16: Pig Parasites

Swine trichostrongyle parasite

Hyostrongylus rubidus

Hyostrongylus rubidus common name

Red stomach worm

Hyostrongylus rubidus is similar to which ruminant parasite

Ostertagia ostertagi

Where do Hyostrongylus rubidus juveniles set up shop

Gastric glands

Where do Hyostrongylus rubidus adults set up shop

They hang out in the stomach

CS associated with Hyostrongylus rubidus

Chronic vomiting ± ulcerative gastritis

How to diagnose Hyostrongylus rubidus

Eggs in feces

Parasiticide of choice for Hyostrongylus rubidus

MCL for fenbendazole

Swine roundworm

Ascaris suum

Demographic commonly affected by Ascaris suum

Outdoor pigs

LC type of Ascaris suum

Direct

Why do we assume that every outdoor pig has Ascaris suum

The larva develops in the egg shell and can live for a really long time in the soil

Stage of Ascaris suum associated with most clinical signs

Mechanical destruction due to juvenile migration

CS associated with Ascaris suum juveniles

• Focal liver and respiratory hemorrhages

• Resp signs: dyspnea, pneumonia, edema

• ± Hypersensitivity

CS associated with Ascaris suum adults

• Diarrhea

• Decreased growth

• Obststruction

Gross lesions associated with Ascaris suum

Milk spots on liver from liver fibrosis

Egg morphology of Ascaris suum

Thick walled, single celled egg ± protein coat

Diagnostic used for Ascaris suum

Centrifugal sugar fecal float

Parasiticide of choice for Ascaris suum

• MCL

• Fenbendazole

• Levamisole

• Pyrantel

Common name of Strongyloides ransomi

Pig threadworm

Where does Strongyloides ransomi set up shop

Small intestine

Stage of Strongyloides ransomi that is parasitic

Females of any stage

How do Strongyloides ransomi females reproduce

Parthenogenesis

Routes of infection for Strongyloides ransomi

• Ingestion

• Transmammary

• Cutaneous

Conditions where Strongyloides ransomi is parasitic

They are facultative parasites, and enter the host if the environment is not hospitable

How long does it take for Strongyloides ransomi eggs to become infectious

Infectious when passed from the host

Patient demographic affected by Strongyloides ransomi

Young animals

CS associated with Strongyloides ransomi

• Diarrhea

• Anorexia

• Decreased production

Why is Strongyloides ransomi not as common anymore

Indoor management of pigs

Egg morphology of Strongyloides ransomi

Larvated egg

Parasiticide of choice for Strongyloides ransomi

MCL for any stage

Coccidia in swine

Cystoisospora suis

Cystoisospora suis life cycle

Apicomplexan life cycle

Routes of infection for Cystoisospora suis

Direct transmission through ingestion of sporulated oocysts or through ingestion of a paratenic host that has encysted sporulated oocysts

How are Cystoisospora suis eggs different than other coccidia eggs

Cystoisospora suis only has two sporozoites when it is sporulated, the eimeria we have talked about have four sporozoites

Patient demographic in swine affected by clinical coccidiosis

Young pigs

CS associated with Cystoisospora suis

BAD yellow diarrhea ± blood

Parasiticide of choice for Cystoisospora suis

No FDA approved drug, can’t use off label ponazuril unless the pig is not going into the food chain ever

Control for Cystoisospora suis

Keep farrowing crates clean of feces to

Strongylid in pigs

Oesophagostomum spp.

Egg morphology of Oesophagostomum spp.

HOTTCOmplex eggs (usually trichostrongyles!)

Where does Oesophagostomum spp. adults set up shop

Cecum and colon

Where does Oesophagostomum spp. juveniles set up shop

Mucosal glands of the ileum, cecum, and colon

Economic loss associated with Oesophagostomum spp.

