HELMINTH PART II
DR SAMUEL AGUAZIM
CESTODE
•
•
•
•
•
•
•
•
•
•
•
TAPE WORM
TAENIA SAGINATA
INTERMEDIATE HOST: CATTLE
DEFINITIVE HOST: HUMANS
FORMS/TRANSMISSION
- Rare beef containing cysticerci is ingested
Interstinal tapeworm( affects small intestine)
Asymptomatic to vague abdominal pain
Chronic indigestion
Diagnosis: eggs or proglottids in feces
Treatment: praziquantel
TAENIA SOLIUM
• INTERMEDIATE HOST: SWINE
• DEFINITIVE HOST: HUMANS
• Humans can be both intermediate and
definitive host.
• Forms/transmission
• Intestinal tape worm
• Raw pork containing the cysticerci ingested by
humans
• CYSTICERCOSIS(INTERMEDIATE HOST): Humans
ingest eggs directly.
• Water and food contaminated with eggs auto
inoculation.
• disease/organ involvement/symptoms
• -intestinal tapeworm( same as taenia saginata)
• Larvae penetrate intestinal wall and migrate via the
blood to brain, heart, lungs and eye
• Diagnosis: eggs or proglottids in feces
• Treatment: praziquantel…
T. SOLIUM
T. SAGINATA
MOT: INGESTION OF CYSTICERCUS (larval worm)
IN PORK/BEEF PRODUCTS
CT Scan of Cysticercosis
DIPHYLLBOTHRIUM LATUM
•
•
•
•
•
•
INTERMEDIATE HOST: CRUSTACEANS
DEFINITIVE HOST: HUMANS, MAMMALS
HUMANS can be both IH & DH
Forms/transmission
SPARGANUM
Drinking pond water with copepods crustaceans
carrying the larval forms
• Intestinal tape worm
• Rare, eating raw prickled fish containing
sparganum
FISH TAPEWORM
Diphyllobothrium latum
longest tapeworm found in man
3-10 meters with more than 3000 proglottids.
Fish tapeworm:
Scolex has two
elongated sucking
grooves; no circular
suckers or hooks
Fish tapeworm:
Oval eggs have
an operculum
(lidlike opening)
at one end
MOT: INGESTION OF PLEROCERCOID LARVAE/SPARGANUM
IN INFECTED FISH
Copepod
• Disease/organ involvement/symptoms
• Sparganosis: larvae penetrate intestinal wall and
encyst
• Interstinal tape worm in the small intestine that
absorb vitamin B12 leading to PERNICIOUS
ANEMIA
• DIAGNOSIS: Eggs or proglottids in feces
• Biopsy for sparganosis
• Treatment: praziquantel
Echinococcus granulosus( dog tape
worm)
• INTERMEDIATE HOST: HERBIVORES
• DEFINITIVE HOST: Carnivores in sheep- raising
area
• Humans are intermediate hosts
• Forms/ transmission
• Ingestion of eggs
• Larvae can migrate to anywhere( liver is the
most common place)
Dog
tapeworm.
Scolex has four
suckers and a
double circle of
hooks.
• Disease: HYDATID CYST DISEASE
• Liver and lungs where cyst containing brood capsules
develop
• Eggs are ingested by sheep (and humans) and hatch
larvae in the gut that migrate in the blood to various
organs, especially the liver and brain.
• Larvae form one large, unilocular hydatid cyst
containing many minor pathogen and daughter cysts.
• Diagnosis- imaging and serology
• Treatment: surgery and albendazole
Echinococcus multilocularis
•
•
•
•
•
•
IH: RODENTS
DH: CANINES & CATS
HUMANS are intermediate hosts
Forms/transmission
Ingestion of eggs
Larvae can migrate to anywhere( liver is the
most common place)
• Disease: ALVEOLAR HYDATID CYST DISEASE
• Much more serious than echinococcus
granulosus : cyst metastasis: exogenous
budding cyst
• Diagnosis: difficult: MRI OR CT
• TREATMENT: SURGICAL RESECTION
E. Multilocularis multilocular, liver
Hymenolepis nana (dwarf tapeworm)
 most frequently
diagnosed cestode
infection in theUS
 small tapeworm
 infects children
 Reservoirs: Rodents
 vague abdominal pain
 enteritis
 Diagnosis :eggs
 DOC: Nicolsamide
MOT: INGESTION OF EGGS/ CYSTICERCOID
IN INSECTS
Spirometra
 sparganosis
 MOT: ingest polluted
water raw or inadequately
cooked flesh of
snakes or frogs
 southeastern region of the
United States
 east Asia (China, Japan,
and Korea)
 southeast Asia (Malaysia,
India, and the Philippines)
Sparganosis
•
•
•
•
•
•
subcutaneous edema
Muscles
Eyes
urogenital system
abdominal viscera
central nervous system
Sparganosis
• Treatment
Surgical removal of sparganum larvae
Praziquantel
no available treatment for proliferative
sparganosis
Trichuris trichiura
Disease: Whipworm infection
Characteristics: Intestinal nematode. The
characteristic of “whiplike” apperance of the
adult worm.
