Helminths (Strongyloidea)

Question 1

What is the superfamily of Strongyloidea characterized by?

Answer 1

Strongyloids tend to be larger and stouter-bodied than trichostrongyloids, with a large buccal cavity surrounded by a sclerotized wall.

Question 2

What are the stomal structures of strongyloids used for?

Answer 2

They permit identification of species with occasional reference to other characters.

Question 3

What are the leaf crowns in strongyloids?

Answer 3

They are structures surrounding the stomal opening, significant in the taxonomy of strongyloids.

Question 4

What is the function of the teeth found in some strongyloids?

Answer 4

They lacerate the plug of mucous membrane drawn into the buccal cavity.

Question 5

What family do large strongyles belong to?

Answer 5

Family Strongylidae; subfamily Strongylinae.

Question 6

What are the primary hosts for members of the subfamily Strongylinae?

Answer 6

• Equines
• Elephants
• Macropodid marsupials
• Ostriches

Question 7

Which strongyles are among the most destructive parasites of horses?

Answer 7

• Strongylus vulgaris
• Strongylus edentatus
• Strongylus equinus

Question 8

What life stage of Strongylus vulgaris is infective?

Answer 8

Third-stage larvae.

Question 9

What environmental conditions are required for S. vulgaris larvae to reach the infective stage?

Answer 9

Adequate moisture and temperatures in the range of 8°C to 39°C.

Question 10

How does scattering droppings affect strongylid larva populations?

Answer 10

It reduces populations by drying out the manure before larvae reach the desiccation-resistant third stage.

Question 11

What was hypothesized by Otto Bollinger in 1870 regarding S. vulgaris?

Answer 11

Occlusion of intestinal arteries by verminous thrombi and emboli could account for equine colic cases.

Question 12

What happens to S. vulgaris larvae after being ingested by a horse?

Answer 12

They cast off their sheaths and penetrate the wall of the cecum and ventral colon.

Question 13

What is the typical prepatent period for Strongylus edentatus?

Answer 13

Usually cited as 11 months but may be as short as 6 months.

Question 14

What anthelmintics are adult S. vulgaris susceptible to?

Answer 14

• Febantel
• Fenbendazole
• Ivermectin
• Moxidectin
• Oxibendazole
• Pyrantel pamoate

Question 15

Which strongyle has been reported to show resistance to pyrantel?

Answer 15

Strongylus edentatus.

Question 16

Fill in the blank: The copulatory bursa of strongyloids is _____ developed.

Answer 16

well

Question 17

What occurs after S. vulgaris larvae migrate back to the intestinal lumen?

Answer 17

The arterial lesions heal.

Question 18

What is a significant outcome of the migration of fourth-stage S. vulgaris larvae?

Answer 18

Arteritis, thrombosis, and embolism of the cranial mesenteric artery.

Question 19

True or False: Fatal infarction of the bowel wall is frequent in horses infected with S. vulgaris.

Answer 19

False

Question 20

How does the colic vessels’ blood supply in horses affect the impact of S. vulgaris?

Answer 20

It has an elaborate system of anastomoses allowing effective collateral circulation.

Question 21

What treatment can resolve verminous arteritis caused by S. vulgaris?

Answer 21

Larvicidal therapy with anthelmintics such as albendazole.

Question 22

What is the significance of the first report of large strongyle resistance?

Answer 22

It highlights the emergence of resistance to anthelmintics in large strongyles

Question 23

What stage are anthelmintic medications effective against for Strongylus vulgaris?

Answer 23

They are effective against migrating larvae of S. vulgaris in the cranial mesenteric artery

Question 24

What is the effective dose of Ivermectin for treating S. vulgaris?

Answer 24

0.2 mg/kg

Question 25

What doses of Moxidectin are effective against fourth-stage larvae os Strongylus vulgaris?

Answer 25

0.3, 0.4, and 0.5 mg/kg

Question 26

What is the treatment protocol for Strongylus vulgaris larvae using Fenbendazole?

Answer 26

Single dose of 30 to 60 mg/kg or five daily doses of 7.5 to 10 mg/kg

Question 27

What is the effective dose of Oxfendazole for Strongylus vulgaris?

Answer 27

10 mg/kg

Question 28

What concern has arisen regarding small strongyle treatment programs?

Answer 28

They may have allowed an increase in the prevalence of large strongyles

Question 29

What is the recommendation for treating horses based on fecal egg counts?

Answer 29

Only treat horses with a fecal egg count above a preset value

Question 30

What legislation was enacted in Denmark regarding anthelmintics?

Answer 30

A prescription-only restriction on anthelmintic administration requiring a parasitologic diagnosis

Question 31

What percentage of Danish horses were found to be positive for S. vulgaris in a recent study?

Answer 31

12.2%

Question 32

What is the clinical disease caused by large numbers of arrested cyathostomin larvae?

