introduction to parasitology and amoebas

Question 1

overview of microbes

Answer 1

1. Bacteria
   ● Unicellular
   ● Prokaryotes
   ● Lack a nuclear membrane and a true nucleus, mitochondria, an endoplasmic reticulum, and Golgi bodies
   ● DNA is suspended in the cytoplasm
2. Fungi
   ● Heterotrophic
   ● Eukaryotes
   ● Most are multicellular, and many can reproduce sexually and asexually
   ● Molds
   ● Yeast
3. Virus
   ● Acellular
   ● Consist of DNA or RNA and rarely both
   ● Require host cells for replication and metabolism
4. Parasites
   ● Some are unicellular (protozoa) and some are multicellular (metazoa)
   ● Eukaryote

Question 2

Study of parasites, organisms that live on and obtain their nutrients from another organism

Answer 2

parasitology
*Area of biology with the phenomenon of dependence of one living organism on another
[part of biology that studies how one organism depends on another.]

Question 3

a type of symbiotic relationship where the parasite benefits while the host suffers because the parasite competes for nutrients.

Answer 3

Parasitism
Symbiotic relationship – living together

Question 4

briefly explain the 2 phases of the parasitic life cycle

Answer 4

Endoparasite – inside the host:
Example: Protozoa (single-celled parasites)
They invade the body, often in the intestines, blood, or tissues.

Ectoparasite – outside:
Example: Arthropods (like fleas, ticks, and lice)
Example: Human head lice – live on the scalp and cause infestation.

Question 5

How Parasites Infect Humans

Answer 5

Parasite Contact – The parasite comes into contact with humans (e.g., through food, water, or insect bites).

Infective Stage – The parasite enters the body and finds a place to live.

Multiplication – The parasite grows and competes for nutrients inside or on the body.

Diagnostic Stage – The parasite leaves the body (e.g., through feces, urine, or skin).

Environment Stage – The parasite enters the soil, water, or another host (like an insect or animal).

💡 Example:
A person drinks contaminated water → Parasite enters intestines → Multiplies and causes illness → Leaves the body in feces → Enters the environment → Can infect another person.

Question 6

Parasite Nomenclature and Classification
Scientific Name Format:
Naming Structure:

Answer 6

Scientific Name Format:
Typewritten → Italicized
Handwritten → Underlined
In Research Papers → Can be abbreviated after the first mention (e.g., E. histolytica)

Naming Structure:
Genus (First Part)
First letter capitalized
Example: Entamoeba

Species (Second Part)
Always lowercase
Example: histolytica

Question 7

briefly explain the 3 major groups of clinically significant parasites

Answer 7

(index card)
- protozoa
- metazoa
-arthropods

Question 8

amoeba morphology and life cycle

Answer 8

index card

Life Cycle Process:
Ingestion of Cyst – Humans consume contaminated food or water.
Excystation – Cyst → Trophozoite (occurs in the small intestine).
Trophozoites Multiply – Reproduce by asexual binary fission.
Encystation – Trophozoite → Cyst (occurs in the large intestine due to harsh conditions).
Cysts Exit via Feces – Cysts survive in the environment and infect new hosts.

Question 9

Why Trophozoites Turn into Cysts?

Answer 9

Overpopulation of amoebas.
Changes in pH, food supply, or oxygen levels.
Harsh conditions force transformation into protective cysts.

Question 10

Transmission & Infection of Amoeba

Answer 10

Cysts are the main infectious stage.
Spread through contaminated food, water, or surfaces.
Trophozoites do not usually transmit because they are easily destroyed

[Trophozoites (active form of amoebas) die quickly outside the host because they are delicate.
Cysts, on the other hand, have a protective wall, so they can survive outside for a long time.]

Question 11

Prevention & Treatment of Amoeba

Answer 11

Drink clean, filtered water and eat hygienic food.
Proper sanitation and handwashing = prevent infections.
Meds: metronidazole to treat infections.

