ch. 3/4 parisitology nematodes

types of nematodes

• free living (in water and soil)

• those that parasitize plants

• those that parasitize domesticated/wild animals and humans

nematode anatomy

• spicules

• unsegmented

• elongated

• round on both ends

• bilaterally symmetric

• 2mm to 100 cm in size

• dioecious (separate sexes)

Spirocerca lupi

• GI tract; esophageal worm

• forms nodule in esophageal wall

• eggs in feces and vomit

• paper clip shape

• 30 - 37 micrometers

• 6 month prepatent period

spirocerca lupi

Ollulanus tricuspis

• common name: feline trichostrongyle

• GI tract; in stomach

• identify in cat vomit/fecal float

• females = larviparous (bear live larva)

• L3 infective stage

ascarids

• large roundworms

• host: canine, feline, raccoon

• location: small intestines

• route of infection: ingestion of larvated eggs, contaminated environment, transplacental, transmammary

• Toxocara canis, Toxocara cati, Toxascaris Leonina, Baylisascaris procyonis

• detect with fecal flotation

ascarid egg

transplacental migration of ascarids

larvae migrate through liver and lungs, get coughed up, get swallowed, then develop in small intestine

Toxocara adults

• 3 - 18 cm

• tan

• 3 prominent lips of anterior end

• cati has smaller, arrowhead appearance

• swim to stay in intestines and sometimes stomach

ascarid diseases

• V/D

• pot belly

• poor hair coat

• abdominal pain

• gastroenteritis-inflammation, hypersensitivity

zoonotic ascarids

• visceral larval migrans

• ocular larval migrans

• neural larval migrans

ascarid life cycle

• adults mate in small intestine

• eggs passed in the host’s feces

• become stage 2 larvae on ground

• ingested by a host and the larvae migrate to grow

• migrate to lungs, coughed up, swallowed, restart cycle

ascarid treatment

• pyrantel pamoate (strongid): vermifuge; paralyzes worms that are passed in feces

• fenbendazole (panacur): vermicide; kills parasites and they are broken down by body

Baylisascaris procynosis

• mostly from small intestine of raccoons

• can attack brain in humans

• neurological larval migrans can lead to neurologic signs

• use monthly heartworm prevention

• corticosteroids as supportive care

hookworms

• location: small intestine

• route of infection: ingestion of 3rd stage larvae, contaminated environment, larval penetration of skin, transplacental migration, transmammary transmission

• attach to small intestine; do not swim; suck blood

• fecal flotation to detect

• Ancylostoma: caninum, tubaeforme, braziliense

• Unicinaria stenocephala

hookworm life cycle

• adults attach to small intestines

• voracious feeding and secondary hemorrhage cause anemia in host

• eggs passed through host’s feces

• eggs mature to L1 larvae in external

• L1 hatch, feed, grow, molt to L2

• L2 do same thing to L3 infective stage

• L3 can be ingested or penetrate through skin, migrate to lungs, coughed up, swallowed, start process over

hookworm diseases

• severe and more common in puppies and kittens

• dark/tarry diarrhea

• anemia/pale mm

• weight gain or weight loss

zoonotic hookworms

• cutaneous larval migrans; “creeping eruptions”

• not transmitted person to person

hookworm treatment

• pyrantel (monthly)

• fenbendazole (panacur): vermicide; kills parasites, broken down by body

Strongyloides stercoralis

• intestinal threadworm

• in mucosa of dogs, cats, humans

• only female is parasitic

• route of infection: penetrate skin or oral ingestion

• partheogenesis: reproduction without fertilization from male

• zoonotic by fecal-oral

• facultative parasites

Strongyloides stercoralis (intestinal threadworm) life cycle

• eggs laid in mucosa

• eggs hatch into rhabditiform larvae (non infective)

• larvae penetrate glandular epithelium and pass to lumen

• pass out of feces

Strongyloides stercoralis diseases

• bloody mucoid diarrhea

• dehydration

• stunted growth

diagnosis/treatment of Strongyloides stercoralis

• use Baermann technique for diagnostic

• treat with ivermectin or fenbendazole

whipworms

• location: cecum and colon

• route of infection: ingestion of eggs, contaminated environment

• canine and feline

• suck blood

• larvated eggs can be viable for several years

• fecal flotation for detection

• Trichuris: vulpis, campanula, serrata

whipworm eggs

• barrel shaped

• yellow/brown

• bipolar end plugs / operculum on ends where larvae come out

• smooth shell

• unembryonated when laid

• intermittently shed

whipworm diseases

• diarrhea

• mucous coated stool

• anemia

• some may be asymptomatic or subclinical

whipworm treatment

• fenbendazole (panacur)

