Micro Test II

What are the three lifestages of parasites?

Define deifnitive host

Define intermediate host

Which parasites fall under the catagory of protozoa?

Entamoeba Histolytica Causes What?

Giardia Lamblia Causes what?

Trichomonas Vaginalis causes what?

Trypanosoma Brucei causes what?

Trypanosoma Cruzi causes what?

Leishmania Donovani causes what?

Leishmania Tropica causes what?

Leishmania Braziliensis causes what?

Balantidum Coli Causes what?

Plasmodium causes what?

Plasmodium vivax causes what?

Plasmodium Malarie causes what?

Plasmodium Falciparum causes what?

Toxoplasma gondii causes what?

Cryptosporidum Parvum causes what?

What are the three types of sporozoa?

How are roundworms tranmitted?

largest nematode parasitizing the human intestine

Although infections may cause stunted growth,
adult worms usually cause no acute symptoms

·     
High worm burdens may cause abdominal pain and
intestinal obstruction 

·     
Migrating adult worms may block bile duct

·     
During the lung phase of larval migration,
pulmonary symptoms can occur

Who am I?

Ova (eggs) are ingested
Larvae hatch in duodenum and move into blood vessels
Larvae move to lungs to molt and mature
In 3 weeks larvae are coughed up and swallowed
Upon reaching small intestine develop into adult worms
Female produces about 200,000 eggs daily
Eggs pass out in feces
Eggs in soil are viable for up to 3 years

Life cycle
Eggs are ingested 
Eggs hatch in small intestine
Larvae then migrate to the cecum and mature into adults
Adult female produces up to 10,000 eggs daily which are shed in feces
The adult worms live in the cecum and ascending
colon.  They are fixed in that location, with the anterior portions threaded into the mucosa

Pathology
Fewer than 100 worms rarely cause clinical symptoms, and the majority of infections are asymptomatic
Heavy worm burden results in 

Anemia --consume blood cells with anterior end buried in mucosa
--Damage to epithelia layer can lead to secondary bacterial infection
--In extreme cases of heavy infection prolapse of the rectum can occur

The worm is considered the pinworm, humans are considered to be the only hosts

Life cycle
Gravid adult female worm is nocturnal 
Migrates out of intestine to lay up to 20,000eggs on perianal skin at night
Eggs are transferred to fingernails by scratching
Eggs are then ingested 
Larvae hatch in small intestine and migrate to colon where mature into adults

Epidemiology     
Worldwide, but appears to be more common in temperate than tropical countries
The most common helminthic infection in the United States (estimated 40 million persons infected)
Infections more frequent in school- or preschool- children and in crowded conditions

Pathology
Frequently asymptomatic.  The most typical symptom is perianal itching, especially at night, which may lead to secondary bacterial infection
Occasionally, invasion of the female genital tract causing vulvovaginitis

These are Roundworms transmitted by direct penetration of infectious larvae

Life cycle
Adult female in small intestine lays 10 to 20,000 eggs daily
Eggs in feces
Larvae hatch, feed on bacteria
Rhabditiform larva molts to filariform larva
Filariform is infective
Filariform larva penetrates bare skin
Moves to lung, are swallowed

Pathology
Larval penetration of skin usually causes little damage, possible dermatitis
Larvae may cause pulmonary symptoms, rarely pneumonitis
Adult worms in small intestine attach to mucosa with strong cutting plates, beginning feeding on blood. 
Anemia, malnutrition

Life cycle
Larvae penetrate skin and wander
Life cycle is not complete in humans, continue to wander aimlessly = creeping eruption (visceral larval migrans)
Intense itching and eosinophilia (excessive eosinophils)

Female in small intestine is ovoviviparous - develop within eggs that remain within the mother up until they hatch or are about to
Eggs are deposited in mucosa, hatch and move to lumen
Larvae are excreted in feces, or cause auto infection
Become free-living adults in soil
Free living adults produce eggs that develop into infectious filariform larvae
Larvae penetrate skin, move through blood to lungs
Molt in lungs, are swallowed and become adults in small intestine

Roundworm Tissue Parasites

Larvae are ingested by humans in flesh of raw fish
Produce intestinal obstruction, pain, nausea and vomiting
higher incidence in areas where raw fish is eaten (e.g., Japan, Pacific coast of South America, the Netherlands) 
No effective drug treatment – surgical only

Life cycle
Encysted larvae are ingested and during digestion reach small intestine where molt to become adults
Adult females produce 100s of larvae
Shortly followed copulation adult male dies, following larval production adult female dies
Larvae are carried via blood to muscle where they encyst
If the host is not consumed, larvae calcify and die
Humans are a dead end host

Pathology
Light infections may be asymptomatic 
Larval migration into muscle tissues can cause facial edema, conjunctivitis, fever, myalgias, rashes, and blood eosinophilia
Occasional life-threatening manifestations include myocarditis, central nervous system involvement, and pneumonitis

Wuchereria bancrofti causes what and is vectored by what?