Question 12

what are the forms found in the specimen used in lab diagnosis of amoebas

Answer 12

✔ Specimen Used: Stool Sample
✔ Forms Found:
Trophozoites (Active Stage): Found in soft, loose, or liquid stool
Cysts (Dormant Stage): Found in formed stool

Question 13

what are the microscopic identification and techniques used in lab diagnosis of amoebas

Answer 13

✔ Microscopic Identification:
Size Determination → Measured using an ocular micrometer
Nuclear Characteristics → Number, shape, and positioning of nuclei
Cytoplasmic Inclusions → Observing structures inside the cytoplasm
Motility → Only trophozoites show movement

✔ Microscopic Techniques:
Saline Wet Preparation → Helps observe trophozoite motility
Iodine Wet Preparation → Enhances visibility of internal structures
Permanent Stain → Confirms diagnosis, but may cause shrinkage

Question 14

Asymptomatic Infections vs Symptomatic Infections

Answer 14

🔹 Asymptomatic Infections → Many infected people show no symptoms
🔹 Symptomatic Infections → Often present as diarrhea without a clear cause

• it spreads through
  ✔ Contaminated food or water
  ✔ Poor sanitation & crowded environments increase risk
  ✔ Common in underdeveloped countries & travelers

Question 15

Pathogenic vs. Nonpathogenic Amoebas

Answer 15

✔ Nonpathogenic Amoebas → Suggest contaminated food/water intake
✔ Pathogenic Amoebas → Can cause diseases (Only E. histolytica is a universal pathogen)

Question 16

Extraintestinal Infections (Beyond the intestines)

Answer 16

mouth
eye
brain

Question 17

what are the 2 classifications of Amoeba

Answer 17

1.Intestinal Amoebas
- Affect the Digestive System

2. Extraintestinal Amoebas
   - Infect Other Parts of the Body

Question 18

who named Entamoeba histolytica

Answer 18

Fritz Schaudinn
“Histo-“ (tissue) + “-lytica” (destruction) = “tissue-destroying”

Question 19

Why Does E. histolytica Ingest RBCs?

Answer 19

E. histolytica is pathogenic (causes disease) and feeds on red blood cells (RBCs).
This helps it survive and multiply inside the human intestine.

Question 20

difference between Entamoeba histolytica Trophozoites and Entamoeba hartmanni Trophozoites

Answer 20

Size → E. histolytica is bigger, E. hartmanni is smaller.
Motility → E. histolytica moves fast and directional, E. hartmanni moves slow and random.
Inclusions → E. histolytica can have ingested RBCs, while E. hartmanni may have ingested bacteria but never RBCs.
Pathogenicity → E. histolytica causes disease, E. hartmanni is harmless.

Question 21

difference between Entamoeba histolytica Cyst and Entamoeba hartmanni Cyst

Answer 21

Size is the most reliable feature → E. histolytica cysts are larger than E. hartmanni cysts.

E. histolytica cysts are pathogenic, while E. hartmanni cysts are harmless.

E. hartmanni cysts often have round-ended chromatoid bars and diffuse glycogen mass.
[E. histolytica → Cigar-shaped, longer, with sharper ends.
E. hartmanni → Rounded ends, shorter, less distinct.]

Question 22

What Do Pseudopods Look Like in
- Entamoeba histolytica
- Entamoeba hartmanni

Answer 22

In Entamoeba histolytica:
Long, slender, and finger-like pseudopods
Unidirectional movement (moves in one main direction)

In Entamoeba hartmanni:
Shorter, less defined pseudopods
Nonprogressive movement (does not move in one clear direction)

Question 23

Why Does Entamoeba Ingest Bacteria?

Answer 23

Food Source – Bacteria provide nutrients that E. coli needs to survive and grow.
Saprophytic Lifestyle – Unlike E. histolytica, which eats red blood cells, E. coli only consumes debris and bacteria, making it harmless to humans.
Digestive Process – E. coli engulfs bacteria using its pseudopodia (extensions of its body) and digests them inside vacuoles (small sacs in its cytoplasm).

Question 24

distinctive features of each

Answer 24

Entamoeba histolytica
Ingests RBCs, causes dysentery, 4 nuclei cyst, cigar-shaped chromatoid bars

Entamoeba hartmanni
Smaller than E. histolytica, non-pathogenic, rounded chromatoid bars

Entamoeba coli
Up to 8 nuclei in cyst, splintered chromatoid bars, sluggish movement

Entamoeba polecki
1 nucleus in cyst, angular chromatoid bars, often found in pigs

Endolimax nana
Blot-like karyosome, 4 nuclei cyst, no chromatoid bars, smallest amoeba

