11th Lecture: Classification 23.1.2018

Kingdom Animalia

Subkingdom Metazoa

Phylum Nematoda (Nemathelminthes)

Class Secernentea

Order Ascaridida Oxyurida

Family Ascarididae Oxyuridae

Genus &

Species

Ascaris

lumbricoides

Enterobius

vermicularis

(Pinworm)

General characteristics of Phylum: Nematoda (round worms):

1. Nematodes live either as freeliving in water and soil, predatory,

saprophytic or parasitic worms that attach plant or intestine,

blood and tissues of animals.

freeliving Nematodes predatory Nematodes

saprophytic Nematodes parasitic Nematodes

General characteristics of Phylum: Nematoda (round worms):2. Body is cylindrical, elongate, clear, unsegmented and pseudocoelomate.

Anterior end (Mouth) is armed with lips, teeth or plates, but posterior end of

male bears copulatory spicules...etc. Both ends are pointed.

3. Digestive system is complete, i.e., mouth, buccal cavity, pharynx

(oesophagus), intestine (gut) and anus are found.

General characteristics of Phylum: Nematoda:4. Respiratory and Circulatory systems are not found.

They are done by diffusion.

5. Excretory system is consisted of glandular cells and

canals opened in a pore.

6. Nervous system is consisted of brain (pharyngeal

nerve ring) and nerve cord.

General characteristics of Phylum: Nematoda (round worms):

7. Reproduction is sexual. They either oviparous or viviparous worms.

Male has one testis, female has two ovaries. Sexes are separated. Female

is longer and male end is curved.

8. Lifecycle includes Larva that undergoes 4 moulting then becomes

adult. Egg (1st larva 2nd larva 3rd larva 4th larva) Adult

Egg Larva Adult

nematoda Egg Larva 1 Larva 2 Larva 3 Larva 4 Adult

Kingdom: Animalia

Subkingdom: Metazoa

Phylum: Nemathelminthes (Nematoda)

Class: Secernentea

1. Order: Ascaridida

Family: Ascarididae

Ascaris lumbricoides

1. Order: Ascaridida: Example:Genus: Ascaris lumbricoides: Characteristics:

1. Adult lives in intestine of Man.

2. Body is cylindrical in shape, creamy white or pinkish in color. Mouth

bears 3 lips with teeth.

A:, B: Adult female Ascaris lumbricoides

C: Anterior end of an adult A. lumbricoides. Note the three lips.

Common name: round worm,

Habitate: small intestines

Source of Infection: Polluted soil and water.

Infective Stage: Fertilized (embryonated) egg.

Site of Infection: Adult unattached in intestine of Man; but

larval stage in lungs of Man.

Host: Man, Intermediate Host: None

Diagnosis: eggs in stool.

Disease: Ascariasis

Lifecycle of Ascaris lumbricoides:

Unfertilized Egg with feces wet soil Fertilized Egg ingestion by Man

Larva that penetrates intestine wall blood stream liver, heart, lung

alveoli then trachea molts to be coughed up, swallowed intestine of

Man to become Adult.

the larva discards

its body outer

parts (cuticle) for

4 times to

become bigger in

size, in a process

called Moulting.

11Lifecycle of Ascaris lumbricoides

Order: oxyurida

Family: oxyuridae

Enterobius vermicularis

Consmopolitan, 30%~50% of the population,

more prevalent in children than adults.

Most common where people live under

crowded conditions (orphanages / large

families / kindergartens / primary school).

Common name: pin worm, seat worm, anal worm

Habitate:Adult in large intestine- caecum, colon and appendix.

Source of Infection: Contaminated fingertips or other things.

Infective Stage: Eggs.

Host: Man (direct life cycle) especially children.

Diagnosis: By using scotch tape test to get eggs.

Disease: Enterobiasis.

The female release eggs on the periananl skin at night

types of infection:Infection, Autoinfrction, Retroinfection

16Lifecycle of Enterobius vermicularis

Life Cycle:

Anterior part of E. vermicularis.