NEMATODES (roundworms)

Organism Common name

Distinct Characteristics

Habitat MOT Infective Stage

Diagnostic Stage

Host Vector Diagnosis Pathogenicity

Treatment Clinical Manifestations

Ascaris lumbricoides

Human Roundworm

Largest nematode; presence of albuminoid coat in fertilized egg

Small intestine

Ingestion of fertilized egg (oral-fecal)

Fertilized ova Unfertilized andd fertilized ova

DH: human Kato technique Ascariasis (P)

Albendazole

Enterobius vermicularis

Human pinworm

Colorless, D-shaped ova

Colon Inhalation of ova; oral-fecal

Ova Ova DH: human Scotch tape swab

Enterobiasis

Mebendazole Pruritus ani

Ancylostoma duodenale

Old world hookworm

2 pairs of ventral teeth; c-shaped

Small intestine

Skin penetration

Filariform larvae

Ova DH: human Ancylostomiasis (Wakana disease)(P)

Culture of larvae

Albendazole Ground itch

Necator americanus

New world hookworm

1 pair of cutting plated; s-shaped

Small intestine

Skin penetration

Filariform larvae

Ova DH: human Direct fecal smear/ culture

Necatoriasis (Uncinariasis)(P)

Albendazole Ground itch

Strongyloides stercoralis

Human threadworm

Small intestine

Skin penetration

Filariform larvae

Rhabditiform larvae

DH: human (may be dogs and cats)

Direct fecal smear, sputum sample

Strongyloidiasis

Albendazole,Ivermectin,Thiabendazole

Larva currens

Trichostrongylus spp.

Small intestine

Ingestion of filariform larvae; skin penetration

Filariform larvae

Ova DH: cattle, sheep, etcIN: human

Fecal smear trichostrongyliasis

Thiabendazole, Fenbendazole, Ivermectin, Mebendazole

Trichuris trichiura

Human whipworm

Barrel/football shaped ova; 2 prominent polar plugs

Colon Oral-fecal Embryonated ova

Embryonated and unmebryonated ova

DH: human Zinc sulfate floatation

Trichuriasis Albendazole Prolapsed of the rectum

Capillaria philippinensis

Peanut-shaped ova; 2 flat polar plugs

Small intestine

Ingestion of raw or undercooked fish (bagsic, bagsang, birut)

Embryonated ova

Embryonated or unembryonated ova

DH: humanFish-eating birdsIH: Fish (bagsic, bagsang, birut)

Stool analysis, intestinal biopsy

Capillariasis Albendazole,Mebendazole

Initial: borborygmi and vague abdominal pain

Trichenella spiralis

porkworm Found in nurse cell; smallest

Skeletal muscle

Ingestion of raw or

Encysted larvae

Encysted larvae

DH: humanRH: pig,

Muscle biopsy Trichinosis Thiabendazole, Mebendazole

CNS and heart

nematode tissue undercooked meat

human damage, pneumonia, meningits, pleurisy, etc

Toxocara canis

Dog roundworm

Small intestine

Dogs:transmammary, transplacentalHuman:Ingestion of embryonated ova

Embryonated ova

Larvae DH: dogsPH: human

ELISA/EIAWestern-Blot analysis

Toxocariasis Dogs: AntihelminthicsHumans: Albendazole

Visceral larva migrans, Ocular larva migrans

Toxocara cati

Feline roundworm

Small intestine

Cats : transmammaryHuman : Ingestion of embryonated ova

Embryonated ova

Larvae DH : dogsPH : human

ELISA/EIAWestern-Blot analysis

Toxocariasis Cats: AntihelminthicsHumans: Albendazole

Visceral larva migrans, Ocular larva migrans

Drancunculus medinensis

Guinea worm

Triangular mouth with sclerotized plate

Abdominal tissue; lower limbs

Drinking of contaminated water (with infected copepods)

Larvae Adult female worm

DH: humanIH: water fleas or copepods

Water fleas or copepods

Direct observation

Dracunculiasis

Stick; no antihelminthic treatment

Blister formation

Angiostrongylus cantonensis

Rat lungworm

Lacks buccal capsule; adult female show red digestive organ

Brain, CSF, eyes

Ingestion of undercooked infected snails and fish and infected vegetables; ingestion of rat feces

