Single celled eukaryotes
How do yeasts divide?
Divide by binary fission or budding
Multicellular fungi that produce mycelia
What are Hyphae?
long, branching filament that, with other hyphae, forms the feeding thallus of a fungus called the mycelium
What is the mycelium?
feeding thallus of a fungus
Hyphae are either?
Septate- walls that divide hyphae into cells/ Aseptate- no walls
What are the 4 groups of mold?
- Deuteromycetes (Fungi imperfecti)
Describe 1. Phycomycetes
a. Sexual spores are free zygotes
b. Asexual spores are enclosed in sac-like structure called a sporangium
Describe 2. Ascomycetes
a. Sexual spores enclosed in sacs called asci
b. Asexual spores are exogenous, formed at the end of the hyphae
Describe 3. Basidiomycetes
a. Sexual spores found on basidia
Describe 4. Deuteromycetes (Fungi imperfecti)
a. No sexual stage
What are the types of Systemic mycoses?
- Histoplasmosis (Spelunker’s Disease)
- Coccidiomycosis (Valley Fever)
Describe • Histoplasmosis (Spelunker’s Disease)
o Caused by Histoplasma capsulatum (Ascomycota)
o Found worldwide, concentrated in U.S. in Midwest and Eastern U.S.
o Found in soil contaminated with bat and bird feces (frequently in caves)
o Spores are inhaled
Describe • Coccidiomycosis (Valley Fever)
o Caused by Coccidioides immitis
o Found in Southwestern U.S. (NM, AZ)
o Inhale arthrospore (spores united in the form of a string of beads, formed by fission
o Most infections are asymptomatic, maybe only slight fever
Describe • Blastomycosis
o Caused by Blastomyces dermatitis
o Spores are inhaled into lungs where they transform to a yeast form of the microbe
o 50% of individuals are symptomatic, with flu-like illness with productive cough
Describe reatment of systemic fungi.
• Amphotericin B- binds to sterols, preferentially to the primary fungal cell membrane sterol, ergosterol. Disrupts cell, causing lysis
Sporotrichosis- “rose handler’s disease” is what kind of mycosis?
Describe Sporotrichosis- “rose handler’s disease”.
o Caused by Sporothrix schenckii
o Occupational hazard for greenhouse workers, gardeners
o Fungi enter via skin lesion, transform to yeast form
o Nodules and skin lesions appear along lymphatic system
Describe Dermatophytoses (general).
- Invade dead keratinized tissue (hair, nails)
- Major genera include:
What kind of infections are Tinea infections?
What are the types of Tinea infection?
o Tinea pedis – athlete’s foot
o Tinea corporis – trunk or extremities
o Tinea capitis – head, causes hair loss
o Tinea unguium – nails
Tinea versicolor is what type of mycosis?
Describe Tiena versicolor.
o Yeast is part of normal flora.
o Heat, humidity, and sweat help it proliferate in some people
o Tinea versicolor is not contagious
o KOH wet mount looking for yeast cells
o 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
List the 3 Pathogenic yeasts.
o Caused by Candida albicans
o Part of normal flora in mouth, gut, vagina
o Pathogen when normal conditions are altered- antibiotics, depressed immunity
o Thrush, skin infections
o Caused by Cryptococcus neoformans
o Large encapsulated yeast
o Microbe enters the host via respiratory route
o After some time in the lungs C. neoformans spreads to extrapulmonary tissues
o It has a predilection for the brain, infected persons usually contract meningoencephalitis
- It is not yet established whether P carinii 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
Life stages of a parasite include?
- Immatures = larvae (nymph)
Definitive host = ?
one in which parasite reproduces
Intermediate host = ?
one in which development occurs, but no reproduction
Diagnosis of Intestinal parasites includes?
Diagnosis of Blood parasites includes?
thick (finding parasite) and thin (ID parasite) specimens
Diagnosis of Tissue parasites includes?
biopsy, especially muscle
Protozoa are what kind of parasites?
