This article offers a list of the most common parasites of sheep, both external (ectoparasites) and internal (endoparasites) parasites. Most sheep parasites are also goat parasites, although goats may be affected by some specific parasites that do not affect sheep.

Diseases caused by parasites are called parasitosis.

Detail information on the biology and control (life cycle, anatomy, prevention, chemical control, etc.) of each species is available in specific articles in this site. To visit these specific articles click the corresponding link or use the site map.

  • «$» to «$$$$$» indicates the magnitude of the economic damage on cattle caused by a parasite on a worldwide basis. The more «$», the higher the damage.
  • «R» to «RRRRR» indicates the magnitude of the resistance problems of these parasites to parasiticides on a worldwide basis. The more «R», the higher the risk of resistance.


External Parasites

Biting insects (hematophagous), i.e. they suck blood

  • Black flies, gnats. $-R. Local problem in endemic regions, wordlwide.
  • Fleas. $-R. Local problem in livestock kept indoors by warm and humid weather, worldwide.
  • Keds (Melophagus)$$. Can be a problem worldwide, mainly in regions with cold winters.
  • Midges. $. Local problem in endemic regions, worldwide.
  • Mosquitoes. $-RRR. A worldwide problem in all kind of livestock, but usually not the major issue for sheep and goats.
  • Stable flies. $. A worldwide problem in sheep and goats, both outdoors and indoors, particularly by warm and humid weather, but not as serious as for cattle.
  • Tsetse flies. $$$. A serious problem in Africa in all livestock kept outdoors.
  • Horse flies. $. Usually not a big issue; mainly on sheep and goats kept outdoors by warm weather, worldwide.

Non-biting insects, do not suck blood

  • Filth & nuisance flies. $. Usually a secondary issue in dairy operations and in housed livestock worldwide, mainly during the warm and humid season.
  • Head flies. $$. Can be a problem fot grazing sheep in parts of the Northern Hemisphere by moist and warm weather.
  • Houseflies. $ Can be a serious problem in dairy operations and in housed livestock worldwide, mainly during the warm and humid season.
  • Lice. $$-RR. Very common problem worldwide. Particularly during the cold season in regions with temperate climate.

Insect larvae, myiasis

  • Blowflies. $$$$-RRR. A very serious problem for grazing sheep in many regions with warm or temperate climate (Australia, New Zealand, UK, Ireland, South Africa, etc.).
  • Human bot flies, Dermatobia. $. A serious problem in many regions of Central and South America.
  • Nasal bot flies. $$. Can be a serious problem in endemic regions. Worldwide, mainly during the warm season in regions with temperate climate.
  • Screwworm flies. $$. A serious threat for all livestock outdoors in endemic regions in tropical and subtropical countries where it has not been yet eradicated.
  • Wohlfahrtia. $. Occasionally a problem in Mediterranean countries during summer on grazing sheep and goats.

Ticks (suck blood) & mites (don't suck blood)

  • Amblyomma ticks. $$. Can be a significant problem for grazing sheep and goats in tropical and subtropical regions, mainly in Latin America and Africa. 
  • Dermacentor ticks. $. Usually a secondary problem for grazing sheep and goats in Europe and America.
  • Haemaphysalis ticks. $. Usually a secondary problem for grazing sheep and goats in parts of Asia, Africa and Europe.
  • Hyalomma ticks. $$. Can be a serious problem in some regions in Asia and Europe.
  • Ixodes ticks. $$. Usually a secondary problem for grazing sheep and goats in regions with temperate climate during summer.
  • Rhipicephalus ticks. $$. Can be a significant problem for grazing sheep and goats in tropical and subtropical regions, mainly in Africa.
  • Scab and mange mites. $$$$-R. A serious problem worldwide in all kind of sheep, mainly indoors, particularly during the cold season in regions with temperate climate.


