Parasiology Exam 4- nematodes Kima UF

D. Medinensis aka Guinea worm- taxonomy

Nematoda → Secernentea → Rhabditida → Spirurida → Dracunculus

D. medinensis- general

• females up to 120 cm

• Vulva rarely seen in gravid females

• Live in body cavities- loose connective tissue around peritoneal cavity

D. medinensis- life cycle

• L3 larvae penetrate gut → adults reside in cavities → gravid females migrate to subcutaneous site → Rhhabitiform larvae (L1) released into water → copepod ingest larvae where they metamorphose → ingestion of infected copepod

• blister from worm soaks in water for relief → work burts, releasing hundreds of thousands of L1 larvae →water fleas injest the larvae → larvae become mature L3, 2 wks → someone drinks water w/ contaminated fleas → larvae released in stomahc → migrate to sm int. penetrate int wall into body cavity → grow and mate → fertilized females migrate to connective tissue usually lower limbs → yr later larvae ingested form blister near surface for eruption → blister bursts exposing worm soaking in water for relief

D. medinensis- epidemiology

• SE asia, pockets in NE S america, Iran, Africa

• Canines, felines, racoons → animal reservoirs

D. medinensis- transmission

• sustained by injestion of infected copepod by humans and contact of infected humans stagnat pools of FRESHwater w/ copepods

• WATER WELLS

D. medinensis- pathogenesis

• effects worm mostly associated w/ migrating adultss- may cause eosinophilia, naseua, astham indeuces by worm products

• most significant pathology → cutaneous ulcer formaed by female worm

• dead worm elicit vigorus host response → chronic arthrisits when near joints

• secondary bactrial infection of lesion may occur

D. medinensis- diagnosis

• ID in of worm when blister is seen

D. medinensis- treatment

• mechanical/ surgical removal of worm

• Metronidazole facilitates removal of worms

D. medinensis- prevention

• boidl/filter suspected water

• chemical treatment of water

• limit human bathing in potential drinking water sources

Soil- transmitted helminth infections in children/adolecents

• Ascariasis

• Trichuriasis

• Hookworm

• neglected tropical diseases

• cause: Stunted grwoth, anemia, poor cognitive function

Standard practice of soil-transmitted helminth infections in children/adolecents

• preventive chemotherapy → mass deworming

  • questionable benefit of practice

T. trichiuria aka whipworm- taxonomy

Nematoda → Adenophorea → Trichocephalida → trichuris → trichinella

Trichinella spp.- general

• lack excretory sytem

• mouth simple opening w/o lips

• capillary like esophagus, thin walled containg glands -→ STICHOCYTES

• NO phasmids

• monodelphic

• eggs require mosit soil conditions to complete development → 21 days for egg development

T. trichiuria - epidemiology

• WW —> mainly TROPICS

• second most prevalent nematode

• prevalence up to 20-25% in small children some areas

• aquire infection by ingesting parasite egg in food/water/soil

• children → most infected

• whipworm of pigs/monkeys similar

T. trichiuria - life cycle

• Unembryonated eggs passed in feces →2-cell stage → advanced cleave → L3, embroynated eggs are injested → larvae hatch in Sm. int → adults travel in cecum → released in feces

T. trichiuria - pathogenesis

• asymptomatic

• immaturre t. worms penetrate deep into int walls → worms that penetrat walls of large int most likely to survive

• ant. end o mature worm -. buried in colon sub musocas → post. end exposed in in lumen

• chronically infected: whipworm dysentery, mild anemia, finger/tow clubbing, growth retardation

• heavy infections: found in distal end of colon

• mucosa becomes edematosu → anal sphinter tone lost → rectum tends to PROLAPSE

• secondary bacterial infections

What are distinc characterisits of a Trichuriasis infection?