Eukaryotic single celled parasites
Entamoeba histolytica, describe the life stages.
Two life stages
o Trophozoite- the active feeding stage, pseudopods
o Cyst- similar to endospore, resistant to environment and infective
Entamoeba histolytica describe the transmission.
Cysts ingested in contaminated water, food- use of nightsoil increases chance of contamination. Can be vectored by flies.
Entamoeba histolytica describe pathology caused.
Cysts excyst in intestine causing bloody diarrhea, if trophozoites enter blood move to liver causing hepatic amebiasis- a collection of pus in the liver.
Giardia lamblia is what kind of protozoa?
Giardia lamblia causes what?
– cause of giardiasis, also known as beaver fever
Giardia lamblia: describe life stages.
o Trophozoite- the active feeding stage
o Cyst- similar to endospore, resistant to environment and infective
Giardia lamblia: describe transmission
Cysts ingested in contaminated water, particularly near beaver populations, beavers are reservoir
Giardia lamblia: describe life stages.
Cysts excyst in intestine, reproduce and cover intestinal wall
Interfere with fat absorption, causing fatty stools and diarrhea
Trichomonas vaginalis causes what disease and has what UNIQUE feature(s)?
Causes trichomoniasis, NO CYST formation, 4 flagella.
Trichomonas vaginalis describe transmission
Trophozoites are passed sexually causing urogenital infections
Trichomonas vaginalis describe the pathology
Green discharge, itching in females; urethritis in males
Trypanosoma brucei causes what?
African trypanosomiasis – African sleeping sickness .
Trypanosoma brucei describe life stages.
Life stage is protozoa form called trypanosome, no cyst
Trypanosoma brucei, describe Transmission.
Trypanosoma brucei is vectored by the Tse-Tse fly
Trypanosoma brucei, describe Pathology.
o In vertebrate host trypanosomes live in blood, lymph nodes, spleen and CSF
o Do not invade or live in cells, but rather in tissue spaces particularly in CNS
o Within a few days animals becomes emaciated, uncoordinated, and paralyzed… then dies
o Humans tend to experience mental dullness, tendency to sleep finally coma and death
Trypanosoma cruzi causes what?
Chagas’ disease (Mexico, South, Central Am.)
Trypanosoma cruzi, describe life stage.
o Life stage is protozoa form called trypanosome, no cyst
Trypanosoma cruzi, describe transmission.
T. cruzi is vectored by the reduviid bug (kissing bug) via defecation by bug into wound
Describe Acute Chagas’ disease
o Small red nodule called chagoma at bite site
o Heart, liver, spleen and lymph nodes are infected
o Symptoms include anemia, nervous disorders, muscle and bone pain, heart failure
o Death may ensue after 3 to 4 weeks
o Most common in children
Describe Chronic Chagas’ disease
o Symptoms are primarily nervous dysfunction with may continue for years
o Individual may be virtually asymptomatic and suddenly die of heart failure
Leishmania donovani- causes what?
visceral leishmaniasis- called Kala-azar
Leishmania donovani, describe life stage.
o Life stage is protozoa form, no cyst
Leishmania donovani, describe transmission.
Vectored by the sandfly
Leishmania donovani, describe the pathology.
o Invades liver, spleen, kidney
o Causes enlarged liver, spleen, wasting, and finally death (in untreated) in 2-3 years
o Following treatment a condition known as post-kala azar dermal leishmanoid = a granulomatis reaction on the skin about 2-3 years after treated
Leishmania tropica – causes what?
causes cutaneous leishmaniasis or Oriental sore
Leishmania tropica – describe lifestage.
Life stage is protozoa form, no cyst
Leishmania tropica – describe transmission.
Vectored by the Sandfly
Leishmania tropica – describe the pathology.
o Lesions in the junction of the pharynx result in the break down of the palate of the mouth and nose
Balantidium coli – is what kind of protozoa?
causes ciliary dysentery
Balantidium coli – describe lifestage.
o Large ciliated trophozoite form
o CYST IS PRESENT
Balantidium coli – describe transmission.
