Exam 4 Flashcards
Oviperous
Egg laying-shelled
Viviparous
Live young no shelled eggs
Ovoviviparous
Eggs hatch inside the female
Young are born alive
Whip worm
Trichuris trichiura
Trichuris life cycle
- unembryonated eggs passed in feces (diagnostic)
- 2-cell stage
- advanced cleavage
- embryo after eggs are ingested (infective)
- larvae hatch in small intestine
- adults in cecum
Epidemiology of Trichuriasis
Rectal prolapse
Trichina worm
Trichinella spiralis
Trichinella spiralis
- among the smallest nematode parasites
- same animal or individual serves as both intermediate and primary host
Trichinosis
Stage 1 - penetration of adult female into the mucosa 12hours-2days after infection Low grade infection Worms migration in intestinal epithelium causes -traumatic damage to the host tissue - inflammation - nausea, vomiting, diarrhea -sweating -respiratory difficulties - red skin blotches Stage ends with facial edema and fever
Trichnosis prevention
Cook meat to safe temps Whole cuts- 145F Ground- 160F Clean meat grinders after each use Don’t let pigs and wild animals eat scrap, raw meat or carcasses
Giant kidney worm
Dioctophyme renale
Dioctophyme renale life cycle
- Unembryonated eggs are shed in urine
- Eggs become embryonated in environment
- Eggs ingested by intermediate host. Larvae develop to L3
- Paratenic host consume intermediate; L3 larvae encysted in tissue
- Definitive host becomes infected after ingesting intermediate or paratenic host contains the L3 - infective stage
- Humans become infected accidentally after consuming undercooked paratenic host
Adults in kidney-diagnostic stage
Rhabditiform larvae
L1 and L2 stages
Pathogenic form
Non infective
Feeding
Filariform larvae
Infective form L3 and L4 No skinny Isthmus in esophagus Nonfeeding L4- in body of host
Strongyloides stercoralis
Zoonotic Only the female is parasitic A) parasitic female- homogonic B) free living male C) free living female- heterogonic Female reproduces through parthenogenesis- eggs develop without male - Fecally contaminated soil
Strongyloides life cycle
-Excretion of Strongyloides larvae
-Infective filariform larvae enter through the intact skin
- visceral migration
- adult female living in intestinal mucosa produces eggs that hatch while still in the intestine
(Auto infection cycle)
- some rhabditiform larvae become filariform and renter intestinal mucosa or peri-anal skin and follow the usual infection cycle
Strongyloidiasis
1st phase- cutaneous- invasion of larval stage includes itching swelling
2nd phase- pulmonary phase- migration and bursting out of the lungs can cause lung infection and pneumonia
3rd phase- intestinal phase- female worm in intestinal mucosa cause abdominal pain and shedding of intestinal wall causing blood in fecal matter
Two types of hookworms?
Ancylostoma duodenale (old) Necator americanus (new)
Life cycle of hookworms
- Eggs are passed in feces
- Larvae hatch and develop in soil
- L3 larvae migrate to grass
- L3 larvae penetrate skin causing “ground itch” and enter bloodstream
- L3 larvae enter lungs and alveolar spaces causing coughing
- Coughed up larvae are swallowed
- Larvae reach small intestine, mature and start feeding
What is geophagy and what causes it?
The want to eat soil/dirt
Hookworms
Ascaris lumbricoides
Ascaris suum
Suum- pigs Lum- humans but probably started out with pigs Both can be parasitic for either Large size Probably been around as long as humans Eggs have a thick shell
Life cycle of Ascaris lumbricoides
Eggs in feces 2 cell stage Advanced cleavage 3~4 weeks Infective stage L2 Embryonated egg Ingested Larvae hatches in intestine Burrows into portal circulation Lungs L3 L4 trachea Pharynx Swallowed Adults in small intestine
How can you get infected by Ascaris lumbricoides?
You have to swallow the eggs
Lack of sanitation
Use of night soil
Fly and roaches can be mechanical vectors
Two roundworm types?
Toxocara canis
Toxocara cati
Toxocara life cycle
- eggs passed in feces. Can appear in feces 2-4 weeks after infection
- eggs develop in soil. Become infective 2 weeks after being passed in feces- remaining so for years
-immature worms migrate to liver and then lungs. During migration the larvae can become arrested in organs such as kidneys and liver - adults release eggs in dogs small intestine
- puppies become infected through the placenta and milk
SECONDARY HOST - Secondary host such as earthworms or field mice come in contact with eggs and become carriers
- secondary host is consumed, eggs and larvae hatch in small intestine
OR - humans can accidentally consume roundworm eggs and become infected. Infections can appear in the eyes, brain etc
What kind of larval migrans does canis have
Visceral
Migrate through deep tissue and organs
Parasite of raccoons?
