Microbiology- Exam 3 (Part 3) Eukaryotic Diseases: Fungi, Algae, Protists, Helminths*

Endosymbiotic Theory

proposes that mitochondria and chloroplasts originated as free-living bacteria that were engulfed by ancestral eukaryotic cells.

• Over time, the bacteria and host formed a mutualistic relationship, becoming permanent organelles.

Which organelles are thought to have arisen from endosymbiosis?

Mitochondria and chloroplasts

Describe the evidence mitochondria and chloroplasts provide for the endosymbiotic theory

1. Independent division

2. Circular DNA

3. Prokaryotic-sized ribosomes

4. Double membranes

5. Bacterial ancestry

What is unique about fungal cell walls and membranes?

chitin-based cell walls and

ergosterol-rich membranes

Fungal Infections are classified by ________

depth

Are there approved antifungal vaccines?

No

Candidiasis genus

Candida

*opportunistic pathogen*

Describe Candidiasis Infection

common fungal infection caused overgrowth of Candida yeast, typically Candida albicans, which normally lives on the skin and in the body (mouth, gut, vagina) without causing harm *it is opportunistic*

most common species of Candidiasis

Candida albicans

What is Candidiasis known for causing?

commonly produces white, curd-like patches

As a member of your residential flora, where can you expect candidiasis to be found?

skin, mouth, vagina, gut

Candidiasis Common forms of infection

• Oral thrush

• Cutaneous candidiasis

• Vulvovaginal candidiasis

• Systemic candidiasis

dermatophytes

Invade keratinized tissues: skin, hair, and nails.

*keratin-digesting molds*

3 genus examples of Dermatophytosis (Ringworm, Athlete's Foot)

Trichophyton, Microsporum, and Epidermophyton

What are common diseases examples that dermatophytes may cause

• Tinea pedis - athlete's foot

• Tinea unguium - nails

Dermatophytosis (Ringworm, Athlete's Foot) Treatment

topical antifungals

what signs/symptoms manifest from Dermatophytosis (Ringworm, Athlete's Foot)

circular, red, scaly lesions

Histoplasmosis Common Name

"Ohio Valley Fever"

Histoplasmosis Causative Agent

Histoplasma capsulatum

What organ does Histoplasmosis primarily affect?

Lungs

Where is Histoplasmosis naturally found? And what is it often associated with?

soil and bird or bat droppings

Cryptococcosis Causative Agent

Cryptococcus neoformans

What is Cryptococcosis

Encapsulated yeast found in soil and pigeon droppings

How is Cryptococcosis acquired?

inhalation of fungal cells or spores

Cryptococcosis symptoms

lung infections

severe clinical form of Cryptococcosis

cryptococcal meningitis

Ergotism Causative Agent

Claviceps purpurea

Ergotism transmission results form eating __________

grains (especially rye) contaminated with the fungus Claviceps purpurea

In Ergotism; The fungus replaces grain kernels with ______________ which contain potent _______________

ergot sclerotia; ergot alkaloid toxins

3 effects of ergot alkaloid toxins (Ergotism)

• Vasoconstriction → restricted blood flow → tissue necrosis and gangrene

• Neurotoxic effects → hallucinations, convulsions, and altered behavior

• Uterotonic activity → miscarriage or premature labor

common symptoms of Ergotism

hallucinations, psychosis, severe seizures, muscle spasms, etc.

Is ergotism caused by fungal growth or toxin ingestion?

toxin ingestion

What is the only known algae to infect human tissue?

Prototheca (achlorophyllic *lack chlorophyll and

cannot photosynthesize*, opportunistic)

tissues Prototheca typically infect

human skin, subcutaneous tissues

Instead of infections most algae are a threat to humans because ____________

they produce potent natural toxins (cyanotoxins)

Discuss dinoflagellates and cyanobacteria in context of harmful algal blooms and the toxins they produce

produce potent neurotoxins and hepatotoxins.

• When they overgrow, they form Harmful Algal Blooms (HABs) such as red tides.

