Transcript TISSUE NEMATODES2010.ppt

TISSUE
NEMATODES
TISSUE NEMATODES
Common Tissue Nematodes
• Trichinella spiralis adults in small intestine larvae in tissues (mainly
in muscles).
• Toxocara canis (dog roundworm) larvae in organs (liver brain
eyes), causing visceral larva migrans
• Dracunculus medinensis (guinea worm) adult female in
subcutaneous tissues
• Filarial worms
Life-cycle of Trichinella spiralis
Trichinosis: geographic distribution
Most prevalent in areas where domestic pigs are allowed to roam freely.
Trichinosis
Pathology:
Adults cause mild gastroenteritis.
Larvae cause fever, myositis and multi-system
involvement which may lead to death.
Diagnosis: serology, muscle biopsy.
Treatment: Albendazole or Mebendazole +
corticosteroids
Trichinosis
Visceral larva migrans:
• Mainly affects children who eat soil
contaminated with emberyonated (infective)
eggs of Toxocara canis.
• Larvae do not develop in humans but
migrate continuously in viscera and
encapsulate, causing tissue damage.
Toxocara canis
Toxocariasis
• Pathology: Eosinophilia, hepatomegaly,
retinitis.
• Diagnosis: serology, biopsy.
• Treatment: Albendazole
Dracunculus medinensis
Draunculiasis
Caused by Dracunculus medinensis
Adult female lives in subcutaneous tissues, causing a
skin ulcer through which it protrudes its anterior end.
Main pathology due to secondary bacterial infection and
allergic reactions.
Diagnosis: clinical picture.
Treatment: surgical removal.
FILARIAL WORMS:
(Adult worms + microfilariae)
1 Wuchereria bancrofti, Brugia malayi & B. timori:
Lymphatic filariasis (adults in lymphatics,
microfilariae in blood)
2 Loa loa:
Adults in subcutaneous and subconjunctival
tissues, causing Calabar swellings.
Microfilariae in blood
3 Onchocerca volvulus:
Adults in subcutaneous swellings Microfilariae
: mainly in skin, eyes causing River blindness
LYMPHATIC FILARIASIS
Lymphatic Filariasis
Life-cycle of Wuchereria bancrofi
LYMPHATIC FILARIASIS
Mainly caused by Wuchereria bancrofti
and Brugia malayi
Pathology:
Due to adult worm obstructing lymphatics.
• Acute: lymphadenitis lymphatic varices
• Chronic: lymphedema, hydrocele, chyluria.
LYMPHATIC FILARIASIS
Diagnosis: detection of
microfilariae in blood in
early stages of the
disease:
Blood film, Knott’s method
( concentration of 1 ml of
blood), best 10 PM to 2
AM (nocturnal
periodicity).
Immunological tests
Treatment:
diethylcarbamazine
(DEC) or ivermectin
http://www.mectizan.org/
Loiasis
Loiasis
• Pathology: Adult worm
continously migration in
subcutaneous and
subconjuntival tissues,
causing Calabar swellings
(allergic reactions) and
conjunctivitis.
Loiasis
• Diagnosis: detection of microfilariae in
blood film.
• Treatment: diethylcarbamazine (DEC) or
ivermectin, surgical remonval.
Onchocerciasis
Onchocerciasis
(river blindness)
Pathology:
Adults worms live in subcutaneous nodules.
Main pathology caused by microfilariae in:
• Skin: dermatitis
• Lymph nodes: lymphadenopathy
• Eyes: blindness
Diagnosis: skin snip to identify microfilariae.
Treatment: Ivermectin
Onchocerciasis
Onchocerciasis
NON-FILARIAL TISSUE NEMATODE INFECTIONS
Nematode
species
Disease
Mode of
transmission
Location in
human
Diagnosis treatment
Dracunculus Dracunculias Ingestion of
is, Guinea
medinensis
infected
worm disease cyclops in
water
Subcutaneous,
mainly in lower
limbs
clinical
Surgical
extraction
Trichinella
spiralis
Trichinellosi
s
(trichinosis)
ingestion
larvae in
undercooked pork
Muscles, lungs
brain
Serology,
muscle
biopsy
albendazole
Toxocara
canis
Visceral
larva
migrans
Ingestion of
infective
eggs in soil
Abdominal
organs and
brain
Serology,
ELISA
albendazole
MAJOR FILARIAL INFECTIONS OF HUMANS
species
Disease
Geographic
distribution
Location of
adult in
humans
Location of
microfilaria
vector
Lab.
diagnosis
Wuchereria elephantiasis
bancrofti
Tropical
and
subtropical
areas
Lymphatic
vessels
Blood
(nocturnal
periodicity)
mosquitoes
Blood
film
Brugia
malayi
elephantiasis
Asia
Lymphatic
vessels
Blood
(nocturnal
periodicity)
mosquitoes
Blood
film
Onchocerc
a volvulus
Onchocerciasis
(river
blindness)
Africa,
Central
and South
America,
Yemen
Subcutaneous
Skin, eyes,
no
periodicity
Simulium
spp. (black
fly)
Skin snip
Loa loa
loiasis
Central
Africa
Moving in
Blood
subcutaneous (diurnal
tissues
periodicity)
Chrysops
spp. (deer
fly)
Blood
film
nodules