Parasitology Lab - Nematodes

Pseudocoel

false body cavity - no epithelial lining

Pseudolabia

bilateral lips around the mouth of the nematodes; they develop from the inner wall of the buccal cavity

Papillae

small sensory organs located on the cuticle that act as mechanoreceptors and chemoreceptors detecting touch, water currents, and chemicals

amphids

pair of bilaterally cephalic (head) chemosensory organs located on the side of the head, near the mouth

cordon/epaulets

circular structures found on the anterior end of nematodes, which are used for feeding and attachment

Bursa (nematodes)

a finger-like modification of the male posterior end and is used to grasp onto the body of the female during copulation

Phasmids

near the anus and also function in chemoreception

cuticle

flexible, multi-layered exoskeleton made of collagens and proteins that provide physical protection, maintain body shape, and enable movement

alae

ridged extensions of the cuticle that aids in movement, providing support, and act as sensory receptors

hypodermis

thin cellular layer beneath the outer cuticle that secretes and maintains it

bacillary band

band containing pores on ventral surface of esophageal region

stoma/buccal cavity

cavity in which mouth opens

isthmus

middle part of the pharynx between the corpus and the basal bulb

monodelphic

an adult female only has one functional ovary

amphidelphic

female has two functional ovaries

polydelphic

multiple ovaries

ovijector

muscular terminal portion of the uterus; used to force eggs out of the genital pore

ovoviviparous

The female retains fertilized eggs, which develop and hatch internally, with the larvae emerging from the mother's body, sometimes leading to the mother's death

giving birth to live larvae

what is the infectious stage of the nematodes

J3/M3

viviparous

female gives birth to larvae where the embroys develop and grow within the mother's uterus

oviparous

The female lays eggs which are fertilized inside the uterus and will hatch in the external environemtn

parthenogenesis

Asexual reproduction in which females produce offspring from unfertilized eggs.

gubernaculum (nematodes)

an organ in the male copulatory system that guides the spicules or bursa during copulation

ventriculus

region of the midgut or intestine that produces and secretes enzymes to initiate extracellular digestion

nerve ring

The main mass of the central nervous system, forming a ring around the pharynx

direct/monoxenous life cycle

A parasitic life cycle in which only a single host is used

indirect/dixenous life cycle

Has two or more host organisms. Juveniles pass through an intermediate (vector). The 3rd stage is infective to the final host.

Sylvatic life cycles

involves wild animals and forest-dwelling vectors, with humans often becoming incidental hosts

urban life cycles

involves urban or domestic animals and humans as hosts, with urban-dwelling vectors

general structures of all nematodes

- pseudocoel

- lips

- papillae

- amphids

- pseudolabia

- bursa

- phasmids

- outermost cuticle

- middle hypodermis (dermis or epidermis)

- the interior somatic muscle layer

- alae

- cordons/epulates

- bacillary band

- alimentary canal

- stoma or buccal cavity

- esophagus

- isthmus

- bulb

- intestine

- cloaca

- nerve ring

Nematode head structures include:

lips

papillae

amphids

pseudolabia

Nematode tail structures include:

females: simple

males: varies

- bursa

- phasmids

Nematode body wall structure:

- cuticle

- hypodermis

- somatic muscles

- Alae

- cordons/ epaulets

- bacillary band

Nematode digestive structures include:

- alimentary canal

- buccal cavity

- esophagus

- isthmus

- bulb

- intestine

- cloaca

nematode nervous system structure includes:

- nerve ring

The body wall consists of three layers: the outermost _______________, the middle ___________, and the interior ________________.

cuticle

hypodermis

somatic muscles

cuticle

thin transparent elastic acellular outermost layer of a nematode

alimentary canal

a straight tube that runs the length of the organism

esophagus

muscular organ connecting the buccal cavity to the intestine

The male reproductive system consists of

testes

seminal vesicle

spicules

seminal vesicle is used for

sperm storage

Spicules

protrusible, cuticularized structures that function in mating

female reproductive system consists of

ovaries

oviduct

uterus

cuticular-lines vagina openeing to the external environment

ovijector

the _______________ makes up the central nervous system, forms a conspicuous ringsurround the esophagus and is usually the only visible portion of the nervous system.

nerve ring

A direct or monoxenous life cycle has ___________ host organism. The first and second stages may occur in the egg or in the soil. The _________ stage is infective to the final host.

single

third larvall (L3)

An indirect or dixenous life cycle has ____________ host organisms. Juveniles pass through an________________________, also called a vector. The __________ stage is infective to the finalhost.

two or more

intermediate host

adult stage

____________________ life cycles include wild carnivores such as bears, wild boars, and sealsas sources or human infection

sylvatic

_______________ life cycles involve swine, rodents, and humans, and these tend to be the primary sources of human infection.

urban

_______________ come in various sizes, shapes, and thicknesses and frequently are diagnostic

nematode eggs

nematode eggs all contain

an outer protein layer, thick middle eggshell, and a thin, vitelline membrane

microfilariae

The larval stage found in blood tissue involves an arthropod vector.

