyethylene glycol (PEG) to bind the tannins. Chicory had no effect on the hatching and development of gastrointestinal nematode eggs and larvae. Grazing chicory reduced the number of lungworm larvae developing to the L3 stage, and L1 lungworm larvae from the faeces of chicory-grazed deer were less viable in rumen and abomasal fluid than larvae from pasture-grazed animals. Abomasal fluid was significantly (P < 0.001) less inhibitory to the migration of L1 lungworms than rumen fluid. When the larvae were incubated in rumen and abomasal fluids from chicory-grazed deer, their passage through sieves was significantly (P < 0.001) reduced in comparison with when they were incubated in the fluids from pasture-grazed deer Adding condensed tannins to rumen fluid increased the inhibition of the migration of L1 lungworm larvae but PEG removed this inhibition; this effect was not observed with abomasal fluid.

Protection against Dictyocaulus viviparus in second year cattle after first year treatment with doramectin or an ivermectin bolus

Forty-five calves were assigned randomly to three groups of 15 at turnout (day 0) in the spring of their first grazing season on to separate paddocks on a pasture known to carry infective larvae of Dictyocaulus viviparus. Group 1 calves were left as untreated controls, group 2 were injected with doramectin at 200 micrograms/kg at turnout and again on day 56, and group 3 were treated with an intraruminal bolus containing ivermectin. From day 42 onwards group 1 calves developed parasitic bronchitis which required repeated treatment with levamisole. The two endectocide regimes controlled lungworm infection, although some calves in group 2 developed some coughing during the week before the second dose of doramectin. After the end of the grazing season and again in May of the following year, five cattle from each group were infected experimentally with lungworm larvae and slaughtered 28 days later for lungworm counts and measurements of length to be made. At both times group 1 calves were found to be largely resistant to reinfection; group 2 were slightly more susceptible although the differences from group 1 were not statistically significant. Group 3 calves were more susceptible with no significant difference in worm counts from naive infection controls.

Delay in timing of the oxfendazole pulse release bolus in calves in The Netherlands

The efficacy of the oxfendazole pulse release bolus (OPRB) was tested in a grazing experiment at the University of Utrecht. Three groups of four OPRB-treated calves and one group of four untreated control calves were grazed on separate pastures between 18 May and 21 October 1987. Based on faecal egg counts for strongyle-type eggs and Nematodirus eggs, embryonation of Nematodirus eggs and faecal larval counts for lungworm, the first pulse of oxfendazole was released after 28 to 63 days, which was later than the period of approximately three weeks indicated by the manufacturer and others. As far as could be detected, the second to fifth pulses were not as delayed, but generally the three-week period was also exceeded. This delayed release of the pulse resulted in a build-up of pasture infectivity for gastrointestinal nematode larvae and lungworm larvae. Nevertheless, this did not result in clinical gastrointestinal helminthiasis and husk in the treated groups of calves, whereas severe husk and mild gastrointestinal helminthiasis were seen in the control group.

The helminth parasites of various artiodactylids from some South African nature reserves

The helminth species composition and helminth burdens of 4 grey duikers, 12 bushbuck, 2 nyala, 2 giraffe, a steenbok, an oribi, a waterbuck and a tsessebe from the Kruger National Park (KNP); of a steenbok and a greater kudu from the farm Riekerts Laager, Transvaal; of a single blue duiker from the Tsitsikama Forest National Park, and of a blue wildebeest, a red hartebeest, a gemsbok and 2 springbok from the Kalahari Gemsbok National Park (KGNP) were collected, counted and identified. New parasite records are: Agriostomum equidentatum from the gemsbok, Cooperia neitzi from the bushbuck, Cooperia sp. from the gemsbok and the red hartebeest, Cooperia yoshidai from the waterbuck and the tsessebe, Dictyocaulus viviparus from the bushbuck, Haemonchus bedfordi from the waterbuck, Haemonchus contortus from the gemsbok, Haemonchus krugeri from the steenbok from the KNP, Impalaia nudicollis from the gemsbok and the red hartebeest, Impalaia tuberculata from the oribi and the waterbuck, Impalaia spp. from the kudu, Longistrongylus meyeri from the steenbok from Riekerts Laager and the gemsbok, Longistrongylus sabie from the steenbok from the KNP, Longistrongylus schrenki from the tsessebe, Parabronema sp. from the tsessebe and the red hartebeest, Paracooperia serrata from the gemsbok and the steenbok from the KGNP, Pneumostrongylus calcaratus from the bushbuck, Strongyloides sp. from the gemsbok, Trichostrongylus sp. from the gemsbok, the red hartebeest and the steenbok from the KGNP, Trichostrongylus axei from the blue duiker, Trichostrongylus falculatus from the bushbuck and the oribi, Trichostrongylus instabilis from the bushbuck, the steenbok from the KNP and the oribi and Trichostrongylus thomasi from the grey duikers and tsessebe. Host specificity of the parasites was not marked and crossinfestation was common. This was not true for the giraffe, since none of the helminths of these animals were found in the antelope and vice versa.

