NEMATODES

• also known as ROUNDWORMS

• Among the most abundant animals on Earth

• Unsegmented

• Measure 2mm in length to a meter

• Sexes are separate (dioecious)

• Males are smaller than females

• Posterior portion of the male is curved or coiled

Does nematodes possess a pseudocoel? True or false?

lumen of the pharynx

cortical, median, basal zone

outermost zone and contains a highly resistant protein called cuticulin

contains fine striations

composed of two or three fibrous layers

Most prominent feature of Nematodes’ Nervous System?

is usually a circular opening surrounded by a maximum of six lips located in the anterior end

is tubular or funnel-shaped which for some specie is expanded for sucking purposes. Food ingested moves into a muscular region of the tract known as the esophagus, which is important for identification of the specie.

glandular type and tubular type

Presence of a median ventral duct and pore called?

• Are situated in the posterior third of the body as a single coiled or convoluted tube

  • Various parts are differentiated as testis, vas deferens, seminal vesicle, and ejaculatory duct.

• may either be a single or bifurcated tube, differentiated into the ovary, oviduct, seminal receptacle or uterus, ovijector, vagina, and vulva that opens to the exterior

Oviparous

Larvipirous/ Viviparous

Parthenogenic

• Based on the presence and absence of caudal receptor

• Based on habitat

• Class Enoplea

• Class Rhabditea

• Small intestine

• Large intestine

caudal receptor and caudal gland present

1. Trichuris trichiura

2. Trichinella spiralis

3. Capillaria philippinensis

with caudal receptor but without a caudal gland

1. Ascaris lumbricoides

2. Strongyloides stercoralis

3. Enterobius vermicularis

4. Filarial worms

5. Hookworms

6. Dracunculus medinensis

7. Anglostrongylus cantonensis

1. Ascaris lumbricoides

2. Capillaria philippinensis

3. Hookworms

4. Strongyloides stercoralis

1. Trichuris trichiura

2. Enterobius vermicularis

• Common name: Giant Intestinal Roundworm

• Disease caused: Human Ascariasis

• Cylindrical, elongated, tapering, in the end,

• Containing lateral lines seen as whitish streaks along the entire body length of the body

• Terminal mouth with trilobate lips with a small triangular buccal cavity

10-31 cm

22- 35 cm in length

• Broadly ovoid in shape

• Golden brown in color

• Fertile eggs measure 45 to 70 um by 35 to 50 um

• Includes three thick transparent layers

• Vitelline membrane

• Glycogen membrane

• Albuminous/mamammillary coat

• Longer, larger, elongated or sometimes irregular in shape

• Measure 88 to 94 um by 39 to 44 um

• Two layers present

• Glycogen membrane

• Albuminous/mamammillary coat

As fertilized, but inside structure contains the larva of the embryo.

• Feeds on intestinal contents

• Abdominal pain

• Diarrhea

• Nausea

• Loss of appetite

• Eratic migration may cause regurgitation and escape through the nostrils

• Vomitted worms may pass the larynx and might lead to suffocation or reach the lung to produce gangrene

• Might reach the Eustachian tube to cause otitis media

• DFS

• Kato -Thick

• Kato Katz

• Concentration technique

• Piperazine citrate

• Pyrantel pamoate

• Mebendazole

• Albendazole

• Common Name: Whipworm

• Disease caused: Trichuriasis

• Measures 30mm to 50mm long

• Males are smaller than females

• Esophagus is long occupying about two-thirds of the body length

• Contains stichocytes

• Both sexes have a single gonad

• No excretory system

• Unsegmented barrel shaped, lemon, football shaped ova

• "Bipolar plugged" eggs

• With 3 layers

• Embryonation takes place in the soil where the first stage larvae is formed within 3 weeks

