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 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 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