Increase In Faecal Egg Count Research Articles

Reproductive effort influences intra‐seasonal variation in parasite‐specific antibody responses in wild Soay sheep

Abstract A trade‐off between reproduction and immune function has been suggested to potentially underpin between‐individual and genetic variation in reproductive strategy, immunity and life span, with potential consequences for host and parasite dynamics. Previous studies in wild animal populations have shown that experimentally induced or natural variation in reproductive effort is negatively associated with general immune markers. Few studies, however, have tackled this question by measuring specific immune responses against prevalent pathogens, and only rarely has variation in immune measures been linked to parasite burden, making it impossible to draw conclusions about the functional relevance of covariation between reproductive effort and immune markers. We collected faecal samples in a longitudinal manner from wild female Soay sheep across late pregnancy and early lactation and measured gastrointestinal nematode faecal egg count (FEC) and worm‐specific antibody responses. Faecal egg count was highly repeatable, with c. 80% of variation due to between‐individual differences, while three isotypes of worm‐specific and total antibodies had moderate repeatability (range: 11%–43%). Females making a greater reproductive effort (those that reproduced, and especially those with heavier litters) showed a more rapid increase in FEC across the season, while non‐reproducing females and those producing lighter litters experienced lower FEC and had higher antibody levels. Associations between antibodies and FEC were complex: worm‐specific immunoglobulin (Ig) G was negatively associated with FEC, while total IgM was positively associated, emphasizing the importance of measuring both immune markers and parasite burden in ecological studies. Our results support the predicted trade‐off between reproductive effort and parasite‐specific immunity: high reproductive effort can limit the ability of individuals to defend themselves against prevalent parasites, with potential downstream consequences for fitness and parasite transmission. A plain language summary is available for this article.

In this issue – March 2017

In this issue – March 2017

Resistance of Haemonchus sp. to monepantel and reduced efficacy of a derquantel / abamectin combination confirmed in sheep in NSW, Australia

Early in 2015, sheep in a summer rainfall area of NSW, Australia, displayed signs of haemonchosis despite treatment with monepantel. A faecal egg count reduction test (FECRT) was performed on yearlings with natural field infections using various anthelmintics. Only a four-way combination drench achieved a reduction in faecal egg count (FEC) greater than 95%. The combination contained abamectin, albendazole, levamisole and closantel. Treatments with a derquantel/abamectin combination, monepantel and moxidectin reduced FECs by 93, 31, and 30% respectively. Sheep treated with abamectin displayed an increase in FEC of 22%. Larval differentiation counts conducted 10days post-treatment showed that 100% of survivors were Haemonchus sp. This result confirms for the first time monepantel resistant Haemonchus in sheep in NSW, and is amongst the first of the Australian cases in sheep not associated with goats. A second FECRT was performed using sheep from the moxidectin and abamectin treatment groups in the first FECRT. In this second FECRT, monepantel treatment reduced FECs by 51% and 29% in the sheep previously treated with moxidectin and abamectin respectively. This suggests monepantel, in combination with moxidectin, may give some control against severely abamectin resistant Haemonchus.

Effect of gastro-intestinal nematode infection on sheep performance: a systematic review and meta-analysis.

BackgroundGastrointestinal nematode (GIN) infections are common in domestic sheep and impact directly and indirectly on the health of infected animals as well as on the associated economic production. In this study, we aim at summarizing the current knowledge on the influence of GIN infections on sheep production by conducting a systematic review. A subsequent meta-analysis of relevant studies was performed to provide an estimate of the effect of GIN infections on weight gain, wool production and milk yield.MethodsA literature search was performed on the CAB, Pubmed and Web of Science database for the period 1960–2012. Inclusion criteria were: 1) Measurement of at least one production parameter. 2) Comparison between groups of sheep with different nematode burdens. 3) Same conditions regarding all aspects except parasite burden between groups. 4) Quantitative measurements of one or more production traits.ResultsAltogether, 88 studies describing 218 trials were included in this review. The majority of studies (86 %) reported that GIN infections had a negative effect on production but this was reported to be statistically significant in only 43 % of the studies. Meta-analysis indicated that performances of sheep infected with nematodes was 85, 90 and 78 % of the performance in uninfected individuals for weight gain, wool production and milk yield respectively. Our results suggest a possible reporting bias or small study effect for the estimation of the impact of GIN infections on weight gain. Finally, a general linear model provided an estimate for the decrease in weight gain in relation to the increase in faecal egg count of nematodes.ConclusionThis study underlines the importance of GIN infections for sheep production and highlights the need to improve parasite management in sheep, in particular in face of challenges such as anthelmintic resistance.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1164-z) contains supplementary material, which is available to authorized users.