L3 L3 DH: ratIH: snailsIncH: humanPH: prawn, crab

Snails CT or MRI SCAN, IMMUNO-PCR

Angiostrongyliasis

Surgical operation Eosinophilic meningitis

Angiostrongylus costaricensis

Oral opening surrounded by 3 small lips

Mesenteric arteries in ileocecal region

Ingestion of undercooked infected snails; ingestion of rat feces

L3 L3 DH: ratIH: snailIncH: humanPH: prawn, crab

snails X-RAY Angiostrongyliasis

Surgical operation

Gnathostoma spinigerum

Bulbous head with a pair of lateral lips surrounding

Ingestion of infected raw or

L3 L3 DH: pig, cat, dogIH: cyclops,

ELISA, Intradermal test

Gnathostomiasis

Surgical removal Painful pruritic swellings

the mouth undercooked seafood and meat

snailsIncH: human

Anisakis simplex

Herring worm

Body cavity is reduced to a narrow pseudocoel; Mouth is surrounded by projections used in feeding and sensation

gastrointestinal

Ingestion of infected raw seafood

L3 L3 DH: fish, squidIH: cyclopsIncH: human

Gastroscopic examination during which the 2 cm larvae are visualized and removed

Anisakiasis Surgical removal

Phocanema decipens (Pseudoterranova decipiens)

Cod/seal worm

Ingestion of infected raw seafood

L3 L3 DH: fish, squidIH: cyclopsIncH: human

Histopathologic examination of tissue

Anisakiasis Surgical removal

Wuchereria bancrofti

Bancrofti’s filarial worm

Adult: no nuclei at tail tip; sheathed microfilaria

Lymphatic system

Skin inoculation by a mosquito

L3 Microfilaria DH: humanIH: mosquito – culex, anopheles, aedes

mosquito – culex, anopheles, aedes

Giemsa-stained blood,X-ray,Membrane-filtration method, Ultrasonography

Bancroftian filariasis, Lymphatic filariasis

Diethylcarbamazine (DEC)

Elephantiasis – lower limbs

Brugia malayi

Malayan filarial worm

Adult: 2 discrete nuclei at the tail tip; sheathed microfilaria

Lymphatic system

Skin inoculation by a mosquito

L3 Microfilaria DH: humanIH: mosquito – mansonia, anopheles, aedes

mosquito – mansonia, anopheles, aedes

Thick smear, knott test, antibody detection technique, ultrasound

Brugian filariasis

diethylcarbamazine citrate (DEC), Ivermectin

Elephantiasis – upper limbs

Loa loa African eyeworm

No lips, 8 pairs of pappillae, sheathed microfilaria

Subcutaneous tissue

Skin inoculation by deerfly

L3 Microfilaria DH: definitiveIH: deerfly

Deerfly Visual observation

Loiasis Diethylcarbamazine (DEC)

Calabar swellings

Onchocerca volvulus

Unsheathed microfilaria; different nuclear arrangement; coiled in SQ nodules

Subcutaneous tissue

Skin inoculation by blackfly (Simulium)

L3 Microfilaria DH: humanIH: blackfly

Blackfly Skin snips,Palpating, Slit Lamp Exam, Nodulectomy

Onchocerciasis, River blindness, Onchocercomas

Surgical removal of nematode from eye; chemotherapy.

Changes in skin pigmentation; dermatitis;blindness; true

elephatiasisMansonella ozzardi

Ozzardi’s filarial worm; new world filaria

cylindrical and bilaterally symmetrical worm; pseudocoel, or a false body cavity; unsheathed

Body cavities, mesentery, visceral fat

Skin inoculation by a biting midge

L3 Mircofilatia DH: humanIH: biting midge

Biting midge

thick film or Knott technique

Mansonelliasis ozzardi , Ozzard’s filariasis, Eosinophilia; serous cavity filariasis

Diethylcarbamazine (DEC)

Cold legs; Itchy red spots; Inguinal adenitis

Mansonella perstans

Formerly Diptalonema perstans

Cylindrical; tail is half a coil in females and a full coil in males; unsheathed, have a blunt tail, and nuclei extend to the end of the tail; ability to elongate and contract

body cavities: peritoneal cavity, pleural cavity,

Skin inoculation by midge

L3 Microfilaria DH: humanIH: midge

Culicoides Midges

thick film or Knott technique

Perstans filariasis

doxycycline ocular and abdominal pruritus, and abdominal pain

Mansonella streptocerca

Formerly Diptalonema streptocerca

dermis of the upper trunk, shoulders, and arms.

