Lecture 55 - 3rd Asessment - Intestinal Nematodes

INTESTINAL NEMATODES GENERAL: Non-segmented, alimentary tract, diecious,

size varies,

cuticle,

male/female. Reproductive system: oviparous, viviparous, EOSINOPHILIA

body cavity,

oviviviparous

ATTACHMENT: a. Oral attachment to mucosa eg. hookworm b. Anchorage with attenuated end. c. Penetration of tissues. d. Temporary folds of mucosa. NUTRITION: a. Biting with tooth-like oral structures-ingests torn mucosa(hookworm) b. Ingests blood-sucks blood by action of musculoesophageal pharnyx c. Lysis of tissues eg. Trichuris-digests secretions. d. Feed on intestinal contents e.g - Ascaris. e. Absorption of nourishment from body fluids (Filaria), Larvae.

PHYSIOLOGY:

Energy for ova production

LIFE CYCLE: 1. Oral Infection: Ova in stools, mature outside eg. Trichuris, Enterobius, Ascaris. 2. Percutaneous: Ova, larvae in soil-invade skin. eg. Hookworm, Strongyloides. 3. Insect bite: Larvae in insects, W. bancrofti, Brugia, Loa, Onchocerca. 4. Crustucean ingest: larvae in crustaceans eg. Dracunculus. Larvae: Rhabditiform (L1),

Filariform (L3),

Microfilaria

PATHOGENICITY: No multiplicationIntensity of infection Migration SOIL-TRANSMITTED NEMATODES

TRICHURIS TRICHIURA (Whipworm) IMPORTANCE: 687 million infected; 0.2 cases per 1000 morbidity. GEOG. DISTRIBUTION:

Larvae

Mode of Transmission

HABITAT: Caecum (other sites?) .

MORPHOLOGY: Male, Female, Ova.

LIFE CYCLE: Ova develop in soil, larvae; ova swallowed, larvae penetrate villi (3-10 days),

Caecum. Egg to Egg 3 months.

PATHOLOGY/SYMPTOMS: Toxic or mechanical effects important CLINICALLY: Heavy-blood streaked stools, abdominal pain, weight loss, rectal prolapse. Anaemia?

(0.005 ml/worm), Eosinophilia.

LAB DIAGNOSIS: Direct,

concentration-ova,

Adults? Multiple infections.

TREATMENT: Mebendazole. PREVENTION: Treat, wash vegs.

faecal disposal, wash hands,

Doses between meals. personal hygiene,

ENTEROBIUS VERMICULARIS

(Pinworm)

IMPORTANCE: 42 million infected. GEOG. DISTRIBUTION: MORPHOLOGY: Male, Female (alae),

Ova - flat on one side.

LIFE CYCLE: Ova on perianal skin, ingested, larva,

caecum (appendix)

TRANSMISSION: First infection via food/inhalation. Autoinfection, Retroinfection. PATHOLOGY / SYMPTOMATOLOGY: Perianal, perineal, pruritus ani,

vaginal irritation,

worms migrate.

LAB DIAGNOSIS: Adults: history, purge, exam anal area. OVA: Sellotape swabtiming! TREATMENT: Mebendazole; repeat doses; treat household:

ASCARIS LUMBRICOIDES GEOG. DISTRIBUTION IMPORTANCE: 25% affected; 20,000 die; 1 million die, hospitalization 1%-9%. MORPHOLOGY: Adults: male, female. Ova: fertilized, unfertilized, decorticated, corticated. LIFE CYCLE: Ova swallowed, heart, lungs,

alveoli (moults),

larvae in SI.

MIGRATE: burrow,

upper resp tract,

liver, R oesophagus,

mature in SI (6 weeks). PATHOLOGY: Migrating larvae: Hepatic, lung, trauma, exudate, Adults: Spoilative,

tissue damage,

granulomas. toxic action,

mechanical obstruction,

Ascariasis

SYMPTOMS: Larvae:

lungs,

circulation.