Human illnesses from algal toxins

• Ciguatera fish poisoning

• Paralytic shellfish poisoning (PSP)

• Microcystin poisoning

Giardia Causative Agent

Giardia lamblia

How common is Giardia in the US?

Very common,

-Most frequently diagnosed intestinal parasitic disease in the United States

Where is Giardia found in the environment

contaminated water, food, or direct contact

How is Giardia transmitted

fecal-oral route via contaminated water, food, or direct contact

What portion of Giardia's life cycle can withstand environmental stressors?

cysts

Giardia symptom

greasy, foul-smelling diarrhea

Trichomoniasis Causative Agent

Trichomonas vaginalis

Trichomoniasis: Most common _______ disease in people of ________________

non-viral sexually transmitted; industrialized nations

Are antibiotics useful for Trichomoniasis?

Yes, very

Does Trichomoniasis have a Trophozoite or cyst form?

exists only as a trophozoite

Trichomoniasis symptoms in women then men

• Females – itching, yellow-green discharge, irritation, odor.

• Males – often asymptomatic or mild urethritis.

Trichomoniasis transmission

sexual contact

Toxoplasmosis Causative Agent

Toxoplasma gondii

Toxoplasmosis host?

*Where does sexual reproduction take place?

domestic cats

*sexual reproduction in intestinal epithelium

What group of people should be more cautious of Toxoplasmosis (Toxoplasma gondii)?  

Pregnant women

Toxoplasmosis transmission pathways

ingestion of oocysts from cat feces, or transplacental transfer

Toxoplasmosis synptoms

often asymptomatic; latent

Malaria Causative Agent

Plasmodium spp.

Malaria Vector

mosquitoes

Malaria Life Cycle

Sporozoites enter via mosquito bite → infect liver →

merozoites released → invade red blood cells.

• RBC rupture releases more parasites → cyclic fevers and chills

Malaria symptoms

intermittent fever, anemia, splenomegaly

Is Malaria resistance to medicines?

Resistance to antimalarial medicines is a recurring problem

regions Malaria is commonly found in

sub-Saharan Africa

Malaria prevention methods

bed nets, antimalarial drugs, vector control, and vaccines

Primary Amebic Meningoencephalitis (PAM) Causaitve Agent

Naegleria fowleri

What part of the human body does Primary Amebic Meningoencephalitis infect

human brain and central nervous system

Where Primary Amebic Meningoencephalitis is found in environment

warm freshwater (lakes, rivers, hot springs, poorly chlorinated pools)

How Primary Amebic Meningoencephalitis enters a human host

water containing amoebae enters the nasal passages during swimming or diving

Primary Amebic Meningoencephalitis Mortality Fate

>97% fatal;

*only a handful of survivors documented worldwide.

Ascariasis Causative Agent

Ascaris lumbricoides

Where do you find Ascariasis when infecting humans?

small intestine

Ascariasis cause

ingesting infective eggs

Ascariasis symptoms

mostly asymptomatic;

and growth impairment in heavy infections.

Schistosomiasis (Bilharzia) Causative Agent

Schistosoma spp.

Schistosomiasis alternative name

Bilharzia

Schistosomiasis transmission pathway

Trematode (fluke) transmitted by freshwater snails that release infectious larva.

Schistosomiasis initial and severe symptoms

initial: abdominal pain, blood in stool or urine

severe: liver and bladder scarring

Example of a NTD (what does this mean?)

Schistosomiasis

NTD: neglected tropical disease

Elephantiasis alternative name

Lymphatic Filariasis

Elephantiasis Causative Agents

Wuchereria bancrofti and Brugia malayi

Elephantiasis vector

mosquitoes

Elephantiasis relationship to the lymph system

Adult worms inhabit lymphatic vessels, obstructing drainage of lymph.

• Leads to extreme swelling (lymphedema) of limbs, breasts, or genitals → elephantiasis

• Hardening and thickening of skin

Locations of lymphedema (in Elephantiasis)

limbs, breasts, or genitals