Hostname: page-component-cd9895bd7-7cvxr Total loading time: 0 Render date: 2025-01-03T15:18:08.723Z Has data issue: false hasContentIssue false
  • English
  • Français

Gastrointestinal nematode infection in sheep – a review of the alternatives to anthelmintics in parasite control

Published online by Cambridge University Press:  08 March 2007

G. Sayers  and
T. Sweeney
G. Sayers*
Affiliation:
School of Agriculture, Food Science and Veterinary Medicine & Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Ireland
T. Sweeney
Affiliation:
School of Agriculture, Food Science and Veterinary Medicine & Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Ireland
*
*Corresponding author: Email: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Efforts to curb production losses caused by nematode parasitism in sheep have led to the development of a number of control methods to complement or replace anthelmintics. The need for alternative control measures stems from the emergence of anthelmintic-resistant parasitic nematodes with reports of multi-class resistance to these drugs now emerging. A number of these control methods such as predacious microfungi, protein supplementation, plant extracts in feed and vaccines have demonstrated potential to control infection but require development and examination under natural conditions. Breeding for natural resistance to nematode infection has already shown success in controlling the disease under natural conditions. Selection for resistance is currently based on fecal egg count measurements but identification of genetic indicators of resistance will provide a more efficient method of selection. Current quantitative trait loci for nematode resistance include the MHC genes, interferon gamma gene, IgE gene and microsatellites on chromosome 1, 5 and 6. This paper reviews the current alternatives to anthelmintics to control infection, with an emphasis on breeding for host resistance and identification of genetic indicators of resistance.

Keywords

sheepgastrointestinal nematodesQTLanthelmintics
Type
Research Article
Information
Animal Health Research Reviews , Volume 6 , Issue 2 , December 2005 , pp. 159 - 171
Copyright
Copyright © CAB International 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Alarcon, JB, Waine, GW and McManus, DP (1999). DNA vaccines: technology and applications as anti-parasite and anti-microbial agents. Advances in Parasitology 42: 344–410.Google Scholar
Amarante, AF, Bricarello, PA, Rocha, RA and Gennari, SM (2004). Resistance of Santa Ines, Suffolk and Ile de France sheep to naturally acquired gastrointestinal nematode infections. Veterinary Parasitology 120: 91–106.CrossRefGoogle Scholar
Andrews, SJ, Hole, NJK, Munn, EA and Rolph, TP (1995). Vaccination of sheep against haemonchosis with H11, a gut membrane-derived protective antigen from the adult parasite: prevention of the periparturient rise and colostral transfer of protective immunity. International Journal for Parasitology 25: 839–846.CrossRefGoogle ScholarPubMed
Andrews, SJ, Rolph, TP and Munn, EA (1997). Duration of protective immunity against ovine haemonchosis following vaccination with the nematode gut membrane antigen H11. Research in Veterinary Science 62: 223–227.CrossRefGoogle ScholarPubMed
Bakker, N, Vervelde, L, Kanobana, K, Knox, DP, Cornelissen, AW, de Vries, E and Yatsuda, AP (2004). Vaccination against the nematode Haemonchus contortus with a thiol-binding fraction from the excretory/secretory products (ES). Vaccine 22: 618–628.CrossRefGoogle ScholarPubMed
Beh, KJ, Hulme, DJ, Callaghan, MJ, Leish, Z, Lenane, I, Windon, RG and Maddox, JF (2002). A genome scan for quantitative trait loci affecting resistance to Trichostrongylus colubriformis in sheep. Animal Genetics 33: 97–106.CrossRefGoogle ScholarPubMed
