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Most common internal worms (parasite) encountered in veterinary as well as human medicine.
_________ and ________ mean the same thing. These two terms are used interchangeably in veterinary and human medicine.
What must happen in order for a disease to be zoonotic?
Animal must be infected and show symptoms and clinical sign of infection.
More than 15,000,000 people in the U.S. are infected with __________ from dogs and cats
Toxocara Genus (ascarids)
________ caused 37% of the cases in retinal disease in children.
Majority of puppies are born with ________ and _______. They can shed the eggs at earliest of ________ weeks old.
- Toxocara canis
- Ancylostoma caninum
- 2-3 weeks
An ascarid of the raccoon that dogs pick up from raccoon poop in a latrine. This is zoonotic. Can cause CNS problems and lead to death in humans.
Hookworms are a well known cause of CLM or ___________ in humans.
__________ causes chronic enterocolitis and eosinophilic eneritis in humans.
People most susceptible to zoonotic diseases:
What are the two most common and why?
- 1. young (most common - low immunity)
- 2. house with dog and cat
- 3. bad hygiene and sanitation
- 4. work with animals
- 5. work in contaminated environment
- 6. pet owners dont routinely deworm their pets
- 7. elderly (most common - low immunity)
- 8. vet professionals
Morphology of nematodes:
Excretory system includes -
Body cavity -
- pair of unicellular glands with a ventral excretory pore, ducts run full length of body.
- large body cavity filled with pressurized fluid.
How does a nematode move?
They move by increasing and decreasing the pressure in the body cavity. They move like a worm would
Differences in Male and female nematodes:
- male: smaller than female, has a copulatory bursa used to grasp female during reproduction
- female: larger, more blood thirsty. Reproductive tract similar to humans, 2 ovaries, oviducts - connect to single vagina
Stages of nematode egg development:
- 1 cell
- vermiform embryo
Nematode life cycle in relation to infection, diagnosis, treatment
- infective stage
- adult stage
Horses do not have hook worms, they have ____________.
- Order: Strongylida
- Family: Ancylostomatidae
- Genus: Ancylostoma
- species: caninum, tuberformae
Hook worm most commonly found in the dog __________ and in the cat _________.
Males are _____mm long and females ____ mm long
Hook worm found in BOTH dog and cat:
- Ancylostoma caninum (dog)
- A. tuberformae (cat)
- Uncineria stenocephlica
Hookworms found in the dog from most common:
- Ancylostoma caninum
- Ancylostoma braziliensis
- Uncineria stenocephlica
Slightly larger than A. caninum and is not commonly found but is highly virulent, can lead to death in small puppies 12 days after birth.
How does hook worm transmission occur?
_________ - easiest way of transmission
1. _________ - only occurs during infective stage larva
- direct transmission
- skin penetration
- oral infection
- consumption of parentenic host
This means of transmission only occurs with Ancylostoma caninum
This means of transmission can only be done by the infective stage larva.
Explain transmission by way of intermediate/parentenic host. Give an example.
- Parentenic host is the host that was unintentional. The parentenic host will consume the parasite, the parasite will not molt inside the parentenic host. The intermediate host will consume the parentenic host and become infected.
- Lizard consumes A. caninum, dog eats lizard, dog becomes infected
The degree of a hook worm or any other infection is dependent on:
- 1. virulence of specific parasite involved
- 2. degree of exposure to infective larva
- 3. degree of resistance of the host
- 4. healthy diet
Ancylostoma is said to be the most virulent or most pathogenic, why?
- They are more numerous.
- Have more routes of transmission
Major signs associated with hooks infection:
What is seen specifically with A. caninum?
Anemia from blood loss and gastrointestinal irritation - weakness, anorexia, diarrhea
Anemia created by blood loss look like what under the microscope?
A. caninum penetrates the skin commonly between the toes, this causes erythema, red swelling and inflammation. This condition referred to as:
hook worm dermatitis
Hook worms larva are known to migrate viscerally leading to 2ndry _________ and _________.
hepatitis and pneumonia
__________ is from the time the dog or puppy becomes infected with the infective stage larva to the time we see evidence of eggs passing in the feces
Pre-patent period for A. caninum
With per-acute anemia, death can occur within:
With acute anemia, death can occur within:
Infected puppies with hook worms in-utero or after birth may produce what signs:
per-acute syndrome with rapid blood loss, anemia, and death.