Life cycle
Females in lymph duct are ovoviviparous and produce 1000s of immature larvae known as microfilariae
Microfilariae released into the lymph and swept into blood through the thoracic duct
Mosquitoes ingest microfilariae in blood meal
Microfilariae mature in mosquito to final infective larval stage

Pathology
When females release microfilariae intense lymphatic inflammation occurs with chills and fever
Lymph nodes become obstructed resulting in swelling
Males – scrotum, legs
Women – legs
Microfilariae exhibit periodicity in the blood, they can be demonstrated during certain times of the day, while other times they seem to disappear from peripheral circulation
Draw blood at night to observe microfilariae

onchocerca volvulus causes what?

onchocerca volvulus is vectored by what?

Life cycle
Adult worms locate under the skin, become encapsulated by host reactions to form nodules
Adult female releases microfilariae 
Microfilariae migrate through skin, to eyes

Pathology
Larvae migrate through skin causing inflammation “lizard skin”
Larvae may migrate to eyes and cause blindness

Platyhelminthes- The Flat Worms
Trematoda - flukes

Name Them

Large
leaf-shaped parasites of herbivores, that can infect humans accidentally

Life cycle
Adult flukes live in the bile duct, eggs are passed out of the liver with the bile and into the intestine to be voided with feces
Larvae penetrate snails
Motile larvae called cercariae leave snail and encyst as metacercariae on water plants
Metacercariae ingested by animal, migrate to liver

Pathology
The liver is damaged by the migration of flukes
Worms in bile ducts cause inflammation, pain, chills and fever

The Chinese liver fluke
Worms mature in the bile ducts and produce up to 4000 eggs a day for at least 6 months

Life cycle
Eggs excreted in feces
Eggs hatch in water and larvae penetrate snails
Larvae mature in snails and cercariae leave snail to penetrate fish
Metacercariae encyst in fish flesh
Humans consume undercooked/raw fish

Life cycle
Eggs in feces hatch in water
Larvae penetrate snails
Cercariae move to plants (usually water chestnuts)
Metacercariae encyst under leaves
Humans or pigs eat water chestnuts

Mature in blood stream of definitive host

Unlike other flukes, schistosomes are dioecious (separate male and female worms)

Schistosoma mansoni

S. haematobium

S. japonicum

All 3 species have similar life cycles

What are all of these Called?

Life cycle
Males and females live in host blood vessels (each species prefer different veins)

Females release 3,000 eggs/day

Eggs pass through tissue to reach intestine or bladder

Eggs reach fresh water in urine or feces

Eggs hatch in fresh water

Infective larval stage penetrates snail

Snail excretes infective cercariae form with a forked tail

Cercaria penetrate the skin of a vertebrate host, mature into adults and reside in veins


Adults may live 20-30 years

Swimmer’s itch – dermatitis from penetration of skin by cercaria
In 1-2 months of infection develop fever, chills, cough 
Most serious damage is done by the eggs

     Eggs lodged in venules and tissue cause immune system                         to respond to foreign invader
       As eggs accumulate enlarged spleen (splenomegaly), ascites (accumulation of fluid in abdominal cavity)
      High eosinophilia

live in the small intestine of the human by attaching to the
intestinal wall by means of a head called a scolex

The body is composed of segments called
proglottids

Each proglottid contains a set male and female organs that
produce eggs

The beef tapeworm

The pork tapeworm

The fish tapeworm

Life cycle

Cattle consume gravid proglottids or eggs in contaminated feeds
The eggs hatch and the larvae migrate to muscle
Larvae encyst in muscle as cysticerci

Pathology
produces only mild abdominal symptoms. 
The most striking feature consists of the passage of proglottids

Life cycle
Morphology and life cycle are similar to T. saginata
Proglottids and eggs eliminated in feces
Pigs consume gravid proglottids or eggs in contaminated feed
The eggs hatch and the larvae migrate to muscle
Larvae encyst in muscle as cysticerci
Cysticercus consists of scolex within a large "bladder;" hence, cysticerci are often referred to a "bladder worms”