Benavides, MV, Weimerb, TA, Borbaa, MFS, Bernec, MEA and Saccoa, AMS (2002). Association between microsatellite markers of sheep chromosome 5 and faecal egg counts. Small Ruminant Research 46: 97–105.CrossRefGoogle Scholar
Blattman, AN, Hulme, DJ, Kinghorn, BP, Woolaston, RR, Gray, GD and Beh, KJ (1993). A search for associations between major histocompatibility complex restriction fragment length polymorphism bands and resistance to Haemonchus contortus infection in sheep. Animal Genetics 24: 277–282.CrossRefGoogle ScholarPubMed
Bird, J, Shulaw, WP, Pope, WF and Bremer, CA (2001). Control of anthelmintic resistant endoparasites in a commercial sheep flock through parasite community replacement. Veterinary Parasitology 97: 219–225.CrossRefGoogle Scholar
Bishop, SC and Stear, MJ (2003). Modelling of host genetics and resistance to infectious diseases: understanding and controlling nematode infections. Veterinary Parasitology 115: 147–166.CrossRefGoogle ScholarPubMed
Bisset, SA and Morris, CA (1996). Feasibility and implications of breeding sheep for resilience to nematode challenge. International Journal for Parasitology 26: 857–868.CrossRefGoogle ScholarPubMed
Bisset, SA, Vlassoff, A, West, CJ and Morrison, L (1997). Epidemiology of nematodosis in Romney lambs selectively bred for resistance or susceptibility to nematode infection. Veterinary Parasitology 70: 255–269.CrossRefGoogle ScholarPubMed
Buitkamp, J, Filmether, P, Stear, MJ and Epplen, JT (1996). Class I and class II major histocompatibility complex alleles are associated with faecal egg counts following natural, predominantly Ostertagia circumcincta infection. Parasitological Research 82: 693–696.CrossRefGoogle Scholar
Burke, JM and Miller, JE (2002). Relative resistance of Dorper crossbred ewes to gastrointestinal nematode infection compared with St. Croix and Katahdin ewes in the southeastern United States. Veterinary Parasitology 109: 265–275.CrossRefGoogle Scholar
Burke, JM, Miller, JE and Brauer, DK (2005). The effectiveness of copper oxide wire particles as an anthelmintic in pregnant ewes and safety to offspring. Veterinary Parasitology 131: 291–297.CrossRefGoogle ScholarPubMed
Chandrawathani, P, Yusoff, N, Wan, LC, Ham, A and Waller, PJ (2004a). Total anthelmintic failure to control nematode parasites of small ruminants on government breeding farms in Sabah, East Malaysia. Veterinary Results Communication 28: 479–489.CrossRefGoogle ScholarPubMed
Chandrawathani, P, Jamnah, O, Adnan, M, Waller, PJ, Larsen, M and Gillespie, AT (2004b). Field studies on the biological control of nematode parasites of sheep in the tropics, using the microfungus Duddingtonia flagrans. Veterinary Parasitology 120: 177–187.CrossRefGoogle ScholarPubMed
Charon, KM, Moskwa, B, Rutkowski, R, Gruszczynska, J and Swiderek, W (2002). Microsatellite polymorphism in DRB1 gene (MHC class II) and its relation to nematode faecal egg count in Polish healthy sheep. Journal of Animal Feed Sciences 11: 47–58.CrossRefGoogle Scholar
Clarke, RA, Burn, AL, Lenane, I, Windon, RG and Beh, KJ (2001). Molecular analysis and nematode resistance association of a polymorphism at the 5' end of the sheep IgE gene. Veterinary Immunology and Immunopathology 10: 15–29.CrossRefGoogle Scholar
Coles, GC (2005). Anthelmintic resistance–looking to the future: a UK perspective. Research in Veterinary Science 78: 99–108.CrossRefGoogle Scholar
Colglazier, ML, Kates, KC and Enzie, FD (1974). Cambendazole-resistant Haemonchus contortus strain in sheep: further experimental development. Journal for Parasitology 60: 289–292.CrossRefGoogle ScholarPubMed
Coltman, DW, Wilson, K, Pilkington, JG, Stear, MJ and Pemberton, JM (2001). A microsatellite polymorphism in the gamma interferon gene is associated with resistance to gastrointestinal nematodes in a naturally-parasitised population of Soay sheep. Parasitology 122: 571–582.CrossRefGoogle Scholar