Pre-natal infection of hooks does not become patent until the _____ day
The primary cause of canine hook worm disease, found in ______ regions of the world.
________ of cats will have a similar but sparser geographical distribution. A. braziliensis of cats found:
- A. caninum
- tropical and subtropical
- A. tuberfromae
- Florida to N Carolina in the US
Why do some people say hook worms are blood suckers? Include why the stool is dark and tarry with this infection. (they are not blood suckers)
Hook worms attach themselves and feed on mucosal lining (glucose) of the small intestine. By doing so they disrupt small blood vessels and cause bleeding in the small intestine. The blood flows through intestines causing the feces to be dark and tarry when passed.
Clinical signs associated with Ancylostoma caninum
- blood loss anemia
- dark tarry stool (A. caninum)
- gastrointestinal irritation (A. caninum)
Ancylostoma caninum geographical distribution:
Found in dogs throughout Canada and US
Prevalence of A. caninum:
- ♦ most common in dogs in warmer climates
- ♦ found in 19.19% of shelter dogs
Primary means of transmission:
Transmammary infection by Uncineria stenocephalica can cause what in puppies:
profound anemia and death within 12 days
Hook worms can penetrate the skin of man causing cutaneous larval migrans (aka _________) especially ________.
- creeping eruptions
- Ancylostoma brazilienses
Conditions of CLM in people are more prevalent in _______ and _______. Humans become infected by contact of larva in _____________.
- Southern states and Northeast
- soil with contaminated dog or cat feces
Infection of A. tuberformae is not as commonly seen as A. caninum in dogs due to ___________.
eating habits of cats
Clinical signs of Ancylostomiasis
- More devastating in puppy or kitten
- dark tarry stool diarrhea
- pale mucous membranes with anemia
- microcytic, hypochromic
- playing today, motionless tomorrow
- dead 3rd day
Most common and most virulent of hooks seen in ___________.
Life cycle of Ancylostoma
- ♦ eggs hatch 5-6 days
- ♦ dog consumes infective 3rd stage larva (2 weeks reproduce) or 3rd stage penetrates the skin (4 weeks reproduce)
- ♦ one of two avenues can occur, 1. stage 3 larva mature to adult in small intestine or 2. larva penetrate intestine wall and migrate and encyst in skeletal muscle or gut wall becoming dormant.
- ♦ larva goes to small intestine where it will molt to stage 5 adult and feed
- ♦ adult reproduce and eggs will pass in the feces and hatch in 2 - 8 days
Explain Larval leak syndrome.
- ♦ host ingests infective stage larva
- ♦ larva goes to intestine and penetrates the intestinal wall where it becomes dormant
- ♦ Larva will return to circulation when dog undergoes hormonal changes such as a dog in heat
- ♦ larva will then continue the life cycle and evidence will appear in the feces
Hookworm transmission is _______ transmission and by: (indicate most common for A. caninum)
- 1. ingestion
- 2. skin penetration
- 3. inutero
- 4. transmammary (A. caninum)
- 5. mammalian intermediate host
These two species of hookworm can penetrate the skin of humans and cause what condition? Include its common name.
- A. caninum
- A. braziliensis
- cutaneous larval migrans
- creeping eruptions
Diagnosis for hooks:
Common drugs of choice:
- eggs present in the feces
- 14 days prepatent period
- pyrantel pamoate (nemex
- panacur (fenbendazole)
List as many Benzimendazoles as you can:
Why are they commonly used?
- mix well with other drugs
What puts the "plus" in Drontal Plus, what drug was added?
