Med Micro exam 2

Sparganosis

-Human infection with a plerocercoid larva (spraganum) of a dog or cat tapeworm -Acquire the infection by: ingesting reptiles, amphibians, or other animals containing the plerocercoid larva -Most common in SE Asia, where a poultice has been applied to the eye to relieve an infection. -Diagnosis is by finding the small, ribbonlike worm in a nodule.

Dipylidium caninum

-Humans are accidental hosts -Usually children are infected when swallowing a flea carrying larvae -Eggs released in bundles -Eggs in feces -Pumpkin seed shaped proglottids

Metagonimus yokogawai & Heterophyes Life Cycle

-host become infected by ingesting undercooked fish -Embryonated eggs each with a fully developed miracidium are passed in feces -cercariea penetrate the skin of fresh/brackish water fish and encyst as Metacercariae in the tissue of the fish

microfilariae

-live borne larvae of roundworms -infective stage for the insect

Taenia solium

-pork tapeworm -7m -7-15 uterine branches -rostellum with hooks -attach to intestinal wall, but can also be harbored in the tissues -Human can be accidental intermediate host by ingested of embryonate eggs -can cause Cysticercosis

Hymenolepis diminuta

-rat tapeworm -inconspicuous polar thickenings, no polar filaments

Hookworms

-secrete anticoagulants -Pierce capillaries and ingest blood as a source of nourishment -sample must be preserved/refrigerated in order to prevent hatching -patient may experience bronchitis like symptoms during worm migration to lungs

Cercaria

2nd stage larve; infective

The scolex of Taenia saginata has:

4 suckers

What is the pathology of primary concern with a hydatid cyst?

anaphylaxis if the cyst ruptures

Metacercariae

hatched cercaria that is released into the water and attaches to vegetation or invades flesh of aquatic organisms(2nd intermediate host); can be infective

Which is the diagnostic stage for the filarial worms?

microfilariae

Which is one way that schistosomes differ from other flukes:

not opperculated

Swimmer's Itch

-Caused by penetration of humans by cercaria of bird and mammalian flukes -Schistosomal dermatitis -Foreign protein in cercaria elict immune response papules 3 - 5 mm in diameter, edema, erythema, intense itching -Symptoms last about a week and disappear as cercaria die and degenerate

Wuchereria bancrofti

-Causes elephantiasis/Bancroftian filariasis -Adults live in lymphatics and lymph nodes -The adults block the lymphatic fluid and it builds up in the tissues -Blood specimen obtained at night (10p - 2a) -Sheathed; no nuclei in tip of tail

Paragonimus westernmani Life Cycle

-Cercariae invade the crustacean and encyst in the metacercariae -human ingest inadequately cooked or pickled crustaceans -adults in cystic cavities in the lungs lay eggs passed in sputum -unembryonated eggs can be swallowed in sputum and passed in feces

Schistosoma spp. Life Cycle

-Cercariae released by snail into water and are free swimming -Penetrates skin -loses tail becomes schistosomeulae -migrate to portal blood and liver to mature -eggs passed in urine or feces

Ascaris lumbricoides

-Tropical and temperate areas, kids; SE US -Often found concurrently with whipworm -Abdominal discomfort, loss of appetite, colicky pains -Intestinal obstruction -Can cause lactose intolerance, & malabsorption of some vitamins -Chronic infection in kids can hinder normal growth and development -Larvae can be seen in sputum of patients with heavy infections.

Which 2 parasites are commonly co-transmitted?

A. lumbricoides and T. trichiura

How is D. medinensis acquired?

Drinking water containing infective copepods

What is the most prevalent helminth in the US?

E. vermicularis

Filarial larvae

Infective form of roundworms in humans

All of the following have sheathed microfilariae, except: W. bancrofti B. malayi Loa loa M. ozzardi

M. ozzardi

Which filarial parasite causes elephantiasis?

W. bancrofti & B. malayi

What is the term used to describe the number of worms an individual is initially infected with that will directly correlate to the severity of symptoms?

