Microbiology - Final - Part 2

davidwurbel7's version from 2015-08-14 02:56


Question Answer
Flattened shape. Hermaphrodites. Worms are segmented. Scolex (head). Proglottids (segments). Gravid proglottids. Terminal segments are gravid (produce eggs)Cestodes (Tapeworms)
Contracted by eating undercooked Pork (larva in muscle). Larva attaches to small intestine → adult worms. Eggs / proglottids passed out in stoolTaenia solium (Pork Tapeworm)
Distribution = Africa, India, SE Asia, China, Mexico, Latin America, E Europe. Most infections asymptomatic. Patients become concerned when they pass one or more proglottids in stool. Diagnosis – O&P exam (ova & parasite exam) look for eggs, proglottids in stoolTaenia solium (Pork Tapeworm)
Taenia solium treatmentPraziquantel or Niclosamide
Transmission – Fecal-oral. Ingestion of eggs. Autoinoculation. Eating raw vegetables / drinking water. Encysted larvae in muscles, brain, lungs, eye, connective tissuesTaenia solium Cysticercosis
Larvae encysted in brain which causes seizures, visual defects and hydrocephalusNeurocysticercosis
Cysticercosis treatmentPraziquantel / Albendazole + Corticosteroid
Eating undercooked beef. Adult worm – intestine (up to 10 meters long). Eggs in stool / proglottids. No cysticercosis.Taenia saginata (Beef Tapeworm)
Distribution – worldwide, most common tapeworm infection in the US/Canada. Clinical disease – usually asymptomatic. Diagnosis O&P exam – eggs/proglottids in stoolTaenia saginata (Beef Tapeworm)
Most common tapeworm infection in the US/CanadaTaenia saginata (Beef Tapeworm)
Taenia saginata (Beef Tapeworm) treatmentPraziquantel or Niclosamide
Tapeworm found in freshwater fish. Distribution – worldwide, freshwater lakes, Northern lakes (US). Eating undercooked freshwater fish. Associated with dumping raw/improperly treated sewage into lakes. Adult worm – intestine. Eggs – stoolDiphyllobothrium latum (Fish Tapeworm)
Mostly asymptomatic. Occasionally - pain, cramping, nausea, vomiting, weight loss vitamin B12 deficiency. Pernicious anemia. Tapeworm competes for Vitamin B12. Diagnosis – O&P, eggs in stoolDiphyllobothrium latum (Fish Tapeworm)
Diphyllobothrium latum (Fish Tapeworm) treatmentPraziquantel / Niclosamide
Tapeworm of canids. Dog, fox, wolf, coyote, jackal, dingo. Normal hosts are dogs (adult tapeworm in intestine). Eggs passed in feces -> Ingested by sheep. Sheep (larvae in organs). Sheep die/slaugtered -> raw viscera fed to dogsEchinococcus granulosus (Canis Tapeworm)
Humans are accidental hosts ingestion of eggs. Larvae develop in tissues as hydatid cysts. Human infection associated with sheep-raising areas In US - California, Arizona, Utah, New MexicoEchinococcus granulosus (Canis Tapeworm)
Hydatid cysts – liver, lungs, CNS. Slow-growing, tumor-like, space-occupying structure enclosed in laminated membrane. Larval tapeworm heads inside. See on slide as "Hydatid sand" once cysts are opennedEchinococcus granulosus (Canis Tapeworm)
Clinical disease – Asymptomatic for 5-20 years (cysts are slow-growing). Symptoms of space-occupying lesions in liver / lung. Rupture of cysts (20% cases) – fever, urticaria, anaphylactic shock. Rupture also results in dissemination of infectionEchinococcus granulosus (Canis Tapeworm
Echinococcus granulosus treatmentSurgical Resection PAIR Technique
Percutaneous Aspiration of cyst contents. Injection of formalin (to kill & detoxify remaining fluid. Re-aspiration of formalinPAIR Technique
Tapeworm of feral canids (foxes, wolves. Human infection – ingestion of eggs. Larvae reach the liver, lungs, brain and form alveolar hydatid cyst (multilocular cyst). Cysts grow via exogenous budding – eventually resemble a carcinomaEchinococcus multilocularis
Common in children - Daycare centers. Ingestion of eggs. Usually asymptomatic. Diarrhea, nausea. Diagnosis - O&P exam eggs in stoolHymenolepis nana