Steps taken to control hooks:
- 1. feces be removed from earth runs. No more than 24 hrs
- 2. Treat soil periodically with salt 160g/liter boiling water or sodium borate 14 kg/sq meter
- 3. Hose and wash concrete runs
- 4. de-worm bitch prior to breeding
2nd most common nematode parasite of cats and dogs:
- Toxocara, Toxascaris, Physaloptera, Bayliascaris
3 members of Ascarida of the dog and cat that have direct only transmission:
- 1. Toxocara canis
- 2. T. cati
- 3. Toxascaris leonina
Toxocara parasite morphology:
- females larger in size
- male, 7-9 cm
- female, 10-17 cm
Infections of Toxocara can be passed via:
- consumption of the eggs
- second stage larvae consumption
- predation of parentenic host
Infective stage for all ascarids:
2nd stage infective
A non-intentional host is also known as a:
Update on infectious routes:
25% of 60 dogs tested contained roundworm eggs at various stages of maturity found where? Proving what?
- Hair of 60 dogs tested 25% had roundworm eggs
- man can be infected by petting his dog.
- 1st stage larvae can mature to infective 2nd stage on hair of infected animal
____ and ________ follow what is called Trans Tracheal Migration Route. Explain.
- T. canis and cati
- Dog consumes 2nd infective stage larva
- Larva penetrates stomach wall and enters the liver
- Larva migrates through the liver parenchyma In pigs this causes white spots to appear
- on the liver. Called, milk spots
- Larva enters posterior vena cave via the RIGHT AURICLE, RIGHT ATRIUM, TRICUSPID VALVE, RIGHT VENTRICLE, PULMONIC VALVE, and PULMONARY ARTERY arriving at the lungs
- Larva migrate up the trachea to the pharynx causing
- the dog to cough up and then swallow the larva
- 2nd stage larva will molt to 3rd
- stage in the stomach, then will molt twice more in the small intestine. Reproduction occurs in the small intestine
Largest ascarid in dogs living in the small intestine:
Ascarid of the dog that lives in stomach and is continuous C shaped larval stage.
Toxocara cycle of infection inutero:
(bitch to pups)
- passed inutero by 2nd stage larvae
- pups can have 3rd stage in their lungs when born and a 3rd-4th molt during 1st week of life
- 3 days after birth can have 4th stage present in the intestines
Prepatent period for ascarids:
(T. cati, T. canis)
Flow of blood staring from:
Left ventricle, aortic valve, aorta, right auricle, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, lungs, pulmonary vein, left auricle, left atrium, mitral valve, left ventricle
This ascarid has NO MUCOSAL MIGRATION, it stays in the intestines
Why do we only deworm once if only parasite involved is Toxascaris leonina?
- Does not undergo mucosal migration
- stays in the intestines
If larva of a viscerally migrating ascarid does not follow trans tracheal migration, what can occur?
larva will encyst in the muscle and become dormant (larval leak syndrome)
Larva that do not follow the normal routes of migration result in a state of arrested development, where they encyst in the muscle and become dormant. This state is referred to as:
What happens to encysted larva when female hormones rise during gestation?
- Hormones will activate the encysted larva to move out of muscle and either pass transplacental or transmammary thus infecting the inutero/new borns with infective 2nd or 3rd stage larva.
- these encysted larva are non detectable and non reachable with antihelminthics while in dormant state
3 forms of both the Ascarid and Ancylostoma in the animals body, not in egg form:
- 1. adult - in the intestines mostly
- 2. visceral migrating larvae
- 3. encysted larval
What is treatment protocol for dogs and cats positive for ascarids and ancylostoma/
Require at least 2 treatments 2 weeks apart for the visceral larvae
Primary means of transmission concerning (1) ascarids and (2) ancylostoma.
- 1. transplacental, inutero, transovarial
- 2. transmammary, galactogenic
Signs of ascarid infection in
1. prenatal pups
- 1. abdominal cramps, intersussception with constipation/obstipation
- 2. gastrointestinal upset (diarrhea and vomiting), respiratory disorders due to tracheal migration, "pot bellied" appearance and emaciation, dull hair coat
Difference between symptom and clinical sign:
symptom can be seen with the naked eye (pale mucous membranes, diarrhea, vomit) and clinical sign is something diagnosed in a lab with aid from medical technology such as a microscope (anemia, lysed rbc, hepatitis)
Chemotherapy for ascarids (rounds)
- Drontal Plus (pyrantel pamoate, fenbendazole, praziquantel)
- Drontal (praziquantel, pyrantel pamoate)
- Task (diclorvos)
Control of ascarids:
- 1. bitch screened and deworm twice prior to breeding
- 2. pups in an enclosed environment with frequent disposal of feces
- 3. pup screening at 4-8 weeks
Ascarid transmission to man can occur and result in blindness, this refers to:
Ocular larval migrans
Most authorities attribute VLM to _______ and ______ but VLM can also be seen with _______.