Worm burden

All roundworms have 2 sexes.

YES!!!! KNOW THIS

Norwegian scabies is

a form a scabies seen in the immunocompromisd

Rediae

contain partially digested germinal structures

cysticercus

larval form of the tapeworm.

Miracidium

-1st stage fluke larva -Ciliated larval form of trematodes that develops in the egg and hatches to be ingested by or penetrate a snail

Tapeworm Generalities

-3mm - 10m -Hermaphrodites -Require intermediate host -Ribbon-like with segments called proglottids

Enterobius vermicularis

-AKA: pinworm -Prevalent in kids 5-10 years old -spread through families, daycares, kindergartens, & crowded areas -Presents with perianal itching -Eggs are resistant to drying & spread well in the environment -embryonated eggs are infective for humans -Eggs and/or adult worms in cellophane tape test. -Football shaped

Trichuris trichiura

-AKA: whipworm -Co-transmitted with Ascaris -Common in South East US -Heavy infections cause: intestinal bleeding, abdominal pain, nausea & vomiting, and chronic diarrhea -Hypochromic anemia

Visceral Larva Migrans

-Accidental ingestion of dog or cat roundworm, Toxocara canis or Toxocara cati, respectively -Larva hatch in intestine and enter circulation, entering brain, lung, liver, eyes

Schistosoma mansoni

-Blood fluke -Most commonly found in Africa, parts of South America, the West Indies, and Puerto Rico -Direct cercarial penetration -Lives in venules of mestentary and small intestine -eggs found in feces -Snails are intermediate host -diarrhea

Blood Flukes

-Cause schistosomiasis -Have a male and a female form -Eggs are unoperculated -Humans are infected by direct cercarial skin penetration -Cylindrical shape rather than dorsoventrally flattened

Schistosoma spp. Clinical Symptoms

-Cercarial penetration self-limiting local dermatitis - irritation, redness, and a rash that lasts for 3 days -Larval migration Generalized symptoms - urticaria, fever, and malaise that lasts up to 4 weeks Cause little inflammatory response because they acquire human leukocyte antigens and ABO blood antigens on their surface -Chronic infections Granulomatous formation, leading to thickenings and fibrotic changes Scarring of the veins, development of ascites Pain, anemia, hypertension, hepatomegaly, splenomegaly

Cutaneous Larva Migrans

-Commonly seen in SW, Mideast, and Gulf Coast US -Commonly caused by accidental ingestion of Dog or cat hookworm filariform larva -Cannot enter circulation, so it dies under skin and causes severe allergic response

Trichuris trichiura life cycle

-Eggs need 14 days in the soil to become infective. -The soil needs to be both warm and moist to support their maturation and development. -The egg is ingested -The larva are released in the small intestine. -They go through several molts before they become adults, living in the cecum.

Ascaris lumbricoides life cycle

-Eggs require 14 days to become infective in the warm, moist soil. -larvae need to migrate through the lungs to complete their development. -This can cause an immune response that is characterized by an asthma-like appearance. -If the patient presents with fever from another illness, the worms kind of go crazy and will leave the intestines and seek refuge in other organs of the body. -The adults ultimately settle in the large intestine and the female can lay thousands of eggs per day.

Loa loa

-Eye worm -African equitorial rainforest -Insect vector is the Chrysops - fly -Adults live up to 15 years in human -Calabar swellings -Sample during the day - noon -Sheathed; nuclei in the tip of the tail

Dracunculus medinensis

-Fiery worm of the Isrealites, guinea worm -Ingestion of an infective copepod -Adult worms migrate to connective tissue and when the female is gravid, she migrates to the subcutaneous tissue, creates an ulceration, and lays her eggs when she senses water

Strongyloides stercoralis Life Cycle

-Filarial form larvae penetrate the skin -Enter circulation and are transported to the lungs -penetrate alveolar spaces -Carried to trachea, swallowed -Reach small intestine where they mature -Rabditiform larvae are excreted in stool -Auto-infection can occur in the immunocompromised