• Mebendazole - drug of choice

• Albendazole alternative drug

• Pyrantel pamoate

• Small streaked diarrheic stool

• Abdominal pain and tenderness

• Nausea and vomiting

• Hypochromic anemia

• Weight loss

• Rectal prolapse

• Direct fecal smear analysis

• Kato-thick or kato Katz

• Concentration technique

• Common name: Trichina worm

• Disease caused: Trichinosis, Trichinellosis

• Whitish color in color with the anterior end of the body consisting of esophagus filled with stichosomes.

measures 0.62 to 1.58 mm by 0.025 to 0.033 mm with a single testis

measures about 1.26 to 3.35 mm by 0.029 to 0.038 mm, and has a single ovary

• 80-120 microns by 5.6 microns at birth

• Spear-like burrowing anterior

• Incubation and intestinal invasion

  • Includes diarrhea, constipation, vomiting abdominal cramps, nausea

• Larval migration muscle invasion

  • Fever, facial edema, urticaria, pain, and swelling weakness

  • Splenomegaly, gastric and intestinal hemorrhages

• Encysment and encapsulation

  • Fever, weak, pain

• Muscle biopsy (0.2 to 0.5g of muscle)

• Serological- ELISA

• Positive (Western blot technique)

• Mebendazole - larvicidal

• Thiabendazole

• Pinworm or seatworm

• Enterobiasis or oxyuriasis

• Small whitish or brown in color

2-5 mm coiled tail end

8-13mm pointed tail end

• Elongated

• 50-60 by 20-30 microns

• Flattened lateral side, lopsided D

• Two egg-shell layer

• Albuminous layer- outer

• Embryonic or lipoidal membrane- inner

• Embryonated when laid

• Resistant to disinfectant

• Under favorable condition, it remains viable for 13 days

• Poor appetite

• Insomnia

• Weight loss

• Irritability

• Grinding of teeth

• Nausea

• Vomiting

• Pruritus ani

Scotch tape swab (Perianal cellulose tape swab)

• Mebendazole - drug of choice

• Pyrantel pamoate

• Albendazole

• Hand to mouth

• Inhalation

• Retroinfection - gravid female after laying their eggs in the perianal area, goes back thru the anus to the large intestine. The larvae, upon hatching, migrate back the large intestine

• Common name: Thread worm

• Disease: Strongyloidiasis

• Distribution: tropical, subtropical area and temperate climate. Mostly moist and areas of low hygiene

• Affect 30-100 million annually

• It is characterized by free-living rhabditiform and a parasitic filariform stages.

3 stage filariform larva

duodenum & upper jejunum

skin penetration; autoinfection

rhabditiform larva

human, dogs, cat

• Size: 50-58 x 30-34 um

• Shape: ova, clear, thin shelled

• Similar to hookworm but are smaller.

  • (Eggs are seldom seen in stools)

1. Invasive: Skin penetration phase (filariform larva)

• S/S: erythema, pruritic hemorrhagic papules (pin pointed rashes)

2. Pulmonary: Larval migration phase

• s/s: lobar pneumonia with hemorrhages

3. Tissue Destruction Intestinal mucosa penetration phase (adult female worm)

• S/S; diarrhea

can't be stopped even with medication

alternate episodes of diarrhea and no diarrhea

• Death

• Neurological and pulmonary complications shock.

• CBC

• Stool (wet, Harada Mori, Baele's String Test)

• Baermann Funnel Method

• WBC usually wnl for acute and chronic cases, can be elevated in severe cases

• Eosinophilia common during acute infection, +/- in chronic infection (75%), usually absent in severe infection

• Microscopic ID of S. sterocoralis larvae is the definitive diagnosis

• Ova usually not seen (only helminth to secrete larva in the feces). In chronic infection, sensitivity only 30%, can increase to 75% if 3 consecutive stool exams

• Albendazole: 400 mg x 3days (adult)

• Ivermectin: 200 Ug /kg/day x 1-2 days

• Thiobendazole: 50 mg/kg/d in 2 doses (up to 3 g/d) x2 days