helminth part ii dr samuel aguazim. cestode tape worm taenia saginata intermediate host: cattle...
TRANSCRIPT
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…
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 TAPEWORMDiphyllobothrium latum
longest tapeworm found in man3-10 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
• TreatmentSurgical removal of sparganum larvaePraziquantel 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 DiseasesWhipworm – Rectal Prolapse
Infectious DiseasesWhipworm – 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 causedisease.
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 nematodeDracunculus
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: StrongyloidiasisCharacteristics: 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 BRAZILIENSEANCYLOSTOMA 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