Fasciolopsis buski Diagnosis

-Finding adult or eggs is diagnostic -Passed in feces -Eggs are identical to F. hepatica and should be reported as F. hepatica/F. buski -Adults are 2 - 7mm, Flattened, and Lacks a cephalic cone

Diphyllobothrium latum

-Fish tapeworm -largest tapeworm -Pickled and raw freshwater fish -Humans usually only harbor a single worm, which makes since as they can reach 10 flippin' meters in length. -B12 deficiency leading to megaloblastic anemia -ONLY operulated tapeworm eggs

Schistosoma haemotobium

-Found in Nile Valley, Mideast, and East Africa -Lives in venules surrounding the bladder -Eggs passed in urine -Associated with bladder cancer -blood in urine

Fasciola hepatica Life Cycle

-Free swimming cercariea encysts on water plants -Metacercariae on water plant ingested by human, sheep, or cattle -Unembryonated eggs passed in feces

Fasciolopsis buski

-Giant intestinal fluke -Found in Far East: China, India, -Vietnam -Dogs and pigs may serve as reservoir -Humans acquire by ingesting metacercaria on water vegetation such as Bamboo and Water Chestnut

Ancyclostoma duodenale

-hookworm -southern Europe and northern Africa -Teeth in ducal cavity

Which organism is responsible for a "creeping eruption?"

"Dog and Cat Hookworm"

Schistosoma japonicum

-Commonly found in Far East: Japan, China, Phillipines -Lives in venule of small intestine -Has many mammalian reservoir hosts -Katayama fever - serum sickness-like illness in egg laying period

Echinococcus granulosus

-Hydatid cyst disease -Dogs are definitive hosts -most often seen in sheep-raising areas of the world -Sheep and other grazing animals harbor the larval stage - hydatid cyst -Humans get infected when they accidentally ingest the eggs - which look like Taenia -eggs hatch in the intestine, penetrate, and most often travel to the liver -Forms a brood capsule in the liver, in which hydatid sand develops

Trichinella spiralis

-Infection of muscles with larvae -Normally adult lives in small intestine -Acquire by eating undercooked pork, or sometimes from wild game. -The female releases liveborne larvae that penetrate the intestinal wall, enter the circulation, & are carried through the body. -When they enter striated muscle, they begin to mature & after about a month the larvae coil & become encapsulated. -They can live for years, but eventually die and calcify.

Fasciolopsis buski Life Cycle

-Intestinal Fluke -Metacercariae on water plant ingested by human or pigs -excysts in duodenum -adults in small intestine -miracidia hatch penetrate snail -matures to free living cercariae

Metagonimus yokogawai & Heterophyes heterophyes

-Intestinal Flukes -Found in Far East and Mideast -Humans acquire metacercaria in undercooked and raw fish -Adults live in small intestine and produce few symptoms -A heavy worm burden may result in diarrhea, colic, and stools with large amounts of mucus

Trichinella spiralis symptoms

-Intestinal phase : few symptoms -Migration and encapsulation: intense inflammatory response, splinter hemorrhages beneath nails

Brugia malayi

-Limited to Far East (Korea, China, Phillipines) -Same pathology as Wuchereria bancrofti -Life cycle is the same -Sheathed; nuclei in the tip of the tail

Clonorchis sinensis

-Liver Fluke -Limited to Far East -Dogs and cats serve as reservoir hosts -Adults live in distal bile ducts -Adults are 1.5 - 2.5cm long, Thin, and Tapered at both ends -Humans acquire by eating metacercaria in raw, undercooked, or pickled fish -Light infections have few or no symptoms -Heavy infections may cause inflammation, pain, fever, diarrhea, or obstruction of the bile ducts

Fasciola hepatica

-Liver Fluke -Sheep liver fluke -Sheep-raising areas of the world, including SE US -In sheep, causes liver rot -Humans acquire by ingesting raw water vegetation, including watercress