Coop, RL and Kyriazakis, I (2001). Influence of host nutrition on the development and consequences of nematode parasitism in ruminants. Trends in Parasitology 17: 325–330.CrossRefGoogle ScholarPubMed
Crawford, AM and McEwan, JC (1999). Identification of Animals Resistant to Nematode Parasite Infection. UK Patent GB2337587.Google Scholar
Datta, FU, Nolan, JV, Rowe, JB, Gray, GD and Crook, BJ (1999). Long-term effects of short-term provision of protein-enriched diets on resistance to nematode infection and live-weight gain and wool growth in sheep. International Journal for Parasitology 29: 479–488.CrossRefGoogle ScholarPubMed
Diez-Tascon, C, MacDonald, PA, Dodds, KG, McEwan, JC and Crawford, AM (2002). A screen of chromosome 1 for QTL's affecting nematode resistance in an ovine outcross population. In: Proceedings of the 7th World Congress of Genetic Applications in Livestock Productions, Montpellier, 19–23 August 2002, INRA, France. Communication No. 13–37.Google Scholar
Diez-Tascon, C, Keane, OM, Wilson, T, Zadissa, A, Hyndman, DL, Baird, DB, McEwan, JC and Crawford, AM (2005). Microarray analysis of selection lines from outbred populations to identify genes involved with nematode parasite resistance in sheep. Physiological Genomics 21: 59–69.CrossRefGoogle ScholarPubMed
Dominguez-Torano, IA, Cuquerella, M, Gomez-Munoz, M, Mendez, S, Fernandez-Perez, FJ and Alunda, JM (2000). Vaccination of Manchego lambs against Haemonchus contortus with a somatic fraction (p26/23) of adult parasites. Parasite Immunology 22: 131–138.CrossRefGoogle ScholarPubMed
Douch, PG, Green, RS, Morris, CA, McEwen, JC and Windon, RG (1996). Phenotypic markers for selection of nematode-resistant sheep. International Journal for Parasitology 26: 899–911.CrossRefGoogle ScholarPubMed
Eady, SJ, Woolaston, RR and Barger, IA (2003). Comparison of genetic and nongenetic strategies for control of gastrointestinal nematodes of sheep. Livestock Production Science 81: 11–23.CrossRefGoogle Scholar
Else, KJ and Finkelman, FD (1998). Intestinal nematode parasites, cytokines and effector mechanisms. International Journal for Parasitology 28: 1145–1158.CrossRefGoogle ScholarPubMed
Flores-Crespo, J, Herrera-Rodriguez, D, Mendoza de Gives, P, Liebano-Hernandez, E, Vazquez-Prats, VM and Lopez-Arellano, ME (2003). The predatory capability of three nematophagous fungi in the control of Haemonchus contortus infective larvae in ovine faeces. Journal of Helminthology 77: 297–303.CrossRefGoogle ScholarPubMed
Fontenot, ME, Miller, JE, Pena, MT, Larsen, M and Gillespie, A (2003). Efficiency of feeding Duddingtonia flagrans chlamydospores to grazing ewes on reducing availability of parasitic nematode larvae on pasture. Veterinary Parasitology 118: 203–213.CrossRefGoogle ScholarPubMed
Gasbarre, LC and Miller, JE (2000). Genetics of helminth resistance. In: Axford, RFE, Bishop, SC, Nicholas, FW and Owen, JB (eds) Breeding for Disease Resistance in Farm Animals, 2nd edn. Wallingford, UK: CABI Publishing, pp. 129–152.Google Scholar
Gauly, M and Erhardt, G (2001). Genetic resistance to gastrointestinal nematode parasites in Rhon sheep following natural infection. Veterinary Parasitology 102: 253–259.CrossRefGoogle ScholarPubMed
Gill, HS, Altmann, K, Cross, ML and Husband, AJ (2000). Induction of T helper 1- and T helper 2-type immune responses during Haemonchus contortus infection in sheep. Immunology 99: 458–463.CrossRefGoogle Scholar
Githigia, SM, Thamsborg, SM, Larsen, M, Kyvsgaard, NC and Nansen, P (1997). The preventative effect of the fungus Duddingtonia flagrans on Trichostrongyle infections of lambs on pasture. International Journal for Parasitology 27: 931–939.CrossRefGoogle ScholarPubMed
Githigia, SM, Thamsborg, SM and Larsen, M (2001). Effectiveness of grazing management in controlling gastrointestinal nematodes in weaner lambs on pasture in Denmark. Veterinary Parasitology 99: 15–27.CrossRefGoogle ScholarPubMed
