Biological  Sciences  318-­‐  Parasitology  Lab      

Nematoda    

Kingdom:  Animalia    

(unranked):  Protostomia    

(unranked):  Spiralia    

clade:  Nematoida    

 

 

 

Phylum:    

 

 

 

Order Class Trichinella    Trichuris      Mermis                Strongyloides  Rhabdina      Hooksworms  Trichostrongyles    Ascaris  Anisakis  Enterobius    Filarial  worms  Dracunculus  

Characteristics:

Nematodes occupy almost every possible niche: As parasites they infect vertebrates, insects, and plants, as free-living organisms they are found in soil, fresh water and sea water. They are a highly successful group of organisms, second only to the insects. Despite their diversity of habitat, the nematodes have a remarkable consistency of shape. This consistency of form is brought about by the constraints of their morphology:

1) bilaterally symmetrical animals (non-segmented)

2) Body contains internal cavity (pseudocoelom)

3) Vermiform, long and slender with pointed ends

4) Complete Digestive System

5) Most are dioecious; (Female w. vulva, Males w. cloaca)

6) Develop by molting, shedding cuticle

7) Development: egg, egg fertilization, embryo in egg, larva, 4 molts, adult

Nematodes

J1 J2 J3 J4 Adult Egg

M1 M2 M3 M4

Morphology •  tube within a tube •  Body wall: thick cuticle, a hypodermis, layer of longitudinal muscle •  Pseudocoel functions as hydrostatic skeleton- common in invertebrates •  Digestive system is complete- mouth, gut, anus • Reproduction: ♀ tube subdivided into Ovary, oviduct, uterus, vulva (gential pore) ♂ chitinous spicule, vas deferens joins digestive tract to form cloaca

Nematoda

Nematoda  

Enoplea  

Order  Trichurida  

(Whipworms)  

Rhabditea  

Order  Ascaradida  

Order  Oxyurida  (Pinworms)  

Order  Strongylida  (Hookworms)  

Order  Spirurida  

(Filarial  worms)  

Learning Objectives 1. Know general characteristics -  Know what is special about their cuticle + epidermis -  Know development + morphology 2. Order Trichurida -  Know general characteristics for id + anatomy 3. Trichuris trichura -  Human whipworm -  Epidemiology, anatomy -  Purpose of thick and thin end -  Visual id males, females, eggs -  Embryonation, infectivity 4. Trichinella spiralis -  (adult slide not good) -  Largest intracellular parasite -  Life cycle, tissue + transmission -  Females are viviparous -  What is special about larvae? -  Why are they hard to eradicate? lots of reservoir hosts -  Visual id male , female, larvae encysted, muscle infected / larvae section 5. Order Ascarida -  General characteristics 6. Ascaris lumbricoides -  Epidemiology, pathology -  Size -  Life cycle, transmission, bronchial escalator -  Eggs, embryonated or unembryonated, number of eggs (thick outer shell, persistence) -  Cross section: id parts+ sex 7. Order Oxyurida -  Know general charactersitics 8. Enterobius vermicularis -  Pinworm -  Most common nematode parasite of human -  Life cycle, transmission -  Itchy bum -  Visual id female, male 9. Order Strongylida 10. Superfamily Ancylostomatoidae -  Hookworms -  General characteristics -  Life cycle

Vocabulary Cuticle Epidermis Dioecious Cloaca Vulva Filiform Stichosome Stichocytes Viviparous Nurse cell Bronchial escalator Spicule Oviparous Caudal bursa Buccal capsule Microfilaria Nocturnal periodicity Filarial worms Pinworms Hookworms Whipworms

11. Ancylostoma caninum - Where? - Host, mouthparts – buccal capsule, caudal bursa (copulatory bursa) - Visual id in copula, male, female 12. Necator americanus - Where? - Visual ID male, female, eggs - Mouthparts – caudal bursa 13. Order Spirurida - General characteristics 14. Superfamily Filarioidae - Filarial worm - General characteristics 15. Onchocerca volvulus - Life cycle, pathology - Vector - Visual id nodule cross-section containing adults containing microfilariae 16. Wuchereria bancrofti - Life cycle, pathology, disease, transmission - Visual id mircofilariae