Enoplids 2

Question 1

List some of the defining characteristics of the enoplids.

Answer 1

Don’t have tails

Lay eggs with bi-polar plugs (except Trichinella sp.)

L1 is the infective stage (except Dioctophyme renale)

*Dioctophyme is also unique in that it requires an intermediate host. All other enoplids have direct life cycles.

Question 2

What is a stichosome?

Answer 2

A narrow tube surrounded by large gland cells (stichocytes) arranged in a single-file column.

Each stichocyte communicates with the lumen of the esophagus with a pore.

*Stichosomes are found in members of superfamily Trichinelloidea

Question 3

Which nematode clade possesses stichosomes?

Answer 3

Superfamily Trichinelloidea

Question 4

Which whipworm species infects ruminants?

Answer 4

Trichuris discolor

Question 5

Which whipworm species infects swine?

Answer 5

Trichuris suis

Question 6

Which whipworm species infects canids?

Answer 6

Trichuris vulpis

Question 7

Which whipworm species infects primates (including humans)?

Answer 7

Trichuris trichiura

Question 8

Which whipworm species infects horses?

Answer 8

JK

No species known to infect horses

Question 9

How common are feline whipworm infections in the US?

Answer 9

Rare

More common in the Caribbean

Question 10

Where do whipworms typically live in the host?

Answer 10

Lower GI tract

Question 11

Why is the common name for enoplids “whipworms?”

Answer 11

Shaped like a bullwhip.

Note that the skinny part of the worm is the anterior portion.

Question 12

Describe how whipworms associate with the host gut mucosa.

Answer 12

Anterior end of the worm is stitched into the mucosa.

Posterior end is free in the lumen.

Question 13

True or False

Enoplids tend to be fairly host-specific

Answer 13

TRUE

Question 14

Describe the characteristics of the egg of Trichuris spp.

Answer 14

Rust brown to orange color

Thick shell with smooth surface

Bipolar plugs with ridges

Perfectly symmetrical on the longitudinal axis

One-cell stage when laid

Question 15

Which species is this?

Answer 15

Trichuris sp.

Note the rust-brown color, bipolar plugs with ridges, and perfect symmetry.

Question 16

What species is this?

Answer 16

Trichuris sp.

Note the ridges within the bipolar plug. This is a good way to distinguish this egg from a capillarid egg.

Question 17

What species is this?

Answer 17

Capillarid

Note the pale color, plugs with no ridges, and asymmetrical shape.

(This egg is from Eucoleus aerophila)

Question 18

What species is this?

Answer 18

Capillarid

Note the pale color, bipolar plug with no ridges, and asymmetry.

Question 19

Which stage of Trichuris is infectious?

Answer 19

L1

(All enoplids except Dioctophyme renale have infections L1’s)

Question 20

Can you find the L1 of Trichuris in the environment?

Answer 20

Nope

The L1 develops inside the egg and does not hatch until the egg is swallowed by a new host.

Question 21

Describe the migration of Trichuris spp.

Answer 21

Mucosal migration only

L1 penetrates into large intestine mucosa, matures, and emerges into the lumen

Question 22

The feeding of adult Trichuris spp. can cause intestinal bleeding. Would you expect to see frank blood or melena in the feces?

(Don’t worry, this isn’t a Goff question.)