TABLE OF CONTENTS
Mecistocirrus digitatus: Morphology, Life Cycle, Pathogenesis, Clinical Signs & Treatment
Mecistocirrus digitatus is a large, blood-feeding gastrointestinal nematode of domestic and wild ruminants, particularly cattle, buffaloes, sheep, and goats. It belongs to the family Haemonchidae and primarily inhabits the abomasum, where both immature and adult worms feed on blood, leading to anemia, reduced productivity, and poor body condition in heavily infected animals. Although it closely resembles Haemonchus in its biology and pathogenic effects, Mecistocirrus digitatus is distinguished by its larger size and longer prepatent period.
The parasite has a direct life cycle, with infection occurring through the ingestion of infective third-stage (L3) larvae from contaminated pasture. It is distributed mainly in tropical and subtropical regions and is considered an economically important parasite of ruminants because of the production losses associated with chronic blood loss, decreased growth, and reduced productivity.
Parasite Overview
- Host: Sheep, goats, cattle, and buffaloes
- Predilection Site: Abomasum
- Habitat: Abomasal mucosa and lumen
- Life Cycle: Direct (monoxenous)
- Infective Stage: Third-stage larva (L3)
- Diagnostic Stage: Eggs in feces (strongyle-type eggs)
- Transmission: Ingestion of infective L3 larvae while grazing on contaminated pasture
- Prepatent Period: Approximately 8–10 weeks
- Zoonotic Importance: None
Taxonomical Classification
- Kingdom: Animalia
- Phylum: Nematoda
- Class: Chromadorea
- Order: Rhabditida
- Suborder: Strongylina
- Superfamily: Trichostrongyloidea
- Family: Haemonchidae
- Genus: Mecistocirrus
- Species: Mecistocirrus digitatus
Morphology
- Male: 31 mm; Female: 43 mm
- The cuticle has 30 longitudinal striations.
- It has prominent spine-like cervical papillae.
- It has a small buccal cavity with a small dorsal tooth (lancet).
- In females, the vulval knob or flap is absent.
- In males, the bursa has pincer-like lateral lobes and a small, symmetrical dorsal lobe.
- Spicules are long, slender, and united throughout their entire length.
Life Cycle and Pathogenesis
The life cycle and pathogenesis are similar to those of Haemonchus, but the L4 stage has a longer duration.
Control
Control of Mecistocirrus digitatus relies on an integrated approach that combines strategic deworming, grazing management, refugia, FAMACHA scoring (where applicable), and other Integrated Parasite Management (IPM) practices. Since these control measures are common to most members of the Trichostrongylidae family, they are discussed in detail in our dedicated article: Trichostrongylidae Parasite Control: Refugia, FAMACHA & IPM.