Good, B, Hanrahan, JP, Crowley, BA and Mulcahy, G (2005). Texel sheep are more resistant than Suffolks to natural helminth challenge based on faecal egg count and nematode burden. Veterinary Parasitology: in press.Google Scholar
Gray, GD (1987). Genetic resistance to haemonchosis in sheep. Parasitology Today 3: 253–255.CrossRefGoogle ScholarPubMed
Grencis, RK (2001). Cytokine regulation of resistance and susceptibility to intestinal nematode infection–from host to parasite. Veterinary Parasitology 100: 45–50.CrossRefGoogle Scholar
Gruner, L, Aumont, G, Getachew, T, Brunel, JC, Pery, C, Cognie, Y and Guerin, Y (2003). Experimental infection of Black Belly and INRA 401 straight and crossbred sheep with trichostrongyle nematode parasites. Veterinary Parasitology 116: 239–249.CrossRefGoogle ScholarPubMed
Gruner, L, Bouix, J and Brunel, JC (2004a). High genetic correlation between resistance to Haemonchus contortus and to Trichostrongylus colubriformis in INRA 401 sheep. Veterinary Parasitology 119: 51–58.CrossRefGoogle ScholarPubMed
Gruner, L, Bouix, J, Vu Tien Khang, J, Mandonnet, N, Eychenne, F, Cortet, J, Sauve, C and Limouzin, C (2004b). A short-term divergent selection for resistance to Teladorsagia circumcincta in Romanov sheep using natural or artificial challenge. Genetic Selection Evolution 36: 217–242.CrossRefGoogle ScholarPubMed
Haile, A, Tembely, S, Anindo, DO, Mukasa-Mugerwa, E, Rege, JEO, Yami, A and Baker, L (2002). Effects of breed and dietary protein supplementation on the responses to gastrointestinal nematode infections in Ethiopian sheep. Small Ruminant Research 44: 247–261.CrossRefGoogle Scholar
Hanrahan, JP and Crowley, BA (1999). Evidence for breed differences in resistance to nematode parasitism. Sheep and Goat Commission of European Association for Animal Production (50th Annual Meeting, Zurich) Session IV: 4 pages.Google Scholar
Hertzberg, H, Schallig, HDFH and Deplazes, P (1999). Development of a protective immunity against Ostertagia leptospicularis in trickle-infected sheep and parallel changes of serum gastrin, pepsinogen and antibody levels. The Veterinary Journal 157: 148–159.CrossRefGoogle ScholarPubMed
Hounzangbe-Adote, S, Zinsou, FE, Hounpke, V, Moutairou, K and Hoste, H (2005). In vivo effects of Fagara leaves on sheep infected with gastrointestinal nematodes. Tropical Animal Health Production 37: 205–214.CrossRefGoogle ScholarPubMed
Hughes, PL, McKenna, PB and Murphy, A (2004). Resistance to moxidectin and abamectin in naturally acquired Ostertagia circumcincta infections in sheep. New Zealand Veterinary Journal 52: 202–204.CrossRefGoogle ScholarPubMed
Hughes, PL, McKenna, PB and Dowling, AF (2005). A survey of the prevalence of emerging macrocyclic lactone resistance and of benzimidazole resistance in sheep nematodes in lower North Island of New Zealand. New Zealand Veterinary Journal 53: 87–90.CrossRefGoogle ScholarPubMed
Hulme, DJ, Windon, RG, Nicholas, FW and Beh, KJ (1991). Association between MHC Class II RFLP and Trichostrongylus resistance. In: Gray, GD and Woolaston, RR (eds) Breeding for Disease Resistance in Sheep. Melbourne: Australian Wool Corporation, pp. 115–120.Google Scholar
Huntley, JF, Schallig, HDFH, Kooyman, FNJ, MacKellar, A, Jackson, F and Smith, WD (1998). IgE antibody during infection with the ovine abomasal nematode, Teladorsagia circumcincta: primary and secondary responses in serum and gastric lymph of sheep. Parasite Immunology 20: 565–571.CrossRefGoogle ScholarPubMed
Ishikawa, N, Goyal, PK, Mahida, YR, Li, K-F and Wakelin, D (1998). Early cytokine responses during intestinal parasitic infections. Immunology 93: 257–263.CrossRefGoogle ScholarPubMed
Kahn, LP, Knox, MR, Gray, GD, Lea, JM and Walkden-Bown, SW (2003). Enhancing immunity to nematode parasites in single-bearing Merino ewes through nutrition and genetic selection. Veterinary Parasitology 112: 211–225.CrossRefGoogle ScholarPubMed