Answer 32

Cyathostominosis

Question 33

What characterizes the clinical signs of cyathostominosis?

Answer 33

Watery diarrhea, severe inflammation, and can lead to death

Question 34

What is the recommended treatment protocol for encysted cyathostomin larvae?

Answer 34

Fenbendazole at 10 mg/kg per day for 5 days

Question 35

Which anthelmintic drugs have shown reduced efficacy against small strongylids?

Answer 35

Phenothiazine, thiabendazole, cambendazole, mebendazole, fenbendazole, oxfendazole, and febantel

Question 36

What is a notable finding regarding macrocyclic lactones in small strongyles?

Answer 36

Resistance has not yet been documented

Question 37

What is the suggested method for pasture management to control strongyles?

Answer 37

Immediate removal of fecal matter after deposition

Question 38

What are Oesophagostomins commonly referred to as?

Answer 38

Nodular worms

Question 39

What do the larvae of Oesophagostomins cause in their host?

Answer 39

They become encapsulated by reactive inflammation, forming nodules

Question 40

What are the clinical signs associated with Oesophagostomins in ruminants and swine?

Answer 40

Fetid diarrhea and possible fatality

Question 41

Fill in the blank: The larvae of Triodontophorus spp. do not migrate far beyond the _______.

Answer 41

mucous membrane of the colon

Question 42

What is the characteristic of cyathostomins compared to strongylins?

Answer 42

Smaller buccal cavities

Question 43

True or False: Cyathostomin larvae migrate beyond the mucous membrane of the cecum and colon.

Answer 43

False

Question 44

What is the main effect of Oesophagostomum sp. in swine?

Answer 44

Formation of nodules in the gut wall by developing third-stage larvae ## Footnote Nodule formation may interfere with maximum growth of young swine and be accompanied by catarrhal enteritis.

Question 45

What clinical signs are associated with acute inflammation due to parasitic larvae of Oesophagostomins?

Answer 45

Fetid diarrhea, marked weakness, and rapid emaciation ## Footnote Acute inflammation may lead to clinical disease that can be fatal.

Question 46

What is the appearance of feces in cases of nodular worm disease?

Answer 46

Watery, dark, and very fetid

Question 47

What is a significant epidemiologic factor related to swine infections with Oesophagostomum?

Answer 47

A rise in egg output by sows peaking at 6 or 7 weeks after farrowing ## Footnote This rise is followed by a rapid drop-off.

Question 48

What are the two disease syndromes caused by Conoweberia stephanostomum in gorillas?

Answer 48

The** chronic syndrome** consisted of intermittent diarrhea, paleness of the mucous membranes, and the presence of eggs in the feces. In the **acute form**, the gorilla refuses to eat or nibbles a little and suffers some diarrhea, but very soon passes only small quantities of glairy mucus streaked with blood, much like that observed in acute amoebic dysentery of humans. The gorilla remains lying down or sitting with both hands on its head in an attitude of human desperation.

Question 49

What are the symptoms of the chronic syndrome caused by C. stephanostomum in gorillas?

Answer 49

Intermittent diarrhea, paleness of mucous membranes, presence of eggs in feces

Question 50

What does the acute form of C. stephanostomum disease in gorillas involve?

Answer 50

Refusal to eat, diarrhea, passing small quantities of glairy mucus streaked with blood

Question 51

What is Stephanurus dentatus commonly known as?

Answer 51

The kidney worm of swine

Question 52

What is the size of Stephanurus dentatus?

Answer 52

Up to 2 by 40 mm

Question 53

What intermediate hosts are involved in the life cycle of S. dentatus?

Answer 53

Earthworms

Question 54

How long do larvae of S. dentatus spend wandering destructively in the liver?

Answer 54

4 to 9 months

Question 55

What is the time frame for egg appearance in urine after S. dentatus infection?

Answer 55

9 to 16 months after infection

Question 56

What are the approved anthelmintics for treating S. dentatus infection in the USA?

Answer 56

Doramectin and fenbendazole

Question 57

What is the subfamily of Family Syngamidae that includes Syngamus and Mammomonogamus?

Answer 57

Syngamidae

Question 58

What is the key characteristic of the buccal capsules in the subfamily Syngamidae?

Answer 58

Large buccal capsules

Question 59

True or False: Males and females of Syngamus spp. are permanently joined in copula.

Answer 59

True

Question 60

What treatment was effective for Syngamus trachea infections in farmed rheas?

Answer 60

Fenbendazole at 25 mg/kg

Question 61

What was the percentage of stray cats shedding Mammomonogamus eggs in a fecal survey in St. Kitts?

Answer 61

45%

Question 62

What percentage of slaughtered cattle in Colombia were found to have Mammomonogamus laryngeus?

Answer 62

14.8%

Question 63

Fill in the blank: The clinical signs of S. dentatus infection are otherwise not ______.

Answer 63

distinctive