- T. canis
- T. cati
- A. caninum
The cause for Cutaneous Larval Migrans in humans is due to _________ and _________.
However, most authorities and text will list __________ as the main culprit.
- A. brazilienses and A. caninum
- A. brazilienses
CLM in humans has a nickname but only when it is found in humans and ONLY when caused by this hookworm:
- "Creeping Eruption"
- A. brazilienses
The common ascarid to cats like T. canis is to the dog.
Transtracheal migration is the same in the two ascarids common to the cat and common to the dog: ________ and _________
T. cati and T. canis
Difference between route of infection concerning T cati and T canis:
- Transplacental route does not occur with T. cati
- transmammary is the route in cats
Ascarid found in both the dog and cat
2 mechanisms of transmission with Toxascaris leonina
- ingestion of eggs
- ingestion of paratenic host
Signs of infection with Toxascaris leonina
- minimal due to the lack of pathogenicity with no transplacental and no transmammary transmission
- animal not affected until near adulthood
Toxascaris leonina life cycle
- No visceral migration.
- ingestion of eggs
- 1st stage migrates mucosally
- 2nd and 3rd molts occur in mucosal wall
- 4th stage enters lumen of gut to mature and reproduce
- prepatent period 10 weeks
Ascarid of raccoons but canine infections are common
Responsible for severe neurological disease and death of several children in the US.
Area where dogs and children are commonly infected with B. procyonis, an area where raccoons defecate over and over. Called
3rd most common nematode - whipworms.
Common whip worms:
man, pig, monkey
- Trichuris vulpis
- T. campanula, serrate
- T. trichura
Trichuris inhabit the ______ where they attach the anterior end and embed in mucosa.
The egg of this parasite is double operculated
- Parasenema plica
Ancylostoma and ascarids inhabit the _________.
- direct transmission
- eggs directly consumed
The egg of this nematode is double operculated. It's larva can be found in the cecum of the canine where it firmly attaches to the anterior end and embed in the mucosa
- (T. vulpis in dog)
Trichuris life cycle is _______. It's pre-patent period is ______.
- Direct life cycle
- 3 months
Seen with dogs that have Trichuris infection. These dogs wioll occasionally turn their head to the left and chew on their left side in the paralumbar area
Signs and symptoms seen with Trichuris infection
- Weight loss
- bright red blood in the feces
- abdominal pain
- flank sucking
List the infective stages for:
- Ancylostoma - 3rd stage
- Toxccara - 2nd stage
- Trichuris - 3rd stage (egg directly consumed)
Trichuris life cycle:
- Direct, no intermediate host
- adults pass egg out in feces
- egg can hatch or be directly consumed
- egg directly consumed (need high temp)
- egg will hatch and develop in jejunal wall (will incubate for 1 month in egg)
- adults will then move to the cecum where they mature and reproduce (occurs after 11 weeks after ingestion of egg)
Eggs of Trichuris are very heavy and require a flotation medium with a specific gravity of at least _______ in order to get the eggs to float to the top
Treatment of choice for whipworms
fenbendazole (Panacur) for at least 3 days
Benzimendazoles mix well with other drugs and are used frequently:
From a public health standpoint this intestinal parasite of animals is most pathogenic. Can kill people
Taxonomy for Strongyloides
- Phylum - Nematoda
- Oder - Rhabditida
- Family - Rhabdiasoidea
Strongyloides belong to the family ______ and are called ________.
A Rhabditoid, it's eggs have very thin walls and all are in the vermiform embryo stage when seen in the feces.
