UNIT 19 strongyldia

UNIT 19

ORDER STRONGYLIDA

  • Dimensions: 200μm

  • Author: María Magdalena Garijo Toledo

  • Category: Biological Agents of Veterinary Interest

CLASS NEMATODA

SUBCLASS SECERNENTEA
ORDER STRONGYLIDA

  • Morphological Characteristics:

    • Males: Presence of copulatory bursa and two spikes.

    • Oesophagus Shape: Strongiliform, either pear-shaped or mace-shaped.

    • Radiated Crown: Commonly present in the structures of this order.

Superfamilies

  1. Superfamily Strongyloidea:

    • Characteristics: Lacks a buccal capsule.

  2. Superfamily Trichostrongyloidea:

    • Characteristics: Characterized by the presence of a buccal capsule.

FOUNDATIONS OF ORDER STRONGYLIDA

  • Egg Type: Strongylid type eggs.

SUPERFAMILY TRICHOSTRONGYLOIDEA

FAMILY TRICHOSTRONGYLIDAE

  • Genera:

    • Ostertagia

    • Marshallagia

    • Cooperia

    • Nematodirus

    • Haemonchus

    • Trichostrongylus

    • Hyostrongylus

  • Habitat: Abomasum and small intestine (S.I.) of ruminants.

FOUNDATIONS: GASTROINTESTINAL STRONGYLES

  • Habitat Location: Stomach of swine.

  • Characteristics: Lacks a buccal capsule.

SUPERFAMILY STRONGYLOIDEA

FAMILY STRONGYLIDAE

  • Genera:

    • Strongylus

    • Triodontophorus

    • Craterostomum

    • Oesophagodontus

  • Characteristics:

    • Size of Strongyles: Large strongyles (>2.5 cm) and small strongyles (cyathostomins, <2.5 cm).

    • Habitat: L.I. of swine and ruminants.

    • Characteristics: Presence of a buccal capsule.

FAMILY TRICHONEMATIDAE

  • Genera:

    • Chabertia

    • Oesophagostomum

  • Characteristics:

    • Location: Gastrointestinal strongyles of ruminants.

    • Structure: Characterized by the presence of a buccal capsule.

FAMILY ANCYLOSTOMATIDAE

  • Genera:

    • Ancylostoma

    • Uncinaria

    • Bunostomum

  • Habitat: Found in the duodenum of domestic and wild carnivores as well as humans. Also present in the urinary system of swine and gastrointestinal system of birds.

SUPERFAMILY TRICHOSTRONGYLOIDEA

FAMILY TRICHOSTRONGYLIDAE
BIG Nematodes of the Abomasum

  • Primary Genera:

    • Haemonchus

SMALL Nematodes

  • Genera:

    • Ostertagia/Teladorsagia

    • Cooperia

    • Nematodirus

    • Rest of Trichostrongylus

  • Habitat: Gastrointestinal strongyles of ruminants, abomasum, and small intestine.

  • Characteristics: Lacks a buccal capsule.

Genus Haemonchus

  • Female Characteristics:

    • Features a vulvar flap.

    • Appearance: Asymmetrical dorsal lobe, with short thick spicules.

    • Color: Hematophagous, red (streaked aspect), females have white ovaries winding spirally around the blood-filled intestine, referred to as “barber's pole.”

    • Species:

    • Haemonchus contortus: Found in small ruminants, exhibits contouring body shape.

    • Haemonchus placei: Found in cattle.

Genus Ostertagia/Teladorsagia

  • Size: Measures 9-12 mm.

  • Color: Brown.

  • Spicule Characteristics: Symmetrical medium-sized spicules.

  • Species Types:

    • O. ostertagi: Found in cattle.

    • T. circumcincta: Found in sheep and goats.

    • O. trifurcata: Less frequent, found in small ruminants and cattle.

Genus Marshallagia

  • Size: Measures 13-20 mm.

  • Structure: Large copulatory bursa with a large dorsal ray.

  • Frequent Species: Marshallagia marshalli.

Genus Trichostrongylus

  • Characteristics: Very small and thin (2.5-5 mm), reddish-brown coloration.

