NEMATODES: A LABORATORY PERSPECTIVE

GENERAL CHARACTERISTICS OF NEMATODES

They assume three basic morphologic forms: Egg, Larvae and Adult worms

Reproduce sexually with male and female worms

Complete digestive tract and complete reproductive systems

TAXONOMIC CLASSIFICATION

Phylum Nemathelminthes

Class Nematoda

Intestinal Species

Intestinal- Tissue Species

E. vermicularisT. trichuraN. americanusA. duodenaleA. lumbricoidesS. stercoralis

T. spiralisD. medinensis

ASCARIS LUMBRICOIDES

Ascaris lumbricoidesCommon Name Giant Intestinal RoundwormInfective Stage Embryonated Egg

Habitat Small IntestineMode of Transmission Ingestion of contaminated food/ waterDiagnostic Specimen Feces

ASCARIS LUMBRICOIDES 2

A. lumbricoides Adult worms

ENTEROBIUS VERMICULARIS

Enterobius vermicularisCommon Name PinwormInfective Stage Embryonated Egg

Habitat Large IntestineMode of Transmission Ingestion of egg/ autoinfectionDiagnostic Specimen Feces/ Cellophane Tape prep

TRICHURIS TRICHURA

Trichuris trichuraCommon Name WhipwormInfective Stage Embryonated Egg

Habitat Large IntestineMode of Transmission Ingestion of egg via contaminated food/ waterDiagnostic Specimen Feces

TRICHURIS TRICHURA 2

NECATOR AMERICANUS AND ANCYLOSTOMA DUODENALE

Necator americanus and Ancylostoma duodenaleCommon Name HookwormInfective Stage Third Stage Filariform Larvae

Habitat Small IntestineMode of Transmission Skin Penetration of Infective LarvaeDiagnostic Specimen Feces

HOOKWORMS 2

A. duodenale N. americanus

STRONGYLOIDES STERCORALIS

Strongyloides stercoralisCommon Name ThreadwormInfective Stage Third Stage Filariform Larvae

Habitat duodenum and upper jejunumMode of Transmission Skin Penetration of Infective Larvae/ autoinfectionDiagnostic Specimen Feces

TRICHINELLA SPIRALIS

Trichinella spiralisCommon Name Trichinia wormInfective Stage Encysted Larvae

Habitat Striated muscle tissueMode of

Transmission Ingestion of raw/ undercooked contaminated meatDiagnostic Specimen skeletal muscle biopsy/ Blood (LDH, Aldolase, CPK, eo ct)

CAPILLARIA PHILIPPINENSIS

Capillaria philippinensisCommon Name NAInfective Stage Encysted Larvae

Habitat Small IntestineMode of Transmission Ingestion of raw/ undercooked contaminated fishDiagnostic Specimen Feces

THE FILARIAE- GENERAL CHARACTERISTICS

Two morphologic forms: Adult worms and Microfilariae

Adult worms are usually creamy white and assume a filariform shapeHave both male and female forms

Females lay live microfliariaeRequire arthropod vectors

Exhibit periodicity (Nocturnal/ diurnal)

WUCHERERIA BANCROFTI

Wuchereria bancroftiCommon Name Bancroft's FilariaInfective Stage L3 Larva

Habitat Lymphatics and bloodMode of Transmission Bite from infected mosquito (Culex, Aedes or Anopheles)Diagnostic Specimen Giemsa stained smear (collected at night)/ Knott's Technique

BRUGIA MALAYI

Brugia malayiCommon Name Malayan FilariaInfective Stage L3 Larva

Habitat Lymphatics and Blood

Mode of TransmissionBite from infected mosquito ( Anopheles, Aedes, Mansonia, Amigeres)

Diagnostic Specimen Giemsa stained smear (collected at night)/ Knott's Technique

WUCHERERIA BANCROFTI V.S. BRUGIA MALAYI

Distinguishing Characteristics

Wuchereria bancrofti

Brugia malayi

Sheath in Giemsa unstained PinkNuclei Regularly spaced,

separately situatedIrregularly spaced and overlapping

Tail none Single row of nuclei that reach tail’s end

Terminal Nuclei None 2 nuclei, which bulge the cuticle;

conspicuously placed

Appearance in Blood film

Smoothly curved Kinky

LOA LOA

Loa loaCommon Name African Eye WormInfective Stage L3 Larva

Habitat Subcutaneous tissue, the eye and bridge of noseMode of

Transmission Bite from infected Chrysops silacea or C. dimidiata (Deer Fly)Diagnostic Specimen

Giemsa stained smear (collected at midday 10:15to 2:15)/ Knott's Technique

ONCHOCERCA VOLVULUS

Onchocerca volvulusCommon Name Blinding FilariaInfective Stage L3 Larva

Habitat Subcutaneous tissue, nodules and eyesMode of Transmission Bite from infected Simulium BlackflyDiagnostic Specimen Giemsa stained smear of skin snips

MANSONELLA OZZARDI AND MANSONELLA PERSTANS

Mansonella ozzardi and Mansonella perstansCommon Name Ozzard's Filaria and Perstans FilariaInfective Stage L3 Larva

Habitat Blood and various tissue Mode of Transmission Bite from infected Simulium Blackfly or Culicoides (sucking midge fly)Diagnostic Specimen Fresh Giemsa stained blood smear

The End

Long Quiz next meeting?

PART 2: KATO-KATZ, KATO-THICK AND CONCENTRATION TECHNIQUES

KATO KATZ TECHNIQUE

Step 1

Step 2

KATO-KATZ TECHNIQUE CONT’D

Step 3

KATO-KATZ TECHNIQUE CONT’D

Step 4

Step 5

KATO-KATZ TECHNIQUE CONT’D

Step 6

KATO-KATZ TECHNIQUE CONT’D

Step 7

KATO-KATZ TECHNIQUE CONT’D

CONCENTRATION TECHNIQUES

Flotation Techniques

Sedimentation Techniques

Acid Ether Concentration TechniqueFormalin-Ether CT

Zinc Sulfate FT

Sheather’s Sugar FTBrine Flotation T

FORMALIN- ETHER CONCENTRATION TECHNIQUE (FECT)

Ethyl Acetate

Plug of debris

Formalin

Sediment

ACID ETHER CONCENTRATION TECHNIQUE (AECT)

Ethyl Acetate

Plug of debris

Sediment

HCl

ZINC SULFATE FLOTATION TECHNIQUE

Floating Material

Zinc Sulfate Sol’n

HARADA MORI CULTURE

Culture Tube

Strip of filter paper

Smear of Feces

water