Strongyloides inhabit what part of the alimentary tract?
live in mucosa of anterior half of small intestine
Strongyloides adult occur in three forms:
_______ is the most viscerally migrating larva of the 3
- 1. sexual male - passed as vermiform embryo
- 2. sexual female - passed as vermiform embryo
- 3. asexual and pathogenic female - most pathogenic females will pass eggs only except S. stercoralis (most VLM)
Known as the "Intestinal threadworm" and occurs commonly in the dog and cat producing ________ like the whips
- Strongyloides stercoralis (dog)
- Strongyloides tumefaciens (cat)
- bright red blood in the feces
_______ are part of the Rhabdiasoides family like the Genus Strongyloides and are common in horses invading the CNS on occasion, along with __________ another parasite known to invade the CNS
- Micronema species
- Bayliascaris procynosis
Strongyloides can be diagnosed using what technique
Life cycle of Strongyloides
- After passing larva molts twice to stage 3 infective stage.
- 3rd stage may penetrate the skin or be consumed
Strongyloides stercoralis lives in the _______ and causes ________
- anterior half of small intestine
- bright red blood
This parasites lives in the anterior half of the small intestine and causes bright red blood in the feces. How is this possible?
- Strongyloides stercoralis
- causes bright red blood due to rapid movement through the small intestine, seen with explosive diarrhea
Diagnosis of Strongyloides stercoralis:
Identifying larva in the fresh feces on direct or flotation
Transmission of Strongyloides stercoralis
Due to penetration, _________ can inhabit man and create debilitating pneumonia
Chemotherapy for Strongyloides
ivermectin orally or thiabendazole for 3 straight days
___________ is a true zoonotic concern in the dog. Causes pneumonia and death in man. All other species that house this parasite will not experience life threatening results. It's pathogenic female occurs _____ of the time in the canine species.
Which parasites cause bleeding?
- Trichuris - bright red blood
- Ancylostomiasis - dark tarry stool
- Strongyloides - bright red blood
- Physaloptera - dark tarry stool
Which parasites exit the host as larva?
lungworms and Strongyloides
Which parasites inhabit small intestine?
- Ancylostoma - A. caninum, A. tuberformae, U. stenocephalica
- Ascarids - T. cati, T. canis, Toxascaris leonina
- Phylum - Nematoda
- Order - Trichinellida
- Family - Trichinelloidea
- Genus - Eucoleus, Aelurostrongylus (cat), Crenosoma, Oslerus, Filaroides (filarids), Paragonimus (trematode)
Lungworms of dogs and cats belong to the order _________. Lungworms are __________, eggs may hatch in lungs or alimentary tract resulting in 1st stage larva on fecal examination.
________ and ________ are the only parasites of any significance that can be passed as 1st stage larvae as well as in the oviparous form.
lungworms and Strongyloides
__________ is the "fox lungworm" is the lungworm of dogs and foxes.
The facultative, intermediate host for Eucoleus aerophila ("the fox lungworm") lungworm of dog and fox is _________
The eggs of Eucoleus resemble what other parasite egg by being _________.
Aelurostrongylus abstrusus is the lungworm of the _____. It's life cycle is ________
The mollusc is the facultative host of ___________, the lungworm of the cat.
Other Eucoleus species include:
___________ - crop worm of poultry
___________ - inflammation of mucosa in ducks
- Eucoleus annulata
- E. contorta
Clinical signs seen in dogs with Eucoleus aerophila:
cough turning into pneumonia
Cats infected with Aelurostrongylus will have what clinical signs:
Few clinical signs. Cough will be followed by dyspnea, anorexia, and fever. Sneezing maybe present
This parasite seen in the dog is a trematode and its natural definitive host is in the mink.
Paragonimus kellicotti life cycle:
- strictly indirect
- eggs coughed up and swallowed
- pass in water and are picked up by the snail
- crayfish eats the snail, dog eats the crayfish.
___________ ("French heartworm")
This is a nematode in the pulmonary arteries and right side of the heart in dogs and wild canides, then wind up in the lungs.
This is a lungworm of foxes and can occasionally be found in dogs. It occurs in the trachea, bronchi and bronchioles of wild canides occasionally in dogs NE of the US, in Europe.