Iodamoeba butschlii
Large glycogen mass in cyst, 1 nucleus, vacuolated cytoplasm

Entamoeba gingivalis
No cyst stage, ingests WBCs, found in mouth (associated with poor oral hygiene)

Naegleria fowleri
Brain-eating amoeba, flagellated stage, causes fatal meningoencephalitis

Acanthamoeba
Eye & brain infections, double-walled cyst, spiny pseudopods

Question 25

life cycle of parasites

Answer 25

Ingestion of Cyst: Infection begins when a person swallows an infective cyst. Excystation in the Small Intestine: The cyst opens, releasing eight motile trophozoites due to nuclear division. Colonization in the Large Intestine: Trophozoites settle in the lumen of the large intestine, multiply by binary fission, and feed on host cells. Possible Organ Migration: Some trophozoites move to other organs, like the liver, where they may cause abscesses. If trophozoites do not return to the intestine, their life cycle ends, and diagnosis must rely on serologic (blood) tests. Formation and Excretion of Cysts: Encystation (Cyst Formation): Trophozoites transform into cysts inside the intestine. A mature cyst has four nuclei and is ready to be excreted. Cysts in the Environment: Infective cysts are excreted in feces and survive for up to a month in contaminated environments. They are resistant to harsh conditions. Trophozoites vs. Cysts in Stool Samples: Trophozoites appear in liquid or semi-formed stools (when digestion is fast). Cysts appear in normal stools (when digestion is regular).

Question 26

life cycle of Entamoeba gingivalis

Answer 26

Habitat & Spread: E. gingivalis is commonly found around the gum line, in tartar, and in gingival pockets, especially in unhealthy mouths. It can also inhabit the tonsillar crypts and bronchial mucus. E. gingivalis may be found in the sputum and lung abscesses, making it important to differentiate from E. histolytica, which can also be present in these samples. Surprisingly, it can be present even in individuals with good oral hygiene. Life Cycle & Reproduction: E. gingivalis is a scavenger, feeding on dead and disintegrated cells. It multiplies through binary fission (simple cell division). No cyst stage exists, meaning it cannot survive outside the host for long. Survival & Transmission: E. gingivalis cannot survive stomach acid, so it does not spread through ingestion like other amoebas. It has been recovered from vaginal and cervical samples of women using intrauterine devices (IUDs). The parasite often disappears after IUD removal, suggesting a temporary colonization.

Question 27

life cycle of Naegleria fowleri

Answer 27

Life Cycle & Transformation: The ameboid trophozoites reproduce by binary fission (simple cell division). In water, they can temporarily transform into flagellate trophozoites, but these do not divide. The cyst stage is only found in the environment, allowing survival in harsh conditions. The full life cycle (trophozoites ↔ flagellates ↔ cysts) only occurs outside the human body. Infection & Transmission: Main source: Contaminated water, especially warm freshwater lakes, hot springs, and poorly maintained pools. Enters the body through the nasal mucosa when swimming or diving. Travels to the brain, causing rapid tissue destruction and a fatal condition called primary amebic meningoencephalitis (PAM). Rarely, infection may occur by inhaling dust contaminated with N. fowleri.

Question 28

Forms of Naegleria fowleri and Acanthamoeba

Answer 28

Forms of Naegleria fowleri: Ameboid trophozoites (only form found in humans, responsible for infection). Flagellate trophozoites (temporary form in water, does not reproduce). Cysts (exist only in the environment, not in the human body). Forms of Acanthamoeba: 1. Trophozoites (active form, responsible for infection). 2. Cysts (dormant form, survives in harsh conditions). Can switch between these two forms in the external environment.

Question 29

how is Acanthamoeba different from Naegleria fowleri

Answer 29

🚫 Acanthamoeba is not linked to swimming in dirty water like N. fowleri. 🐌 It causes slower infections, while N. fowleri acts fast and is often deadly. 🦠 There are 10 types of Acanthamoeba that can infect humans, but Acanthamoeba castellanii is the most common cause of brain and eye infections.

Question 30

life cycle of Acanthamoeba

Answer 30

Respiratory or Skin Entry (CNS Infection Route): Inhalation of dust or aspiration of contaminated material brings Acanthamoeba into the body. It can also enter through skin ulcers or wounds. Once inside, the parasite spreads via the bloodstream (hematogenous spread) to the brain, leading to severe CNS infections. Direct Eye Entry (Eye Infection Route): Contact lens users who use nonsterile, homemade saline solutions are at high risk. The parasite directly invades the cornea, causing Acanthamoeba keratitis, a painful and vision-threatening infection. Eye trauma can also allow the parasite to enter.