Kaplan, RM (2004). Drug resistance in nematodes of veterinary importance: a status report. Trends in Parasitology 20: 477–481.CrossRefGoogle ScholarPubMed
Knox, DP (2000). Development of vaccines against gastrointestinal nematodes. Parasitology 120: S43–S61.CrossRefGoogle ScholarPubMed
Knox, MR (2002). Effectiveness of copper oxide wire particles for Haemonchus contortus control in sheep. Australian Veterinary Journal 80: 224–227.CrossRefGoogle ScholarPubMed
Knox, DP and Smith, WD (2001). Vaccination against gastrointestinal nematodes of ruminants using gut expressed antigens. Veterinary Parasitology 100: 21–32.CrossRefGoogle ScholarPubMed
Knox, MR, Josh, PF and Anderson, LJ (2002). Deployment of Duddingtonia flagrans in an improved pasture system: dispersal, persistence and effects on free-living soil nematodes and microarthropods. Biological Control 24: 176–182.CrossRefGoogle Scholar
Knox, DP, Redmond, DL, Newlands, GF, Skuce, PJ, Pettit, D and Smith, WD (2003). The nature and prospects for gut membrane proteins as vaccine candidates for Haemonchus contortus and other ruminant trichostrongyloids. International Journal for Parasitology 33: 1129–1137.CrossRefGoogle ScholarPubMed
Larsen, M (2000). Prospect for controlling animal parasitic nematodes by predacious micro fungi. Parasitology 120: S121–S131.CrossRefGoogle ScholarPubMed
Le Jambre, LF, Geoghegan, J and Lyndal-Murphy, M (2005). Characterization of moxidectin resistant Trichostrongylus colubriformis and Haemonchus contortus. Veterinary Parasitology 128: 83–90.CrossRefGoogle ScholarPubMed
Maddox, JF, Davies, KP, Crawford, AM, Hulme, DJ, Vaiman, D, Cribiu, EP, Freking, BA, Beh, KJ, Cockett, NE, Kang, N, Riffkin, CD, Drinkwater, R, Moore, SS, Dodds, KG, Lumsden, JM, van Stijn, TC, Phua, SH, Adelson, DL, Burkin, HR, Broom, JE, Buitkamp, J, Cambridge, L, Cushwa, WT, Gerard, E, Galloway, SM, Harrison, B, Hawken, RJ, Hiendleder, S, Henry, HM, Medrano, JF, Paterson, KA, Schibler, L, Stone, RT and van Hest, B (2001). An enhanced linkage map of the sheep genome comprising more than 1000 loci. Genome Results 11: 1275–1289.CrossRefGoogle ScholarPubMed
Matika, O, Nyoni, S, van Wyk, JB, Erasmus, GJ and Baker, RL (2003). Resistance of Sabi and Dorper ewes to gastro-intestinal nematode infections in an African semi-arid environment. Small Ruminant Research 47: 95–102.CrossRefGoogle Scholar
McClure, SJ, Davey, RL, Emery, DL, Colditz, IG and Lloyd, JB (1996). In vivo depletion of T-cells and cytokines during primary exposure of sheep to parasites. Veterinary Immunology and Immunopathology 54: 83–90.CrossRefGoogle ScholarPubMed
Meeusen, ENT and Piedrafita, D (2003). Exploiting natural immunity to helminth parasites for the development of veterinary vaccines. International Journal for Parasitology 33: 1285–1290.CrossRefGoogle ScholarPubMed
Miller, JE, Bahirathan, M, Lemarie, SL, Hembry, FG, Kearney, MT and Barras, SR (1998). Epidemiology of gastrointestinal nematode parasitism in Suffolk and Gulf Coast Native sheep with special emphasis on relative susceptibility to Haemonchus contortus infection. Veterinary Parasitology 74: 55–74.CrossRefGoogle ScholarPubMed
Molan, AL, Waghorn, GC and McNabb, WC (2002). Effect of condensed tannins on egg hatching and larval development of Trichostrongylus colubriformis in vitro. Veterinary Record 150: 65–69.CrossRefGoogle ScholarPubMed
Mosmann, TR (1994). Properties and functions of interleukin-10. Advances in Immunology 56: 1–26.CrossRefGoogle ScholarPubMed
Mugambi, JM, Wanyangu, SW, Bain, RK, Owango, MO, Duncan, JL and Stear, MJ (1996). Response of Dorper and red Maasai lambs to trickle Haemonchus contortus infections. Research in Veterinary Science 61: 218–221.CrossRefGoogle ScholarPubMed