Ageing in a variable habitat: environmental stress affects senescence in parasite resistance in St Kilda Soay sheep

Despite widespread empirical evidence for a general deterioration in the majority of traits with advancing age, it is unclear whether the progress of senescence is chronologically determined, or whether factors such as environmental conditions experienced over the lifespan are more important. We explored the relative importance of ‘chronological’ and ‘environmental’ measures of age to changes in parasite resistance across the lifespan of free-living Soay sheep. Our results show that individuals experience an increase in parasite burden, as indicated by gastrointestinal helminth faecal egg count (FEC) with chronological age. However, chronological age fails to fully explain changes in FEC because a measure of environmental age, cumulative environmental stress, predicts an additional increase in FEC once chronological age has been accounted for. Additionally, we show that in females age-specific changes are dependent upon the environmental conditions experienced across individuals' life histories: increases in FEC with age were greatest among individuals that had experienced the highest degree of stress. Our results illustrate that chronological age alone may not always correspond to biological age, particularly in variable environments. In these circumstances, measures of age that capture the cumulative stresses experienced by an individual may be useful for understanding the process of senescence.

Epidemiology of gastrointestinal nematode parasitism in a commercial sheep flock and its implications for control programmes

The epidemiology of nematode infections in a uk commercial crossbred sheep flock was studied from January 2004 to January 2005. The ewes were treated orally with moxidectin when they were...

Major Histocompatibility ComplexDRB1 gene: its role in nematode resistance in Suffolk and Texel sheep breeds

A potential control strategy for nematode infection in sheep is the implementation of a breeding programme to select for genes associated with resistance. The Texel breed is more resistant to gastrointestinal nematode infection than the Suffolk breed, based on faecal egg count, and this difference should enable the identification of some of the genes responsible for resistance. The objective of this study was to determine if variation at the ovine MHC-DRB1 locus was associated with variation in faecal egg count in Suffolk and Texel sheep. Ovar-DRB1 alleles and faecal egg count were determined for Texel (n = 105) and Suffolk (n = 71) lambs. Eight Ovar-DRB1 alleles, including 1 previously unknown allele, were identified in the Texel breed by sequence-base-typing. Seven Ovar-DRB1 alleles were identified in the Suffolk breed. Two Ovar-DRB1 alleles were common to both breeds, but were among the least frequent in the Suffolk population. In the Suffolk breed 1 Ovar-DRB1 allele was associated with a decrease in faecal egg count and 2 alleles with an increase in faecal egg count. This locus accounted for 14% of the natural variation in faecal egg count in Suffolks. There was no evidence for an association between Ovar-DRB1 alleles and faecal egg count in the Texel breed and the Ovar-DRB1 locus accounted for only 3% of the phenotypic variation in faecal egg count. These results suggest that the Ovar-DRB1 gene plays an important role in resistance to nematode infection in the Suffolk breed. The difference in faecal egg counts between these breeds may be attributable in part to the different allele profile at the Ovar-DRB1 locus.

Periparturient increase in faecal egg counts in a captive population of mohor gazelle (Gazella dama mhorr)

The objective of this study was to assess whether there was a periparturient rise in the faecal egg output of a population of North African gazelles (Gazeia dama mhorr) kept...

