micro

Cestodes

Tapeworms

Where do tapeworms live?

Small intestine

scolex

Head of the tapeworm

Schistoma

Blood flukes

How do you get Schistoma

Intermediate/definitive host

Swimming

Snails/human

Lifecycle of Schistosoma and symptoms

Eggs, leave body in urine/feces

Eggs hatch into miracidia

Infect snails

Snails release cercariae

Penetrate human skin

Adults mature in blood vessels

Adult lay eggs

Swimmers itch, fever, enlarged spleen and liver, bloody urine, intestinal disease

Ascaris lumbricoides transmission, symptoms, reservoir

Vehicle (fecal oral route food water soil)

Abdominal pain, intestinal blockage, cough during lung migration malnutrition

Reservoir is humans

Lifecycle of ASCARIS

Egg swallowed

Lava hatching intestine

Travel through bloodstream to lungs

Cough up/swallowed

Adults develop in intestine

Trichinella Spiralis transmission and symptoms

Eating undercooked pig/wild game, encysted in muscle

Muscle pain, fever, swollen eyelids weakness, eosinophilia

Ancylostoma duodenale

Nector americanus

Hookworm

Transmission of hookworm and symptoms

Larvae penetrates bear skin

Ground itch, iron deficiency, fatigue, weakness

Anisakis simplex transmission reservoir symptoms

Eating raw/undercooked marine fish

Marine mammals

Sudden abdominal pain, nausea, vomiting allergic reaction reactions

Enterobius Vermicularis transmission and symptoms

Pinworms

Vehicle (Fecal oral)

Intense nighttime anal itching, trouble, sleeping irritability

Pinworms lifecycle

Swallow eggs

Adults develop in intestine

Female lays eggs around anus

Scratching spreads the eggs

Amphotercin B

Targets and side effects

ergosterol Informed spores causing cell contents to leak out

Kidney toxicity/fever/chills during infusion

Azoles

Targets

Ergosterol synthesis (prevents ergosterol production)

Examples: ketoconazole, itraconazole

Fluconazole

Griseofuluin

Targets microtubules

Stops fungal mitosis

Used for derm infections

5-Flucytosine

Targets DNA/RNA

often used with Amphotercin B

Echinocanding

Targers B- fungal cell wall

Inhibits glucan synthesis weakening cell wall

Examples: caspofungin, micafungin, anidulafungin

Histoplasma capsulatium

Reservoir

Symptoms

Transmission

Soil contaminated with bird/bat droppings near Ohio/Mississippi river valley

Inhaling

Fever, dry, cough, chest pain, fatigue

Blastomyces Dermatiditis (Blastomycosis)

Reservoir

Transmission

Symptoms

Moist soil, decaying wood/leaves, Great Lakes

Inhaling

Starts in lungs, skin, ulcerated lesions, bones, prostate

Coccidioides immitis (coccidioidomycosis)

Transmission

Reservoir

Symptoms

Inhaling

Desert soil, southwest United States

Fever, chest pain, dry, cough, fatigue, joint pain

Forms spherules in tissue

Paracoccidioides Brasiliensis

Soil in central/South America

Transmitted through inhalation

Lung infection, mouth, ulcers, swollen, lymph nose

Pneumocystis jirovecii (pneumocystis pneumonia)

Contact

Most opportunistic infections in AIDS

Symptoms are dry, cough, fever, shortness of breath low O2 diagnose through chest x-rays and examined respiratory samples

Candida albicans

Normal flora lives on mouth, skin G.I. tract in vagina

Overgrowth due to antibiotics, diabetes, pregnancy, HIV/AIDS steroids chemo

Cryptococcus neoformans

Pigeon droppings soil

Transmitted through inhaling

Symptoms are meningitis headache, fever confusion, neck, stiffness

Dermatophytes

Ringworm

In fact, skin nails hair

Tinea pedis

Athletes foot

Itching peeling cracks between toes

Tinea cruris

Jock itch

Red itching rash groin area

Tinea unguium (onychomycosis)

Nail Fungus

Thick nails, yellow nails, brittle nails

Entamoeba histolytica (Amebic Dysentery)

• Fecal-oral route

• Ingestion of cysts in contaminated food or water

Infectious Stage

✅ Cyst

Disease Stage

✅ Trophozoite

Symptoms

• Bloody diarrhea (dysentery)

• Abdominal pain

• Liver abscess (can spread from the intestine)

Reservoir

Humans

Unique Feature

Flask-shaped ulcers in the intestinal wall

Memory Trick: Entamoeba Eats the intestine.

Naegleria fowleri

Brain eating amoeba

Reservoir

Warm freshwater:

• Lakes

• Hot springs

• Poorly chlorinated pools

Transmission

Water forced up the nose (not by drinking).