• finger and toe clubbing

• rectal prolapse

T. trichiuria -diagnosis

• presence of characteistic eggs in stool

• whipworm dance → ultrasound; lumen of appendix wriggles continuously

T. trichiuria - prevention

• limiting fecal oral transmission

• naisl kept clean, wash hands

T. trichiuria - treatment

• mebendazole and albendazole

Trichuris -egg characteristics

• barrel shapped

• triple shell in addition to vitelline membrane

• bipolar, unstianed intralaminar proccess that look like → mucoid plugs

T. spiralis- taxonomy

nematoda → adenophorea → trichocephalida → trichuris → spiralis

T. spiralis - epidemiology

• WW

• strain diff in geographically distinct regions

• parasite maintained by human-pig-tate cycles (domestic)

• wild carnivores- prey cycles (sylvatic)

• aquire thru eating minimally cooked infected meat, pork, sausage

• Europe → game widely consumed

T. spiralis - life cycle

• injestion of undercooked infected meat → larvae released in sm. inte → adults migrate to sm int -. larvea deposited in mucosa → encysted larva in striated muscle, systemactic circulation → expuslion of adults a few wks after primary infetion, dead end infection,

• females in messenteric LN

• larva intracellular parasite

• muscle de-differentiaties → metaplasia

• Nurse cell → multi-nuc, fformed

• capsule forms around nurse cell -. derived from host muscle/inflammatroy cells

• larva - developmental arrest

Trichuris- molecular mediators

• tyvelose-bearing glycoproteins

• role of excreory/ secretory products →

• phosporylcholine bearing molecules

Trichuris- immunity

• rapid rejection/ expulsion of L1 in sm. int. —> IgE

• IL 10 → limits inital inflammation

T. spiralis - pathogenesis

• marked eosinophilia

• early symptoms: w/in 2 days of larva ingestion → nausea, fever, profuse perspiration, facial edema, secondary bacterial infection

• parasites move into tissue → pneumonia, encephalitis, myocarditis

• parasites in muscles/nervous tissue

• infections → lethal

T. spralis- diseases/presentation

• periorbital edema

• organ damage: central nervous system, heart, lung

• muscle pain

• abdominal discomfort

• diarrhea

• subungual hemorrahges in fingernails

T. spralis- diagnosis

• serological/ skin tests

• negative results -→ early infections

• intradermal injection of larval suspension should result in appearance ofa wheel

• detection of live larevae in biopsy

T. spralis - treatment

• Mebendazole → minimaly effective

T. spralis - prevention

• pork/sausage should be cooked at temperatures greater than 70C

• meat pigs (scraps) should be sterilized

A. lumbricoides- taxonomy

Nwmatoda -. secernentea Rhabditida → Ascardidia → Ascaris

Ascaris lumbricoides - general

• largest of common nematode parasites

• females up to 45 cm

• didelphic w/ vulva towards ant end of body

• cylindrical esophagus, well developed lips

• prolific egg producers → 200k/day

Ascaris lumbricoidea- epidemiology

• WW → prevalent in tropics

• maintained by favorable qualites of soil, frequent fecal contamination of soil

• eggs killed by prolonged dry conditions → NEED MOIST

• ingested by eating dirt-eating ages 5-9 children,

• eating raw vegetables where eggs lodge

• disperesed by animals/beetles that eat human feces → eggs passes trhu animals unchanged

• PIGS → Ascaris Suum; suseptible to human ascaria, vice versa w/ humans

Ascaris lumbricoides- life cycle

• adults in sm int. → passed thru feces→ unfertilized eggs will not undergo further development→ embryonated egg w/ L3 larvae ingested → hatched larvae enter circulation and migrate to lungs → larvare cough up/swallowed, reentering GI → maturation proceeds in Sm. int.

• pre patent period → 8 to 9 wks

Ascaris lumbricoides - diseases caused

• Pneumonitis

• liver granulomas and fibrosis

• intestinal discomfort

• nutriotonal impairment/ obstruction

• abnormal migration of adults to bile ducts, appendix, peritoneum, etc.

In. nematods 3 slide 9 ***

Ascaris lumbricoides - Pathogenesis"***

• adult worms cause obstructive appendicitis/ lodge in bile duct, liver

• fevers tend to induce worm migration, worms are passed through mouth/anus

• host reaction to larvae, especially in lungs can cause Ascaris pneumonitis →Loeffler’s pneumonia