The sequential analysis of local inflammatory cells during abomasal nematode infection in periparturient sheep.

A technique to take sequential tissue biopsy samples in multiparous, periparturient ewes from the abomasal mucosa is described, developed in parallel in Scotland and New Zealand. Samples were extracted via abomasal cannulae inserted into the wall of the abomasum and exteriorised through dorso-ventral laparotomy. Animals recovered quickly post-surgery, and tolerated the cannula and sampling without any adverse signs of pain or discomfort. The technique was deployed in two pilot studies to investigate the sequential mucosal inflammatory cell responses in well-defined parasitological models, during the periparturient relaxation of immunity in ewes infected with gastrointestinal nematodes and subjected to different feeding treatments. One experiment (Moredun Research Institute, Scotland) involved the infection of twin-bearing ewes with Teladorsagia circumcincta L3 either before, or after lambing. By feeding ewes with different levels of protein supplementation, preliminary data on the impact of nutrition on the eosinophil, mucosal mast cell and globule leucocyte responses during this period were investigated. A similar study was also performed at Lincoln University, New Zealand, to investigate these cell responses in sheep fed relatively high or low protein diets during pregnancy, and infected with a combined immunisation regime of T. circumcincta and Trichostrongylus colubriformis L3. These studies confirmed the phenomenon termed the periparturient relaxation in immunity (PPRI) where a transitory increase in faecal egg counts is observed during late pregnancy and lactation, and this effect was exacerbated during protein undernutrition. Although the number of animals was low in each experiment and the cell responses variable, the results together suggest a reduction in the number of mucosal mast cells and globule leucocyte during the PPRI when protein supply was restricted. The present paper thus describes a successful technique to monitor ovine mucosal cell populations during local immune responses in normal and pregnant sheep. It is envisaged that this technique will be a powerful adjunct to investigations into mucosal immune mechanisms and disease pathogenesis, and will be employed to confirm the influence of dietary protein on the local inflammatory cell responses during the PPRI.

Consequences of long-term feeding with condensed tannins on sheep parasitised with Trichostrongylus colubriformis

Naive wethers were used to investigate the long-term effects of dietary condensed tannins from Quebracho extract, during an intestinal parasitic infection in sheep. Sheep were allocated to eight groups; seven groups were daily infected with 3000 L 3 Trichostrongylus colubriformis for 10 weeks and the eighth group was the uninfected control. The 10-week experiment was divided into two periods; Period 1 (P 1, week 1–5) corresponded to high worm establishment and acquisition of immunity, whereas Period 2 (P 2, week 6–10) to the established worm population and expression of host immunity. Three experimental foods with similar composition were formulated: Q0, Q3 and Q6. Their difference was in the content of Quebracho extract which was 0, 30 and 60 g per kg fresh matter, respectively. All foods were offered at an allowance of 3.5% of sheep liveweight. During P 1, parasitised sheep were offered one of the three experimental foods and during P 2 they either remained on the same food or changed food according to the design (P 1–P 2): Q0–Q0, Q0–Q3, Q0–Q6, Q3–Q0, Q3–Q3, Q6–Q0, Q6–Q6. Control sheep were offered the allowance of Q0 throughout. Sheep that consumed Q3 and Q6 reduced their faecal egg counts (FEC) compared to sheep offered Q0, during both periods ( P<0.05). No differences were observed in the FEC between sheep offered Q3 and Q6. The changeover from Q0 in P 1 to either Q3 or Q6 during P 2, was accompanied by a reduction in FEC ( P<0.05), whereas an increase in FEC was observed when food changed from Q3 or Q6 to Q0 ( P<0.05). Worm burdens and fecundity at the end of the experiment were reduced in sheep offered foods Q3 and Q6 compared to sheep offered Q0. A significant decrease in liveweight gain and in food conversion efficiency of parasitised sheep offered Q3 and Q6 compared to sheep offered Q0, was observed in P 1 ( P<0.05) but not in P 2. By the end of the experiment control sheep had achieved higher liveweight and converted food more efficiently than parasitised sheep ( P<0.05). In conclusion, evidence for a long-term effect of Quebracho extract, during both the initial establishment and on the established T. colubriformis population in sheep, was provided by the present study. It is suggested that the effect observed was a direct anthelmintic effect of the condensed tannins included in sheep diets.