Baylisascaris procyonis
Life cycle of Baylisascaris procyonis
- Eggs are passed in the raccoons feces
- eggs become infective after 3-4 weeks after passage
DIRECT - raccoons are infected when they ingest infective eggs
- adult roundworms reside in the small intestine of raccoons
INDIRECT - eggs are ingested by other paratenic hosts such as squirrels
- larvae from eggs migrate to and encysted in tissues particularly the central nervous system and eyes
- direct pathways ensues
Pinworm
Enterobius vermicularis
Where does Enterobius vermicularis wander
Adults occupy the ileocecal region of intestine
-primarily large intestine
Wandering of intestinal tract occurs
Females wander out of anal opening trailing eggs
Which parasite has no intermediate hosts?
Enterobius vermicularis
Life cycle of Enterobius vermicularis
Human ingests infective eggs Larvae released in intestine Complete maturation Adults in intestine Females migrate out anus at night Deposit eggs in perinatal areas Eggs mature in several hours - retroinfection Larvae hatch Renter intestine Adults in intestine
What parasite cannot complete its life cycle in humans?
Gnathostoma spinigerum
Gnathostoma spinigerum life cycle
- Eggs become embryonated in water, and eggs release sheathed first-stage larvae (L1) image . -Freshwater copepods, first intermediate hosts, ingest the free-swimming L1, and the larvae molt twice to become early third-stage larvae (EL3)
- Following ingestion of the copepod by a suitable second intermediate host, the EL3 migrate into the tissues of the host and develop further into advanced L3 larvae (AL3)
- When the second intermediate host is ingested by a definitive host, the AL3 develop into adult parasites in the gastric wall
- Alternatively, the second intermediate host may be ingested by a paratenic host, in which the AL3 do not develop further but remain infective
- Humans become infected by eating raw or undercooked meat of second intermediate or paratenic hosts containing AL3
First intermediate host in Gnathostoma spinigerum life cycle?
Copepod
What parasite has a swollen head bulb with ballonets?
Gnathostoma spinigerum
Physaloptera spp.
Occurs in variety of vertebrates Mainly in stomach of mammals Life cycle not completely known Beloved to be transmitted by an insect Syphalic collar contains teeth or spines
Spirocerca lupi
Causes esophageal nodules in dogs
These range from nonneoplastic to malignant
Spirocercosis
Spirocerca lupin life cycle
- L3 larvae emerge from dung beetle in the stomach, penetrate the stomach wall and migrate to gastric arteries. Larvae then travel upstream to aorta
- the L3 larvae may spend up to 3 months inside nodules in the wall of the aorta. Here the L4 larval stage finally emerge from the nodules as young adults. Results in aneurism formation with aortic wall which may burst at any time leading to acute death
- migration through the aorta and into the wall of the esophagus occurs where more do dukes each containing several adult worms are formed. Adults emerge forms. Small opening to lay eggs into the esophagus. Nodules may impede swallowing and often become cancerous
- eggs are swallowed passed out in feces and are ingested by dung beetles. Larvae hatch from the eggs and encysted in the dung beetles. Beetles may be directly ingested or ingested with feces by coprophagous dogs.
Or paratenic host
Intermediate host in the life cycle of Spirocerca lupi?
Dung beetle
What is the vector for Wuchereria bancrofti
Mosquito
Aedes
Anopheles
Culex
Life cycle of Lymphatic filariasis
- infected mosquito deposits larvae on the skin while biting and they enter the wound
- larvae migrate to vessels and nodes of the lymphatic system where they develop into thread like adult worms
- adults live 5-7 years and can do serious damage causing infections that lead to swelling blockages and fever
- fertilized female worms release embryonic offspring called microfilariae that enter the blood stream. They circulate at night when mosquitos bite in blood vessels near the skin
- mosquito takes an infected blood meal
- in several stages inside a mosquitos midgut they develop into infectious stages
- larvae migrate to the proboscis
- infected mosquito continues cycle
Larvae in an infected mosquito
Mosquito Infective 3rd larval stage L3 Migrate to lymphatic (gut) Molt into adult Microfilariae Mosquito L1 L2 L3
Plays a roll in the worms ability to create inflammation as well as probably reproduce
Wolbachia bacteria
What drug is used to combat Wuchereria bancrofti
DEC
Dicthylcabomazine
- impacts mainly by killing the microfilariae
What causes river blindness
Onchocerca volvulus
What is the vector for Onchocerca volvulus
Black fly (Simulium)
What kind of habitat does the black fly require for its larvae?
Needs lots of oxygen
Flowing water
Eye worm
Loa loa
What is the vector for Loa loa
Deer fly (Chrysops)
What time of day are the Loa loa microfilariae in the blood?
During daylight hours when the vector is active
Dog heart worm
Dirofilaria immitis
Vector for Firofilaria immitis?
Mosquito
Where does the adult worm Dirofilaria immitis stay
Primarily in right ventricle
Guinea worm
Dracunculus medinensis
What is one of the longest know nematodes?
Dracunculus medinensis
Life cycle of Dracunculus medinensis
Larvae are consumed by water fleas
Humans drink water contaminated with infected water fleas
Larvae mature to worms and reproduce inside human
Females migrate to skin and release larvae into water