• WANDERING WORMS**

• mechanical effects of adults worms

• immmune rxn of host

• milder infection may cause loss of appetite, colickly cramps

• effect adult worms on host nutrition

• growth may be impaired; periodic deworming encouraged

Ascaris lumbricoides - Diagnosis

• ID eggs in feces

• fertlized eggs broadly ovoidal, thick transparent middle layer

• unfertilized eggs → elongateed w/ relativley thin middle layer

• both egs bile stianed

Ascaris lumbricoides - treatment

• w/ mebendazole, peperazine citrate, cyclobendazole

Ascaris lumbricoides - prevention

limit fecal of soil

E. vermicularis aka Pinworm - taxonomy

Nematoda → secernentea → rhabditida → Ascaridia → enterobius

• family oxyuroidea

Enterobius vermicularis - general

• primarliy inhabit ileocecal region, spread to adjacent areas of sm./lg. int,

• males 1-4 mm lomng —> SINGLE spicule

• females 8-13 mm; post end extends into long slender pt.

• Alae- wind like extensions at ant. end

• didelphic worms

Enterobius vermicularis - epidemiology

• most common nematode

• cosmopolitan distribution, WW → temperate regions

• infrequent b athing habits in temperate climates -. may cause high prevalence

• eggs been found on seats, armrests in public places

• more common in chilren → daycares, institutions and in families

Enterobius vermicularis aka PINWORM Tape on asshole atnight- life cycle

• eggs on perianal folds → larvae inside the eggs mature w/in 4-6 hrs -. embryonated eggs ingested → larvae hatch in sm. int. _. adults in lumen of cecum → gravid female migrates to perianal region at night to lay eggs

Enterobius vermicularis - modes of transmission

• self infection when infected person reinfected by hand to mouth

• cross-infection, when infective eggs are ingested from fingers that been in contact with contaminated surface

• inhalation/ airborne eggs

• retro-infection → parasite hatches and migrates back to cecum → minimal evidence

Enterobius vermicularis - disease caused

• worms may enter female gential tract

• perianal itching

Enterobius vermicularis - pathogenesis

• minimal effects

• perineall/perianal itching

• excessive scratching → scarification

• girls: owrms migrate to vagina, heavy infection mucoid vaginal discharge observed, rare cases → migrate up to fallopian tubes, get trapped, granuloma formation ensues

• worms found in the urinary tract, peritoneum cause abdominal/urinary tract infections in girls as well as older women

Enterobius vermicularis - diagnosis

• detection of adult worms in perianal area/eggs

• eggs elongate-ovoidal, flattened on 1 side

• shell thick/colorless

• eggs recovered by cellophane technique → eggs stick to tape

Enterobius vermicularis - treatment

• mebendazole

• pyrantel pamoate

Enterobius vermicularis - prevention

• scrupulous personal hygiene

• wash beddings/clothes of infected children → HOT water

Eosinophils and Eosinophilia

express CR3, IgA, IgE receptors

Toxocara spp. - visceral larval migrans

• infection w/ nematodes of animals

• paasites of genus toxocara → T. canis/cati (OLM) that infect dogs/puppies and cats (materlan-fetal transmission

• high infection rate in puppies

• ingestion of eggs harbouring L2 larvae, migrate thru human tissue, liver,

• host rxn _. inflmmation

Angiostrongylus

• infect humans

• parasites of wild rates → rat lung worms

• utlize crustaceans/ mollusks as Ih

• humans aquire thru eating L3 larvae in crustaceans/mollusks; migrate to brian

• SE asai, C/S America

• may cause meningoencephalitis

Anisakis spp. - general

• adult stages of Anisakis found in stomach of amrine ammals, dolphins, porpoisses, seals

• IH → crusteaceasn, marine fish

Anasakis spp. - life cycle

• eating contaminated fish → larvae enter int. tissue, cause eoxinophilic granuloma → fish eaten by marine mamals → L3/4 larvae migrate thru tissue back to int. → adult males/female in int of marine mammals -. eggs in water → larvae hatches from egg → larvae enter euphauslids and reaches hemoccoel → euphausids eaten by fish, larvae penetrate int. tissue and enter abdominal caivty, larvae kie on surface of rogamn, in messenteries or musculature -. then eaten by marien animal

Anasakis spp. - epidemiology

• areas where salt water fish, herring are eaten raew sashimi; → Japan, Scandinavian countries, U.S. both coasts