Resistance of Galla and Small East African goats in the sub-humid tropics to gastrointestinal nematode infections and the peri-parturient rise in faecal egg counts

A study was carried out from 1994 to 1996 to compare the resistance to naturally acquired gastrointestinal (GI) nematode infections (predominantly Haemonchus contortus) of 88 Galla and 114 Small East African (SEA) goats (does) in the sub-humid coastal region of Kenya. Live weights (LWT), blood packed cell volume (PCV) and faecal egg counts (FEC) were recorded each year at mating, 3–4 months after mating, 1–2 weeks before kidding and 1–4 months after kidding. There was a significant increase in FEC and a decline in PCV in lactating does compared to non-lactating does over the peri-parturient period. This peri-parturient rise in FEC occurred in both breeds but was more marked and persistent in the Galla than in the SEA. The SEA does were more resistant to GI nematode infections than Galla does as shown by their significantly lower FEC and higher PCV at all sampling times over the reproductive cycle, but this breed difference was particularly marked over the lactation period.

Observations on the epidemiology of gastrointestinal nematodes of farmed red deer in central southern England

The epidemiology of the gastrointestinal nematodes of farmed red deer was followed over three years on two farms in north Hertfordshire. Worm counts on 10 animals (four months to 10 years old) between November and March showed that mixed ostertagid infections were dominant with very small numbers of Trichostrongylus axei, Cooperia punctata and Oesophagostomum species also present in some individuals. An increase in the faecal nematode egg count of the hinds in summer was followed by an increase in pasture larval counts which peaked between September and November. Many calves had patent infections by the first week of September. Although the pasture larval counts were very low at the beginning of the 1989 season, anthelmintic treatment at turnout in May had little influence either on the summer increase in faecal egg count or on the subsequent pasture larval counts, and repeated treatments had only a moderate influence. However, the movement of one of the calving groups to an aftermath in mid-July did reduce the infection to which their calves were exposed. Nevertheless, none of the calves showed significant effects of parasitism when they were removed from the pasture and treated at weaning in early September.

Emergence from inhibited development of cyathostome larvae in ponies following failure to remove them by repeated treatments with benzimidazole compounds

The effect of three albendazole treatments at 5-week intervals, beginning at turnout in April, on cyathostome infections in Shetland ponies was compared with the effect of sequential treatments with albendazole, oxfendazole and oxibendazole. The results showed a substantial reduction in faecal egg output after the first albendazole treatment. Since faecal egg counts remained very low, no estimation of the effect of the second treatment was possible. The third treatment with albendazole and oxibendazole was followed by an increase in faecal egg counts to values of greater than 100 eggs g-1 within 4 weeks. A final albendazole treatment in December, 1 week before necropsy, failed to reduce faecal egg counts. These results suggest resistance to albendazole and oxibendazole in the cyathostome populations of the ponies. The increase in faecal egg counts after the third anthelmintic treatment in July occurred, although overwintered pasture infectivity was very low. The most likely explanation for this increase is resumption of the development of worms which overwintered as inhibited larvae in the host.

Schistosoma mattheei in Cattle: the Host-Parasite Relationship

Summary Calves were injected experimentally with Schistosoma mattheei. Eggs were first detected in the faeces 6-7 weeks after infection and the egg count rose sharply to a peak at 10-11 weeks and then declined rapidly to a low level which was maintained until 75 weeks in some animals. The decline in egg count was due mainly to suppression of egg laying by the host. The percentage of parasites administered that was recovered at slaughter showed a highly significant decrease between 8 and 78 weeks after infection. Animals subjected to reinfection showed little or no increase in faecal egg count but there was no reduction in the establishment of parasites.