worm diagnostics

III. Diagnostic tools for worm control FAMACHA© system, Five Point Check©, lab tests

How do I tell if my sheep or goats are infected with parasites?

They all are.

• Almost all sheep and goats have parasites, probably of different kinds.

• “Positive” egg or oocyst counts are “normal.” Negative tests are rare (during the periods of risk).

• Some level of parasite infection is required for immunity.

They all are. Accept it!

• Clinical disease occurs at a certain level of infection that can vary by animal.

• Not all parasites are pathogenic or highly pathogenic.

• Not all straings of parasites are pathogenic.

The more important question to ask is:How do I tell if my sheep or goat is clinically parasitized (suffering negative effects) and requires anthelmintic treatment?

Diagnostic tools

1) On-farm1) Animal2) Fecal

2) Laboratory1) Blood2) Fecal3) Larvae

Diagnostic tools

ON FARM• Animal

– FAMACHA©– Five Point Check® NEW!

• Fecal– Simple flotation– Fecal egg counts

• Fecal egg count reduction test (FECRT)

– Dipstick

• Carla® saliva test

LABORATORY

• Blood– Packed cell volume

• Fecal– Simple flotation– Fecal egg counts

• FECRT– Lectin staining test NEW!– Larvae

• Larvae culture• Larval development assay

[DrenchRite®]• Pasture

The FAMACHA© System• Develop for small-scale sheep

producers in South Africa in response to the widespread development of anthelmintic-resistant worms.

• A practical system for assessing barber pole worm infection in sheep and goats and determining the need for deworming individual animals.

• Named for its originator:Dr. Francois “FAffa” MAlan CHArt

FAMACHA©

Clinical Category

Eye Lid Color

Packed Cell

VolumeDeworm?

1 Red > 28 No

2 Red-Pink 23-27 No

3 Pink 18-22 ?

4 Pink-White 13-17 Yes

5 White < 12 Yes

General treatment recommendationsDeworm adults at scores 4 and 5*Treat lambs and kids at categories 3, 4, and 5

*The South Africans recommend goats be treated at categories 3, 4, and 5

Using FAMACHA©

• Must take training to get card.

• Use card• Replace card periodically

(colors fade)• Do not use in a vacuum;

consider other factors.• Frequency of checking varies

by risk.• Should incorporate

FAMACHA© into an integrated parasite management program.

Benefits of FAMACHA©• Reduces number of

anthelmintic treatments.

• Reduces dollars spent on anthelmintics.

• Identifies susceptible and resilient animals.

• Increases refugia • Prolongs effectiveness

of anthelmintics

Using the FAMACHA© system to control internal parasites in grazing lambs

10-J

un24

-Jun

11-J

ul22

-Jul

5-A

ug19

-Aug

2-S

ep19

-Sep

30-S

ep

0

0.5

1

1.5

2

2.5

3

3.5

0

10

20

30

40

50

60

Avg FAMACHA Score

# Lambs Dewormed

26.2%

41.7%

16.7%

7.1%

4.8%1.2%1.2%

0

1

2

3

4

5

6

% Lambs/No. times treated

Limitations of FAMACHA©• Doesn’t save time.

– LESS deworming– MORE monitoring

• Only useful where (when) barber pole worm is the primary parasite.

• Must know which anthelmintics are effective.

The Five Point Check © (5.©)• Expands the FAMACHA©

system to include evaluation criteria for other internal parasites.

• Check five places on animal’s body1. FAMACHA© score2. Bottle jaw3. Body condition score4. Dag score5. Nasal discharge

Backbody condition (and coat condition)

Tailsoiling , dags

(scours)

Nosenasal discharge

(nose bots)

Jawswelling, edema

“bottle jaw”

Eyeanemia

FAMACHA© score

FIVE POINT CHECK©

(5.©)FOR TARGETED SELECTIVE TREATMENT OF INTERNAL PARASITES IN SMALL

RUMINANTSG.F. BATH AND J.A. VAN WYK, FACULTY OF VETERINARY SCIENCE, UNIVERSITY OF PRETORIA, SOUTH

AFRICA

1 3

2

4 5

Five Point check©Point What to check Specificity

1 EyePaling of ocular membranesFAMACHA© eye anemia score

Barber pole wormLiver fluke

2 Back Body condition score All

3 RearDag scorefecal soilingevidence of scouring

Brown stomach wormHair wormThreadneck wormNodule wormCoccidia

4 JawSub-mandibular edema

(bottle jaw)Barber pole wormLiver fluke

5 Nose Nasal discharge Nasal bots

Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa

FAMACHA© eye anemia scoreEye lid color Packed cell

volumeTreatment

recommendation

1 Red > 28 Optimal No

2 Red-Pink 23-27 Acceptable No

3 Pink 18-22 Borderline ?

4 Pink-White 13-17 Dangerous Yes

5 White < 12 Fatal Yes

Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa

Bottle jawSub-mandibular edema

Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa

Body condition score (BCS)Spine Transverse

processes Muscle Fat

1 Individually clearly felt, sharp, obvious

Fingers easily pass underneath Very little No

2 Form a smooth line with deep undulations

Smooth round edges

Concave Very thin

3Only slightly detectable undulations

Well coveredhave to push firmly

to get fingers underneath

Not concaveNot convex

Moderate

4 Only detectable with firm pressure Cannot be

felt at all

Maximally developed

Convex

Thick

5 Not detectable Very thick

Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa

Dag Scoresbritch soiling, evidence of scouring (diarrhea)

Dag score Description Treatment recommendation

0 No fecal soilingNo indication for

treatment

1 Very slight soiling on edge of tail

No treatment

2 Slight soiling on edge of tail and on each side

Usually no treatment

3 Moderate soiling of tail and woolDag formation

Consider treatment

4Severe soiling extending far into

woolSevere dag formation

Treatment, crutching recommended

5Very severe

watery diarrhea extending to hocks

Treatment and crutching essential

Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa

Nasal discharge

Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa

Packed cell volume (PCV)

• Portion of whole blood occupied by red blood cells.