Parasites in lungs of dead equids in Kentucky: emphasis on Dictyocaulus arnfieldi

Prevalence of natural infections of parasites from the lungs of 488 dead Thoroughbreds in Kentucky was investigated. The horses varied from 1 to 32 years of age; 419 horses were from 215 farms and 69 horses were from 68 individual sources for which a specific farm was not identified. Examinations of the lungs were made from Mar 1, 1983 through Feb 29, 1984. Dictyocaulus arnfieldi was recovered from 56 (11%) of the horses. Other parasites found were larvae of Parascaris equorum in 37 (8%) and of Habronema/Draschia in 67 (14%) of the horses. The possible effect of ivermectin treatment on the prevalence of D arnfieldi in the lungs is discussed. Presence of D arnfieldi in 20 other selected dead equids was also investigated.

Lungworms (Dictyocaulus arnfieldi): prevalence in live equids in Kentucky

Prevalence of natural infections of the lungworm, Dictyocaulus arnfieldi, was investigated in Kentucky in 5,437 live equids (horses, ponies, and asses) on 91 farms by examination of fecal samples over a 15-month-period from January 28, 1983 to April 19, 1984. For the 91 farms investigated, asses only were examined on 1 farm; for the other 90 farms, examinations were made of horses on all of them, of ponies on 4 farms, and of asses on 9 farms. Larvae of D arnfieldi were found in fecal samples of 112 (2%) of 5,379 horses on the 90 farms of which 38% had greater than or equal to 1 infected animal; none of 19 ponies examined was infected. For 39 asses (donkeys and mules) examined, 21 (54%) were infected; infected asses were present on 80% of the 10 farms on which they were examined. The equids, excluding asses, that were examined and the percentage (in parentheses) infected with D arnfieldi included 4,329 (2%) Thoroughbreds, 684 (2%) Standardbreds, 78 (0%) American Saddle Horses, and 307 (3%) miscellaneous (other breeds or mixed breeds of horses and ponies). Equids were separated into 3 categories relative to previous treatment with ivermectin: A (no treatment), B (treatment), and C (treatment unknown).(ABSTRACT TRUNCATED AT 250 WORDS)

The helminths of various antelope species from Natal

Helminth parasites were collected from 2 bushbuck, Tragelaphus scriptus, 2 red duiker, Cephalophus natalensis, 1 oribi, Ourebia ourebi, and 4 reedbuck, Redunca arundinum, that died or were culled in various parts of Natal. One trematode genus, 1 cestode genus and 12 nematode species were recovered. Haemonchus contortus. Ostertagia harrisi, Trichostrongylus capricola, Trichostrongylus vitrinus, Cooperia rotundispiculum and Setaria scalprum are new parasite records for the red duiker. Trichostrongylus colubriformis is a new parasite record for the oribi and Longistrongylus schrenki, Trichostrongylus falculatus, Trichostrongylus colubriformis and Dictyocaulus viviparus are recorded from the reedbuck for the first time. An unidentified paramphistome was also recovered from the reedbuck.