  • Spicule Characteristics: Short, thick, twisted spicules; unequal in length (right shorter than left).

  • Species:

    • T. axei: Found in the abomasum of ruminants.

    • T. colubriformis, T. vitrinus, and T. capricola: Found in the small intestine of ruminants.

    • T. tenuis: Found in the small intestine and cecum of gamebirds and poultry.

Genus Cooperia

  • Length: 4.5-9 mm.

  • Color: Reddish-brown.

  • Spicule Characteristics: Short spicules.

  • Species:

    • C. curticei: Found in sheep and goats.

    • C. punctata and C. pectinata: Found in cattle.

    • C. oncophora: Found in cattle and sheep.

Genus Nematodirus

  • Characteristics:

    • Length: 11-25 mm.

    • Spicule Characteristics: Two long fused spicules, which are longer than the copulatory bursa.

  • Species:

    • N. spathiger, N. battus, and N. filicollis: Frequently found in sheep, less so in cattle.

    • N. helvetianus: Found in cattle.

Egg Structure

  • Nematodirus sp. Eggs:

    • Characterized by fewer than 16 blastomeres.

    • Common oval shape with a thin smooth shell.

    • Segmenting process occurs upon laying.

Daily Egg Production

  • Females of various genera can produce:

    • Haemonchus: 5,000-15,000 eggs per female

    • Oesophagostomum, Chabertia: 5,000-10,000 eggs per female

    • Cooperia: 1,000-3,000 eggs per female

    • Ostertagia, Trichostrongylus: 100-200 eggs per female

    • Nematodirus: production varies generally

Lifecycle – Family Trichostrongylidae

  • Development Stages:

    • Direct lifecycle: Eggs released in morula stage.

    • L1 develops and hatches in the environment to become L2, then L3 (infective stage) in grass.

    • Optimal conditions allow for L3 development within 1 week; under adverse conditions, development may take 2-3 months (development halts below 9ºC).

  • Behavioral Characteristics: Larvae show phototropism (positive phototropic response to light) and geotropism (negative geotropic response). Highest abundance in grass occurs during the first hour in the morning and late evening.

  • Infection Process: When L3 is ingested by the definitive host (DH), they excrete a substance to dissolve their shell (remaining L2 cuticle) triggered by host stimuli (low pH, CO2, etc.). They locate in the abomasum or small intestine and develop to L4 in about 7 days, then L5-adult in the digestive lumen.

    • Prepatent period: Approximately 3 weeks.

    • Patent period: Variable duration.

Hypobiosis and Its Implications

  • Hypobiotic Larvae: L4 larvae can enter a dormant state within the mucosa during adverse conditions (such as strong immune responses). Upon encountering suitable conditions, L4 can reactivate and form ulcers.

Implications of Parasitism

  • Pathology Related to Haemonchus contortus:

    • Associated with significant anemia due to blood-feeding behavior.

Summary of Gastrointestinal Strongyles

  • Characterized under SUPERFAMILY STRONGYLOIDEA with FAMILY TRICHONEMATIDAE:

    • Genera: Chabertia, Oesophagostomum displaying various structural adaptations to thrive in the gastrointestinal tract.

Superfamily Strongyloidea, Family Trichonematidae

  • Genus Chabertia: Common in the large intestine (L.I.) of ruminants.

    • Key Features: Includes a large buccal capsule with a radiated crown structure (utilized for mucosal attachment during feeding).

    • Size: 13-20 mm long.

    • Lifecycle: Direct lifecycle; L1 forms within the egg in approximately 24 hours, while L3 formation requires about 5-6 days; upon ingestion by DH, it matures in the small intestine leading to further development into adult stages in the cecum and the L.I.

  • Genus Oesophagostomum:

    • Known for causing nodules in the colon, often referred to as 'nodule worm of the colon.' It can also infect swine.

    • Size: Approximately 1-2 cm, featuring a small buccal capsule with the anterior display of cervical alae and papillae, exhibiting a copulatory bursa in males.

Final Notes

  • The lifecycle and infective stages of the nematodes discussed contribute to broader ecological and veterinary implications, affecting ruminant health and livestock management practices.