• A measure of anemia – Primary symptom of Haemonchosis (or barber pole worms).

• A measure of resilience.

Clinical CategoryPacked Cell

Volume Tx (?)

1 Non-anemic > 28 No

2 Non-anemic 23-27 No

3 Mildly anemic 18-22 ?

4 Anemic 13-17 Yes

5 Severely anemic < 12 Yes

Uses of fecal testing1. Identify worm eggs and

determine existence and level of infection

a) Simple fecal flotationb) Fecal egg counting

2. Determine parasite species a) Larvae cultureb) Lectin staining test

3. Determine effectiveness of anthelmintic treatment

a) Fecal egg count reduction test (FECRT)

b) Larval development assay (LDA) or DrenchRite® test

Fecal testingQuantitativeFecal egg count (FEC)

• Use McMaster egg counting slide

• Weigh feces and measure flotation solution

• Determine general egg types Strongyle vs. coccidia vs. tape

• Determine level of infection– Eggs per gram of feces

QualitativeSimple fecal flotation

• Use simple slide and cover slip

• Determine general egg typesStrongyle vs. coccidia vs. tape

• Determine existence and general level of infection– Eggs per field of view

e.g. Eggs Plus system

What you need to do your own fecal egg counts

1) Microscope40x objective x 10x eye piece = 400Only need 100xMechanical stage recommended

2) Flotation solutionSaturated salt or sugar solutionSpecific gravity of 1.2Can also purchase

3) McMaster egg counting slide www.vetslides.com

4) Miscellaneous suppliesscale, beaker, pipettes, vials, craft sticks, cheese cloth or strainer

Fecal egg countseggs per gram of feces

• Indicate “potential” parasite burden in animal.

• Indicate potential parasite burden on pasture..

• Use to determine level of drug efficacy.

• Use to determine genetic differences in parasite resistance.

Fecal egg counts are not definitive.• Fecal egg counts are not

always well-correlated with clinical disease.

– Presence of eggs or does not mean that the animal is clinically parasitized and needs treatment.

– Absence of eggs or oocytes (coccidia) or a low count does not mean that the animal is parasite-free and not needing treatment.

Limitations to fecal egg counts• Some parasite eggs look the same and

cannot be identified at the egg stage).• There is a fairly regular fluctuation in

fecal egg output.• Egg output varies by season of the

year.• Eggs are not always evenly distributed

in the feces.• Parasite species vary in their egg

producing capacity.

– Some parasites are prolific egg producers (e.g. Haemonchus)

– Some parasites do not produce very many eggs. (e.g. Nematodirus)

– Some parasites produce eggs intermittently

– Some parasites can produce asexually– Immature worms (L4’s) do not lay eggs– Inhibited larvae do not lay eggs

• Not all parasites are pathogenic (disease-causing)

• Total egg counts may include a mixture of species with different levels of fecundity and pathogenicity.

• Diarrhea increases fecal moisture and may dilute the number of eggs.

• Human error.

Clinical significance of fecal egg counts

Fecal egg count reduction test (FECRT)

• First and most widely used method to access efficacy of anthelmintics.

• Before and after fecal egg counts.– d 0 and d 7-14 post

treatment– With or without

untreated controls – Minimum of 10 animals.

DrenchRite® Larval Development Assay (LDA)

• In vitro test for the detection of anthelmintic resistance.

• Evaluates resistance to all major anthelmintics from a single pooled fecal sample.

• Requires pooled fecal sample from 10 or more animals – Mean FEC of > 350 epg minimum– Mean FEC of > 500 epg preferred.– Select feces from animals scored as

FAMACHA© 3, 4, or 5.

• Available through University of Georgia (jscb@uga.edu)

Larvae culture and differentiation• It is difficult to differentiate

the eggs of many common species of worms during a worm egg count.

• Culture of the feces for the purpose of hatching parasite eggs and obtaining larvae for morphological identification.

Image source: Dr. Woodgate, Western Australia Department of Agriculture

Western Maryland Pasture-Based Meat Goat Performance Test (2009)

Lectin staining test• Fast, easy, less-expensive way to test

for the presence and quantity of barber pole worms.

• Lectin-staining test based on peanut agglutin that binds to egg of barber pole worm.

• Only requires a small amount of feces.

• Results available in as little as two days.

• Available through Oregon State University and University of Georgia.

Image source: University of Georgia College of Veterinary Medicine.

New tests (not available in U.S.)

CARLA® SALIVA TEST• Measures antibodies against

worm larvae.• Use to select animals which

suffer less from parasites and pass fewer eggs onto pasture.

HAEMONCHUS DIPSTICK TEST• Detects blood in feces to

determine presence of barber pole worm and level of infection.

Thank you for your attention.

Any questions?

SUSAN SCHOENIANsschoen@umd.edu

www.sheepandgoat.com

SMALL RUMINANT PROGRAM

Next webinar (last) : Using anthelmintics effectively - May 26