Angiostrongylus vasorum ("_________") occur where in the dog and wild canides
right side of the heart and can be swept by blood into lungs
Filaroides osleri and F. hirthi (lungworms) infective stage:
- 1st stage larva are infective
- Do not require an intermediate host
Clinical picture seen with the lungworms Filaroides osleri and Filaroides hirthi
fairly uncommon in the US except for the East coast
Clinical symptoms and signs for Filaroides osleri and F. hirthi
cough to dyspnea to death
Review intermediate hosts:
- Eucoleus - earthworm
- Aelurostrongylus - molluscs
- Paragonimus - crayfish
- Filaroides - do not require intermedite host
- Diagnosis: Baermann apparatus
Treatment and control for most common lungworms of the dog and cat:
- Ivermectin at 1∕4mL/40lbs
- Aelurostrongylus - keep cats from molluscs
- Eucoleus - wire bottom cage or clean often
The "Esophageal Worm". Bright red worms dwelling in nodules in the esophagus or sometimes the aortic walls of the dogs and other carnivores
These two parasites are the only ones considered to produce neoplasms, tumors that are malignant.
- Spirocerca lupi - esophageal sarcomas in the dog
- Draschia megastoma - cause tumors or cancer in the horse
Symptoms and diagnosis of Spirocerca lupi:
- vomiting, dysphagia, aortic aneurysm, and esophageal neoplasms. This can lead to secondary osteoarthropathy.
- diagnosis: eggs on flotation
Life cycle of Spirocerca lupi ("________")
- Eggs are deposited from the dog into the stool
- eggs only hatch after consumed by the coprophagus beetle
- larva become ineffective and encyst in the tracheal tubes of the beetle
- beetle is ingested by paretenic host (lizard)
- paretenic host is then ingested by the definitive host (dog)
- larva will penetrate stomach wall and find their way via arterial system to the aorta and up to esophagus.
- Some larva will stay in aorta, some in stomach but most will go to the esophagus
Treatment for Spirocerca lupi
- quarter of an mL per 40 pounds
- 1/4mL / 40lbs
Physaloptra is the "______" of dogs and cats
- Stomach worm
- dog - P. rara
- cat - P. praeputialis
Physaloptera look a lot like ascarids but differ in five ways:
- 1. They are in the stomach only
- 2. in the shape of a C
- 3. eggs are almost always in a vermiform stage
- 4. eggs appear transparent
- 5. they feed on mucosa and cause bleeding (dark)
Why are Physaloptera so difficult to diagnose?
Eggs are very heavy and require a high specific gravity of 1.24. Must constantly focus up and down when looking at a fecal
Life cycle of Physaloptera:
- Beetle consumes the eggs or larva
- molting occurs within the beetle as being ingested by definitive host
- larva will penetrate the adventitia of aorta and migrate up into the walls of the stomach and esophagus
- adults will attach to the mucosa of the stomach causing bleeding
- eggs are passed out in the feces
Signs seen with Physaloptera:
dark tarry stool
The "eyeworm" of dogs and cats. Occur in conjunctival sac and on conjunctiva of dogs and cats
Intermediate host flies for Thelazia californiensis ("________")
- Musca domestica and Musca autumnalis
Thelazia in horses -
cattle and horses -
dog, sheep, wild animals -
- Thelazia lacrymalis
- T. skrjabini
- T. gulosa
- T. californiensis
Diagnosis for Thelazia
Finding the worms in the eye or 1st stage larvae in the tear ducts
12 steps to pet owner knowledge concerning the prevention of Companion Animal Zoonosis
- 1. Purchase from reputable breeders and she
- 2. Annual vet visits for wellness exam
- 3. Broad-spectrum internal parasite ctrl - heart and intestinal worm
- 4. Consult when you see diarrhea in pets and pet owners
- 5. support leash laws and fecal removal policies
- 6. Use commercial feeding. No raw, under cooked meat
- 7. do not feed wildlife
- 8. Don't believe everything you read; discuss with your vet
- 9. Dispose of kitten and puppy feces
- 10. do not empty feline litter box if pregnant
- 11. fully cook meat before eating
- 12. avoid direct contact with soil that animals defecate in. Wash hands and feet afterwards