101PARASITOLOGY

SUSAN SCHOENIAN (Shāy-nē-ŭn)Sheep & Goat Specialist

Western Maryland Research & Education Centersschoen@umd.edu – www.sheepandgoat.com

WHAT IS A PARASITE?

A (generally undesirable) living organism that exists by stealing the resources

produced/collected by another living organism

Source: Wiktionary

TWO KINDS OF PARASITES

1. Internal (endo) – a parasite that lives inside another organism.

2. External (ecto) – parasites that live on the blood of the host or lay eggs on their hide or in their nose.

EXTERNAL PARASITES

1. Ticks2. Lice3. Mites4. Flies5. Mosquitos

Symptoms: hair/wool loss, pelt damage, respiratory distress, reduced performance, deathTreatment: permethrin-based insecticides and some anthelmintics

TWO KINDS OF INTERNAL PARASITES

1) Helminths (multi-cellular)→ Nematodes (roundworms)• Cestodes (tapeworms)• Trematodes (flukes)

2) Protozoa (single cell)→ Coccidia• Giardia• Cryptospordium

Internal parasites are mostly species-specific.

NEMATODESROUNDWORMS

1) Over 20,000 species2) Multi-cellular3) Long4) Round5) No segments6) Usually microscopic7) Sexual reproduction

Male and female worms

Internal parasites are mostly species-specific.

COMMONROUNDWORM SPECIES1) Haemonchus contortus

barber pole worm2) Trichostrongylus spp.

hair worm3) Nematodirus spp.

threadneck worm spp.4) Oesophagostomum

nodule worm5) Ostertagia spp.

brown stomach worm6) Cooperia spp.

intestinal worm7) Strongyloides

intestinal threadworm8) Tricuris spp.

Whipworm9) Lungworms10) Meningeal worm

Internal parasites are mostly species-specific.

CESTODESTAPEWORMS

1) Over 1,000 species2) Multi-cellular 3) Ribbon-like4) Flat 5) Segmented6) Hermaphrodites7) Intermediate host8) Visible in feces

Tend to be non-pathogenic, so we don’t usually need to worry about them.

TREMATODESFLUKES

1) Multi-cellular2) Flatted oval shape3) Hermaphrodites4) Require intermediate host

Not considered to be a problem in Maryland.

PROTOZOACOCCIDIA

1) Single cell2) Spore forming3) Microscopic4) Asexual and sexual5) Species-specific

Control with good sanitation and management and coccidiostats.

Treat with Corid or sulfa drugs.

SHEEP AND GOATS

1) The main roundworm affecting sheep and goats is Haemonchus contortus (barber pole worm).

2) Deadly blood-sucking parasite that causes anemia and bottle jaw.

3) Can use FAMACHA© system to monitor level of infection.

CATTLE

1) The main roundworm affecting cattle is Ostertagia

(brown stomach worm)

2) Causes diarrhea and ill thrift.

LLAMAS AND ALPACAS

1) Can be affected by the parasites than infect sheep, goats, as well as cattle.

2) Meningeal worm can be a significant problem; otherwise, camelids tend to be more resistant to parasites than sheep and goats.

SWINE

1) Ascaris suunLarge roundworm

2) Trichuris suisWhipworm

3) OesophagostomumNodule worm

INTERNAL PARASITE CONTROL

1) Good management2) Good sanitation3) Good nutrition4) Good genetics5) Pasture rest and rotation6) Mixed species grazing7) Minimum grazing heights8) Zero grazing9) Selective deworming

HOW DO YOU KNOW WHEN TO DEWORM?

1) Look for clinical symptoms Body condition Coat condition Dagginess (scours) Performance Eye anemia score

2) Fecal egg analysis Qualitative

Fecal flotation Quantitative

Fecal egg count

FECAL EGG COUNTING: WHAT YOU NEED

1) Microscope (at least 100 x)2) Scale that measures in grams3) McMaster egg counting slide4) Flotation solution

(saturated salt or sugar)5) Measuring vials (and cups)6) Pipettes, syringes, or eye dropper7) Tongue depressors or craft sticks8) Tea strainer or cheese cloth9) Fresh or refrigerated fecal sample

MODIFIED MCMASTERPROCEDURE1) Collect fresh fecal sample

2) Weigh out 2 to 4 grams of feces

3) Measure flotation solution

4) Mix feces with flotation solution

5) Strain fecal slurry

6) Fill chambers of McMaster slide

7) Allow eggs to rise to top

8) Count eggs in both chambers

9) Multiple by “x” to determine number of eggs per gram of feces (epg)

COLLECT FECAL SAMPLE

• Freshly deposited

• Collect from rectum

• Samples can be refrigerated

EXAMINE AND WEIGH SAMPLE

4 gramsApproximately 1 tablespoon

If you don’t have a scale, you can use volume displacement

Click icon to add picture

ADD SAMPLE TO FLOTATION SOLUTION

• Thoroughly break up and mix with 26 ml of flotation solution.

• Strain slurry through cheesecloth (double-layered) or tea strainer into another container.

TRANSFER SLURRY TO SLIDE

• Fill pipette or syringe with slurry

• Fill chamber with slurry

• Repeat for other side of chamber

• Let sample sit for 2 to 5 minutes to allow eggs to float to the top.

Image from Langston University

COUNT EGGS• Count each type of egg separately• Focus on top layer• Go up and down lanes of each side of the slide• Ignore eggs outside of the grid• Add number of eggs found in each chamber• Multiple by 25

NOW WHAT?WHAT DOES IT TELL YOU?

1) Kind(s) of parasites present

2) Number of parasite eggs being shed per gram of feces.

1) Potential pasture contamination

2) Potential parasite burden in animal

3) Efficacy of treatment (if before and after egg counts are done)

3) There are many limitations to fecal egg analysis.

IT IS “NORMAL” FOR ANIMALS TO HAVE SOME PARASITES.

Various studies suggest that parasites can regulate the

immune system in ways that prevent it from going "wild"

and attacking healthy tissue.

SMALL RUMINANT PROGRAM

Susan Schoeniansschoen@umd.eduwww.sheepandgoat.com