Paragonimus westernmani

-Lung fluke -Found primarily in SE Asia, also in focal areas of Latin America and Africa -Humans ingest metacercariae in raw, pickled, vine-soaked, or undercooked freshwater crabs and crayfish -Sputum is primary diagnostic specimen -Persistent coughing, chest pain, hemoptysis -1cm long, Reddish brown, Live within bronchioles

Clonorchis sinensis Life Cycle

-Metacercariae in flesh or skin of fresh water fish are ingested by human -embyronated eggs passed in feces

Taenia Life Cycle

-Pig or cow eats eggs or gravid proglottids -Oncospheres hatch, penetrate the intestinal wall and circulate to musculature -Oncospheres develop into cysticerci in pig or cow muscle -Humans infected by ingesting raw or undercooked infected meat -Scolex attaches to the small intestine and adults mature there

Onchocerca volvulus

-River blindness -Simulium - biting black fly -Adults live in encapsulated nodules in subcutaneous tissues -Microfilariae collect in cornea and iris causing hemorrhaging -Wolbachia symbiotic bacteria appear to be needed for the inflammatory reaction -Rarely found in blood or lymphatics -Sample is a skin snip -not sheathed

Hookworm lifecycle

-Small itchy red papule where the organism penetrates the skin. -Travels to the lungs. -Then the adults move to the small intestine, where they mate and the female lays her eggs. -Eggs develop in the soil - 1-2 days -Then release the 1st stage, feeding, non-infective larva, rhabditiform larva, and it carries about its business eating bacteria in the soil. -The 2nd stage larva is a nonfeeding, infective form called a filariform larva. Humans are infected when this stage of development pierces the skin. -Usually because you are barefoot.

Cysticercosis

-The human ingests the eggs of Taenia solium and becomes an intermediate host, rather than an accidental host -Ingestion of egg -Hexacanth embryo releases into intestine -Penetrates intestinal wall to enter circulation -Travels to ANY tissue or organ - lives there up to 7 years

Strongyloides stercoralis

-Threadworm -Endemic in the tropics and subtropics. -100-200 million people infected -Can persist in the host for decades after initial infection -Can progress to a hyperinfection if the host becomes immunocompromised -ONLY roundworm capable of causing autoinfection -Filariform larva in stool

Fasciola hepatica Clinical Symptoms

-Tissue migration: inflammatory reaction secondary infection fibrosis in biliary ducts -Heavy worm burden: diarrhea upper right quadrant abdominal pain hepatomegaly cirrhosis liver obstruction jaundice -Chronic infections are usually asymptomatic

Diphyllobothrium latum Life Cycle

-Unembryonated eggs are passed in the feces -Eggs embryonate in water -Coracidia hatch from eggs & are ingested by crustaceans -Procercoid larvae in body cavity of crustaceans -Crustacean ingested ingested by fish -Procercoid larvae released from crustacean -develops into plerocercoid larva -Small fish is eaten by larger fish -Human ingests plerocercoid larva by consuming undercooked infected fish -moves to small intestine

Mansonella streptocerca

-Usually not associated with serious infections -Transmitted by midges -skin for sample

Taenia saginata

-beef tapeworm -10m -15-20 uterine branches -attach to intestinal wall -4 suckers; no rostellum or hooks

Mansonella perstans

-blood for sample -Usually not associated with serious infections -Transmitted by midges

Mansonella ozzardi

-blood for sample -Usually not associated with serious infections -nonpathogenic -Transmitted by midges

Hymenolepis nana

-dwarf tapeworm -More common; no intermediate host -required -Kids spread this easily -Egg has polar filaments -Egg has two polar thickenings -4-8 polar filaments

Necatur americanus

-hookworm -South East US -Cutting plates in ducal cavity

intestinal obstruction associated with heavy worm burdens

A. lumbricoides

What do A. lumbricoides, N. americanus, and S. stercoralis have in common?

