Nematodes intro small intestine nematodes , large intestine nematodes , heart worm, lungworms , eye worms

What is the other name for a nematode

Roundworm fyi, about 80% of animals on earth are nematodes

Nematode morphology, body cavity? digestive tract? rest and circulatory system? Dioecious or monoecious?

• In addition, to their digestive cavity, roundworms have a body cavity called pseudocoelom consisting of a fluid-filled space between the body wall and digestive tract. 

• Nematodes have a complete digestive tract with a mouth and an anus

• Nematodes lack respiratory and circulatory systems 

• Excretory cells empty waste from the pseudocoelom into two lateral excretory canals. 

• Nematodes are covered by a thick, non-cellular cuticle that is produced by a thin, multinucleate epidermis. 

• Nematodes have only longitudinal muscles and these are divided into 4 bundles or quadrants. 

• Most nematode species are diecious, with separate male and female individuals 

• Males are usually smaller than females 

• During copulation, one or more chitinized rods (spicules) are inserted into the genital pore of the female

Picture female is left and male is right

What is a bursa in nematodes

 lobular modification of the male posterior end, which is highly elaborated in some nematodes, e.g; those in order stronglyida. It is a distinctive clasping organ with finger-like projections (“birsal rays”) that have sensory function 

What is the purpose of the four larval mounts in nematodes

They must undergo it for larval development. Sexually mature adults form from the final mould. The adults mate and produce eggs and in most cases nematodes leave the host as eggs in the feces. Eggs can leave embyonated or unembyonated

What is the infectious stage in nematodes

It is often the L3 larva (either in a egg or outside)

Family Ascarididae, common name? what do adults feed on? tell me about the females? give me some examples of ascarididae and who they infect?

Common name→ ascarids

feed on→ gut contents in SI

Females→ lay relatively thick-walled, unembyonated eggs

Examples→

Ascaris – infecting pigs, people

Parascaris – infecting horses

Toxocara – infecting dogs, cats

Toxocara leonina - infecting dogs and cats 

Baylisascaris procyonis - infecting racoons 

For ascaris suum, tell me the host? Where adults are found? importance of this nematode? Clinical signs? Main route of parasite?

Host: Pigs

Adults found→ SI

Importance→ is the most important swine nematode due to economic loss

Clinical signs→

• unthriftiness

• weight lloss

• coughing: rapid shallow breathing

• colic

Main route of parasite→ Mouth to SI to bloodstream to lungs to SI

Life cycle and type of life cycle of Acaris suum

Direct life cycle:

• Infection occurs on ingestion of infective eggs (#1).

• The eggs hatch in the small intestine and the L3 larvae penetrate the intestinal wall, enter the blood stream,

• and then migrate intravascularly to the liver, heart and lungs (#4).

• Here they molt and burrow out of the blood vessels to enter the bronchioles.

• From here they migrate up through the air passages of the lungs, to the trachea. They then enter the throat and are swallowed (#2),

• finally ending up in the small intestine where they mature and mate (#3). 

• The adult parasite lives in the lumen of the small intestine. The female parasite lays unembryonated eggs (#5) which embryonate/larvate outside the host yielding eggs containing infective L3s (#6). 

Pathophysiology of Ascaris suum

• Due to hepatopulmonary migration of larvae

  • •Liver

    • –Interstitial hepatitis

    • –Localized fibrotic areas; reaction to larvae - “milk spots”

  • •Lungs

    • –Hemorrhage, bronchitis, edema

    • –Pneumonia in young pigs

• Due to L4/adults in the small intestine

  • - Catarrhal enteritis (small intestine inflammation)

  • - Obstruction or perforation (rare)

Parascaris equorum (horse roundworm), Where is it found, where does infection mainly manifest? some symptoms? life cycle?

Found→ in SI

Manifestation→ mainly in nursing and weaned foals less than a year old

Symptoms→ due to slow growth get diarrhea and GI blockage

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Life cycle same as ascaris suum just with equine

What is the name of the human roundworm

Ascaris lumbrivoides

Tell me about the Dog roundworm, main name?DH? Pathogenesis? clinical signs? Diagnosis? Treatment and prevention? Zoonoses?

