Trichostrongylus spp.: Elongated Hookworm-Like Egg
Bench-card visuals for Trichostrongylus spp. eggs: larger, more elongated, and with at least one tapered end compared to hookworm. Advanced morula when passed. A size-matched hookworm mimic that requires careful measurement to distinguish.
Trichostrongylus egg vs. hookworm comparator
Trichostrongylus: elongated oval, 73-95 x 40-50 um, asymmetric, one or both ends tapered. Advanced morula (~16 cells) when freshly passed. Hookworm (comparator): rounder oval, 55-75 um, symmetric blunt ends, early morula (4-8 cell...
73-95 x 40-50 um. More elongated than hookworm. One or both ends tapered or pointed. Advanced morula (often 16+ cells, or near larval stage) when freshly passed - more developed than hookworm at time of passing. Thin shell with clear space between shell and embryo. A zoonotic infection from soil or plant contamination in regions with sheep, goats, and other grazing animals (Asia, Middle East, Africa, rural South America).
55-75 x 35-45 um. Rounder, symmetric oval with blunt ends at both poles. Early morula (2-8 cells) when freshly passed - less developed than Trichostrongylus at time of passing. Thin shell with clear space between shell and embryo. Differentiation from Trichostrongylus requires careful size measurement and assessment of end shape and morula cell count.
73-95 x 40-50 um. More elongated than hookworm. One or both ends tapered or pointed. Advanced morula (often 16+ cells, or near larval stage) when freshly passed - mo...
55-75 x 35-45 um. Rounder, symmetric oval with blunt ends at both poles. Early morula (2-8 cells) when freshly passed - less developed than Trichostrongylus at time...
Trichostrongylus vs. hookworm - key discriminators
| Visual clue | Meaning | Student shorthand |
|---|---|---|
| More elongated oval, asymmetric outline | Trichostrongylus, not hookworm | Higher length-to-width ratio; one end typically more tapered - key low-power shape clue |
| 73-95 um long (larger than hookworm) | Trichostrongylus | Size overlap exists; use calibrated ocular micrometer for critical ID - key discriminator in practice |
| One or both ends tapered or pointed | Trichostrongylus morphology | Hookworm ends are blunt and rounded; pointed or tapered ends increase suspicion for Trichostrongylus |
| Advanced morula when passed (16+ cells) | Trichostrongylus - more developed | Hookworm morula is at 4-8 cell stage at time of passing; Trichostrongylus is further along in embryonation |
| Thin shell, clear space between shell and embryo | Feature shared with hookworm - not discriminating | Both Trichostrongylus and hookworm share thin shell and clear space; use size, shape, and morula stage for ID |
Trichostrongylus egg identification guide
| Pattern | What to call it | How to think about it |
|---|---|---|
| Elongated oval, tapered end(s), 73-95 um, advanced morula | Trichostrongylus spp. - positive | Report with size measurement; clinical correlation required; anthelmintic treatment as clinically indicated |
| Rounder oval, blunt ends, 55-75 um, early morula | Hookworm (Ancylostoma or Necator) | Differentiate by size and end shape; both respond to similar anthelmintics; report with clinical context |
| Elongated egg, uncertain species | Trichostrongylus vs. hookworm - equivocal | Measure carefully; report with morphologic description; larval culture or molecular testing for definitive species ID; confirm per lab SOP |
- Elongated oval + tapered end(s) + advanced morula = Trichostrongylus over hookworm.
- Size (73-95 um vs. 55-75 um for hookworm) is the most reliable discriminating feature - use a calibrated ocular micrometer.
- Both species respond to similar anthelmintic treatment; precise species ID is primarily of epidemiologic importance.
Elongated + pointed end(s) + advanced morula = Trichostrongylus. Rounder + blunt ends + small morula = hookworm. Measure both.