Anasakis spp. - pathology

• caused by inflammatory response

• larvae in humans → bore into throat/gastric mucosa

• swelling of GI tract walls → cause obstruction/ peritonitis

Anasakis spp. - diagnosis

• biospy/endocsopy

• biopsy of larvae distinged by large body

• moderate thick cuticle, large lateral cords

Anasakis spp. - prevention

• infectivity of larvae in infected fish can be reduce if fish kept frozen after catch

• prevents parasites from migrating to tissues

Anasakis spp. - treatment

• surgical removal of larvae

S. stercoralis aka threadworm - taxonomy

Nematoda → secernentea → rhabitida → rhabditia → rhabditina → strongyloides

Strongyloides stercoralis - general

• phasmids

• didelphic

• protandrogonous females

• parthenogenesis:

What is didelphic

2 uteri and oviducts

What is protandrogonous females

male reproductive organs develop fst and then disappear; then female reproductive organs develop

Parthenogenesis

development of an unfertilized egg into an adult

S. stercoralis - morphology

• parasitic females longer and have an esophagus that extends 1/3 the length of the body

  • vulva at posterior end

• free-living female is wider

  • vulva at mid section

S. stercoralis - epidemiology

• eggs seldom seen in feces

• dogs/cats infected w/ strains indistinguisbable from those that infect humans

• zoonosis

• WW

• high incidence in mental institutions → adults are more often infected that children

S. fuelleborni - epidemiology

• infection of monekys

• sub-saharan africa

• Papua-new guinea

• affects children more

• EGGS in FECES

• acquired from mothers milk

• swollen belly syndrome

S. stercoralis - life cycle

• Rhabditiform L1 larvae in int excreded in stool → development into free-living adult worms → eggs are produced by fertilized femaleworms → rhabditiform larvae hatch from embryonated eggs → rhabditiform larvae develop into filariform larvae L# → infective filariformlarvae penetrate intacts skin of DH → filariform larvae migrate by various pathways to small int. where they become adults → parasitic adult female in sm. int. → eggs deposited in int. mucosa rhabditiform larvae hatch and migrate to int. lumen → autoinfection: rhabditiform larvae in lg int. become filarifrom, penertrate int. mucosa or perianal skin and migrate to other organs

• prepatent period: 25-30 days

• L3 larvae migrate via bloodstream/ lymphatics to lungs → coughed up and swallowed → L3 larvae appear capable of migrating to int. via alt routes, thru abdomincal viscera/connective tissue → in sm. int. larvae molt TWICE and become adult female worms

S. stercoralis - diseased caused

• Pneumonaitis

• Abdominal pain

• Malabsorption syndrome

• Mucosal damage

• Doarrhea

S. stercoralis - autoinfection

• development of 1st stage to infective larvae on hosts intestine

• linear skin lesions → perianal origin

• Disseminated infection → stomach, colon, lungs, CNS, liver, etc.

• Bacteremia

S. stercoralis - pathogenesis

• cutaneous phase - swelling/ intense itching at sites transversed by infective filariform larvae ground itch, host response may slow parasite migration thru skin → creeping eruption

• secondary infection

• pulmonary phase - migration thru lung induces host cellular rxn, parasites develop maturity in lung if passage blocked, larvae may also seen in sputum

• Intestinal infection: significant in heavy infections, abdominal pain, vomiting/ intermittent dirrhea, sysentery, weight loss in chronic infections

• problemtic in immunocompromised

• heavy strongyloids infections can be fatal

S. stercoralis - Diagnosis

• IDing of rhabditifrom larvae in feces, sometimes flarifrom larvae

• Strongyloides fuellebornie eggs → passed in feces

• sputum maybe contain larvae

• Serological test (ELISA ) → definitive diagnosis

S. stercoralis - treatment

• albendazole

• ivermectin

S. stercoralis - prevention

• especially where S. fuelleborni is suspected,

• screening of pregnant women/treatment

• appropriate disposal of human waste

A. duodenale aka hookworm - taxonomy

Nematoda → secernentea → rhabitida → strongylida → Ancylostoma

N.americanus aka hookworm - taxonomy

Nematoda → secernentea → rhabitida → strongylida → necator

N. americanus/ A. duodenale - general

• well developed buccal bearing cutting plates/teetj

• males → umbrella shaped burse for mating at post.

• life cycle diff.

