Camelid Gastrointestinal Nematodes. Lisa Williamson, DVM, MS UGA College of Veterinary Medicine

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1 Camelid Gastrointestinal Nematodes Lisa Williamson, DVM, MS UGA College of Veterinary Medicine

2 The Issue

3 Understanding Parasites Parasite From Greek word parasitos one who eats off the table of another" Parasitism is a natural state All living creatures are hosts to parasites Killing the host is generally not the intent Small numbers of parasites stimulate immunity Infection is OK -- Disease is NOT Infection does NOT equal disease

4 Life Cycle of GI Worms L 3 L 3 L 1 L L 3 2

5 Mild Infections Are Well Tolerated

6 Symptoms of Health-Threatening Burdens: weakness, weight loss, change in fecal consistency

7 Common Camelid Parasites Third Compartment Haemonchus contortus (barber pole worm) Small intestine Trichostrongylus colubriformis (black scour worm) Nematodirus spathiger (thread neck worm) Monezia spp (tapeworms) Eimeria spp (coccidia) Large Intestine Trichuris spp (whipworm)

8 Microscopic View Haemonchus Capillaria Whipworm Trichostrongyle Tapeworm Nematodirus

9 Prevalence of Anthelmintic Resistant Gastrointestinal Nematodes in Camelids SSLA

10 Haemonchus contortus: the major killer Image courtesy of Sue Howell

11 Haemonchus contortus wireworms, barber pole worms Egg to egg layer in 3 weeks 1 female: 5,000 eggs/day Thrives in heat and humidity

12 Signs of heavy infection: anemia and low blood proteins

13 Favorite Hosts Young Weak Pregnant Lactating

14 H. contortus Survival Strategies Adults in the host (llama and alpaca) Arrested larvae in the host Free living larvae in the environment *Hypobiosis

15 Haemonchosis When it Rains, It Soars!

16 Laboratory Diagnosis Fecal Egg Counts Modified McMasters Centrifugation tests Fecal culture Peanut lectin stain Only Oregon State and University of Georgia perform the IFA test to differentiate haemonchus.

17 Peanut Lectin Staining: Haemonchus contortus goes green!

18 Treatment Considerations

19 Macrocyclic Lactones

20 Different Moxidectin Preparations Cydectin Sheep Drench (1 mg/ml) Cyectin Pour on for Cattle (5 mg/ml) Cydectin Injectable for Cattle (10 mg/ml) Quest gel for horses

21 Benzimidazoles Fenbendazole Albendazole (Valbazen ) Avoid in early pregnancy Be careful of repeat day dosing: can be toxic with accidental overdose, especially in crias

22 Membrane Depolarizers Levamisole Safety issues Currently inavailable Pyrantel pamoate Better for use in horses Morantel tartrate

23 Larval Developmental Assay Results from 25 Camelid Farms Haemonchus contortus Ivermectin and benzimidazole was resistance commonly found Levamisole was effective on over 90% of the farms Moxidectin was effective, but borderline between sensitivity and resistance on a few farms

24 A word of caution Effective anthelmintics are a precious, dwindling resource! Use them selectively based on need rather than the calendar

25 How to Determine Which Dewormers work against Haemonchus contortus Fecal Egg Count Reduction Tests DrenchRite (Larval Developmental Assay)

26 Fecal Egg Count Reduction Test Pre-treatment FEC Deworm animal Perform posttreatment FEC days after deworming Effective dewormer: > 95% reduction

27 DrenchRite Test (Larval Developmental Assay)

28 Anthelmintic Resistance is a Reality in Camelids

29 Perform Quantitative Fecal Egg Counts

30 Perform Fecal Checks Before and 2 Weeks After Treatment

31 Practice common sense biosecurity with new or visiting animals

32 Be a Good Pasture and Poop Manager

33 The weather has major impact on pasture infectivity

tested Score of 1- not anemic, 3 borderline, 5 severe anemia

34 Ocular mucus membranes (lower conjunctiva) compared to FAMACHA chart Resulting score relates to anemia status of animal being tested Score of 1- not anemic, 3 borderline, 5 severe anemia Decision to treat based on score => only drench animals that need treating

35 The ability of certain worms in a population to survive drug treatments that are generally effective against the same worm species and stage of infection Caused by changes in levels of resistance genes carried by worms in a population Result of drug treatment that produces genetic selection of resistant worms in a population of worms

36 Resistant Resistant Parents Selection for Drug Resistance Drug Treatment Next Generation

37 Percent of Worms that Are Resistant Changes in Resistance Genes in Response to Drug Selection Apparent as a clinical problem Detection level with tests Worm Generations (exposed to repeated treatments)

38 Given that resistance is inevitable and resistance is forever, how do we slow it down? Reduce genetic selection pressure Maintaining a pool of sensitive genes REFUGIA Treat individuals, not herds Utilize selective treatment

Parasites are not equally distributed in groups of animals Overdispered / aggregated distributions 20-30

39 Parasites are not equally distributed in groups of animals Overdispered / aggregated distributions % of animals harbor most of worms Few animals are responsible for most of egg output Freq Number of Worms

40 FEC FEC Distribution of FEC in herds Million 66% 230 M 33% Treating high 33% Greatly Reduces Daily Pasture Contamination With Eggs % of herd % of Eggs Treating 1/3 of herd gives just as good control as treating the entire herd 0 Individual Goats

41 FEC FEC What Happens If We Treat Only the High 33%??? Individual Animals Treating high 33% with a drug that causes a 99% FECR reduces daily pasture contamination with eggs by 80% 33% of herd < 5% of Eggs Following treatment > 95% of eggs are being shed by untreated goats = REFUGIA Less Resistance

42 Much thanks to University of Georgia faculty and staff, in particular Dr. Lisa Williamson and Mr. Bob Storey from which this Powerpoint presentation was developed. Also to Dr. Chris Cebra of Oregon State University for his help and collaboration with our study of haemonchus contortus and anthelminthic sensitivity in our area (still in the works.)

Why Do Sheep and Goat Fecal Egg Counts

Why Do Sheep and Goat Fecal Egg Counts Quantitative fecal egg counting is a procedure that determines the number of eggs per gram (EPG) of strongylid eggs, including barber pole worm (Haemonchus contortus),