Mugambi, JM, Bain, RK, Wanyangu, SW, Ihiga, MA, Duncan, JL, Murray, M and Stear, MJ (1997). Resistance of four sheep breeds to natural and subsequent artificial Haemonchus contortus infection. Veterinary Parasitology 69: 265–273.CrossRefGoogle ScholarPubMed
Nieuwoudt, SW, Theron, HE and Kruger, LP (2002). Genetic parameters for resistance to Haemonchus contortus in Merino sheep in South Africa. Journal of South African Veterinary Association 73: 4–7.CrossRefGoogle ScholarPubMed
Niezen, JH, Charleston, WA, Hodgson, J, Miller, CM, Waghorn, TS and Robertson, HA (1998a). Effect of plant species on the larvae of gastrointestinal nematodes which parasitise sheep. International Journal for Parasitology 28: 791–803.CrossRefGoogle ScholarPubMed
Niezen, JH, Robertson, HA, Waghorn, GC and Charleston, WA (1998b). Production, faecal egg counts and worm burdens of ewe lambs which grazed six contrasting forages. Veterinary Parasitology 80: 15–27.CrossRefGoogle ScholarPubMed
Niezen, JH, Robertson, HA, Sidey, A and Wilson, SR (2002). The effect of pasture species on parasitism and performance of lambs grazing one of three grass-white clover pasture swards. Veterinary Parasitology 105: 303–315.CrossRefGoogle ScholarPubMed
Niven, P, Anderson, N and Vizard, AL (2002). The integration of grazing management and summer treatments for the control of trichostrongylid infections in Merino weaners. Australian Veterinary Journal 80: 559–566.CrossRefGoogle ScholarPubMed
Outteridge, PM, Andersson, L, Douch, PG, Green, RS, Gwakisa, PS, Hohenhaus, MA and Mikko, S (1996). The PCR typing of MHC-DRB genes in the sheep using primers for an intronic microsatellite: application to nematode parasite resistance. Immunology and Cell Biology 74: 330–336.CrossRefGoogle ScholarPubMed
Paterson, KA, McEwan, JC, Dodds, KG, Morris, CA and Crawford, AM (2001). Fine mapping a locus affecting host resistance to internal parasites in sheep. Proceedings of the Associations for Advancement in Animal Breeding and Genetics 13: 91–94.Google Scholar
Pena, MT, Miller, JE, Fontenot, ME, Gillespie, A and Larsen, M (2002). Evaluation of Duddingtonia flagrans in reducing infective larvae of Haemonchus contortus in faeces of sheep. Veterinary Parasitology 103: 259–265.CrossRefGoogle ScholarPubMed
Pernthaner, A, Cole, SA, Morrison, L and Hein, WR (2005). Increased expression of interleukin-5 (IL-5), IL-13, and tumor necrosis factor alpha genes in intestinal lymph cells of sheep selected for enhanced resistance to nematodes during infection with Trichostrongylus colubriformis. Infection Immunology 73: 2175–2183.CrossRefGoogle ScholarPubMed
Raadsma, HW, Gray, GD and Woolaston, RR (1997). Genetics of disease resistance and vaccine response. In: Piper, L and Ruvinsky, A (eds) The Genetics of Sheep. Wallingford, UK: CAB International, pp. 199–225.Google Scholar
Radford, AJ, Hodgson, AL, Rothel, JS and Wood, PR (1991). Cloning and sequencing of the ovine gamma-interferon gene. Australian Veterinary Journal 68: 82–84.CrossRefGoogle ScholarPubMed
Redmond, DL and Knox, DP (2004). Protection studies in sheep using affinity-purified and recombinant cysteine proteinases of adult Haemonchus contortus. Vaccine 22: 4252–4261.CrossRefGoogle ScholarPubMed
Riffkin, M, Seow, H-F, Jackson, D, Brown, L and Wood, P (1996). Defence against the immune barrage: helminth survival strategies. Immunology and Cell Biology 74: 564–574.CrossRefGoogle ScholarPubMed
Sargison, ND, Gilleard, JS, Mitchell, G and Jackson, F (2004). Ivermectin resistance in a terminal sire sheep flock. Veterinary Record 155: 343.Google Scholar
Sauermann, U, Stahl-Hennig, C, Stolte, N, Muhl, T, Krawczak, M, Spring, M, Fuchs, D, Kaup, FJ, Hunsmann, G and Sopper, S (2000). Homozygosity for a conserved MHC class II DQ - DRB haplotype is associated with rapid disease progression in simian immunodeficiency virus-infected macaques: results from a prospective study. Journal of Infectious Diseases 182: 716–724.CrossRefGoogle ScholarPubMed