Grain products contaminated with infected insects. Ingestion of eggs. Usually asymptomatic. Diarrhea, nausea. Diagnosis - O&P exam eggs in stoolHymenolepis diminuta
Tapeworm of dogs and cats. Their fleas are infected – get crushed in the dog/cat’s mouth. Dog/cat licks kid’s mouth. Diagnosis – O&P eggs & proglottids in stool. “Pumpkinseed” tapewormDipylidium caninum


Question Answer
Hermaphrodites (except Schistosoma sp.). One or more intermediate hosts. Operculated eggs (except Schistosoma sp.). None are strict human pathogens, all have natural reservoirsTrematodes
Adult fluke (thumb size). Eating Water vegetation. Eg. waterchestnuts Small intestine. Eggs in stoolFasciolopsis buski
Giant Intestinal Fluke (thumb size !). Many animal reservoirs. Transmission– ingestion of water vegetation (eg.chestnuts) (contain larva). Adult fluke – small intestine. Distribution – China & SE Asia In US – cases seen are imported from areas of endemicity. Heavy infections – abdominal pain (resembles duodenal ulcer), diarrhea. Eosinophilia. Diagnosis – operculated eggs in stool (O&P)Fasciolopisis buski
Fasciolopsis buski treatmentPraziquantel or Niclosamide
Sheep liver fluke. Sheep-raising areas - Infects sheep, cattle and humans. Transmission - Ingestion of watercress (containing larvae). Adult worm – liver, bile ducts. Distribution–Japan, Egypt, Latin America. Clinical disease - Migration of parasite through liver – fever, pain, hepatomegaly, eosinophilia. Infestation of bile ducts – hepatitis, biliary obstruction. Worms may migrate back to liver – necrotic foci termed “liver rot”. Diagnosis – operculated eggs in stoolFasciola hepatica
Fasciola hepatica treatmentTriclabendazole
Chinese liver fluke. Ingestion of undercooked freshwater fish (larva present). Raw, pickled, smoked, dried fish. Adult worms – bile ducts. Distribution – China, Korea, Japan, Vietnam. One of most frequent infections among Asian refugees/immigrants. Severe infections (many flukes in bile ducts). Fever, epigastric pain, diarrhea, hepatomegaly, sometimes jaundice, eosinophilia. Biliary obstruction. Chronic infection is associated with adenocarcinoma of the bile ducts (adult flukes live up to 50 yrs). Diagnosis – operculated eggs in stoolClonorchis (Opisthorchis) sinensis
Clonorchis (Opisthorchis) sinensis treatmentPraziquantel
Eating uncooked crabmeat / crayfish (larvae). Larvae migrate → intestine wall → diaphragm → pleural cavity → lung (adult fluke). Adult flukes – Lungs. Distribution – Asia, Africa, Latin America. In eastern and midwestern US – P.kellicotti 1% of all Indochinese immigrants to the US are infected. Clinical disease - Migrating larva – fever, eosinophilia. Flukes (lungs)–cough, blood-tinged sputum, dyspnea, chronic bronchitis, pleural effusion and chest painParagonimus westermani
Diagnosis - detection of operculated eggs. sputum, pleural effusion. Stool (O&P exam)Paragonimus westermani
Paragonimus westermani treatmentPraziquantel or Bithionol
Disease called Schistosomiasis or Bilharziasis. Distribution – Africa, Asia, Latin America, Egypt. 3 species. Penetration of skin by schistosome cercariae in fresh water. Adult flukes - obligate intravascular parasites. Eggs have spines and are not operculatedSchistosomes
Flukes in mesenteric veins. Abdominal pain, diarrhea, liver may be involved. Eggs - stool (eggs have lateral spines). Diagnosis - O&P examSchistosome mansoni and Schistosome japonicum
Flukes in venous plexus around urinary bladder. Hematuria, urinary frequency. Eggs - urine (terminal spine) - diagnosis. Chronic infection associated with squamous cell carcinoma of bladderSchistosome haemtobium
Schistosomes treatmentPraziquantel


Question Answer
Most common helminth worldwide. Largest roundworm (20-30cm long). Ingestion of eggs/ova (contaminated food/water). Larva migrate. Through lungs (cough - pneumonitis). Adult worms - Intestine. Obstruct intestine, bile duct. Diagnosis by O&P stool – knobby eggsAscaris lumbricoides
Ascaris lumbricoides treatmentMebendazole