Fecal contaminated water, particularly associated with infected pig feces
Balantidium coli – describe the pathology.
o Abdominal pain, watery, bloody stools
List the Eukaryotic single celled parasites – The Sporozoa.
- Cryptosporidium parvum
Toxoplasma causes what?
Toxoplasma – describe lifestage.
- Sporozoites are infectious form
- Sporozoites are within oocyst that passes out in feces
Toxoplasma – describe transmission.
Definitive host = domestic cat and wild cats
o Ingestion of undercooked infected meat containing Toxoplasma oocysts
o Ingestion of the oocyst from fecally contaminated hands or food
o Transplacental transmission
Toxoplasma – describe the pathology.
o Infection with Toxoplasma in immunocompetent persons is generally an asymptomatic infection
o In patients with AIDS, toxoplasmic encephalitis is the most common cause of intracerebral mass lesions and is thought to be caused by reactivation of chronic infection
o Congenital toxoplasmosis results from an acute primary infection acquired by the mother during pregnancy
o Infection during the 1st trimester is most damaging
o T. gondii invades CNS and may cause blindness, encephalitis, mental retardation
Describe Cryptosporidium parvum
o Difficult to detect in water (water treatment)
o Ingestion of cysts cause watery diarrhea (similar to Giardia infection)
List the Nematodes (Roundworms)
- Ascaris lumbricoides
- Trichuris trichiura
- Enterobius vermicularis
Ascaris lumbricoides - describe.
largest nematode parasitizing the human intestine
Ascaris lumbricoides - describe lifecycle.
- 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
Ascaris lumbricoides - describe the pathology.
- 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
Trichuris trichiura, what is it?
– the whip worm
Trichuris trichiura - describe the 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
Trichuris trichiura - describe the Pathology.
• Fewer than 100 worms rarely cause clinical symptoms, and the majority of infections are asymptomatic
• Heavy worm burden results in
o Anemia – consume blood cells with anterior end buried in mucosa
o Damage to epithelia layer can lead to secondary bacterial infection
o In extreme cases of heavy infection prolapse of the rectum can occur
Enterobius vermicularis - what is it?
– the pinworm, humans are considered to be the only hosts
Enterobius vermicularis - describe the Life cycle
- Gravid adult female worm is nocturnal
- Migrates out of intestine to lay up to 20,000 eggs 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
Enterobius vermicularis - describe 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
Enterobius vermicularis - describe the 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
How are roundworms transmitted?
Roundworms transmitted by direct penetration of infectious larvae
American hookworm – give the 2 names.
Ancylostoma duodenale and Necator americanus
American hookworm – describe the 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
American hookworm – describe the 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
Ancylostoma braziliense - what are they?
Dog and cat hookworm
Ancylostoma braziliense - describe lifecycle.
- Larvae penetrate skin and wander
* Life cycle is not complete in humans, continue to wander aimlessly = creeping eruption (visceral larval migrans)
Ancylostoma braziliense - describe symptoms.
• Intense itching and eosinophilia (excessive eosinophils)
Strongyloides stercoralis, what is unique about them?
- alternates between free-living and parasitic forms
Strongyloides stercoralis, give a general description.
- 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
List the hookworms
American hookworm, Ancylostoma braziliense, & Strongyloides stercoralis
List the Roundworm Tissue Parasites
- Trichinella spiralis
- Filarial worms – Wuchereria bancrofti & Onchocerca volvulus
What are Anisaka?
- parasites in the stomachs of marine fish and birds
Anisaka - describe them.
- 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
Trichinella spiralis – describe hosts.
low host specificity, bears, pigs, rats
Trichinella spiralis – describe their 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
Trichinella spiralis – describe the 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 - cause what?
Bancroftian filariasis is better known as elephantiasis
Wuchereria bancrofti - vectored by?