All of these organisms migrate through the lungs

Nematodes that produce microfilariae and live in tissues require which of the choices below to carry out their life cycles? A)developmental period in soil B)an arthropod vector C)larval development period in water D)ingestion of infective eggs by the definitive host

B)an arthropod vector

A stool specimen for ova and parasite examination contained numerous rhabditiform larvae. What factor does not aid in the identification of the larvae? A)larva tail morphology B)type of water vegetation consumed C)endemic area traveled D)appearance of genital primordium

B)type of water vegetation consumed

A patient presented to the ER after living abroad for a year in the tropics. He exhibited minor but painful swelling and edema in his left leg and the following microfilariae were present with terminal well-separated nuclei in his blood sample taken at 11pm. Which organism is this?

B. malayi

The only cestode with an operculated egg is:

Diphyllobothrium latum

Two helminth eggs that may resemble one another are:

Diphyllobothrium latum & Paragonimus westernmani

Arthropods

Directly cause or transmit over 80% of diseases

The examination of human feces is no help in the detection of:

Echincoccus granulosus

When humans have hydatid disease, the causative agent and classification are:

Echinococcus granulosus - accidental intermediate host

A football shaped egg with a curled larvae inside is seen on a cellophane tape specimen. What is the most likley identification?

Enterobius vermicularis

Fasciolopsis buski Clinical Symptoms

Heavy worm burden: persistent diarrhea, anorexia, adema, ascites, nausea, vomiting, and intestinal obstruction

D. caninum is seen primarily in children and is acquired by

Ingesting infective fleas

Which of the microfilarial worms lacks a sheath and nuclei are not present in the tip of the tail?

M. perstans

A skin snip was taken from a patient when the lesion was noticed by a primary physician, although no illness was noticed. A sherpards crook was observed on an unsheathed filarial worm with nuclei extending to the tip of the tail. Which organism is this?

M. streptocerca

A patient presents with ground itch, pneumonitis, and anemia.Which organism is it?

N. americanus

Which microfilariae is unlikely to be isolated from blood?

O. volvulus lives in nodules in the subcutaneous tissues, so it is highly unlikely it will ever be recovered in the patients blood

A fibrous skin nodule is removed from the back of a patient from Central America. A microfilaria seen upon microscopic exam of the nodule is:

Onchocerca volvulus

Which microfilariae are usually not found circulating in the peripheral blood?

Onchocerca volvulus

Which of the choices below is the crab or pubic louse?

Phthirus pubis

Which is the free-living larval form of nematodes that is non-infective and feeding?

Rhabditiform

associated with sharp, stabbing ulcer-like pains

S. stercoralis

Examination of a 24-hour unpreserved urine specimen is sometimes helpful in the recovery of:

Schistosoma haematobium eggs

The first (or only) intermediate host for trematodes:

Snails -these organisms do not undergo any stage of development in the soil.

What is the most important reason diagnostically to process fecal specimens in a timely manner?

Some helminth eggs may hatch to release larval forms, leading to misdiagnosis

A 45-year-old hunter developed fever, myalgia, and periorbital edema. He has a history of bear meat consumption. The most likely causative agent is:

Trichinella spiralis

A helminth is described as having terminal polar plugs. It is most likely to be:

Trichuris trichiura

Rectal prolapse is associated with which pathogen?

T. trichiura

For all roundworms, humans are the definitive host.

Tell me you knew this

Entomophobia

Term to describe a pathological fear of insects

Myiasis is

Term to describe fly larvae being laid in skin/wound

necrotic arachnidism

Term to describe non-healing lesion of brown recluse bites

Tick paralysis

Term to describe paralysis resulting from a tick being lodged in the scalp 4 or more days

Hypochromic anemia

can result in children with inadequate protein and iron intake in the presence of constant, low-level bleeding with chronic Trichuris trichiura infection.

Sporocysts

contain undifferentiated germinal structure

Characteristics of the rhabditiform (noninfective) larvae of Strongyloides stercoralis include a:

short buccal capsule and large genital primordium