Internal parasites (endoparasites, worms, helminths)

Gastrointestinal roundworms (Nematodes)

  • Bunostomum spp. $$-R. Hookworms. Small intestine. Mostly in mixed infections, worldwide, mainly in warm and moist regions.
  • Chabertia ovina$$. Large-mouthed bowel wormLarge intestine. Worldwide. Mostly in mixed infections.
  • Cooperia spp. $$-RR. Small intestinal worms. Small intestine. Mostly in mixed infections, worldwide, mainly in warm and moist regions
  • Gongylonema spp. $. Esophagus and stomach. Mostly a secondary issue. Worldwide.
  • Haemonchus spp. $$$$$-RRRRR. Barber's pole worms, red stomach worm. Stomach. Number one worm problem in sheep and goats in warm and moist regions worldwide. Mostly in mixed infections.
  • Mecistocirrus digitatus. $$. Stomach. Usually a secondary issue. Mostly in mixed infections. Worldwide, mainly in warm and moist regions worldwide.
  • Nematodirus spp. $$-RR. Thread-necked worm. Small intestine. Mostly in mixed infections. Worldwide, mainly in regions with temperate climate.
  • Oesophagostomum spp. $$. Nodular worm. Large intestine. Mostly in mixed infections. Worldwide.
  • Skrjabinema spp. Large intestine. Worldwide.
  • Teladordsagia spp. = Ostertagia spp. $$$$-RRRR. Brown stomach worm. Stomach and small intestine. Number one worm problem in sheep and goats in regions with temperate climate. Mostly in mixed infections.
  • Strongyloides spp. $$. Threadworms, pinworms. Small intestine. Mainly in warm and moist regions worldwide.
  • Trichostrongylus spp. $$-RRR. Hairworms. Mostly in the small intestine in mixed infections. Worldwide.
  • Trichuris spp. $. Whipworms. Large intestine. Usually a secondary issue. Worldwide.

Respiratory roundworms (Nematodes)

  • Dictyocaulus spp. $$$. Lungworms. Trachea, bronchi and bronchioles. A serious problem worldwide, mainly in regions with temperate and cold climate.
  • Mammomonogamus spp. Larynx and nasal cavities. Mainly in Africa, usually not a serious issue.
  • Muellerius capillaris. $. Bronchi, bronchioles, alveoli. Worldwide. Mostly in mixed infections.
  • Protostrongylus rufescens. $. Bronchi, bronchioles. Worldwide. Mostly in mixed infections.

Roundworms (Nematodes) in the skin, heart and other organs

  • Setaria spp. Various organs. Occasionally a problem for sheep and goats as accidental hosts. Worldwide, different species.
  • Thelazia spp. $. Around the eyes. Worldwide, normally a minor issue.

Flukes (Trematodes, flatworms)

  • Dicrocoelium spp. $$. Lancet fluke. Bile ducts and gall bladder. Worldwide, mainly in grazing livestock.
  • Eurytrema pancreaticum. $. Pancreas fluke. Pancreatic ducts. Usually a minor issue in South America, Africa and Asia.
  • Fasciola hepatica. $$$$-RR. Common liver fluke. Biliary ducts and gallbladder. Number one fluke problem for grazing sheep and goats worldwide.
  • Fasciola gigantica. $$$. Tropical liver fluke. Liver tissue, biliary ducts and gallbladder. A serious problem for grazing sheep in regions with warm and moist climate.
  • Fascioloides magna. $. Giant liver fluke. Usually a minor issue in Europe and North America.
  • Paramphistomum spp. $$. Rumen flukes. Stomach and small intestine. Worldwide.
  • Schistosoma spp. $. Blood flukes. Blood vessels. Usually a minor issue in parts of Asia and Africa.

Tapeworms  (Cestodes)

  • Avitellina centripunctata. Small intestine. Parts of Africa, Asia and Europe. Usually a minor issue.
  • Cysticercus ovis. $. Sheep measles. Muscles and heart. Worldwide, normally a secondary problem.
  • Cysticercus tenuicollis. $. Abdominal organs. Worldwide, usually a minor issue.
  • Echinococcus granulosus. $. Hydatid worm. Various organs. Worldwide, usually a secondary issue in sheep and goats.
  • Moniezia spp. $$. Small intestine. Worldwide, usually not a serious issue, but nevertheless the major tapeworm problem for sheep and goats.
  • Stilesia hepatica. Liver tapeworms. Bile ducts. In parts of America, Asia and Africa. usually a minor issue.
  • Thysanosoma actinioides$. Fringed tapeworm. Bile and pancreatic ducts, small intestine. In America.