Soil-Transmitted Nematodes - PowerPoint Presentation

Slide1

Soil-Transmitted Nematodes(And pinworms later on)

Hookworms

Ascaris

Whipworm

Slide2

Nematodes

The most common

macroparasite

and can infect humans along with other organisms (mammals to plants)

Impermeable cuticle and have a complete digestive system with a mouth and anus

Often their mouths are made up of

papillae

,

cutting plates, lips

and/or

auxiliary sensory organs

(DIAGOSTIC FEATURES)

The majority are

dioecious

with extreme sexual dimorphism

Females tend to be larger and are packed with eggs or LARVAE

Slide3

Nematodes cont.

Males have a single testis, seminal vesicle and

copulatory

spicules

Spicules are inserted into the vulva of the female and assist the passage of sperm

There is quite a diversity of spicules and can be used for identification

In some cases males have a

copulatory

bursa that aids in reproduction. Some have muscular rays that are used to clasp female during copulation

Slide4

Nematodes cont.

Females usually have two ovaries which appear to elongate threads that gradually widen to become the oviduct and eventually the uterus

BASIC pattern

Eggs (

L1 or J1 larva develops)

Ecdysis

occurs and usually (some cases the second) juvenile stage hatches from egg (if intermediate host is present it is the L1 or L2 that is infective to

ind.

host)  L3’s are the infective stage to definitive hosts

Slide5

Taxonomy

Kingdom

Animalia

Phylum

Nematoda

Class

Adenophorea

Subclass

Enoplia

Order

Trichurata

Super Family

Trichocephaloidea

Family

Trichuridae

Genus species

Trichuris trichiura

Slide6

Trichuris trichiura

The odd structure of this worm is generated by the esophagus (whipworm)

The feed by embedding their anterior section (

stichosome

) into the intestinal mucosa

Your slides will be females (males are rare since they have a short lifespan)

The posterior portion contains the gonads

The mouth lacks

lips

Slide7

Adult

 eggs (L1 environment) L2L3(infective, but still enclosed in the egg eggs hatch in stomach and molt to an L4 stage and mature

Slide8

Egg (slide 20)

21 Adult Female, 22 Adult Male

Stichosome esophagus

Slide9

Hookworms

Kingdom

Animalia

Phylum

Nematoda

Class

Rhabditea

Order

Strongylida

Family

Ancylostomatidae

Genus species

Necator americanus or Ancylostoma duodenale

Slide10

Hookworm (Necator americanus)

New World Hookworm (Americans and Australia, BUT can be found in Africa and Asia)

Males have a copulatory bursa and a set of muscular bursal rays. This structure functions to envelope the vuvla of the female during copulation to transfer sperm.

Chitinous specialization of buccal capsule (chitonous plates)

The copulatory bursa has two spicules and fused tipped with a barb

Slide11

Slide12

N. americanus

Copulatory Bursa

Buccal capsule, cutting plate (arrow)

Hookworm egg (species indistinguishable)

Slide13

Ancylostoma duodenale

Old world (Africa and Asia)

NO cutting plates

This species of hookworm has “TEETH”

Larger than

Necator

(more damage in intestinal tract)

Slide14

A. duodenale

Cutting plates

Slide15

N. americanus and A. duodenale

0.10 mm length, 0.4 mm diameter. Female > Male9000 eggs/day, eggs have 3-5 yrs survivalBuccal capsule set with two crescent-shaped cutting plates on ventral side Ingests 30 µl blood/day

12 mm in length, 0.6 mm in diameter. Female > Male20,000 eggs/day, eggs have 1 yr survivalBuccal capsule set with symmetric pair of sharp teeth on ventral side. Ingests 260 µl blood/day

Slide16

Taxonomic Classification

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animalia

Nematoda

Rhabditea

Ascaridida

Ascarididae

Ascaris

lumbricoides

Slide17

Ascaris lumbricoides

Up to a half of a meter200,000 eggs released per daySubjecting their eggs to formalin, potassium dichromate, and even a 50% solution of sulfuric acid does not prevent eggs from developingObserve the cross sections of Ascaris

Slide18

Worldwide, the most common helminth infection in humans

More common in tropical and subtropical areas Occurs in S.E. United States

Eggs (J1)J2(still in egg)eggs are consumed and hatch in the intestine and penetrate into the circulatory system and move to the lungs where they molt twice to the J4 stage Migrate up to the pharynx and are swallows  once in the intestine the worms develop into maturity

Slide19

Ascaris

fertilized egg.

Ascaris

egg containing a larva, which will be infective if ingested.

Ascaris

unfertilized egg.

Female

Male

Ascaris lumbricoides

Slide20

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Slide23

Taxonomic Classification

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animalia

Nematoda

Secernentea

Ascaridida

Oxyuridae

Enterobius

vermicularis

Slide24

And Pinworms

Slide25