Pathology
Cysticercosis
Only occurs with pork tapeworm, T. solium
Infective larvae migrate into muscles and tissue of human host and develop into cysticerci
adult worms rarely cause symptoms
The main symptom is often the passage of proglottids 
The most important feature is the risk of development of cysticercosis 
Cysticerci can develop in brain or eye
This can cause meningitis, visual disturbance and acute inflammation

Life cycle
Eggs are eliminated in feces
Eggs hatch in water, larvae are called coracidium
Coracidium are ingested by copepods
Copepods are eaten by fish
Larvae mature to sparganum and encyst in fish muscle
Infection from undercooked fish

Pathology
Infections can be a long-lasting (decades) 
Most infections are asymptomatic 
Manifestations may include abdominal discomfort, diarrhea, vomiting, and weight loss
Vitamin B12 deficiency with anemia may occur. 
Tapeworm absorbs large amounts of B12

Life cycle
Adult worms infect canines and release eggs in small intestine
Eggs eliminated in feces and ingested by sheep, cattle, pigs etc.
Humans are accidental hosts, transmission is usually by contact with infected dog
Dogs may be infected by eating viscera of livestock

Human infection
Larvae move into liver or lung and form hydatid cyst
Cyst contains infectious worms called hydatid sand

Pathology
infections remain silent for years before the enlarging cysts
cause symptoms in the affected organs
Hepatic involvement can result in abdominal pain, a mass in the hepatic area, and biliary duct obstruction
Pulmonary involvement can produce chest pain and cough
Rupture of the cysts can produce fever, eosinophilia, and anaphylactic shock, as well as cyst dissemination
In addition to the liver and lungs, other organs (brain, bone, heart) can also be involved, with resulting symptoms

Pathology
Immunocompetent persons is generally an asymptomatic infection 
In patients with AIDS, is the most common cause of intracerebral mass lesions and is thought to be caused by reactivation of chronic infection  
Results from an acute primary infection acquired by the mother during pregnancy 
Invades CNS and may cause blindness, encephalitis, mental
retardation

Transmission
Ingestion of undercooked infected meat containing oocysts
Ingestion of the oocyst from fecally contaminated hands or food
Transplacental transmission

Very low host specificity
Definitive host  = domestic cat and wild cats
Life stages
Sporozoites are infectious form
Sporozoites are within oocyst that passes out in feces

Similar to P. vivax
Common in Africa
Produces fewer merozoites
Relapse is common

Common in the tropics, most serious disease
Multiple sporozoites infect one RBC- creating “signet ring” formation
Daily fever, becoming tertian (36 to 48 hours) 
Chills, nausea
Infection restricted to liver and spleen
Blackwater fever is characterized by intravascular hemolysis and kidney failure
Cerebral malaria can ensue- mental status changes, coma, death

Less common than P. vivax
No enlarged RBCs
Distinctive banding pattern
Asexual forms in RBCs appear as rosettes
No relapses
Fever occurs in 72 hour pattern
Called quartan or malarial malaria

Most common cause of malaria called benign tertian malaria
Infected red cells have unique pink dots = Schuffner’s dots
Stage in RBC is ring shaped
Infected RBC is large
Characterized by fevers that typically occur every other day
Relapse from latent liver infection common

In the vertebrate host two cycles occur
Exoerythrocytic stage – in liver
Erythrocytic stage – in RBCs
Merozoites in RBCs produce waste product called malarial pigment
Lysis of RBCs cause anemia and jaundice of malaria

Lifestages
Sporozoites released from mosquito into human host, go to liver
Undergoasexual reproduction (schizogony) to produce merozoites
Merozoites = infect and destroy red blood cells causing symptoms of malaria
Gametocytes = produced as result of erythrocytic stage in RBC, taken up by female mosquito

Large ciliated trophozoite form
Cyst form is present
Transmission
Fecal contaminated water, particularly associated with infected pig feces
Pathology
Abdominal pain, watery, bloody stools

Life stage is protozoa form, no cyst
Transmission
Vectored by the sandfly
Pathology
Lesions in the junction of the pharynx result in the break down of the palate of the mouth and nose 

Life stage is protozoa form, no cyst
Transmission
Vectored by the sandfly
Pathology
Invades liver, spleen, kidney
Causes enlarged liver, spleen, wasting, and finally death (in untreated) in 2-3 years
Following treatment a condition known as post-kala azar dermal leishmanoid = a granulomatis reaction on the skin about 2-3 years after treated