Sayers, G, Mitchel, S, Ryan, M, Stear, MJ, Hanrahan, JP and Sweeney, T (2004). Analysis of DRB1 exon 2 genotyping by STR size analysis in Suffolk and Texel sheep breeds. Irish Journal for Agriculture and Food Research 43: 177–183.Google Scholar
Sayers, G, Hanrahan, JP, Good, B, Ryan, M, Angles, JM and Sweeney, T (2005a). Major histocompatibility complex DRB1 locus: its role nematode resistance in Suffolk and Texel sheep. Parasitology 131: 1–7.CrossRefGoogle ScholarPubMed
Sayers, G, Hanrahan, JP, Good, B, Ryan, M and Sweeney, T (2005b). Intron 1 of the ovine interferon gamma gene: its role in nematode resistance in Suffolk and Texel sheep. Research in Veterinary Science 79: 191–196.CrossRefGoogle ScholarPubMed
Schallig, HD (2000). Immunological responses of sheep to Haemonchus contortus. Parasitology 120: S63–S72.CrossRefGoogle ScholarPubMed
Scheerlinck, JP, Karlis, J, Tjelle, TE, Presidente, PJ, Mathiesen, I and Newton, SE. (2004). In vivo electroporation improves immune responses to DNA vaccination in sheep. Vaccine 22: 1820–1825.CrossRefGoogle ScholarPubMed
Schmidt, P, Ludt, C, Kuhn, CH and Buitkamp, J (1996). A diallelic tetranucleotide repeat, (GT 3) 5 or 6, within intron 1 of the ovine interferon-γ gene. Animal Genetics 27: 437.CrossRefGoogle ScholarPubMed
Schwaiger, F-W, Buitkamp, J, Weyers, E and Epplen, JT (1993). Typing of the Artiodactyl MHC-DRB genes with the help of intronic simple repeated DNA sequences. Molecular Ecology 2: 55–59.CrossRefGoogle ScholarPubMed
Schwaiger, F-W, Gostomski, D, Stear, MJ, Duncan, JL, McKellar, QA, Epplen, JT and Buitkamp, J (1995). An ovine major histocompatibility complex DRB1 allele is associated with low faecal egg counts following natural, predominantly Ostertagia circumcincta infection. International Journal for Parasitology 25: 815–822.CrossRefGoogle ScholarPubMed
Shaw, RJ, Gatehouse, TK and McNeill, M (1998). Serum IgE responses during primary and challenge infections of Sheep with Trichostrongylus colubriformis. International Journal for Parasitology 28: 293–302.CrossRefGoogle ScholarPubMed
Simm, G (ed.) (1998). New technologies. In: Genetic Improvement of Cattle and Sheep, Chapter 9. Ipswich, UK: Farming Press.Google Scholar
Sreter, T, Kassai, T and Takacs, E (1994). The heritability and specificity of responsiveness to infection with Haemonchus contortus in sheep. International Journal for Parasitology 24: 871–876.CrossRefGoogle ScholarPubMed
Stear, MJ, Bishop, SC, Duncan, JL, McKellar, QA and Murry, M (1995). The repeatability of faecal egg counts, peripheral eosinophil counts and plasma pepsinogen concentrations during deliberate infections with Ostertagia circumcincta. International Journal for Parasitology 25: 375–380.CrossRefGoogle ScholarPubMed
Stear, MJ, Bairden, K, Bishop, SC, Buitkamp, J, Epplen, JT, Gostomski, D, McKellar, AQ, Schwaiger, F-W and Wallace, DS (1996). An ovine lymphocyte antigen is associated with reduced faecal egg counts in four-month-old lambs following natural, predominantly Ostertagia circumcincta infection. International Journal for Parasitology 26: 423–428.CrossRefGoogle ScholarPubMed
Stear, MJ, Strain, SC and Bishop, SC (1999). How lambs control infection with Ostertagia circumcincta. Veterinary Immunology and Immunopathology 72: 213–218.CrossRefGoogle ScholarPubMed
Stear, MJ, Mitchell, S, Strain, S, Bishop, SC and McKeller, QA (2000). The influence of age on the variation among sheep in susceptibility to natural nematode infection. Veterinary Parasitology 89: 31–36.CrossRefGoogle ScholarPubMed
Stear, MJ, Eckersall, PD, Graham, PA, McKellar, QA, Mitchell, S and Bishop, SC (2001). Fructosamine concentration and resistance to natural, predominantly Teladorsagia circumcincta infection. Parasitology 123: 211–218.CrossRefGoogle ScholarPubMed