Question 31

briefly explain the cyst and trophozoites feeding stage

Answer 31

Trophozoites: The trophozoite is the active, feeding stage of a protozoan. It is the "live" stage where the organism is actively eating, growing, and reproducing inside its host (like your intestines). This stage is usually when the protozoa cause symptoms or infection because they are actively multiplying and feeding on nutrients.] Cysts: The cyst is the dormant, protective stage. When conditions are not favorable (like when the environment becomes dry or when the host's immune system attacks), the protozoa turn into cysts. Cysts can survive outside the host in harsh conditions and are resistant to things like dehydration. When the cysts enter a new host or favorable environment, they turn back into trophozoites to begin feeding and growing again. In simple terms, the trophozoite is the "active, hungry" form, and the cyst is the "resting, protective" form of the protozoan.

Question 32

E. hartmanni MOT INFECTIVE STAGE DIAGNOSTIC STAGE ASSOCIATED DISEASE TREATMENT PREVENTION AND CONTROL

Answer 32

not: Fecal oral route Ingestion of contaminated food or water Contact with contaminated surface Infective stage: mature cysts Diagnostic stage: both trophozoites and cysts Associated disease: Normal asymptomatic Treatment: nil Prevention and control: Good sanitation Personal hygiene practices Protection of food from vectors Same w E. nana Same w I. Butschlii (mot - contaminated hog feces)

Question 33

Life cycle of E. hartmanni

Answer 33

Host ingest mature cysts through contaminated food, water or direct contact (Those schists are highly resistant and can survive in the environment for days to weeks) Upon reaching the small intestine, excysstation occurs, release trophozoites Migrate to colon Feeds on intestinal contents without causing tissue damage When conditions become unfavorable, trophozoites undergo encystation = form protective cysts in the large intestine Both cyst and trophozoites are secreted in the feces, with cyst remaining viable in moist environment = allow transmission to new hosts

Question 34

E. coli life cycle

Answer 34

Index card

Question 35

E. coli INFECTIVE STAGE DIAGNOSTIC STAGE

Answer 35

nil it is a bacterium that multiplies directly by splitting in two, without needing special forms to infect or be detected like parasites do.

Question 36

Life cycle of E. Polecki

Answer 36

Ppt

Question 37

E. polecki EPIDEMIOLOGY MOT INFECTIVE STAGE DIAGNOSTIC STAGE ASSOCIATED DISEASE TREATMENT PREVENTION AND CONTROL

Answer 37

Southeast Asia and New Guinea Human to human Pigs to human Mature cysts through trophozoites and cysts (Lad diagnosis: stool analysis) Normally asymptomatic Only documented discomfort associated: diarrhea Combi of metronidazole (flagyl) + diloxandie furoate (furamide) Good sanitation Personal hygiene Protect food from food vectors

Question 38

E. gingivalis life cycle

Answer 38

Transes

Question 39

E. gingivalis MOT INFECTIVE AND DIAGNOSTIC STAGE LAB DIAGNOSIS ASSOCIATED DISEASE TREATMENT PREVENTION AND CONTROL

Answer 39

Mouth to mouth Droplet contamination Trophozoites Microscopic examination - mouth scraping from gingival area - tonsillar cryots and pulmonary abscess - vaginal and cervica, material Mouth and genital tract: no symptoms Recovered from patients suffering pyorrhea alveolar is Improve oral hygiene Prompt removal of IUDs in infected patients

Question 40

Naegleria Fowleri MOT INFECTIV STAGE DIAGNOSTIC STAFE LAB DOAGNOSIS ASSOCIATED DISEASE TREATMENT

Answer 40

Sniffing contaminated water Contaminated dust Trophozoites stage Trophozoites found in CSF Microscopic examination of CSF Other specimens: nasal and tissue discharge Cultured agar plate PAM, primary a,epic meningoencephalitis - smell and taste alterations -vomit - blocked nose Kernig’s sign - inability to fully straighten the leg when the hip is flexed at 90mdegrees Death occurs 3 to 6 days Amphotericin B Amphotericin B with rifampin or miconazole