Life stage is protozoa form called trypanosome, no cyst
Transmission
vectored by the reduviid bug (kissing bug) via defecation by bug into wound
Pathology
Acute Chagas’ disease 
Small red nodule called chagoma at bite site
Heart, liver, spleen and lymph nodes are infected
Symptoms include anemia, nervous disorders, muscle and bone pain, heart failure
Death may ensue after 3 to 4 weeks
Most common in children
Chronic Chagas’ disease
Symptoms are primarily nervous dysfunction with may continue for years
Individual may be virtually asymptomatic and suddenly die of heart failure

Life stage is protozoa form called trypanosome, no cyst
Transmission
vectored by the Tse-Tse fly 
Pathology
In vertebrate host trypanosomes live in blood, lymph nodes, spleen and CSF
Do not invade or live in cells, but rather in tissue spaces particularly in CNS
Within a few days animals becomes emaciated, uncoordinated, and paralyzed… then dies
Humans tend to experience mental dullness, tendency to sleep finally coma and death

Trophozoite has 4 flagella
NO CYST form
Transmission
Trophozoites are passed sexually causing urogenital infections
Pathology
Green discharge, itching in females; urethritis in males

Two life stages
Trophozoite- the active feeding stage
Cyst-similar to endospore, resistant to environment and infective
Transmission
Cysts ingested in contaminated water, particularly near beaver populations, beavers are reservoir
Pathology
Cysts excyst in intestine, reproduce and cover intestinal wall
Interfere with fat absorption, causing fatty stools and diarrhea

Two life stages
Trophozoite- the active feeding stage, pseudopods
Cyst- similar to endospore, resistant to environment and infective
Transmission
Cysts ingested in contaminated water, food- use of nightsoil increases chance of contamination.  Can be vectored by flies.
Pathology
Cysts excyst in intestine causing bloody diarrhea, if trophozoites enter blood move to liver causing hepatic
amebiasis- a collection of pus in the liver.

Single celled eukaryotes
Divide by binary fission or budding

Fungi that produce mycelia
Multicellular
Composed of hyphae - long, branching filament that, with other hyphae, forms the feeding thallus of a fungus called the mycelium

Hyphae are either 

Septate- walls that divide hyphae intocells
Aseptate- no walls

Sexual spores are free zygotes
Asexual spores are enclosed in sac-like structure called a sporangium

Sexual spores enclosed in sacs called asci
Asexual spores are exogenous, formed at the end of the hyphae

Sexual spores found on basidia

No sexual stage
"fungi imperfecti"

Found worldwide, concentrated in U.S. in Midwest and Eastern U.S.
Found in soil contaminated with bat and bird feces (frequently in caves)
Spores are inhaled 

Found in Southwestern U.S. (NM, AZ)
Inhale arthrospore (spores united in the form of a string of beads, formed by fission
Most infections are asymptomatic, maybe only slight fever

Spores are inhaled into lungs where they transform to a yeast form of the microbe
50% of individuals are symptomatic, with flu-like illness with productive cough

Amphotericin B- binds to sterols, preferentially to the primary fungal cell membrane sterol, ergosterol.  
Disrupts cell, causing lysis

Occupational hazard for greenhouse workers, gardeners
Fungi enter via skin lesion, transform to yeast form
Nodules and skin lesions appear along lymphatic system 

Invade dead keratinized tissue (hair, nails)
Major genera include:
Trichophyton
Microsporum
Epidermophyton

Tinea infections- Tinea is the name given to a fungal skin infection. Synonymous with dermatophyte (are contagious)
Tinea pedis – athlete’s foot
Tinea corporis – trunk or extremities
Tinea capitis – head, causes hair loss
Tinea unguium – nails

Yeast is part of normal flora.
Heat, humidity, and sweat help it proliferate in some people
Tinea versicolor is not contagious
KOH wet mount looking for yeast cells
Wood’s lamp - lamp emits ultraviolet light. If there is an infection on the area where the Wood's lamp is illuminating, the area will fluoresce. Normally the skin does not fluoresce, or shine, under ultraviolet light 

Part of normal flora in mouth, gut, vagina
Pathogen when normal conditions are altered- antibiotics, depressed immunity 
Thrush, skin infections

Large encapsulated yeast
Microbe enters the host via respiratory route 
After some time in the lungs C. neoformans spreads to extrapulmonary tissues
It has a predilection for the brain, infected persons usually contract meningoencephalitis 

It is not yet established whether it is a fungus or a protozoan.
Antigenic differences have been found in strains derived from the various mammalian hosts. 
In normal individuals, asymptomatic infection of the lungs occurs in early life.
The organism persists in an
inactive or latent state unless the host becomes immunocompromised