Stear, MJ, Henderson, NJ, Kerr, A, McKellar, QA, Mitchell, S, Seeley, C and Bishop, SC (2002). Eosinophilia as a marker of resistance to Teladorsagia circumcincta in Scottish Blackface lambs. Parasitology 124: 553–560.CrossRefGoogle ScholarPubMed
Stern, LJ, Brown, JH, Jardetzky, TS, Gorga, JC, Urban, RG, Strominger, JL and Wiley, DC (1994). Crystal structure of the human class II MHC protein HLA-DR1 complexed with an influenza virus peptide. Nature 368: 215–221.CrossRefGoogle ScholarPubMed
Sutherland, IA, Brown, AE, Leathwick, DM and Bisset, SA (2003). Resistance to prophylactic treatment with macrocyclic lactone anthelmintics in Teladorsagia circumcincta. Veterinary Parasitology 115: 301–309.CrossRefGoogle ScholarPubMed
Thorsby, E (1999). MHC structure and function. Transplant Procedures 31: 713–716.CrossRefGoogle ScholarPubMed
Thursz, MR, Thomas, HC, Greenwood, BM and Hill, AV (1997). Heterozygote advantage for HLA class-II type in hepatitis B virus infection. Nature Genetics 17: 11–12.CrossRefGoogle ScholarPubMed
Tzamaloukas, O, Athanasiadou, S, Kyriazakis, I, Jackson, F and Coop, RL (2005). The consequences of short-term grazing of bioactive forages on established adult and incoming larvae populations of Teladorsagia circumcincta in lambs. International Journal for Parasitology 35: 329–335.CrossRefGoogle ScholarPubMed
Vanimisetti, HB, Greiner, SP, Zajac, AM and Notter, DR (2004). Performance of hair sheep composite breeds: resistance of lambs to Haemonchus contortus. Journal of Animal Science 82: 595–604.CrossRefGoogle ScholarPubMed
Vervelde, L, Kooyman, FNJ, van Leeuwen, MAW, Schallig, HDFH, MacKellar, A, Huntley, JF and Cornelissen, AWCA (2001). Age-related protective immunity after vaccination with Haemonchus contortus excretory/secretory proteins. Parasite Immunology 23: 419–426.CrossRefGoogle ScholarPubMed
von Samson-Himmelstjerna, G, Harder, A, Sangster, NC and Coles, GC (2005). Efficacy of two cyclooctadepsipeptides, PF1022A and emodepside, against anthelmintic-resistant nematodes in sheep and cattle. Parasitology 130: 343–347.CrossRefGoogle ScholarPubMed
Wallace, DS, Bairden, K, Duncan, JL, Eckersall, PD, Fishwick, G, Gill, M, Holmes, PH, McKellar, QA, Murray, M, Parkins, JJ and Stear, MJ (1998). The influence of dietary supplementation with urea on resilience and resistance to infection with Haemonchus contortus. Parasitology 116: 67–72.CrossRefGoogle ScholarPubMed
Waller, PJ, Bernes, G, Rudby-Martin, L, Ljungstrom, BL and Rydzik, A (2004a). Evaluation of copper supplementation to control Haemonchus contortus infections of sheep in Sweden. Acta Veterinaria Scandinavica 45: 149–160.CrossRefGoogle ScholarPubMed
Waller, PJ, Schwan, O, Ljungstrom, BL, Rydzik, A and Yeates, GW (2004b). Evaluation of biological control of sheep parasites using Duddingtonia flagrans under commercial farming conditions on the island of Gotland, Sweden. Veterinary Parasitology 126: 299–315.CrossRefGoogle ScholarPubMed
Woolaston, RR, Manueli, P, Eady, SJ, Barger, IA, Le Jambre, LF, Banks, DJD and Windon, RG (1996). The value of circulating eosinophil count as a selection criterion for resistance of sheep to Trichostrongyle parasites. International Journal for Parasitology 26: 123–126.CrossRefGoogle ScholarPubMed
Yatsuda, AP, Krijgsveld, J, Cornelissen, AW, Heck, AJ and de Vries, E (2003). Comprehensive analysis of the secreted proteins of the parasite Haemonchus contortus reveals extensive sequence variation and differential immune recognition. Journal of Biological Chemistry 278: 16941–16951.CrossRefGoogle ScholarPubMed
Zinser, EW, Wolf, ML, Alexander-Bowman, SJ, Thomas, EM, Davis, JP, Groppi, VE, Lee, BH, Thompson, DP and Geary, TG (2002). Anthelmintic paraherquamides are cholinergic antagonists in gastrointestinal nematodes and mammals. Journal of Veterinary Pharmacology and Therapeutics 25: 241–250.CrossRefGoogle ScholarPubMed