Ancylostoma spp. - morphology

• buccal capsule large ventral cutting teeth

• vulva in post. half

Necator spp. - morphology

• ventral cutting plates

• vulva in ant. half of body

Ancylostoma spp. - epidemiology

• old world countires

• Southern europe, SE asia, China, Africa

• New world

  • US, Caribbean

• mostly humans infected

• zoonotic

• use night soil for fertilization of crops in ag

• mines

• affected by temperature

• dung beetles appear to make soil suitable for hookworm devel.

Necator spp. - epidemiology

• most prevelant in US

• C/S america

• Africa, china

• infects dogs

• zoonotic

• areas that use night soil for fertilization of crops in ag

• mines

• affected by temperatures

• dung beetles appear to make soil suitable for hookworm devel.

N. americanus - lifecycle

• L3 on vegetation, can survie for 3-4 wks → L3 penetratae skin/enter bloodstream →L3 reach heart, entre pulmonary vasculature, cross into alveolae, → L3 ascend trachea, swallowed, entre GI tract → larvae lot twice L5, mature in sm. int. →eggs passed in feces → larvae hatcha dn develop in soil L1→ L3 → L3 on veg.

• molt twice before reaching sm. int

• no passage thru lungs

Ancylostoma spp. - life cycle

• Egg in feces → rhabditiform L1 larvae hatches → devel to filariform L3 larvae in envrio. →L3 larvae penetrate skin → larvae become developmentally arrests and domant tissues, re-activated larvae may entr sm. int. → larvae exist circulation inlungs, coughed up and swallowed → adults in sm. int.

• aquired trhu contact or ingestion of L3/filariform from soil

• molt twice in Gi tract

• No passage thru lungs

Arrested developemnt - ancylostoma

• parasites ability to halt life cycle as L3 in host tissues, adaption to favorable conditions, later reactivate, causing prolonged/sudden infections

• triggers: pregnancy/lactation

• host immune status

• removal of adult worm

N. americanus/ A. duodenale - pathogenesis

• cutaneou, pulmonary, intestinal phases

• most serious → intestinal infection

• worms burrow in int. wall

• salivary secretions have anticoagulants

• molecules target factor Xa and tissue factor VIIa → platelet inhibitor

• iron deficiency anemia infections

• protein energy deficiency

• blood loss

• heavliy infected individuals ahve craving to eat soil geophagy

• pulmonary infection

What is geophagy

• craving to eat soil

• from heavy infection from intentinal worm infections

Hookworm disease depends on ….

1. # of worms

2. species of hookworm

3. nutrional condition of infected person

A. duodenale - pathogenesis

• 53 days prepatence period

• 10k-25k eggs/day/female

• 20-27 C

• oral route, percutaneous route

• transplacental route

• arrested development

• Lamb, beef, pork

N. americanus - pathogenesis

• 49- 56 days prepatence period

• 5k - 10k eggs/day/female

• percutaneous

• PORK

Ascaris effect

• Reduced growth rate in ages 5 to15

Trichuris effect

• Reduce growth rate, TDA, iron deficiency ages 6 to 18

Ancylostoma/necator effect

• iron deficiency/ anemia ages 10 to 50

Ancylostoma/necator spp. - diagnosis

• clinical symptoms

• characteristic egg in feces- thin walled, transparent shell w/ cleaved embryos

Ancylostoma/necator - treatment

• ivermectin

• mebendazole

How does medendazole works for Ancylostoma/necator infections

• binds helminthic tublin

• blocks microtubule assembly, also inhibits glucose uptake in helminths

Cutaneous larval migrans - general

• CREEPING ERUPTIONS

• zoonotic

• Ancylostoma caninum → dogs

• A. brazillinesis found in SE USA

• passage thru skin results in skin eruptions

• ground itch

• feet/arm most common sites

Filarial - general

• adults live in tissues/ body cavities of vertebrae host

• females produce microfilariae that circulate

• microfilariae less differentiated than L1 larvae of other nematodes

• undergo devel., transmitted by arthropod vectors → cyclodevelopmental transmission

• infected w/ rickettsial bacteria → specificallu Wolbachia

  • affect bacteria reproduction of worms/ host reponse to worms

  • some dont harbor wolbachia

Cyclodevelopmental transmission

• development in arthropod vector