Name→ Toxocara Canis

DH→ Dogs, worms live in SI

Pathogenesis→ majority of dogs affected show no signs of disease

Clinical signs→ Shown more in puppies, noisy breathing, cough, vomiting, diarrhea, stunted growth, distended abdomen. Abdominal discomfort

Diagnosis→ Confirmed when you see eggs in feces. Adults dogs harder to detect.

Prevention→ anthelmintics

Zoonoses→ YES, humans can get it by ingesting parasite eggs. Affected more children due to putting things in there mouths. Migrates to liver, lung.

Life cycle of Toxocara Canis

• Females lay unembyonated eggs→ passed in feces

• Embyonate in soil and become infective

• Eggs ingested by dog, hatch and release larvae

• Penetrate the intestinal wall

• In younger dogs, the larvae migrate through the lungs and bronchial tree; larvae are coughed up, swallowed, and returned to the small intestine, where they mature. Adult female worms deposit eggs in the small intestine. Although older dogs may be infected in the same way, larvae are more likely to encyst in tissues.

• Encysted stages are reactivated in female dogs during late pregnancy and infect the puppies via the transplacental or transmammary route. As a result, adult worms become established in the small intestine of the puppies (a major source of environmental contamination).

How T.canis effects humans, explain Visceral larva migrant and ocular larva migrant

Migrating larvae can damage internal tissues. The migration of helminth larvae through tissue in suboptimal hosts is termed larval migrans and may affect the viscera (visceral larval migrans), the eye (ocular larval migrans), or the nervous system (neural larval migrans). 

• VLM→ Consumed by human and emerges and migrates to liver, lung

• OLM→ Migrate to eyes. Granulomatous mass may form in posterior chamber of eye

Toxocara Cati ( cat roundworm) , 3 ways of infection? pathogenesis and clinical signs? Diagnosis? treatment and prevention? Zoonoses?

3 ways of infection→

• Ingesting infective eggs

• Via paratenic host (rodents, birds)

• Transmammary route

Pathogenesis and clinical signs→

• Same for T.canis

Diagnosis→ seeing eggs in feces

Treatment and prevention→ Regular deworming, kittens assumed to be infected and automatically dewormed.

Zoonoeses→ YES

Life cycle of Toxocara Cati

Is the same as T.canis except that transplacental transmission is not known to occur in cats

What is a cervical alae?

Clear cuticular flanges running along the anterior lateral margins of the worms

Cervical alae of T.canis

Cervical Alae in T.cati

Is more broad and end abruptly. Gives a more “arrow-head appearance

Toxascaris leonina, HOST? LIFE CYCLE, what’s different compared to other toxocara? how are dogs infected? and cats infected? pathogenesis and clinical signs? diagnosis?

Host→ Dogs and cats

Life cycle→ These parasites do not migrate through the body in the way that, e.g., T. canis does. In addition, no prenatal or transmammary infection is seen.

• Dogs are more commonly infected by ingestion of eggs with infective L2 larvae. 

• Cats are most commonly infected by ingestion of paratenic hosts,usually rodents. 

• Subsequent development of T. leonina larvae to adults takes place in the intestines without a migratory phase.

Pathogenesis and clinical signs→ Heavy infection can cause diarrhea, dehydration, poor health, rarely death

Diagnosis→ Found in fecal exam. Has a thick, smooth outer shell.

Review of common cat and dog GI roundworm transmission modes (the toxocaras)

Baylisascaris Procyonis, host? where adult worms live in DH? Zoonoses? Pathogenesis and clinical signs(cause of what in humans, what disease can it cause)? Diagnosis and treatment?

Host

• Racoons

Adult worms → SI

Zoonoses

• YES, widespread geographically

Pathogenesis and signs

• Nonpathogenic in racoons

• The larvae (not adults) occur in humans (and other mammals and birds) where they are one of several causative agents of "larval migrans".

• Outbreaks of fatal central nervous system disease (NLM) caused by B. procyonis have occurred on farms and in zoos and research animal colonies and natural infections have also been recognized in several species.

Diagnosis and treatment

• Identification of parasite eggs in feces

• No effective therapy for incidental hosts, anthelmintics slow down or kill exposed larvae as they migrate. Prevention important!!!

  • Eggs has thick shell that protects from most disinfectants. Best way to rid of contaminated soil or area is flaming it.

Life cycle of Baylisascaris procyonis

When raccoons ingest infective eggs, larvae hatch, enter wall of SI, and develop to adult worms in the small intestine

What are the two general hookworms (nematodes)

Ancylostoma and Unicinaria spp.

Ancylostoma caninum (common dog hookworm) , Life cycle? PPP? What are the 3 ways of transmission?

Life cycle:

• Eggs passed in feces

• Hatch in soil, L3 is infective stage

• Dogs get infected by: skin penetration, oral ingestion, transmmary transmission

• Larva migrate (skin → blood→ lungs→ SI)

PPP

• 2-3 weeks, less in puppies

Hookworm spp. Pathology, clinical signs, diagnosis , treatment, prevention, public health concerns?

Pathology: Hookworms are bloodsuckers 

Clinical signs: Anemia, black tarry feces, death dermatities; esp. Interdigital 

Diagnosis: Fecal exam to look for eggs 

Treatment: fenbendazole, pyrantel and others 

Prevention: sanitation - larva killed by sunlight (larva more susceptible to harsh conditions)

Public health concerns: cutaneous larva migrans (CLM) 

Explain to me Cutaneous larva migraines

• •Humans exposed to L3 stage larvae 

• •L3 penetrate the skins and cause a creeping eruption where localized migration occurs 

• •Extremely pruritic

• •Self-limiting – larvae die in 5-6 weeks 

• •Larvae cannot reach maturity in the human host

• Most commonly occurs with A.braziliense (don’t have to know for exam) 

  • •Also known as “plumber’s itch”, which, as the name implies, affects plumbers who crawled in areas contaminated with larvae

Hookworm of ruminants: Bunostomum phlebotomum, pathogenesis and signs? What can they cause in humans? Life cycle?

Pathogenesis and signs:

• Hematophagous(blood feeders) though generally nonpathogenic; but, heavy infection can produce clinical signs including anemia, intermittent diarrhea, and rapid weight loss 

What can they cause in humans→

• Can cause short-lived CLM(cutaneous larval migrans)  in humans

Life cycle→

• Larvae penetrates skin of cow→ go into blood→ lungs→ alveoli→ small intestine→ produce eggs and is where larval stage emerges which is infectious stage.

What is the large intestine nematode of importance

Trichuris Spp→ whipworms

Trichuris spp→ Type of life cycle? type of egg? What larval stage is infective? Pathology? Clinical signs? diagnosis? where do adults live?

Type of life cycle→ Direct life cycle

Egg→ single celled bipolar egg passed

Adults→ live in colon and cecum

Larval stage→ L1, egg protects larvae and allows it to survive in the environment year-round

Pathology→ Typhlitis (inflammation of the cecum) with heavy worm burden

Clinical signs→ Mucoid diarrhea, mushy stools, rarely blood involved

Diagnosis→ fecal float

Trichuris life cycle

• Adults in large intestine and imbed into intestinal mucosa

• Females lay embryonated eggs

• Eggs passed in feces

• In soil they embryonate and develop into infective L1 larvae

• Host digest embryonated eggs via contaminated food, water, soil

• Eggs hatch in SI and molt locally

  • Immature worms migrate to cecum and colon and mature into adults and embed into mucosa

What is some prevention you could let a client know for parasites

• •Pick up dog feces. If parasite eggs/larvae are not in the environment, other animals cannot become infected. Follow this practice at your clinic and convince your clients to do so at home.

• •Cover sandboxes. Covered sandboxes cannot become contaminated by dogs and cats.

• •Deworm dogs regularly. Using an approved anthelminthic, deworm puppies at 2, 4, 6, and 8 weeks of age and then monthly, if possible.

Heartworm (Dirofilaria immitis), DH? Type of life cycle? What are larvae called? what is the infective stage? Pathology? Clinical signs? Diagnosis? Mosquitos associated?

DH→

• Dogs, ferrets, sea lions, rarely humans (cats considered “atypical” hosts)

Type of life cycle→

• Indirect life cycle

Larvae called →

• Microfilariae

Infective stage→

• L3 is infective

Pathology→

• Due to adult worms (Adult heartworms can live for 5-7 years in dogs and up to 2-3 years in cats)

• •Obstruction of pulmonary arteries

• •Progressive pulmonary endarteritis (inflammation of the inner lining of an artery) & fibrosis (thickening & scarring of connective tissue). Thickened fibrotic arterial lining causes turbulence & decreased blood flow

• •Chronic pulmonary hypertension causes right heart failure 

• •Vena cava syndrome – large number of worms obstruct venous return to vena cava & right atrium 

Clinical Signs→

• chronic progressive cough, Exercise intolerance/ fatigue, weight loss, ascites, Death 

Diagnosis→

• ID microfilariae in blood

• Antigen or antibody detection

• Radiography (enlarged R heart and enlarged pulmonary arterial trunk)

• ECG

• Necropsy

Mosquitoes associated

• Aedes sp, culex sp, anopheles sp
  

Heartworm life cycle

Wolbachia? What is it? How it contributes to Heartworm disease? What is it susceptible to?

