Lecture 2: Nematodes

Nematodes

Features include varying sizes and shapes, most are cylindrical and rounded on both ends. However, they can also be spherical and whiplike.

Thin cuticle is....

an external feautre of nematodes that covers the exterior into all body openings, secreted by the hypodermis.

Cervical alae

Lateral flattened expansions of the cuticle in the anterior region.

Copulatory bursa

Posterior lateral expansion of cuticle.

Somatic muscular layer

Located below the hypodermis; used to move about.

Digestive tract of Nematodes

Mouth surrounded by 2 - 8 lips, with a long winding intestinal tract.

Dioecious

Refers to separate sexes in Nematodes.

Nematode reproductive system - Males

Two tubular testes, vas deferens to the cloaca.

Nematode reproductive system - Females

Two tubular ovaries, oviduct to vagina; can produce thousands of ova daily.

Nematode egg types

Includes Ascarid (3), Strongyle (1), Spiruoid, and Trichuroid (2).

Toxocara spp.

Includes Toxocara canis, Toxascaris leonina, and Baylisascaris procyonis.

Ova features

Spherical/Oval, thick outer shell, large nucleus.

Larvated ova

Infective, larvated ova of Toxocara spp. found in fecal-contaminated soil.

T. canis prepatent period

21 - 35 days.

T. cati prepatent period

50 days.

T. leonina prepatent period

72 - 74 days.

Transmission of Toxocara

Fecal-oral, transplacental migration, ingestion of contaminated milk.

Clinical signs of Toxocara infection

Diarrhea, vomiting, constipation, pot-bellied appearance, ill thrift.

Diagnosis of Toxocara

Detection through fecal flotation; prolific producers make them easy to find.

T. canis egg production

Produces 85,000 eggs daily.

Treatment for Toxocara

Pyrantel pamoate (Strongid) and Fenbendazole (Panacur).

Control and prevention for Toxocara

Routine deworming, monthly intestinal parasite control, fecal exams.

Toxocara canis

Common name: canine roundworm; host: canine.

Toxocara cati

Common name: feline roundworm; host: feline.

Toxascaris leonina

Common name: roundworm of canines and felines; not zoonotic.

Baylisascaris procyonis

Common name: raccoon roundworm; zoonotic and pathogenic to many incidental hosts.

Hookworms

Includes Ancylostoma caninum, A. tubaeforme, and A. braziliense.

Hookworm ova features

Oval/ellipsoidal, thin-walled, 8- to 16-cell morula.

Hookworm prepatent period - A. caninum

2 weeks.

Hookworm prepatent period - A. tubaeforme

22 - 25 days.

Trichuris vulpis

A whipworm parasite affecting canines.

Trichuris Campanula

A whipworm parasite affecting felines.

Trichuris serrata

A whipworm parasite affecting various hosts.

Ova

Barrel-shaped, yellow-brown eggs with prominent bipolar end plugs.

Life Cycle of Trichuris

Prepatent Period: 70 - 90 days.

Transmission of Trichuris

Fecal-oral route; larvated eggs are hardy in the environment.

Clinical signs of Trichuris infection

Diarrhea, mucous-coated stool, anemia, and possible death.

Diagnosis of Trichuris

Fecal flotation; eggs shed intermittently.

Treatment for Trichuris

Fenbendazole (Panacur) is the drug of choice.

Control and Prevention of Trichuris

Monthly intestinal parasite control and fecal exams.

Dirofilaria immitis

Heartworm parasite affecting canines and felines.

Microfilariae

Larval stage of heartworms found in the bloodstream.

Transmission of Heartworms

Bite of an infected female mosquito (intermediate host).

Life Cycle of Heartworms

Prepatent Period: 6 months.

Clinical signs of Heartworm infection

Exercise intolerance, right-sided heart enlargement, ascites.

Diagnosis of Heartworm infection

Observing microfilariae in blood samples; ELISA test for females.

Treatment for Heartworms

Milarsomine (Immiticide) is an adulticide.

Pre-Treatment for Heartworms

Doxycycline to eliminate Wolbachia bacteria.

Prevention of Heartworms

Monthly microfilaricide treatment with Ivermectin or Milbemycin.

Feline Heartworm Disease

Cats can clear L3 - L5 larva; often have low worm burdens.

Diagnosis of Feline Heartworm Disease

Antigen test indicates active infection; antibody test indicates exposure.

Aelurostrongylus abstrusus

Feline lungworm parasite.

Clinical Signs of Lungworm infection

Chronic wasting, cough, dyspnea, and pulmonary wheezes.

Diagnosis of Lungworm infection

Fecal flotation; larvae are coughed up and passed in feces.

Dioctophyma renale

Giant kidney worm of canines.

Clinical Signs of Kidney Worm infection

Hematuria, pollakiuria, weight loss, renal or abdominal pain.

Diagnosis of Kidney Worm infection

Urine sediment analysis.

Pearsonema plica

Bladder worm affecting canines.

Clinical Signs of Bladder Worm infection

Pollakiuria and urinary incontinence.