• mebendazole

• vermicide: kill parasite and are broken down by body

Enterobius vermicularis

• human pinworm

• in human cecum and colon

• NO dogs or cats; omnivores and herbivores

• can be found in primates

• centrifugation or cellophane tape

Oxyuris equi

• common name: equine pinworm

• location: large intestine

• clinical signs: pruritus in anal region, tail rubbing, behavior

• diagnosis: cellophane tape

• treatment: moxidectin, piperazine, pyrantel

Dirofilaria immitis

• common name: canine heartworm

• canine, feline, ferrets, sealions

• location: right ventricle and pulmonary arteries

• dioecious

• born live; no egg

• can cause pulmonary “coin lesions” with humans

heartworm life cycle

• infection from a bite of infected female mosquito

• need intermediate host

• definitive host: dogs

microfilaria

• baby heartworm

• in peripheral/circulating blood

• 6 months to become adult and get to heart

heartworm diseases

• exercise introlerance

• right side heart enlargement

• ascites (fluid in abdominal cavity)

• fainting

• coughing

heartworm diagnosis

• detect microfilariae

• direct smear

• hematocrit test (above buffy coat)

• modified knott’s test

• filter

• antigen test (for adult female) ELISA

• radiographs/ultrasound

modified knott’s test

• 1 mL EDTA mixed with 9 mL 2% formalin

• invert tube

• centrifuge at 1100 to 1500 rpm for 5 to 8 min

• pour liquid off

• add drop of methylene blue

• place on slide with coverslip

• 10x or 40x

• differentiate between Dirofilaria immitis and Acanthocheilonema reconditum

filter test

• 1 mL blood into EDTA or heparin tube

• add 9 mL lysing solution and mix

• attach to filter unit

• remove filter from holder and place on microscope

• add methylene blue stain and add cover glass

feline heartworm disease

• resistant; takes more exposure to induce disease

• can clear L3 to L5 larva

• respiratory symptoms

feline heartworm diagnosis

• antigen test: active infection

• antibody test: indicate exposure

heartworm treatment

• adult stage: malarsomine (immiticide)

• microfilariae: ivermectin or milbemycin

• cage rest for 1 month

• no treatment for cats

macrolitic lactones

• against microfilariae, L3, L4, young adults

• preventatives

• ivermectin, selamectin, moxidectin, milbemycin oxime

• effective for 1 month

• CAUTION with collies and MDR1 deficient dogs

Wolbachia spp.

• intracellular gram neg rickettsiae

• immune complex disease

• treat with doxycycline

caval syndrome

• hundreds of heartworms

• sudden onset of severe lethargy, weakness, anemia, hemoglobinemia, hemoglobinuria

Aelurostrongylus abstrusus

• common name: feline lungworm

• first stage larvae in cat feces

• definitive host: cats

• transport/reservoir host: rodents, frogs/toads, reptiles, birds

feline lungworm diagnosis

• Baermann technique on feces or sputum

• treatment: fenbendazole

Oslerus osleri

• location: trachea, lungs parenchyma, bronchioles

• common name: canine lung worm

• can transmit from mother to pups from licking them

• fecal float or baermann technique

Dioctophyme renale

• common name: giant kidney worm

• location: kidney and peritoneal cavity of canines

• affects/destroys right kidney

• signs: hematuria and dysuria

• no treatment other than surgery

• intermediate host: earthworm, frogs, fish, crayfish

Pearsonema Plica

Pearsonema feliscati

• bladder worms in dogs and cats

• signs: asymptomatic or cystitis

• diagnosis: eggs in urine sediment, bipolar plugs

• intermediate/transport host: earthworm

• treatment: fenbendazole or ivermectin

Dracunnulus insignis

• location: subcutaneous tissue on limbs

• affects raccoons

• signs: chronic skin ulcer and secondary bacterial infection on limbs

• diagnosis: exam of skin lesion

• intermediate hosts: water fleas (cyclops)/copepod

• ingestion of contaminated water, tadpoles, frogs

Thelazia spp.

• common name: eye worm

• location: conjunctival duct and lacrimal duct

• cattle, dogs, horses

• intermediate host: muscid flies (face fly) transmit L3 into tears

• signs: