Parasitology Ascarids

• *Sensory organs (amphids) around head
• Unsegmented
• Bilaterally symmetrical
• Elongated
• Tapered at both ends
• Digestive tract is usually complete
• *most important to distinguish them

Five states: one-cell--> morula--> vermiform embryo (pre-first state larvae)--> First State--> Second State--> Third State (usually infective state)--> Fourth State--> Fifth State (adult)-->

Posterior end of the male end. Baseball like structure that is used to clasp onto the females

Male does not have a bursate but does usually have a curved end which helps the male grab onto the female

On the end of the male worms that open up the females in order for sperm to be injected in

• "Roundworms"
• Thick bodies
• Adults large, white
• They have three lips

• Females pass HUGE numbers of eggs
• Eggs are remarkably resistant to environmental degradation
• Infect young, immunologically naive animals

• Liver or kidney- scarring, hemorrhagic tract, "milk spots"
• Lung- antigenic pulmonary edema, 2-3 day old pups can die, nasal discharge in foals

migrate from small intestine to stomach (causing vomiting)

Large numbers in intestine (mucoid diarrhea, pot-belly, contributes to malnutrition, painful, rough hair coat, fail to thrive)

May block bile duct

• Visceral larva migrans (VLM)
• Ocular larva migrans (OLM)
• CNS disease common
• Hepatomegaly, eosinophilia

• Adults
• Characteristic eggs on fecal float if patent
• Presumptive if within prepatent period (Clinical signs, gross apperance, age)
• Transtracheal aspirate in foal with respiratory disease due to ascarids

• Intestinal large roundworm
• Host: pigs
• Site of infection: Adults in small intestines
• Distribution: Common, pigs raised outdoors

• Ingestion of infetive eggs (3rd State Larvae)
• Paratenic hosts: earthworms and dung beetles
• No transplacental or transmammary
• Prepatent period= 6-8 weeks

Hatches in stomach--> liver--> lungs--> swallowed--> Stomach

Mechanical destruction of tissue- early infection (initial focal hemorrhages, respiratory distress)

Hypersensitivity (hyperemia, edema, eosinophilic infiltrates)

Fibrosis (milk spot lesions)

• Interference with proper nutrition and growth
• Diarrhea
• Occasional occlusion or perforation
• Subclinical effects- reduce growth rate

• Patent infection: eggs in flotations, adults at necropsy
• During prepatent Period: respiratory signs in young pigs, feeder pigs 2 to 5 months

50-70 by 40-60 in size, thick pitted outer wall, golden brown

• Large intestinal roundworm or horse roundworm
• Host: equine species, horses and donkeys
• Site of infection: adults in small intestine, juveniles migrate extensively
• Distribution: common throughout the world

• Similar to A. suum (Hatches in small intestine--> liver--> lungs--> swallowed--> small intestine)
• Prepatent period: 10 weeks
• Prenatal infections are not known to occur
• Ingestion of infective eggs primary route

• Respiratory distress and nasal discharge in foals
• Similar to the for A. suum

• moderate enteritis, colic
• subnormal growth
• dull hair coat

Patent infections: eggs in flotations, adults at necropsy

• Prepatent infections: caughing and greyis-white nasal discharge in foal up to 6 months
• Endoscopy reveals frothy mucous in upper air passages

• Host: canines
• Site of infection: adult in small intestines, juveniles migrate extensively
• Distribution: throughout the world, very common
• Have cervical alae (wings) on head

L3 hatch in small intestines--> goes to liver--> lungs to aveoli--> goes to trachea to get swallowed--> stomach--> small intestine

• Primary way that puppy becomes infected: Arrested larvae in the dams tissue-->Transplacental migration of L3 to fetal liver --> neonatal pup lungs (until puppy is born)--> lungs to aveoli--> goes to trachea to get swallowed--> stomach--> small intestine
• So efficient you can assume every puppy born is infected

• migration of L3s to mammary glands--> L3s ingested by sucking pups--> swallowed--> stomach--> small intestine
• (Rare)

paratenic host ingests egg--> somatic migration L3 into tissue--> dog eats host and larvae released--> develops into an adult in intestines

• Respiratory disease: 2-3 day old pups, transplacental transmission
• Heavy infection of worms in small intestine: nursing and weaned pups, pot-bellied pups, tender abdomens often due to bloating, pups will frequently whimper and cry

• Less susceptible:
• intestinal infection is rare in adult dogs but 5% of dogs 7 years of age in shelters were infected
• Puppies spontaneously purge intestinal infections as they mature and develop immunity to T. canis

• Large round worm of cats
• Host: Feline
• Site of Infection: adults in small intestine, juveniles migrate extensively
• Distribution: common throughout the world

Transmission: ingestion of infective eggs, no prenatal infections, transmammary infections (maybe), ingestion of paratenic hosts important, prepatent period is 2 months

• respiratory signs in newborn kittens are absent
• nursing kittens may obtain heavy infections from transmammary transmissions
• clinical signs may include: abdominal distension and distress, chronic ill thrift

• Roundworm
• Host: dogs, cats, foxes other wild carnivores
• Site of infection: small intestines
• Distribution: worldwide, uncommon in domestic dogs and cats, very common in wild carnivores

• transmission: eggs embryonate in approximately 1 week
• may use mice as paratenic hosts
• does not require somatic migration like Toxocara canis
• no transplacental nor transmammary transmission
• Prepatent period: 2-2.5 months

• not considered as pathogenic as Toxocara canis
• minor clinical significance, however, infected animals may be potbellied and unthrifty

• Host: cattle
• Site of infection: small intestines for adults, VLM in calves this is non-pathogenic
• Distribution: world wide but rare in US

• Hosts: wildlife, carnivores and omnivores
• Raccoon= Baylisascaris procyonis
• Importance: can also infect dogs, public health implications because of the close association of raccoon and humans