Condemned sausage casings due to nodules in the mucosal glands

CS associated with Oesophagostomum spp. in pigs

Diarrhea and poor appetite

Parasiticide of choice for Oesophagostomum spp. in pigs

MCL and benzimidazoles

Trichuris suis common name

Whipworm

Egg morphology of Trichuris suis

Football shaped egg with larva and bipolar plugs

Morphology of Trichuris suis adults

Thin anterior end and thicker posterior end

Why is Trichuris suis not on our differential list for pigs younger than 3 months

The PPP is 1.5-3 mos

Where does Trichuris suis set up shop

Cecum and colon

CS associated with Trichuris suis

• Diarrhea

• LI irritation → hematochezia

• ± Rectal prolapse

Reason we don’t usually see clinical disease associated with Trichuris suis in older pigs

They usually develop immunity to clinical disease, and can be infected with Trichuris suis and not show signs

Parasiticide of choice for Trichuris suis

Fenbendazole

Pig lungworm

Metastrongylus spp.

IH for Metastrongylus spp.

Earthworm

Patient demographic affected by Metastrongylus spp.

Outdoor pigs in the midwest and southeast

Where does Metastrongylus spp. set up shop

Bronchi and bronchioles

CS associated with Metastrongylus spp.

Often subclinical

• Bronchopneumonia

• Secondary bacterial infections

Parasiticide of choice for Metastrongylus spp.

Basically anything: MCL, fenbendazole, levamisole

Pig kidney worm

Stephanurus dentatus

How do we diagnose Stephanurus dentatus

Eggs in the urine sediment!!

Where does Stephanurus dentatus set up shop

Perineal fat

Where do juvenile Stephanurus dentatus go before the kidney

Liver

Patient demographic for Stephanurus dentatus

Outdoor pigs in the southeast

Parasiticide of choice for Stephanurus dentatus

Doramectin > fenbendazole

Why does Trichinella spiralis stump evolutionary biologists

It can’t survive in the environment and is always in a host

Rout of infection for Trichinella spiralis

Ingestion only!!

Replication cycles of Trichinella spiralis

Domestic and sylvatic

Domestic replication cycle of Trichinella spiralis

Cycles between pigs ± mice

Sylvatic replication cycle of Trichinella spiralis

Cycles between bears ± mice

Cause of most human infections of Trichinella spiralis

Undercooked bear meat

Parasiticide of choice for Trichinella spiralis

There are none :)

Pig tapeworm

Taenia solium 

IH for Taenia solium 

Pigs

DH for Taenia solium 

Humans :)

How does Taenia solium exist in the pig

Cysticercus in the muscle

Typical Taenia solium transmission/life cycle

Human passes eggs → ingested by the IH

Atypical Taenia solium transmission/life cycle

Human to human transmission; Taenia solium uses the second human as an IH and forms cysticerci in the muscle like it would it a pig

Treatment of choice for Taenia solium cysticerci in pigs

Vaccine or oxfendazole

T/F: Taenia solium is reportable

Yes; reportable in pork

Parasite that is the reason we still cook pork

Toxoplasma gondii

Significance of Toxoplasma gondii in pigs

Pigs are highly susceptible and considered a significant reservoir of Toxoplasma gondii in humans

Pig population that has a higher prevalence of Toxoplasma gondii

Organic pigs

Methods to kill Toxoplasma gondii in pork

Cooking to 152F or freezing

Scabies variant in pigs

Sarcoptes scabiei variant suis

CS associated with scabies in pigs

• Red macules

• Severe mange

• Severe pruritis

• ± Hypersensitivity

Diagnostic for scabies in pigs

Skin scraping

Parasiticide of choice for scabies in pigs

MCL

Sucking louse in pigs

Haematopinus suis

Haematopinus suis morphology

All claws are the same size

Predilection sites for Haematopinus suis

Humid sites on the pig: ears, neck, skin folds, inside surface of legs

Parasiticide of choice for Haematopinus suis

MCL

General considerations for limiting parasitic disease in pigs

• Bring pigs indoors

• Keep pigs away from feces

• Clean environment

• Don’t feed raw anything

• Strategic deworming!!!

General recommendations for deworming sows

Deworm at least twice yearly with at least one happening 1-2 weeks before farrowing

General recommendations for deworming 6-8 week old pigs

Deworm once at 6-8 weeks with parasiticide of choice, then repeat in one month