What is it→

• Gram negative intracellular bacteria

How it contributes to heart worm dz→

• Symbiotically colonizes dirofilaria immitis.

• Antigen stimulation of mammalian host by released bacterial antigens causes inflammation when the parasite dies.

• Contributor to pathology and clinical signs of D.immits

Susceptible to→

• Tetracycline

What gets confused with D.immitis? What is its DH? IH? Pathology? Clinical signs? Diagnosis? Treatment?

Acanthochellonema reconditum

life cycle: Indirect

DH→ Dog

IH→ ctenocephalides fels flea and heterodoxies sponger lice

Pathology→ none

Clinical signs → none

Diagnosis: Microfilaria in blood - can be differentiated from D. immitis by using modified knotts technique 

Treatment: Ivermectin treats the microfilaria

Differences between morphology of D.immitis and A.reconditum

What are some examples of some nematode lungworms and what is the one that mainly infects cats?

• Capillaria aerophilia

• Eucoleus aerophilus

• Filaroides firthi

One that infects cats→ Aelorostrongylus abstrusus

Aelurostrongylus abstrusus life cycle and type of life cycle? IH? PH? Where are adults found?

Indirect life cycle→

• Eggs passed by adult female worms hatch in the lungs, and larvae pass up the trachea, then down the intestinal tract, and out in feces. 

IH→ Snail and slugs are the intermediate hosts

paratenic hosts→ e.g., rodents, birds, amphibia, and reptiles. 

• Ingested larvae are liberated in the intestine, penetrate the mucosa, and migrate in the blood to the lungs.

Adult worms are found→in the alveolar ducts and terminal bronchioles 8 to 9 days after infection.

Aelurostrongylus abstrusus? Life cycle (what stage passed in feces and what stage is infective)? DH? IH? PH? Pathology? Clinical signs? Diagnosis? Treatment? control?

Life Cycle: L1 larvae passed in feces, L3 infective

• Indirect 

• Definitive Host: cat - passes L1

• Intermediate Host: snails, slugs - 3rd stage 

• Paratenic host: birds, rodents, amphibians, reptiles - 3rd stage 

Prepatent Period: ;1 in feces at about 6 weeks 

Pathology:  

•Eggs induce granulomatous reactions leading to the formation of subpleural nodules within the lung parenchyma 

Clinical signs:  

•Usually none, but could have a chronic cough & dyspnea (labored breathing) 

Diagnosis:  

•Can try Baermann but worm is not very motile – struggle to leave feces

•Direct fecal smear – low concentration may prevent ID

•Radiographic evidence 

•TTW (Transtracheal wash) or BAL (bronchiolar lavage) is the best option

Treatment:  

•Fenbendazole or ivermectin

Control:  

•Prevent interaction w/ snails & slugs, and paratenic hosts 

What is an eye worm nematode?

Thelazia app.

Thelazia SPP. Life cycle type? PPP? Zoonoses? DH? IH? Where are adults found? 3 Thelazia spp important for vet med?

Life cycle → Indirect

• Female worm produces larvae (L1) in conjunctival sac

• Adult flies consume L1

• L1 molts to L3 within fly

• L3 crawls to mouthparts of fly and escapes into the orbit of the DH when the fly feeds

• L3 develops into an adult without migration

PPP→ 3-6 weeks

DH→

• Cattle, horse, dog, cat, sheep, human

IH→

• Diptera

Adults found→

• Conjunctiva and lacrimal ducts

Zoonoses→

• YESSSS

T.californiensis and T.callipaeda→ dogs and cats

T.lacrymalis→ horses

Thelazia californiensis

Both the adult parasites and larval stages can cause pain and discomfort leading e.g., to keratitis (inflammation of the cornea) or conjunctivitis (inflammation of the conjunctiva – the mucous membrane covering the front of the eye).