Skin inoculation by midge

L3 Microfilaria DH: humanIH: midge

Culicoides Midges

skin biopsy and histopathologic examination

Streptocerciasis; Subcutaneous Filariasis

Diethylcarbamazine (DEC)

Patches of reduced skin pigmentation; Itchy skin; Thickened areas of skin; Skin bumps; Enlarged lymph node

Dirofilaria immitis

Dog heartworm

Curled tail; No sheath; Nuclei extend to tail tip

Right side of the heart and pulmonary artery of dogs and other mammals

Skin inoculation by mosquito

L3 microfilaria DH: human, dog, fox, etc.IH: mosquito

Mosquito

finding microfilariae in a blood smear/ ELISA

Dirofilariasis

Immiticide Fever; Cough; Chest pain;Coughing up blood; Lung nodule

CESTODES (tapeworms)

Organism

Common name

Distinct Characteristics

Habitat MOT Infective Stage

Diagnostic Stage

Host Vector Diagnosis Pathogenicity

Treatment Clinical manifestations

Dihyllobothrium latum

fish tapewormbroad tapeworm

Longest tapeworm; operculated ova at one end and a knob at the other end

Small intestine

Ingestion of infected raw/undercooked fish

Plerocercoid larva

Ova DH: humanIH: crustacean, small fish

Endoscopy Diphyllobothriasis

Praziquantel megaloblastic anemia

Dipylidium caninum

Dog tapewormCucumber tapewormDouble-pored tapeworm

2 reproductive system; 8 egg packet

Small intestine

Fecal-oral; ingestion of vector

Cysticercoid larva

Proglottid DH: dog and catOH: human

Fleas; dog lice

Direct fecal smear

Dypilidiasis, dog tapeworm infection

Niclosamide, Prazinquantel

Abdominal pain; Diarrhea; Itchy anus; Urticaria

Hymenolepis nana

Dwarf or human tapeworm

Segments are wider than long; Genital pores are unilateral, and each mature segment contains three testes; ova with fibers

Small intestine

Fecal oral; ingestion of vector

Embryonated ova

Ova DH: human, miceIH: grain beetle

Fleas, beetles

Fecal smear Hymenolepiasis

Prazinquantel, niclosamide

induce enteritis with nausea and vomiting, diarrhea, abdominal pain, and dizziness

Hymenolepis diminuta

Rat tapeworm

Ova: striated outer membrane and a thin inner membrane; ova w/o fibers

Small intestine

Ingestion of vector

Cysticercoid larva

Ova DH: human, ratIH: beetle, caprophilic arthropods

beetle, caprophilic arthropods

Direct Fecal smear

Hymenolepiasis

Prazinquantel,

induce enteritis with nausea and vomiting, diarrhea, abdominal pain, and

dizzinessTaenia solium

Pork tapeworm

7-13 uterine lateral branches

Small intestine

Fecal-oral Cysticercoid larva & embryonated ova

Ova, gravid proglottid

DH: humanIH: pig

Fecal smear Cysticercosis

Prazinquantel, niclosamide

Seizure, abdominal pain, blurry vision, eosinophilia

Taenia saginata

Beef tapeworm

15-30 uterine lateral branches

Small intestine

Fecal oral Cysticercoid larva

Gravid proglottid

DH: humanIH: beef

Scotch tape swab, ELISA

TAENIASIS SAGINATA

Niclosamide, Quinacrine hydrochloride , Bithionol, Mebendazole, Prazinquantel

proglottids may also also crawl out of the anus

Multiceps multiceps

Coenurus tapeworm

Pear-shaped Small intestine

Ingestion of proglottid

Ova, proglottid

Ova, proglottid

DH: dogs, foxIH: sheepPH: human

Gross examination of proglottid, fecal floatation method, necroscopy

coenurosis Prazinquantel, Epsiprantel, Febendazole

Presence of painless nodules