Life cycle:
• Humans ingest eggs, which develop into
adults in gut.
• Eggs are passed in feces into soil, where they
embryonate, ie, become infectious.
Trichuris trichiura
Transmission:
• More than 500 million infected.
• Transmitted by food or water contaminated with
soil containing eggs.
• Humans are the only hosts. Occurs worldwide,
especially in the tropics.
Pathogenesis:
• Worm in gut usually causes little damage.
• The whipworm infects about 2 million children in
the U.S.
• Causes rectal pruritis and tenesmus, which often
results in rectal prolapse.
Infectious Diseases
Whipworm – Rectal Prolapse
Infectious Diseases
Whipworm – Rectal Prolapse
Laboratory Diagnosis:
• Eggs visible in feces.
• The egg is barrel-shape with a plug at each
end, in the stool.
Treatment: Mebendazole.
Prevention: Proper disposal of human waste
FOOTBALL SHAPE EGG
Trichuris trichiura eggs, a typical barrel shape two polar plugs, that are
unstained
LOA LOA
Disease: Loiasis.
Characteristics: Tissue nematode.
Transmission: Transmitted by deer flies. Humans are
the only definitive hosts. No animal reservoir.
Endemic in central and west Africa.
Pathogenesis: Hypersensitivity to adult worms
causes “swelling” in skin. Adult worm seen crawling
across conjunctivas
Laboratory Diagnosis:
• Microfilariae visible on blood smear.
Treatment: Diethylcarbamazine.
Prevention: Deer fly control.
Onchocerca
Disease: Onchocerciasis (river blindness).
Characteristics: Tissue nematodes.
Onchocerca
Transmission: Transmitted by female black flies. Humans are
the only definitive hosts. No animal reservoir. Endemic
along rivers of tropical Africa and Central America.
Pathogenesis:
Microfilariae in eye ultimately can cause
blindness. Adults induce inflammatory nodules in skin.
Laboratory Diagnosis: Microfilariae visible in skin biopsy,
not in blood.
Treatment: Ivermectin affects microfilariae, not adult
worms. Suramin for adult worms.
Prevention: Black fly control and ivermectin
RIVER BLINDNESS/SOWDA
trapped microfilaria in the cornea, choroid, iris and anterior
chambers, leading to photophobia, lacrimation and blindness
Toxocara canis
Disease:
Visceral larva migrans.
Characteristics: Nematode larvae cause
disease.
Life cycle:
• Toxocara eggs are passed in dog feces
• Ingested by humans.
• Hatch into larvae in small intestine
• Larvae enter the blood and migrate to organs,
especially liver, brain, and eyes, where they are
trapped and die.
Transmission:
• ingestion of eggs in food or water contaminated with
dog feces.
• Dogs are definitive hosts. Humans are dead end hosts.
Pathogenesis: Granulomas form around dead larvae.
Granulomas in the retina can cause blindness
Laboratory Diagnosis: Larvae visible in tissue.
Serologic tests useful.
Treatment: Diethylcarbamazine
Prevention: Dogs should be dewormed
Tissue nematode
Dracunculus
Disease: Dracunculiasis.
Characteristics: Tissue nematode.
Dracunculiasis
Transmission:
•
•
•
•
copepods in drinking water.
Humans are definitive hosts.
Many domestic animals are reservoir hosts.
Endemic in tropical Africa, Middle East, and India
Pathogenesis:
• Adult worms in skin cause inflammation and
ulceration.
Treatment:
• Niridazole.
• Extraction of worm from skin ulcer.
Prevention:
• Purification of drinking water
Dracula ate an infected
crustacean and got an ulcer
with protruding worm.
He removed the worm by
winding it around a stick.
Strongyloides
Disease: Strongyloidiasis
Characteristics: Intestinal nematode.
• NOTE: the only helminth to secrete
larvae (and not eggs) in feces
Transmission: Filariform larvae in soil penetrate skin. Endemic
in the tropics.
Pathogenesis:
• Little effect in immunocompetent persons.
• In immunocompromised persons, massive superinfection
can occur accompanied by secondary bacterial infections.
Laboratory Diagnosis: Larvae visible in stool. Eosinophilia
occurs.
Treatment: Thiabendazole.
Prevention: Proper disposal of human waste. Use of
footwear
Memory Tool
• The strongman (Strongyloides) is brought
down by a larvae penetrating his skin causing
pulmonary distress and superinfection. Poor
strongman!
ANCYLOSTOMA BRAZILIENSE
ANCYLOSTOMA CANINUM
• DOG and CAT Hook worm
• Forms/ Transmission.
• Filariform larvae penetrate intact skin but cannot
mature in humans
• Disease/organ most affected
• Cutaneous larvae migrans: intense itching
• Tunnels through tissue
• Diagnosis: clinical signs
• Treatment- ivermectin