NEMATODES COVERED IN LAB

- Trichinella spiralis

- Trichuris trichiura

- Capillaria hepatica

- Strongyloides stercoralis

- Ancylotstoma duodenale

- Tococara canis

- Necator americanus

- Ascaris lumbricoides

- Enterboics vermicularis

- Dirofilaria immitis

- Wuchereria bancrofti

- Onchocerca volvulus

Trichinella spiralis =

pork worm

what is the most widely distributed nematode

Trichinella spiralis

trichinella spiralis is a small organism with a ________________________

posterior slightly thicker than their anterior

trichinella spiralis forms a cyst in

striated muscle tissue of host

The anterior portion of Trichinella spiralis consists of a short, musclulsr ________________________ followed by the

esophageal region terminating in a pseudobulb

stichisome

stichisome

long chain of cuboidal epithelial cells

males of Trichinella spiralis characteristics

no spicule

posterior end blunt with two large copulatory papilla

females of Trichinella spiralis characteristics

blunt posterior with terminal anus

vulva located in the stichosomal region

Trichinella spiralis is what?

ovoviviparous

life cycle of Trichinella spiralis through the domestic cycle

Pigs eat rats who are infected

Encysted larvae in the striated muscle of pigs

Human ingests undercooked meat

larvae released in small intestine

larvae mature in small intestine to adults

Adult females deposit larvae in the mucosa

Encysted larvae in striated muscle

Life cycle of Trichinella spiralis through the sylvatic cycle

Bears and boars eat rats who are infected

encysted larvae in the striated muscle of boars and bears

Humans ingest undercooked meat

larvae released in small intestine

larvae mature in small intestine to adults

Adult females deposit larvae in the mucosa

Encysted larvae in striated muscle

what is the infective stage of Trichinella spiralis

L1

First stage larvae

what is the diagnostic stage of Trichinella spiralis

larval stage

encysted larva in striated muscles

what kind of meat is ingested in Trichinella spiralis

undercooked meat (bear, boar, pig) with encysted larva

in Trichinella spiralis the eggs hatch __________________ and then the ____________________ are deposited into the ______________

within the female

juveniles

intestinal mucosa

newborn juveniles of Trichinella spiralis enter the ___________ and eventually encyst in ______________

bloodstream

striated skeletal muscles

Trichinella spiralis infection of new hosts occur when ___________________ or __________________ is consumed

raw or undercooked meat

after consuming the meat, juveniles of Trichinella spiralis reach sexual maturity within __________.

2-3 days

pathology of Trichinella spiralis within the first week

intestinal edema

nausea

vomitting

abdominal cramps

diarrhea

fever

pathology of Trichinella spiralis within one month

migration phase -

high fever

blurred vision

facial edema

cough

eosinophilia

muscular phase -

local inflammation

edema

pain

weakness

fatigue

diagnosis of Trichinella spiralis is made when

a group of people become symptomatic after a known exposure to undercooked pork products

Trichuris trichiura =

whipworm

Trichuris trichiura is more common where

warm regions with inadequate sanitation

what is the third most common nematode infection in humans

Trichuris trichiura

Trichuris trichiura characteristics

anterior two times thicker than posterior

no lips

tiny "spear" to penetrate the mucosa of the cecum, appendix, or rectum

what is the diagonstic stage of Trichuris trichiura

unembryonated eggs

what is the infective stage of Trichuris trichiura

embryonated eggs

Trichuris trichiura male characteristics

posterior coiled

spicule

Trichuris trichiura female characteristics

blunt posterior

vulva loctaed near posterior end of stichosome

life cycle of Trichuris trichiura is a __________ life cycle

monoxenous

Trichuris trichiura eggs can reach infective stage in _____________ or can remain viable for _____________

three weeks

several years

Ingested eggs of Trichuris trichiura hatch in the intestine of the host. Juveniles migrate to the _______________ and mature in one month.

rectum

life cycle of Trichuris trichiura

1. Embryonated eggs are ingested

2. larvae hatch in small inetstine

3. travels to lower part of the large intestine (rectum)

4. Unembryonated eggs passed in feces

5. 2-cell stage

6. advanced cleavage

7. Embryonated eggs are ingested

unembryonated eggs of Trichuris trichiura are always _________________ and are passed in ___________

plugged on both ends

feces

larvae of Trichuris trichiura hatch in the

small intestine

Juvenile Trichuris trichiura migrate to the ______________

large intestine (rectum)

Pathology of Trichuris trichiura: slight infections

asymptomatic

Pathology of Trichuris trichiura: heavy infections

ulcerative colitis

inflammatory bowel disease

abdominal pain

bloody mucoid diarrhea

rectal prolapse

weight loss

what is a heavy infection of Trichuris trichiura

500-5000 worms

how to diagnose Trichuris trichiura

Eggs in stool (plugged on both ends)

Capillaria hepatica is _____________ to animals however very few __________________

endemic

human infections have been recorded

Capillaria hepatica is most frequently found in

mammals

Capillaria hepatica does not require

an intermediate host

Capillaria hepatica life cycle

1. adults and eggs in liver

2. Unembryonated eggs may be released into the environment upon death and decomposition of host or predation or canibalism leads to another animal consuming it

3. unembryonated eggs released in feces

4. eggs embryonated in environment

5. eggs ingested by definitive host

6. humans infected by ingestion of host

Capillaria hepatica infective stage

embryonated eggs

Capillaria hepatica diagnostic stage

adults and eggs in liver

Capillaria hepatica adults inhabit the _________, where eggs accumulate without developing

liver

Capillaria hepatica eggs require __________________ to embryonate

air and damp soil