Adults: fever, generalized toxaemia, vague, abdominal pains, eosinophilia. TREATMENT: Mixed infection, treat for Ascaris first; Mebendazole-single dose. LAB DIAGNOSIS: Adults: stools/vomit,

x-ray. Ova: Note varied morphology.

HOOKWORMS GENERAL: Two species,

GEOGRAPHICAL DISTRIBUTION:

IMPORTANCE: 1 billion infected.

HABITAT

MORPHOLOGY: Adults: Male-bursa Female. Buccal capsule glands prevent clotting of blood. Ant. end - bend - not in same direction as body.

Ova not distinguishable.

LIFE CYCLE: Ova, L1, L3 - penetrate unbroken skin.

MIGRATE: lymphatics,

venous circulation via heart, lungs, PATHOLOGY: Larva: erythema,

oesophagus,

intestine.

papulo-vascular eruption; Lung - haemorrhages.

Adults: Blood loss A. duodenale 0.2ml, Hyperplastic bone marrow, heart enlarged, lowered metabolism. SYMPTOMS: Larva: Ground itch,

N. americanus 0.03ml. enteritis,

lung

Adults: Acute Chronic: Light to moderate Heavy: LAB DIAGNOSIS: Adult worms, contents

ova,

SPECIFIC DIAGNOSIS: Reasons: treatment,

duodenal blood loss/no of ova.

(a) Ova,

(b) Rhabitiform larva,

(c) filariform larva,

TREATMENT: Treat anemia,

(d) adult worms.

mebendazole.

PREVENTION AND CONTROL:

STRONGYLOIDES STERCORALIS GEOG. DISTRIBUTION:

HABITAT: duodenum,

jejunum.

IMPORTANCE: 50-100 million infected. world ? MORPHOLOGY: Parasitic females, males rare, LIFE CYCLE: DIRECT - L1, L3. into mucosa, INDIRECT: L1, penetrate.

Developed rhabditiform larva (L1).

MIGRATION: males and females, females burrow

oviposit in tissue, larvae hatch, males and females (ext. environment), ova,

enter lumen. L1,

L3

AUTO INFECTION: EXO and ENDO autoinfection. PATHOGENICITY:

Skin lesions Pulmonary lesions-metamorphase to adults. Intestinal lesions-Congestion, haemorraghes. Fatal strongyloidiasis-hyperinfection.

SYMPTOMS: Abdominal, alternate.

colicky pain,

DIAGNOSIS: Rhabditiform larva in stool. Distinguish from other larvae Sputum TREATMENT: Thiabendazole. PREVENTION AND CONTROL:

diarrhoea and constipation Duodenal aspirate.

LARVA MIGRANS Definition Cutaneous: Non human hookworms Human worms Visceral: Non human eg. Toxocara canis, T. cati PATHOLOGY: Liver - granulomas. Larval migration - eye SYMPTOMS: Fever, eosinophilia, hepatomegaly. Hypergammaglobulinaemia. DIAGNOSIS: Serology. TREATMENT PREVENTION AND CONTROL: Deworm puppies

TRICHINELLA SPIRALIS GEOG. DISTRIBUTION: LIFE CYCLE: Ingest meat, copulate, larvae-migrate.

HABITAT: Adults, larvae larvae liberated,

adults,

Alternate as Definitive and Intermediate host. SYMPTOMS AND PATHOLOGY: Orbital oedema, muscle pains, eosinophilia. Intestinal Larval Migration Encystation DIAGNOSIS: Muscle biopsy, TREATMENT: Thiabendazole,

Immunodiagnosis steroid

Trichuris trichiura

Enterobius vermicularis

Ascaris lumbricoides

Ascariasis

Hookworm: Ancylostoma duodenale Necator americanus

Strongyloides stercoralis

Larva Migrans

Trichinella Spiralis