Wuchereria bancrofti - describe the 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
Wuchereria bancrofti - describe 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 – cause what?
Onchocerca volvulus – Vectored by?
a black fly, Simulium
Onchocerca volvulus – describe 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
Onchocerca volvulus – describe Pathology
- Larvae migrate through skin causing inflammation “lizard skin”
- Larvae may migrate to eyes and cause blindness
Platyhelminthes- are what?
The Flat Worms
Platyhelminthes- The Flat Worms - what are the categories?
Trematoda - flukes & Cestoda – Tapeworms
List the Trematoda - flukes.
- Fasciola hepatica – the liver fluke
- Clonorchis sinensis – the Chinese liver fluke
- Fasciolopsis buski- giant intestinal fluke
- Schistosomes: the blood flukes
Fasciola hepatica – what are they?
- the liver fluke
• Large leaf-shaped parasites of herbivores, that can infect humans accidentally
Fasciola hepatica – describe the 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
Fasciola hepatica – describe the Pathology
- The liver is damaged by the migration of flukes
* Worms in bile ducts cause inflammation, pain, chills and fever
Clonorchis sinensis – what are they?
- the Chinese liver fluke
• Worms mature in the bile ducts and produce up to 4000 eggs a day for at least 6 months
Clonorchis sinensis – describe the 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
Clonorchis sinensis – describe the acquisition.
• Humans consume undercooked/raw fish
Fasciolopsis buski- what are they?
giant intestinal flukes
Fasciolopsis buski- describe the Life cycle
- Eggs in feces hatch in water
- Larvae penetrate snails
- Cercariae move to plants (usually water chestnuts)
- Metacercariae encyst under leaves
Fasciolopsis buski- describe how we get them
• Humans or pigs eat water chestnuts
Schistosomes: are what?
the blood flukes
Schistosomes: list the types.
Schistosomes: what is unique about them?
Unlike other flukes, schistosomes are dioecious (separate male and female worms)
Schistosomes: describe the 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
Schistosomes: describe the Pathology (WHAT CAUSES THE MOST DAMAGE?)
• 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
o Eggs lodged in venules and tissue cause immune system to respond to foreign invader
o As eggs accumulate enlarged spleen (splenomegaly), ascites (accumulation of fluid in abdominal cavity)
o High eosinophilia
Cestoda – are what?
The body of the tapeworm is composed of?
segments called proglottids
Each proglottid contains?
A set male and female organs that produce eggs
Four tapeworms of importance to human health, name them.
- The beef tapeworm- Taenia saginata
- The pork tapeworm- Taenia solium
- The fish tapeworm- Diphyllobothrium latum
- Echinococcus granulosus
Taenia saginata describe life cycle.
- Cattle consume gravid proglottids or eggs in contaminated feed
- The eggs hatch and the larvae migrate to muscle
- Larvae encyst in muscle as cysticerci
Taenia saginata describe pathology.
- Taenia saginata produces only mild abdominal symptoms.
- The most striking feature consists of the passage of proglottids
Taenia solium describe
- 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”
Taenia solium describe the Pathology
• Only occurs with pork tapeworm, T. solium
• Infective larvae migrate into muscles and tissue of human host and develop into cysticerci
• Taenia solium adult worms rarely cause symptoms
• The main symptom is often the passage of proglottids
• The most important feature of Taenia solium taeniasis is the risk of development of cysticercosis
• Cysticerci can develop in brain or eye
• This can cause meningitis, visual disturbance and acute inflammation
Diphyllobothrium latum: describe the 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
Diphyllobothrium latum: describe the 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
Echinococcus granulosus: describe the 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
Echinococcus granulosus: describe the Human infection.
- Larvae move into liver or lung and form hydatid cyst
- Cyst contains infectious worms called hydatid sand
Echinococcus granulosus: describe the Pathology.
- E. granulosus 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
What is Plasmodium?
How is Malaria (plasmodium) vectored?