Histopathological findings in the lungs of Scottish red and roe deer

Histopathology on portions of lung collected from 34 red deer (Cervus elaphus) and 15 roe deer (Capreolus capreolus) between 1977 and 1981 revealed evidence of lungworm infestation in 16 red and 14 roe deer. In the red deer, Dictyocaulus species, and the developmental stages of another parasite, believed to be Elaphostrongylus cervi, were involved. Dictyocaulus also affected the roe deer, but in them the major lesions were associated with protostrongylids. Exudative bronchopneumonia, including two cases of fungal infection, was predominantly a problem of red deer under seven months of age. Between the age of four and seven months, parasites frequently accompanied this change. Other conditions encountered were pulmonary congestion, tuberculosis and granulomata of unknown cause.

Studies on the control of bovine ostertagiasis using a morantel sustained release bolus

The efficacy of a morantel sustained release bolus to control ostertagiasis in grazing calves was assessed. Administration of the bolus into the rumen of calves immediately before turnout on to spring pasture in May substantially reduced the level of pasture contamination with infective larvae later in the season. Compared with controls there was a 71 per cent reduction in worm burdens acquired over the entire grazing season with a mean improvement in weight gain of 24 kg. When administration was delayed until midsummer (July) a good anthelmintic effect was obtained but there was little reduction in pasture contamination levels. Worm burdens acquired over the grazing season were reduced by only 48 per cent with a mean weight gain advantage of only 9 kg compared with controls. The control obtained against Dictyocaulus viviparus by both treatments was not absolute, failing to prevent the development of mild parasitic bronchitis.

Control of parasitic bronchitis in calves: vaccination or treatment?

A 16-day infection of Dictyocaulus viviparus in two groups of calves was treated with levamisole and fenbendazole respectively. Five days afterwards the calves were reinfected with 4000 larvae and necropsied 21 days later. Although the lungworm burdens of the two groups of calves were reduced by about 70 per cent compared to a control group the clinical signs of dyspnoea, tachypnoea and coughing were indistinguishable from a primary infection. This was due to pulmonary emphysema, oedema and an acute epithelialising pneumonia apparently associated with the death and disintegration of lungworms in situ, the result of an incompletely developed immune response. The results are compared with those obtained with the lungworm vaccine. It was concluded that the outcome of any system of "control" which depends on drug therapy and reinfection is unpredictable and that vaccination offers the only effective method of prophylaxis.

Immunological studies on Dictyocaulus viviparus infection; immunity produced by the administration of irradiated larvae

Experiments are described on the immunity to Dictyocaulus viviparus infection produced by the administration of 3rd stage D. viviparus larvae partially inactivated by X-irradiation. A high degree of immunity was obtained by this method.

Immunological studies on Dictyocaulus viviparus infection; active immunization with whole worm vaccine

Experiments on the vaccination of calves against Dictyocaulus viviparus infection using whole worm antigen in Freund's adjuvant are described. A reduction in the number of worms developing from a challenge infection was sometimes obtained but the method seems to be of little practical value.

Immunological studies on Dictyocaulus viviparus infection: the immunity resulting from experimental infection

It has been shown experimentally that infection of calves with D. viviparus confers a high degree of resistance to a subsequent reinfection. This acquired immunity can result from a single infection with a sub-lethal dose of larvae or from a series of repeated doses of small numbers of larvae. Animals immunized by a previous infection exhibit on challenge a rapid antibody response and a striking reduction (in some cases to zero) in the numbers of worms reaching the lungs, and in the numbers of larvae appearing in the faeces.

The study of the transmission of the cattle lungworm (Dictyocaulus viviparus) in relation to pasture conditions

1. A series of experiments is described in which the transmission of cattle lung-worm infection has been investigated in relation to four different pasture conditions—long grass, short grass produced by gangmowing, grazing by sheep and grazing by resistant cattle.

2. The methods of study of value in this type of field investigation are discussed. It is suggested that the results can be usefully expressed as a series of coefficients which summarize the factors involved in the process of transmission. The methods of calculation of these coefficients are described.