Route

Nose → Olfactory nerve → Brain

Disease

Primary amoebic meningoencephalitis (PAM)

Symptoms

• Severe headache

• Fever

• Neck stiffness

• Confusion

• Rapid progression to coma

Important Exam Point

❌ You do NOT get infected by drinking the water.

Memory Trick: Nose → Brain.

Trypanosoma cruzi (Chagas Disease)

Vector

🪲 Kissing bug (Triatomine bug)

Transmission

The bug bites, then defecates. Parasites in the feces enter through the bite wound or eyes when the person scratches.

Reservoir

Wild and domestic mammals

Symptoms

Acute

• Fever

• Swelling around one eye (Romaña sign)

Chronic

• Enlarged heart (cardiomyopathy)

• Megaesophagus

• Megacolon

Unique Feature

Xenodiagnosis

• Uninfected kissing bugs feed on a patient.

• The bugs are later examined for the parasite.

Memory Trick: Cruzi = Kissing Bug ❤

Trypanosoma brucei

African sleeping sickness

Vector

🪰 Tsetse fly

Reservoir

Humans and wild animals

Symptoms

• Fever

• Swollen lymph nodes

• Fatigue

• Sleep disturbances

• Confusion

• Coma (late stage)

Unique Feature

Antigenic variation

• Changes its surface glycoproteins (VSGs) to evade the immune system.

This is why it’s difficult for the immune system to eliminate the parasite.

Memory Trick: Brucei = Tsetse fly → Sleep.

Giardia intestinalis (Giardiasis)

Reservoir

• Humans

• Beavers (“Beaver Fever”)

• Other mammals

Transmission

• Fecal-oral route

• Drinking contaminated water

• Daycare centers

• Camping/hiking

Infectious Stage

✅ Cyst

Active Stage

✅ Trophozoite

Symptoms

• Foul-smelling, greasy diarrhea

• Bloating

• Flatulence

• Weight loss

• Malabsorption (fat isn’t absorbed well)

Usually NO blood in the stool.

Full Life Cycle

1. Person ingests cysts in contaminated food or water.

2. Cysts pass into the small intestine.

3. They become trophozoites.

4. Trophozoites attach to the intestinal wall using a ventral adhesive disc.

5. They multiply by binary fission.

6. As they move toward the colon, they become cysts again.

7. Cysts are passed in feces and infect the next host.

Memory Trick

🏕 Camping + Beaver = Giardia

🦠 Trichomonas vaginalis (Trichomoniasis)

Transmission

• Sexually transmitted infection (STI)

Important Feature

❌ No cyst stage

It exists only as a trophozoite.

Symptoms (Women)

• Frothy yellow-green discharge

• Vaginal itching

• Pain with urination

• “Strawberry cervix”

Symptoms (Men)

Often no symptoms, but can cause urethritis.

Diagnosis

Motile trophozoites seen under a microscope or NAAT testing.

Memory Trick

💕 Trichomonas = Sexually transmitted + no cyst

🦟 Plasmodium

Maleria

Vector

🦟 Female Anopheles mosquito

Intermediate Host

👤 Human (asexual reproduction)

Definitive Host

🦟 Mosquito (sexual reproduction)

Full Life Cycle (Know This!)

Step 1

Mosquito bites a human and injects sporozoites.

⬇

Step 2

Sporozoites travel to the liver.

⬇

Step 3

In the liver, they multiply and become merozoites.

⬇

Step 4

Merozoites leave the liver and infect red blood cells.

⬇

Step 5

Inside red blood cells, they multiply and cause the cells to rupture.

This causes:

• Fever

• Chills

• Sweating

⬇

Step 6

Some parasites become gametocytes.

⬇

Step 7

Another mosquito bites the infected person and ingests gametocytes.

⬇

Step 8

Inside the mosquito:

• Gametocytes mature into male and female gametes.

• Fertilization occurs.

• New sporozoites develop.

• They migrate to the mosquito’s salivary glands.

The cycle repeats.

Sporozoite

• Infective stage to humans

• Injected by mosquito

• Travels to the liver

Merozoite

• Leaves the liver

• Infects red blood cells

Gametocyte

• Picked up by mosquito

• Leads to sexual reproduction in the mosquito

human genetic response to malaria

Sickle cell

🐱 Toxoplasma gondii

Toxoplasmosis

Definitive Host

🐱 Cats

Intermediate Hosts

• Humans

• Birds

• Many mammals

Transmission

• Cat feces (oocysts)

• Undercooked meat (tissue cysts)

• Mother to fetus during pregnancy (congenital transmission)

Symptoms

Most healthy people have mild or no symptoms.

Immunocompromised patients may develop:

• Encephalitis

• Seizures

• Brain abscesses

Congenital infection can cause:

• Blindness

• Hydrocephalus

• Intracranial calcifications

Memory Trick

🐱 Cats = Toxoplasma