Nematodes 3

Tissue nematodes

What are tissue Nematodes

1- T. spiralis

2- Dracanculus Medinensis

2- Filarial Worms

* W. Bancrofti
* W. Malayi
* Onchocerca Volvulus
* Loa Loa

What are the Hosts of T.Spiralis

Definitive : Man

Intermediate : Pigs / rats

Habitat of T. spirals

Adults : Small Intestine

Encysted Larva : Striated Muscles

Mode of infection and infective stage of T. spirals

Ingestion of Encysted Larvae

is man dead-end host to T.spirals unlike rates and pigs ?

Yes

Life cycle of T.spiralis

Encysted larvae → Larvae (intestine)

Larvae → adult

adult ---lay--→ motile larvae (circulation)

larvae are deposited in many tissues as Muscles

Muscle Cell filled with larvae of T.spiralis is called

Nurse cell

Pathogensis/ clinical Manifestation of T.spiralis

most characterizing one : HIGH Eosinophilia

Name of Drancanculus Medinensis

Medina/ Guinea worm

Hosts of D. Medinensis

D → Man

R → Dogs

I → Cyclops

Habitat of D. Medinensis

Subcutaneous Tissue

Mode Of infection and infective stage

ingestion of cyclops / infective larvae

life cycle of D. medinensis

* Larvae 1- penetrate gut mucosa

2- turn into adults

* adults → move to skin surface of lower limb

Clinical Manifestation of D. Medinensis

Blisters formation

General Characteristics of Filarial Worms

* Slender, Thread-like
* Females are bigger than males
* Viviparous
* Classified by Habitat into ( Lymphatics , subcutaneous, skin)
* Microfilaria - are found in blood mostly

and have periodicity

Lymphatic Filarial Worms

1- W. Bancrofti

2- W. Malayi

S.C filarial Worms

1- Onchocerca Volvulus

2- Loa Loa

Habitat of Microfilaria

Blood

except Onchocerca Volvulus (S.C)

Periodicity of Microfilaria

1- Nocturnal

2- Diurnal

3- Non-periodic

Nocturnal Periodicity with examples

* Microfilaria reach maximum activity at Midnight
* Lymphatic Filarial Worms

Diurnal Periodicity with examples

* Microfilaria reach maximum activity at Mid-day
* Loa Loa

Non-periodic Periodicity with examples

* no increase or decrease in activity at certain times
* Onchocerca Valvulus

Hosts of W. Bancrofti

D → Man

I → Female Culex Pipiens

Habitat of W. Bancrofti /W. Malayi

adults → Lymphatics

Microfilaria → Blood

Diseases of W. Bancrofti

Bancroftian filariasis / Elephantiasis

Mode of infection/ infective stage of W. Bancrofti

Female Culex Pipien biting

larva

Life cycle of W. Bancrofti / W. Malayi

* in Mosquito

microfilaria → 3rd stage filariform larva (through ex-sheathing & Molts)

* in Man

Larva→ adult (in lymphatics) ---lay→ microfilaria

pathogenesis of W. Bancrofti /W. Malayi

Blockage of Lymphatics & infiltration

Clinical Manifestation of W. Bancrofti

* Hematuria, proteinuria
* Adenolymphangitis
* local adema

Differences Between W. Bancrofti and W. Malayi

Intermediate host

Reservoir host

Disease

\
* otherwise they are similar

\

Name of W. Malayi

Brugia Malayi

Disease of W. Malayi

Malayian Filariasis

Intermediate host of W. Malayi

Mansoni Mosquito

Reservoir host of W. Malayi

Dogs, Cats, Monkeys

What are S.C Filarial Worms

* Loa Loa
* Onchocerca Volvulus

Name of Loa Loa

African Eye Worm

Disease of Loa Loa

Loiasis / Calabar Worms

Hosts of Loa Loa

D → Man

I → Chrysops (Mango, deer fly)

Habitat of Loa Loa

Subconjunctival tissue and S.C tissue

Mode of Infection / Infective Stage of Loa Loa

Ingestion of Chrysops containing 3rd stage larva

life Cycle of Loa Loa

* in fly

microfilaria → 3rd stage filariform larva (through ex-sheathing & Molts)

* in Man

Larva→ adult ---lay→ microfilaria

Hosts of Onchocerca Volvulus

D → Man

I → Black fly/Simulim

Disease of Onchocerca Volvulus

Onchocercosis / River Blindness

Habitat of Onchocerca Volvulus

S.C tissue

Mode of infection/ infective stage of Onchocerca Volvulus

ingestion of Black Flies containing infective larva

Life cycle of Onchocerca Volvulus

* in fly

microfilaria → 3rd stage filariform larva (through ex-sheathing & Molts)

* in Man

Larva→ adult ---lay→ microfilaria