Causes Visceral larva migrans. Ingesting eggs of dog/cat ascarid worms. Children in playgrounds/sandboxes. Eating dirt (habit of Picca). Larva migrate in tissue till they die. Cannot develop into adult worms – humans wrong hostToxocara canis or Toxcara catis
Toxocara canis and Toxcara catis treatmentMebendazole
Pinworm. Most frequent helminth parasite in US. Eggs ingested. Person-person spread, autoinoculation. Adult worm – large intestine. Females lay eggs at night on perianal skin. Perianal pruitis (itching)Enterobius vermicularis
Diagnosis by sticky swab/cellophane-tape prep of perianal area. Ova – planoconvex (one side flattened)Enterobius vermicularis
Enterobius vermicularis treatmentMebendazole
Whipworm. Ingestion of eggs. Adult worms in cecum. Appendicitis. Rectal prolapse (heavy infestations, young children). Sometimes bloody diarrhea. Barrel-shaped (bipolar plugs) eggs in stool. Diagnosis by O&P examTrichuris trichiura
Trichuris trichiura treatmentAlbendazole
Filariform larvae penetrate bare skin / mucous membranes. Larva migrate – through lungs (pneumonitis). Adults – intestine suck small amounts of blood. Long-standing infections – Iron deficiency anemia. Diagnosis by eggs in stool (O&P exam)Ancylostoma duodenale and Necator americanus
Ancylostoma duodenale and Necator americanus treatmentMebendazole (think about iron therapy)
Threadworm. Larvae in soil – penetrate skin/mucous membranes. Migrate through lung – pneumonitis. Adult worms – intestine. Produce Ova → hatch into larva within intestine → penetrate gut wall → bloodstream → migrate through lungs →reach intestine → develop into adult worms - Re-infection/autoinfectionStrongyloides stercoalis
Diagnosis (O&P) – larvae in stool Strongyloides stercoalis
Strongyloides stercoalis treatmentThiabendazole
Cutaneous larva migrans. Serpentine skin rash. Intense itching. Walking barefoot/children playing in sandbox. Larva penetrate skin →cannot mature → wander in subcutaneous tissue and die out. Presumptive diagnosisHookworms of Dogs and Cats
Hookworms of Dogs and Cats treatmentThiabendazole and Antihistamines
Eating Pork, Bearmeat. larva in meat. Adult worms develop in intestine. Produce eggs → hatch in intestine → larvae reach bloodstream → larvae invade striated muscles. Adult worms in GI tract + Encysted larvae in muscleTrichinella spiralis
Diagnosis by muscle biopsyTrichinella spiralis
Clinical – fever, myalgia (larva encysting in muscle), splinter hemorrhages, periorbital edema, eosinophiliaTrichinella spiralis
Trichinella spiralis treatment byMebendazole + Steroids
Adult females release larva. Eggs are released and hatch immediatelyMicrofilaria
Blockage of the lymphatic channels causing edema and hypertrophyLymphatic filariasis (Elephantiasis)
Causes Lymphatic filariasis. Vector – mosquito. Adult worms – lymph nodes. Release microfilaria leading to eosinophilia. Microfilaria – Blood. Noctural periodicityWuchereria bancrofti + Brugia malayi
Equatorial Africa. Vector – Chrysops, mango flies. Adult worms wander in subcutaneous tissues. Pruritis, Calabar swellings, eosinophilia. Across surface of eye (sub-conjunctival). Microfilaria – blood – diagnosisLoa Loa – African eyeworm
Loa Loa – African eyeworm treatmentSurgical removal (eye conjunctiva) DEC or Ivermectin
River blindness. African nations, communities around rivers. Vector – dreaded Black fly (Simulium). Adult worms localize in nodules under skin. Eosinophilia. Microfilaria. Diagnosed by skin snips. If inside eye – cause progressive blindnessOnchocerca volvulus
Onchocerca volvulus treatmentSurgical Removal of Nodules, DEC or Ivermectin
Guinea worm. Drinking comtaminated water (larva). Adult worms – retroperitoneal space. Female worms migrate to extremeties. Form an ulcer * on skin – release larvae into water. Slow extraction of worm around a stick /surgical extraction. Symptoms - Pain, itching at site of ulcerDracunculus medinensis